From 473153aff4b978006f1c5fbc0e9032fd11061709 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Tue, 22 Apr 2014 17:27:57 +0100 Subject: PCI: Update my email address Signed-off-by: Ben Hutchings Signed-off-by: Bjorn Helgaas --- Documentation/ABI/testing/sysfs-bus-pci | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index a3c5a6685036..ab8d76dfaa80 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -117,7 +117,7 @@ Description: What: /sys/bus/pci/devices/.../vpd Date: February 2008 -Contact: Ben Hutchings +Contact: Ben Hutchings Description: A file named vpd in a device directory will be a binary file containing the Vital Product Data for the -- cgit v1.2.3-58-ga151 From 77f2ea2f8d0833f9e976368481fb9a0775acf9e7 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Wed, 30 Apr 2014 11:20:53 -0600 Subject: DMA-API: Clarify physical/bus address distinction The DMA-API documentation sometimes refers to "physical addresses" when it really means "bus addresses." Sometimes these are identical, but they may be different if the bridge leading to the bus performs address translation. Update the documentation to use "bus address" when appropriate. Also, consistently capitalize "DMA", use parens with function names, use dev_printk() in examples, and reword a few sections for clarity. No functional change; documentation changes only. Signed-off-by: Bjorn Helgaas Acked-by: Greg Kroah-Hartman Acked-by: Arnd Bergmann Acked-by: James Bottomley Acked-by: Randy Dunlap --- Documentation/DMA-API-HOWTO.txt | 192 +++++++++++++++++++++++++--------------- Documentation/DMA-API.txt | 139 +++++++++++++++-------------- Documentation/DMA-ISA-LPC.txt | 4 +- include/linux/dma-mapping.h | 6 ++ include/linux/types.h | 1 + 5 files changed, 204 insertions(+), 138 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index 5e983031cc11..fd3727b94ac2 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -9,16 +9,76 @@ This is a guide to device driver writers on how to use the DMA API with example pseudo-code. For a concise description of the API, see DMA-API.txt. -Most of the 64bit platforms have special hardware that translates bus -addresses (DMA addresses) into physical addresses. This is similar to -how page tables and/or a TLB translates virtual addresses to physical -addresses on a CPU. This is needed so that e.g. PCI devices can -access with a Single Address Cycle (32bit DMA address) any page in the -64bit physical address space. Previously in Linux those 64bit -platforms had to set artificial limits on the maximum RAM size in the -system, so that the virt_to_bus() static scheme works (the DMA address -translation tables were simply filled on bootup to map each bus -address to the physical page __pa(bus_to_virt())). + CPU and DMA addresses + +There are several kinds of addresses involved in the DMA API, and it's +important to understand the differences. + +The kernel normally uses virtual addresses. Any address returned by +kmalloc(), vmalloc(), and similar interfaces is a virtual address and can +be stored in a "void *". + +The virtual memory system (TLB, page tables, etc.) translates virtual +addresses to CPU physical addresses, which are stored as "phys_addr_t" or +"resource_size_t". The kernel manages device resources like registers as +physical addresses. These are the addresses in /proc/iomem. The physical +address is not directly useful to a driver; it must use ioremap() to map +the space and produce a virtual address. + +I/O devices use a third kind of address: a "bus address" or "DMA address". +If a device has registers at an MMIO address, or if it performs DMA to read +or write system memory, the addresses used by the device are bus addresses. +In some systems, bus addresses are identical to CPU physical addresses, but +in general they are not. IOMMUs and host bridges can produce arbitrary +mappings between physical and bus addresses. + +Here's a picture and some examples: + + CPU CPU Bus + Virtual Physical Address + Address Address Space + Space Space + + +-------+ +------+ +------+ + | | |MMIO | Offset | | + | | Virtual |Space | applied | | + C +-------+ --------> B +------+ ----------> +------+ A + | | mapping | | by host | | + +-----+ | | | | bridge | | +--------+ + | | | | +------+ | | | | + | CPU | | | | RAM | | | | Device | + | | | | | | | | | | + +-----+ +-------+ +------+ +------+ +--------+ + | | Virtual |Buffer| Mapping | | + X +-------+ --------> Y +------+ <---------- +------+ Z + | | mapping | RAM | by IOMMU + | | | | + | | | | + +-------+ +------+ + +During the enumeration process, the kernel learns about I/O devices and +their MMIO space and the host bridges that connect them to the system. For +example, if a PCI device has a BAR, the kernel reads the bus address (A) +from the BAR and converts it to a CPU physical address (B). The address B +is stored in a struct resource and usually exposed via /proc/iomem. When a +driver claims a device, it typically uses ioremap() to map physical address +B at a virtual address (C). It can then use, e.g., ioread32(C), to access +the device registers at bus address A. + +If the device supports DMA, the driver sets up a buffer using kmalloc() or +a similar interface, which returns a virtual address (X). The virtual +memory system maps X to a physical address (Y) in system RAM. The driver +can use virtual address X to access the buffer, but the device itself +cannot because DMA doesn't go through the CPU virtual memory system. + +In some simple systems, the device can do DMA directly to physical address +Y. But in many others, there is IOMMU hardware that translates bus +addresses to physical addresses, e.g., it translates Z to Y. This is part +of the reason for the DMA API: the driver can give a virtual address X to +an interface like dma_map_single(), which sets up any required IOMMU +mapping and returns the bus address Z. The driver then tells the device to +do DMA to Z, and the IOMMU maps it to the buffer at address Y in system +RAM. So that Linux can use the dynamic DMA mapping, it needs some help from the drivers, namely it has to take into account that DMA addresses should be @@ -29,17 +89,17 @@ The following API will work of course even on platforms where no such hardware exists. Note that the DMA API works with any bus independent of the underlying -microprocessor architecture. You should use the DMA API rather than -the bus specific DMA API (e.g. pci_dma_*). +microprocessor architecture. You should use the DMA API rather than the +bus-specific DMA API, i.e., use the dma_map_*() interfaces rather than the +pci_map_*() interfaces. First of all, you should make sure #include -is in your driver. This file will obtain for you the definition of the -dma_addr_t (which can hold any valid DMA address for the platform) -type which should be used everywhere you hold a DMA (bus) address -returned from the DMA mapping functions. +is in your driver, which provides the definition of dma_addr_t. This type +can hold any valid DMA or bus address for the platform and should be used +everywhere you hold a DMA address returned from the DMA mapping functions. What memory is DMA'able? @@ -123,9 +183,9 @@ Here, dev is a pointer to the device struct of your device, and mask is a bit mask describing which bits of an address your device supports. It returns zero if your card can perform DMA properly on the machine given the address mask you provided. In general, the -device struct of your device is embedded in the bus specific device -struct of your device. For example, a pointer to the device struct of -your PCI device is pdev->dev (pdev is a pointer to the PCI device +device struct of your device is embedded in the bus-specific device +struct of your device. For example, &pdev->dev is a pointer to the +device struct of a PCI device (pdev is a pointer to the PCI device struct of your device). If it returns non-zero, your device cannot perform DMA properly on @@ -147,8 +207,7 @@ exactly why. The standard 32-bit addressing device would do something like this: if (dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32))) { - printk(KERN_WARNING - "mydev: No suitable DMA available.\n"); + dev_warn(dev, "mydev: No suitable DMA available\n"); goto ignore_this_device; } @@ -170,8 +229,7 @@ all 64-bits when accessing streaming DMA: } else if (!dma_set_mask(dev, DMA_BIT_MASK(32))) { using_dac = 0; } else { - printk(KERN_WARNING - "mydev: No suitable DMA available.\n"); + dev_warn(dev, "mydev: No suitable DMA available\n"); goto ignore_this_device; } @@ -187,8 +245,7 @@ the case would look like this: using_dac = 0; consistent_using_dac = 0; } else { - printk(KERN_WARNING - "mydev: No suitable DMA available.\n"); + dev_warn(dev, "mydev: No suitable DMA available\n"); goto ignore_this_device; } @@ -201,8 +258,7 @@ Finally, if your device can only drive the low 24-bits of address you might do something like: if (dma_set_mask(dev, DMA_BIT_MASK(24))) { - printk(KERN_WARNING - "mydev: 24-bit DMA addressing not available.\n"); + dev_warn(dev, "mydev: 24-bit DMA addressing not available\n"); goto ignore_this_device; } @@ -232,14 +288,14 @@ Here is pseudo-code showing how this might be done: card->playback_enabled = 1; } else { card->playback_enabled = 0; - printk(KERN_WARNING "%s: Playback disabled due to DMA limitations.\n", + dev_warn(dev, "%s: Playback disabled due to DMA limitations\n", card->name); } if (!dma_set_mask(dev, RECORD_ADDRESS_BITS)) { card->record_enabled = 1; } else { card->record_enabled = 0; - printk(KERN_WARNING "%s: Record disabled due to DMA limitations.\n", + dev_warn(dev, "%s: Record disabled due to DMA limitations\n", card->name); } @@ -331,7 +387,7 @@ context with the GFP_ATOMIC flag. Size is the length of the region you want to allocate, in bytes. This routine will allocate RAM for that region, so it acts similarly to -__get_free_pages (but takes size instead of a page order). If your +__get_free_pages() (but takes size instead of a page order). If your driver needs regions sized smaller than a page, you may prefer using the dma_pool interface, described below. @@ -343,11 +399,11 @@ the consistent DMA mask has been explicitly changed via dma_set_coherent_mask(). This is true of the dma_pool interface as well. -dma_alloc_coherent returns two values: the virtual address which you +dma_alloc_coherent() returns two values: the virtual address which you can use to access it from the CPU and dma_handle which you pass to the card. -The cpu return address and the DMA bus master address are both +The CPU virtual address and the DMA bus address are both guaranteed to be aligned to the smallest PAGE_SIZE order which is greater than or equal to the requested size. This invariant exists (for example) to guarantee that if you allocate a chunk @@ -359,13 +415,13 @@ To unmap and free such a DMA region, you call: dma_free_coherent(dev, size, cpu_addr, dma_handle); where dev, size are the same as in the above call and cpu_addr and -dma_handle are the values dma_alloc_coherent returned to you. +dma_handle are the values dma_alloc_coherent() returned to you. This function may not be called in interrupt context. If your driver needs lots of smaller memory regions, you can write -custom code to subdivide pages returned by dma_alloc_coherent, +custom code to subdivide pages returned by dma_alloc_coherent(), or you can use the dma_pool API to do that. A dma_pool is like -a kmem_cache, but it uses dma_alloc_coherent not __get_free_pages. +a kmem_cache, but it uses dma_alloc_coherent(), not __get_free_pages(). Also, it understands common hardware constraints for alignment, like queue heads needing to be aligned on N byte boundaries. @@ -381,29 +437,29 @@ type of data is "align" (which is expressed in bytes, and must be a power of two). If your device has no boundary crossing restrictions, pass 0 for alloc; passing 4096 says memory allocated from this pool must not cross 4KByte boundaries (but at that time it may be better to -go for dma_alloc_coherent directly instead). +use dma_alloc_coherent() directly instead). -Allocate memory from a dma pool like this: +Allocate memory from a DMA pool like this: cpu_addr = dma_pool_alloc(pool, flags, &dma_handle); flags are SLAB_KERNEL if blocking is permitted (not in_interrupt nor -holding SMP locks), SLAB_ATOMIC otherwise. Like dma_alloc_coherent, +holding SMP locks), SLAB_ATOMIC otherwise. Like dma_alloc_coherent(), this returns two values, cpu_addr and dma_handle. Free memory that was allocated from a dma_pool like this: dma_pool_free(pool, cpu_addr, dma_handle); -where pool is what you passed to dma_pool_alloc, and cpu_addr and -dma_handle are the values dma_pool_alloc returned. This function +where pool is what you passed to dma_pool_alloc(), and cpu_addr and +dma_handle are the values dma_pool_alloc() returned. This function may be called in interrupt context. Destroy a dma_pool by calling: dma_pool_destroy(pool); -Make sure you've called dma_pool_free for all memory allocated +Make sure you've called dma_pool_free() for all memory allocated from a pool before you destroy the pool. This function may not be called in interrupt context. @@ -418,7 +474,7 @@ one of the following values: DMA_FROM_DEVICE DMA_NONE -One should provide the exact DMA direction if you know it. +You should provide the exact DMA direction if you know it. DMA_TO_DEVICE means "from main memory to the device" DMA_FROM_DEVICE means "from the device to main memory" @@ -489,14 +545,14 @@ and to unmap it: dma_unmap_single(dev, dma_handle, size, direction); You should call dma_mapping_error() as dma_map_single() could fail and return -error. Not all dma implementations support dma_mapping_error() interface. +error. Not all DMA implementations support the dma_mapping_error() interface. However, it is a good practice to call dma_mapping_error() interface, which will invoke the generic mapping error check interface. Doing so will ensure -that the mapping code will work correctly on all dma implementations without +that the mapping code will work correctly on all DMA implementations without any dependency on the specifics of the underlying implementation. Using the returned address without checking for errors could result in failures ranging from panics to silent data corruption. A couple of examples of incorrect ways -to check for errors that make assumptions about the underlying dma +to check for errors that make assumptions about the underlying DMA implementation are as follows and these are applicable to dma_map_page() as well. @@ -516,12 +572,12 @@ Incorrect example 2: goto map_error; } -You should call dma_unmap_single when the DMA activity is finished, e.g. +You should call dma_unmap_single() when the DMA activity is finished, e.g., from the interrupt which told you that the DMA transfer is done. -Using cpu pointers like this for single mappings has a disadvantage, +Using cpu pointers like this for single mappings has a disadvantage: you cannot reference HIGHMEM memory in this way. Thus, there is a -map/unmap interface pair akin to dma_{map,unmap}_single. These +map/unmap interface pair akin to dma_{map,unmap}_single(). These interfaces deal with page/offset pairs instead of cpu pointers. Specifically: @@ -550,7 +606,7 @@ Here, "offset" means byte offset within the given page. You should call dma_mapping_error() as dma_map_page() could fail and return error as outlined under the dma_map_single() discussion. -You should call dma_unmap_page when the DMA activity is finished, e.g. +You should call dma_unmap_page() when the DMA activity is finished, e.g., from the interrupt which told you that the DMA transfer is done. With scatterlists, you map a region gathered from several regions by: @@ -588,18 +644,16 @@ PLEASE NOTE: The 'nents' argument to the dma_unmap_sg call must be it should _NOT_ be the 'count' value _returned_ from the dma_map_sg call. -Every dma_map_{single,sg} call should have its dma_unmap_{single,sg} -counterpart, because the bus address space is a shared resource (although -in some ports the mapping is per each BUS so less devices contend for the -same bus address space) and you could render the machine unusable by eating -all bus addresses. +Every dma_map_{single,sg}() call should have its dma_unmap_{single,sg}() +counterpart, because the bus address space is a shared resource and +you could render the machine unusable by consuming all bus addresses. If you need to use the same streaming DMA region multiple times and touch the data in between the DMA transfers, the buffer needs to be synced -properly in order for the cpu and device to see the most uptodate and +properly in order for the cpu and device to see the most up-to-date and correct copy of the DMA buffer. -So, firstly, just map it with dma_map_{single,sg}, and after each DMA +So, firstly, just map it with dma_map_{single,sg}(), and after each DMA transfer call either: dma_sync_single_for_cpu(dev, dma_handle, size, direction); @@ -623,9 +677,9 @@ or: as appropriate. After the last DMA transfer call one of the DMA unmap routines -dma_unmap_{single,sg}. If you don't touch the data from the first dma_map_* -call till dma_unmap_*, then you don't have to call the dma_sync_* -routines at all. +dma_unmap_{single,sg}(). If you don't touch the data from the first +dma_map_*() call till dma_unmap_*(), then you don't have to call the +dma_sync_*() routines at all. Here is pseudo code which shows a situation in which you would need to use the dma_sync_*() interfaces. @@ -690,12 +744,12 @@ to use the dma_sync_*() interfaces. } } -Drivers converted fully to this interface should not use virt_to_bus any -longer, nor should they use bus_to_virt. Some drivers have to be changed a -little bit, because there is no longer an equivalent to bus_to_virt in the +Drivers converted fully to this interface should not use virt_to_bus() any +longer, nor should they use bus_to_virt(). Some drivers have to be changed a +little bit, because there is no longer an equivalent to bus_to_virt() in the dynamic DMA mapping scheme - you have to always store the DMA addresses -returned by the dma_alloc_coherent, dma_pool_alloc, and dma_map_single -calls (dma_map_sg stores them in the scatterlist itself if the platform +returned by the dma_alloc_coherent(), dma_pool_alloc(), and dma_map_single() +calls (dma_map_sg() stores them in the scatterlist itself if the platform supports dynamic DMA mapping in hardware) in your driver structures and/or in the card registers. @@ -709,9 +763,9 @@ as it is impossible to correctly support them. DMA address space is limited on some architectures and an allocation failure can be determined by: -- checking if dma_alloc_coherent returns NULL or dma_map_sg returns 0 +- checking if dma_alloc_coherent() returns NULL or dma_map_sg returns 0 -- checking the returned dma_addr_t of dma_map_single and dma_map_page +- checking the dma_addr_t returned from dma_map_single() and dma_map_page() by using dma_mapping_error(): dma_addr_t dma_handle; @@ -794,7 +848,7 @@ Example 2: (if buffers are allocated in a loop, unmap all mapped buffers when dma_unmap_single(array[i].dma_addr); } -Networking drivers must call dev_kfree_skb to free the socket buffer +Networking drivers must call dev_kfree_skb() to free the socket buffer and return NETDEV_TX_OK if the DMA mapping fails on the transmit hook (ndo_start_xmit). This means that the socket buffer is just dropped in the failure case. @@ -831,7 +885,7 @@ transform some example code. DEFINE_DMA_UNMAP_LEN(len); }; -2) Use dma_unmap_{addr,len}_set to set these values. +2) Use dma_unmap_{addr,len}_set() to set these values. Example, before: ringp->mapping = FOO; @@ -842,7 +896,7 @@ transform some example code. dma_unmap_addr_set(ringp, mapping, FOO); dma_unmap_len_set(ringp, len, BAR); -3) Use dma_unmap_{addr,len} to access these values. +3) Use dma_unmap_{addr,len}() to access these values. Example, before: dma_unmap_single(dev, ringp->mapping, ringp->len, diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index e865279cec58..1147eba43128 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -4,22 +4,26 @@ James E.J. Bottomley This document describes the DMA API. For a more gentle introduction -of the API (and actual examples) see -Documentation/DMA-API-HOWTO.txt. +of the API (and actual examples), see Documentation/DMA-API-HOWTO.txt. -This API is split into two pieces. Part I describes the API. Part II -describes the extensions to the API for supporting non-consistent -memory machines. Unless you know that your driver absolutely has to -support non-consistent platforms (this is usually only legacy -platforms) you should only use the API described in part I. +This API is split into two pieces. Part I describes the basic API. +Part II describes extensions for supporting non-consistent memory +machines. Unless you know that your driver absolutely has to support +non-consistent platforms (this is usually only legacy platforms) you +should only use the API described in part I. Part I - dma_ API ------------------------------------- -To get the dma_ API, you must #include +To get the dma_ API, you must #include . This +provides dma_addr_t and the interfaces described below. +A dma_addr_t can hold any valid DMA or bus address for the platform. It +can be given to a device to use as a DMA source or target. A cpu cannot +reference a dma_addr_t directly because there may be translation between +its physical address space and the bus address space. -Part Ia - Using large dma-coherent buffers +Part Ia - Using large DMA-coherent buffers ------------------------------------------ void * @@ -33,20 +37,21 @@ to make sure to flush the processor's write buffers before telling devices to read that memory.) This routine allocates a region of bytes of consistent memory. -It also returns a which may be cast to an unsigned -integer the same width as the bus and used as the physical address -base of the region. -Returns: a pointer to the allocated region (in the processor's virtual +It returns a pointer to the allocated region (in the processor's virtual address space) or NULL if the allocation failed. +It also returns a which may be cast to an unsigned integer the +same width as the bus and given to the device as the bus address base of +the region. + Note: consistent memory can be expensive on some platforms, and the minimum allocation length may be as big as a page, so you should consolidate your requests for consistent memory as much as possible. The simplest way to do that is to use the dma_pool calls (see below). -The flag parameter (dma_alloc_coherent only) allows the caller to -specify the GFP_ flags (see kmalloc) for the allocation (the +The flag parameter (dma_alloc_coherent() only) allows the caller to +specify the GFP_ flags (see kmalloc()) for the allocation (the implementation may choose to ignore flags that affect the location of the returned memory, like GFP_DMA). @@ -61,24 +66,24 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle) -Free the region of consistent memory you previously allocated. dev, -size and dma_handle must all be the same as those passed into the -consistent allocate. cpu_addr must be the virtual address returned by -the consistent allocate. +Free a region of consistent memory you previously allocated. dev, +size and dma_handle must all be the same as those passed into +dma_alloc_coherent(). cpu_addr must be the virtual address returned by +the dma_alloc_coherent(). Note that unlike their sibling allocation calls, these routines may only be called with IRQs enabled. -Part Ib - Using small dma-coherent buffers +Part Ib - Using small DMA-coherent buffers ------------------------------------------ To get this part of the dma_ API, you must #include -Many drivers need lots of small dma-coherent memory regions for DMA +Many drivers need lots of small DMA-coherent memory regions for DMA descriptors or I/O buffers. Rather than allocating in units of a page or more using dma_alloc_coherent(), you can use DMA pools. These work -much like a struct kmem_cache, except that they use the dma-coherent allocator, +much like a struct kmem_cache, except that they use the DMA-coherent allocator, not __get_free_pages(). Also, they understand common hardware constraints for alignment, like queue heads needing to be aligned on N-byte boundaries. @@ -87,7 +92,7 @@ for alignment, like queue heads needing to be aligned on N-byte boundaries. dma_pool_create(const char *name, struct device *dev, size_t size, size_t align, size_t alloc); -The pool create() routines initialize a pool of dma-coherent buffers +dma_pool_create() initializes a pool of DMA-coherent buffers for use with a given device. It must be called in a context which can sleep. @@ -102,25 +107,26 @@ from this pool must not cross 4KByte boundaries. void *dma_pool_alloc(struct dma_pool *pool, gfp_t gfp_flags, dma_addr_t *dma_handle); -This allocates memory from the pool; the returned memory will meet the size -and alignment requirements specified at creation time. Pass GFP_ATOMIC to -prevent blocking, or if it's permitted (not in_interrupt, not holding SMP locks), -pass GFP_KERNEL to allow blocking. Like dma_alloc_coherent(), this returns -two values: an address usable by the cpu, and the dma address usable by the -pool's device. +This allocates memory from the pool; the returned memory will meet the +size and alignment requirements specified at creation time. Pass +GFP_ATOMIC to prevent blocking, or if it's permitted (not +in_interrupt, not holding SMP locks), pass GFP_KERNEL to allow +blocking. Like dma_alloc_coherent(), this returns two values: an +address usable by the cpu, and the DMA address usable by the pool's +device. void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t addr); This puts memory back into the pool. The pool is what was passed to -the pool allocation routine; the cpu (vaddr) and dma addresses are what +dma_pool_alloc(); the cpu (vaddr) and DMA addresses are what were returned when that routine allocated the memory being freed. void dma_pool_destroy(struct dma_pool *pool); -The pool destroy() routines free the resources of the pool. They must be +dma_pool_destroy() frees the resources of the pool. It must be called in a context which can sleep. Make sure you've freed all allocated memory back to the pool before you destroy it. @@ -187,9 +193,9 @@ dma_map_single(struct device *dev, void *cpu_addr, size_t size, enum dma_data_direction direction) Maps a piece of processor virtual memory so it can be accessed by the -device and returns the physical handle of the memory. +device and returns the bus address of the memory. -The direction for both api's may be converted freely by casting. +The direction for both APIs may be converted freely by casting. However the dma_ API uses a strongly typed enumerator for its direction: @@ -198,31 +204,30 @@ DMA_TO_DEVICE data is going from the memory to the device DMA_FROM_DEVICE data is coming from the device to the memory DMA_BIDIRECTIONAL direction isn't known -Notes: Not all memory regions in a machine can be mapped by this -API. Further, regions that appear to be physically contiguous in -kernel virtual space may not be contiguous as physical memory. Since -this API does not provide any scatter/gather capability, it will fail -if the user tries to map a non-physically contiguous piece of memory. -For this reason, it is recommended that memory mapped by this API be -obtained only from sources which guarantee it to be physically contiguous -(like kmalloc). - -Further, the physical address of the memory must be within the -dma_mask of the device (the dma_mask represents a bit mask of the -addressable region for the device. I.e., if the physical address of -the memory anded with the dma_mask is still equal to the physical -address, then the device can perform DMA to the memory). In order to +Notes: Not all memory regions in a machine can be mapped by this API. +Further, contiguous kernel virtual space may not be contiguous as +physical memory. Since this API does not provide any scatter/gather +capability, it will fail if the user tries to map a non-physically +contiguous piece of memory. For this reason, memory to be mapped by +this API should be obtained from sources which guarantee it to be +physically contiguous (like kmalloc). + +Further, the bus address of the memory must be within the +dma_mask of the device (the dma_mask is a bit mask of the +addressable region for the device, i.e., if the bus address of +the memory ANDed with the dma_mask is still equal to the bus +address, then the device can perform DMA to the memory). To ensure that the memory allocated by kmalloc is within the dma_mask, the driver may specify various platform-dependent flags to restrict -the physical memory range of the allocation (e.g. on x86, GFP_DMA -guarantees to be within the first 16Mb of available physical memory, +the bus address range of the allocation (e.g., on x86, GFP_DMA +guarantees to be within the first 16MB of available bus addresses, as required by ISA devices). Note also that the above constraints on physical contiguity and dma_mask may not apply if the platform has an IOMMU (a device which -supplies a physical to virtual mapping between the I/O memory bus and -the device). However, to be portable, device driver writers may *not* -assume that such an IOMMU exists. +maps an I/O bus address to a physical memory address). However, to be +portable, device driver writers may *not* assume that such an IOMMU +exists. Warnings: Memory coherency operates at a granularity called the cache line width. In order for memory mapped by this API to operate @@ -281,9 +286,9 @@ cache width is. int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) -In some circumstances dma_map_single and dma_map_page will fail to create +In some circumstances dma_map_single() and dma_map_page() will fail to create a mapping. A driver can check for these errors by testing the returned -dma address with dma_mapping_error(). A non-zero return value means the mapping +DMA address with dma_mapping_error(). A non-zero return value means the mapping could not be created and the driver should take appropriate action (e.g. reduce current DMA mapping usage or delay and try again later). @@ -291,7 +296,7 @@ reduce current DMA mapping usage or delay and try again later). dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction direction) -Returns: the number of physical segments mapped (this may be shorter +Returns: the number of bus address segments mapped (this may be shorter than passed in if some elements of the scatter/gather list are physically or virtually adjacent and an IOMMU maps them with a single entry). @@ -299,7 +304,7 @@ entry). Please note that the sg cannot be mapped again if it has been mapped once. The mapping process is allowed to destroy information in the sg. -As with the other mapping interfaces, dma_map_sg can fail. When it +As with the other mapping interfaces, dma_map_sg() can fail. When it does, 0 is returned and a driver must take appropriate action. It is critical that the driver do something, in the case of a block driver aborting the request or even oopsing is better than doing nothing and @@ -335,7 +340,7 @@ must be the same as those and passed in to the scatter/gather mapping API. Note: must be the number you passed in, *not* the number of -physical entries returned. +bus address entries returned. void dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size, @@ -391,10 +396,10 @@ The four functions above are just like the counterpart functions without the _attrs suffixes, except that they pass an optional struct dma_attrs*. -struct dma_attrs encapsulates a set of "dma attributes". For the +struct dma_attrs encapsulates a set of "DMA attributes". For the definition of struct dma_attrs see linux/dma-attrs.h. -The interpretation of dma attributes is architecture-specific, and +The interpretation of DMA attributes is architecture-specific, and each attribute should be documented in Documentation/DMA-attributes.txt. If struct dma_attrs* is NULL, the semantics of each of these @@ -458,7 +463,7 @@ Note: where the platform can return consistent memory, it will guarantee that the sync points become nops. Warning: Handling non-consistent memory is a real pain. You should -only ever use this API if you positively know your driver will be +only use this API if you positively know your driver will be required to work on one of the rare (usually non-PCI) architectures that simply cannot make consistent memory. @@ -496,26 +501,26 @@ dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, dma_addr_t device_addr, size_t size, int flags) -Declare region of memory to be handed out by dma_alloc_coherent when +Declare region of memory to be handed out by dma_alloc_coherent() when it's asked for coherent memory for this device. bus_addr is the physical address to which the memory is currently assigned in the bus responding region (this will be used by the platform to perform the mapping). -device_addr is the physical address the device needs to be programmed +device_addr is the bus address the device needs to be programmed with actually to address this memory (this will be handed out as the dma_addr_t in dma_alloc_coherent()). size is the size of the area (must be multiples of PAGE_SIZE). -flags can be or'd together and are: +flags can be ORed together and are: DMA_MEMORY_MAP - request that the memory returned from dma_alloc_coherent() be directly writable. DMA_MEMORY_IO - request that the memory returned from -dma_alloc_coherent() be addressable using read/write/memcpy_toio etc. +dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc. One or both of these flags must be present. @@ -572,7 +577,7 @@ region is occupied. Part III - Debug drivers use of the DMA-API ------------------------------------------- -The DMA-API as described above as some constraints. DMA addresses must be +The DMA-API as described above has some constraints. DMA addresses must be released with the corresponding function with the same size for example. With the advent of hardware IOMMUs it becomes more and more important that drivers do not violate those constraints. In the worst case such a violation can @@ -690,11 +695,11 @@ architectural default. void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr); dma-debug interface debug_dma_mapping_error() to debug drivers that fail -to check dma mapping errors on addresses returned by dma_map_single() and +to check DMA mapping errors on addresses returned by dma_map_single() and dma_map_page() interfaces. This interface clears a flag set by debug_dma_map_page() to indicate that dma_mapping_error() has been called by the driver. When driver does unmap, debug_dma_unmap() checks the flag and if this flag is still set, prints warning message that includes call trace that leads up to the unmap. This interface can be called from dma_mapping_error() -routines to enable dma mapping error check debugging. +routines to enable DMA mapping error check debugging. diff --git a/Documentation/DMA-ISA-LPC.txt b/Documentation/DMA-ISA-LPC.txt index e767805b4182..b1a19835e907 100644 --- a/Documentation/DMA-ISA-LPC.txt +++ b/Documentation/DMA-ISA-LPC.txt @@ -16,7 +16,7 @@ To do ISA style DMA you need to include two headers: #include The first is the generic DMA API used to convert virtual addresses to -physical addresses (see Documentation/DMA-API.txt for details). +bus addresses (see Documentation/DMA-API.txt for details). The second contains the routines specific to ISA DMA transfers. Since this is not present on all platforms make sure you construct your @@ -50,7 +50,7 @@ early as possible and not release it until the driver is unloaded.) Part III - Address translation ------------------------------ -To translate the virtual address to a physical use the normal DMA +To translate the virtual address to a bus address, use the normal DMA API. Do _not_ use isa_virt_to_phys() even though it does the same thing. The reason for this is that the function isa_virt_to_phys() will require a Kconfig dependency to ISA, not just ISA_DMA_API which diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index fd4aee29ad10..b9aa2b97aab5 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -8,6 +8,12 @@ #include #include +/* + * A dma_addr_t can hold any valid DMA or bus address for the platform. + * It can be given to a device to use as a DMA source or target. A CPU cannot + * reference a dma_addr_t directly because there may be translation between + * its physical address space and the bus address space. + */ struct dma_map_ops { void* (*alloc)(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, diff --git a/include/linux/types.h b/include/linux/types.h index 4d118ba11349..a0bb7048687f 100644 --- a/include/linux/types.h +++ b/include/linux/types.h @@ -142,6 +142,7 @@ typedef unsigned long blkcnt_t; #define pgoff_t unsigned long #endif +/* A dma_addr_t can hold any valid DMA or bus address for the platform */ #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT typedef u64 dma_addr_t; #else -- cgit v1.2.3-58-ga151 From 88a984ba0795f14a3847edbd7fabe652289ea89b Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Tue, 20 May 2014 16:54:22 -0600 Subject: DMA-API: Change dma_declare_coherent_memory() CPU address to phys_addr_t dma_declare_coherent_memory() takes two addresses for a region of memory: a "bus_addr" and a "device_addr". I think the intent is that "bus_addr" is the physical address a *CPU* would use to access the region, and "device_addr" is the bus address the *device* would use to address the region. Rename "bus_addr" to "phys_addr" and change its type to phys_addr_t. Most callers already supply a phys_addr_t for this argument. The others supply a 32-bit integer (a constant, unsigned int, or __u32) and need no change. Use "unsigned long", not phys_addr_t, to hold PFNs. No functional change (this could theoretically fix a truncation in a config with 32-bit dma_addr_t and 64-bit phys_addr_t, but I don't think there are any such cases involving this code). Signed-off-by: Bjorn Helgaas Acked-by: Arnd Bergmann Acked-by: Greg Kroah-Hartman Acked-by: James Bottomley Acked-by: Randy Dunlap --- Documentation/DMA-API.txt | 9 ++++----- drivers/base/dma-coherent.c | 10 +++++----- drivers/base/dma-mapping.c | 6 +++--- include/asm-generic/dma-coherent.h | 13 +++++-------- include/linux/dma-mapping.h | 7 ++++--- 5 files changed, 21 insertions(+), 24 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 1147eba43128..4f1cdc5febd1 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -497,19 +497,18 @@ continuing on for size. Again, you *must* observe the cache line boundaries when doing this. int -dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, +dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags) Declare region of memory to be handed out by dma_alloc_coherent() when it's asked for coherent memory for this device. -bus_addr is the physical address to which the memory is currently -assigned in the bus responding region (this will be used by the -platform to perform the mapping). +phys_addr is the cpu physical address to which the memory is currently +assigned (this will be ioremapped so the cpu can access the region). device_addr is the bus address the device needs to be programmed -with actually to address this memory (this will be handed out as the +with to actually address this memory (this will be handed out as the dma_addr_t in dma_alloc_coherent()). size is the size of the area (must be multiples of PAGE_SIZE). diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c index bc256b641027..7d6e84a51424 100644 --- a/drivers/base/dma-coherent.c +++ b/drivers/base/dma-coherent.c @@ -10,13 +10,13 @@ struct dma_coherent_mem { void *virt_base; dma_addr_t device_base; - phys_addr_t pfn_base; + unsigned long pfn_base; int size; int flags; unsigned long *bitmap; }; -int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, +int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags) { void __iomem *mem_base = NULL; @@ -32,7 +32,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */ - mem_base = ioremap(bus_addr, size); + mem_base = ioremap(phys_addr, size); if (!mem_base) goto out; @@ -45,7 +45,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, dev->dma_mem->virt_base = mem_base; dev->dma_mem->device_base = device_addr; - dev->dma_mem->pfn_base = PFN_DOWN(bus_addr); + dev->dma_mem->pfn_base = PFN_DOWN(phys_addr); dev->dma_mem->size = pages; dev->dma_mem->flags = flags; @@ -208,7 +208,7 @@ int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma, *ret = -ENXIO; if (off < count && user_count <= count - off) { - unsigned pfn = mem->pfn_base + start + off; + unsigned long pfn = mem->pfn_base + start + off; *ret = remap_pfn_range(vma, vma->vm_start, pfn, user_count << PAGE_SHIFT, vma->vm_page_prot); diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index 0ce39a33b3c2..6cd08e145bfa 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -175,7 +175,7 @@ static void dmam_coherent_decl_release(struct device *dev, void *res) /** * dmam_declare_coherent_memory - Managed dma_declare_coherent_memory() * @dev: Device to declare coherent memory for - * @bus_addr: Bus address of coherent memory to be declared + * @phys_addr: Physical address of coherent memory to be declared * @device_addr: Device address of coherent memory to be declared * @size: Size of coherent memory to be declared * @flags: Flags @@ -185,7 +185,7 @@ static void dmam_coherent_decl_release(struct device *dev, void *res) * RETURNS: * 0 on success, -errno on failure. */ -int dmam_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, +int dmam_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags) { void *res; @@ -195,7 +195,7 @@ int dmam_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, if (!res) return -ENOMEM; - rc = dma_declare_coherent_memory(dev, bus_addr, device_addr, size, + rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size, flags); if (rc == 0) devres_add(dev, res); diff --git a/include/asm-generic/dma-coherent.h b/include/asm-generic/dma-coherent.h index 2be8a2dbc868..0297e5875798 100644 --- a/include/asm-generic/dma-coherent.h +++ b/include/asm-generic/dma-coherent.h @@ -16,16 +16,13 @@ int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma, * Standard interface */ #define ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY -extern int -dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, - dma_addr_t device_addr, size_t size, int flags); +int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, + dma_addr_t device_addr, size_t size, int flags); -extern void -dma_release_declared_memory(struct device *dev); +void dma_release_declared_memory(struct device *dev); -extern void * -dma_mark_declared_memory_occupied(struct device *dev, - dma_addr_t device_addr, size_t size); +void *dma_mark_declared_memory_occupied(struct device *dev, + dma_addr_t device_addr, size_t size); #else #define dma_alloc_from_coherent(dev, size, handle, ret) (0) #define dma_release_from_coherent(dev, order, vaddr) (0) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index b9aa2b97aab5..0c3eab1e39ac 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -192,7 +192,7 @@ static inline int dma_get_cache_alignment(void) #ifndef ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY static inline int -dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, +dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags) { return 0; @@ -223,13 +223,14 @@ extern void *dmam_alloc_noncoherent(struct device *dev, size_t size, extern void dmam_free_noncoherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle); #ifdef ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY -extern int dmam_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, +extern int dmam_declare_coherent_memory(struct device *dev, + phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags); extern void dmam_release_declared_memory(struct device *dev); #else /* ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY */ static inline int dmam_declare_coherent_memory(struct device *dev, - dma_addr_t bus_addr, dma_addr_t device_addr, + phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, gfp_t gfp) { return 0; -- cgit v1.2.3-58-ga151 From f311a724a79669ac0336932d0361325afdb54279 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Tue, 20 May 2014 16:56:27 -0600 Subject: DMA-API: Capitalize "CPU" consistently Sometimes we used "cpu," other times "CPU." Use "CPU" consistently. Suggested-by: Randy Dunlap Signed-off-by: Bjorn Helgaas --- Documentation/DMA-API-HOWTO.txt | 8 ++++---- Documentation/DMA-API.txt | 12 ++++++------ 2 files changed, 10 insertions(+), 10 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index fd3727b94ac2..f59955303475 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -575,10 +575,10 @@ Incorrect example 2: You should call dma_unmap_single() when the DMA activity is finished, e.g., from the interrupt which told you that the DMA transfer is done. -Using cpu pointers like this for single mappings has a disadvantage: +Using CPU pointers like this for single mappings has a disadvantage: you cannot reference HIGHMEM memory in this way. Thus, there is a map/unmap interface pair akin to dma_{map,unmap}_single(). These -interfaces deal with page/offset pairs instead of cpu pointers. +interfaces deal with page/offset pairs instead of CPU pointers. Specifically: struct device *dev = &my_dev->dev; @@ -650,7 +650,7 @@ you could render the machine unusable by consuming all bus addresses. If you need to use the same streaming DMA region multiple times and touch the data in between the DMA transfers, the buffer needs to be synced -properly in order for the cpu and device to see the most up-to-date and +properly in order for the CPU and device to see the most up-to-date and correct copy of the DMA buffer. So, firstly, just map it with dma_map_{single,sg}(), and after each DMA @@ -665,7 +665,7 @@ or: as appropriate. Then, if you wish to let the device get at the DMA area again, -finish accessing the data with the cpu, and then before actually +finish accessing the data with the CPU, and then before actually giving the buffer to the hardware call either: dma_sync_single_for_device(dev, dma_handle, size, direction); diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 4f1cdc5febd1..52088408668a 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -19,7 +19,7 @@ To get the dma_ API, you must #include . This provides dma_addr_t and the interfaces described below. A dma_addr_t can hold any valid DMA or bus address for the platform. It -can be given to a device to use as a DMA source or target. A cpu cannot +can be given to a device to use as a DMA source or target. A CPU cannot reference a dma_addr_t directly because there may be translation between its physical address space and the bus address space. @@ -112,7 +112,7 @@ size and alignment requirements specified at creation time. Pass GFP_ATOMIC to prevent blocking, or if it's permitted (not in_interrupt, not holding SMP locks), pass GFP_KERNEL to allow blocking. Like dma_alloc_coherent(), this returns two values: an -address usable by the cpu, and the DMA address usable by the pool's +address usable by the CPU, and the DMA address usable by the pool's device. @@ -120,7 +120,7 @@ device. dma_addr_t addr); This puts memory back into the pool. The pool is what was passed to -dma_pool_alloc(); the cpu (vaddr) and DMA addresses are what +dma_pool_alloc(); the CPU (vaddr) and DMA addresses are what were returned when that routine allocated the memory being freed. @@ -355,7 +355,7 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems, enum dma_data_direction direction) -Synchronise a single contiguous or scatter/gather mapping for the cpu +Synchronise a single contiguous or scatter/gather mapping for the CPU and device. With the sync_sg API, all the parameters must be the same as those passed into the single mapping API. With the sync_single API, you can use dma_handle and size parameters that aren't identical to @@ -504,8 +504,8 @@ dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, Declare region of memory to be handed out by dma_alloc_coherent() when it's asked for coherent memory for this device. -phys_addr is the cpu physical address to which the memory is currently -assigned (this will be ioremapped so the cpu can access the region). +phys_addr is the CPU physical address to which the memory is currently +assigned (this will be ioremapped so the CPU can access the region). device_addr is the bus address the device needs to be programmed with to actually address this memory (this will be handed out as the -- cgit v1.2.3-58-ga151 From 34c815fbdc1257e823726f8c6bcd9255d495058d Mon Sep 17 00:00:00 2001 From: Emilio López Date: Tue, 20 May 2014 16:54:22 -0600 Subject: DMA-API: Fix duplicated word in DMA-API-HOWTO.txt MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit "coherent" is written twice when it should be just once. Signed-off-by: Emilio López Signed-off-by: Bjorn Helgaas --- Documentation/DMA-API-HOWTO.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index f59955303475..b22ceff35609 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -249,10 +249,10 @@ the case would look like this: goto ignore_this_device; } -The coherent coherent mask will always be able to set the same or a -smaller mask as the streaming mask. However for the rare case that a -device driver only uses consistent allocations, one would have to -check the return value from dma_set_coherent_mask(). +The coherent mask will always be able to set the same or a smaller mask as +the streaming mask. However for the rare case that a device driver only +uses consistent allocations, one would have to check the return value from +dma_set_coherent_mask(). Finally, if your device can only drive the low 24-bits of address you might do something like: -- cgit v1.2.3-58-ga151 From 2af9da8638a139303b3cd535b458a1b2c80dd4f3 Mon Sep 17 00:00:00 2001 From: Gioh Kim Date: Tue, 20 May 2014 17:09:35 -0600 Subject: DMA-API: Update dma_pool_create ()and dma_pool_alloc() descriptions Use "boundary" to be more descriptive than "alloc" in the dma_pool_create() documentation. Replace "SLAB_KERNEL" and "SLAB_ATOMIC" with the correct "GFP_KERNEL" and "GFP_ATOMIC." [bhelgaas: changelog] Signed-off-by: Gioh Kim Signed-off-by: Bjorn Helgaas --- Documentation/DMA-API-HOWTO.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index b22ceff35609..dcbbe3602d78 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -429,13 +429,13 @@ Create a dma_pool like this: struct dma_pool *pool; - pool = dma_pool_create(name, dev, size, align, alloc); + pool = dma_pool_create(name, dev, size, align, boundary); The "name" is for diagnostics (like a kmem_cache name); dev and size are as above. The device's hardware alignment requirement for this type of data is "align" (which is expressed in bytes, and must be a power of two). If your device has no boundary crossing restrictions, -pass 0 for alloc; passing 4096 says memory allocated from this pool +pass 0 for boundary; passing 4096 says memory allocated from this pool must not cross 4KByte boundaries (but at that time it may be better to use dma_alloc_coherent() directly instead). @@ -443,8 +443,8 @@ Allocate memory from a DMA pool like this: cpu_addr = dma_pool_alloc(pool, flags, &dma_handle); -flags are SLAB_KERNEL if blocking is permitted (not in_interrupt nor -holding SMP locks), SLAB_ATOMIC otherwise. Like dma_alloc_coherent(), +flags are GFP_KERNEL if blocking is permitted (not in_interrupt nor +holding SMP locks), GFP_ATOMIC otherwise. Like dma_alloc_coherent(), this returns two values, cpu_addr and dma_handle. Free memory that was allocated from a dma_pool like this: -- cgit v1.2.3-58-ga151 From 7869fc6e295cbb1f80e30555bebbc795abb5b9a7 Mon Sep 17 00:00:00 2001 From: Phil Edworthy Date: Mon, 12 May 2014 11:57:50 +0100 Subject: PCI: rcar: Add R-Car PCIe device tree bindings This patch adds the bindings for the R-Car PCIe driver. The driver resides under drivers/pci/host/pcie-rcar.c Signed-off-by: Phil Edworthy Signed-off-by: Bjorn Helgaas Reviewed-by: Lucas Stach Acked-by: Simon Horman --- Documentation/devicetree/bindings/pci/rcar-pci.txt | 47 ++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 Documentation/devicetree/bindings/pci/rcar-pci.txt (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/pci/rcar-pci.txt b/Documentation/devicetree/bindings/pci/rcar-pci.txt new file mode 100644 index 000000000000..29d3b989d3b0 --- /dev/null +++ b/Documentation/devicetree/bindings/pci/rcar-pci.txt @@ -0,0 +1,47 @@ +* Renesas RCar PCIe interface + +Required properties: +- compatible: should contain one of the following + "renesas,pcie-r8a7779", "renesas,pcie-r8a7790", "renesas,pcie-r8a7791" +- reg: base address and length of the pcie controller registers. +- #address-cells: set to <3> +- #size-cells: set to <2> +- bus-range: PCI bus numbers covered +- device_type: set to "pci" +- ranges: ranges for the PCI memory and I/O regions. +- dma-ranges: ranges for the inbound memory regions. +- interrupts: two interrupt sources for MSI interrupts, followed by interrupt + source for hardware related interrupts (e.g. link speed change). +- #interrupt-cells: set to <1> +- interrupt-map-mask and interrupt-map: standard PCI properties + to define the mapping of the PCIe interface to interrupt + numbers. +- clocks: from common clock binding: clock specifiers for the PCIe controller + and PCIe bus clocks. +- clock-names: from common clock binding: should be "pcie" and "pcie_bus". + +Example: + +SoC specific DT Entry: + + pcie: pcie@fe000000 { + compatible = "renesas,pcie-r8a7791"; + reg = <0 0xfe000000 0 0x80000>; + #address-cells = <3>; + #size-cells = <2>; + bus-range = <0x00 0xff>; + device_type = "pci"; + ranges = <0x01000000 0 0x00000000 0 0xfe100000 0 0x00100000 + 0x02000000 0 0xfe200000 0 0xfe200000 0 0x00200000 + 0x02000000 0 0x30000000 0 0x30000000 0 0x08000000 + 0x42000000 0 0x38000000 0 0x38000000 0 0x08000000>; + dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0 0x40000000 + 0x42000000 2 0x00000000 2 0x00000000 0 0x40000000>; + interrupts = <0 116 4>, <0 117 4>, <0 118 4>; + #interrupt-cells = <1>; + interrupt-map-mask = <0 0 0 0>; + interrupt-map = <0 0 0 0 &gic 0 116 4>; + clocks = <&mstp3_clks R8A7791_CLK_PCIE>, <&pcie_bus_clk>; + clock-names = "pcie", "pcie_bus"; + status = "disabled"; + }; -- cgit v1.2.3-58-ga151 From d47b62f4b1c0374517ccbdf3ee4a7cceead58905 Mon Sep 17 00:00:00 2001 From: Ben Dooks Date: Tue, 20 May 2014 01:10:20 +0400 Subject: PCI: rcar: Add gen2 device tree support Add device tree probing support to the 'pci-rcar-gen2' driver. [Sergei: numerous fixes/cleanups/additions] [bhelgaas: whitespace fix] Signed-off-by: Ben Dooks Signed-off-by: Sergei Shtylyov Signed-off-by: Bjorn Helgaas Acked-by: Simon Horman Acked-by: Arnd Bergmann --- .../devicetree/bindings/pci/pci-rcar-gen2.txt | 66 ++++++++++++++++++++++ drivers/pci/host/pci-rcar-gen2.c | 31 +++++++++- 2 files changed, 95 insertions(+), 2 deletions(-) create mode 100644 Documentation/devicetree/bindings/pci/pci-rcar-gen2.txt (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/pci/pci-rcar-gen2.txt b/Documentation/devicetree/bindings/pci/pci-rcar-gen2.txt new file mode 100644 index 000000000000..d8ef5bf50f11 --- /dev/null +++ b/Documentation/devicetree/bindings/pci/pci-rcar-gen2.txt @@ -0,0 +1,66 @@ +Renesas AHB to PCI bridge +------------------------- + +This is the bridge used internally to connect the USB controllers to the +AHB. There is one bridge instance per USB port connected to the internal +OHCI and EHCI controllers. + +Required properties: +- compatible: "renesas,pci-r8a7790" for the R8A7790 SoC; + "renesas,pci-r8a7791" for the R8A7791 SoC. +- reg: A list of physical regions to access the device: the first is + the operational registers for the OHCI/EHCI controllers and the + second is for the bridge configuration and control registers. +- interrupts: interrupt for the device. +- clocks: The reference to the device clock. +- bus-range: The PCI bus number range; as this is a single bus, the range + should be specified as the same value twice. +- #address-cells: must be 3. +- #size-cells: must be 2. +- #interrupt-cells: must be 1. +- interrupt-map: standard property used to define the mapping of the PCI + interrupts to the GIC interrupts. +- interrupt-map-mask: standard property that helps to define the interrupt + mapping. + +Example SoC configuration: + + pci0: pci@ee090000 { + compatible = "renesas,pci-r8a7790"; + clocks = <&mstp7_clks R8A7790_CLK_EHCI>; + reg = <0x0 0xee090000 0x0 0xc00>, + <0x0 0xee080000 0x0 0x1100>; + interrupts = <0 108 IRQ_TYPE_LEVEL_HIGH>; + status = "disabled"; + + bus-range = <0 0>; + #address-cells = <3>; + #size-cells = <2>; + #interrupt-cells = <1>; + interrupt-map-mask = <0xff00 0 0 0x7>; + interrupt-map = <0x0000 0 0 1 &gic 0 108 IRQ_TYPE_LEVEL_HIGH + 0x0800 0 0 1 &gic 0 108 IRQ_TYPE_LEVEL_HIGH + 0x1000 0 0 2 &gic 0 108 IRQ_TYPE_LEVEL_HIGH>; + + pci@0,1 { + reg = <0x800 0 0 0 0>; + device_type = "pci"; + phys = <&usbphy 0 0>; + phy-names = "usb"; + }; + + pci@0,2 { + reg = <0x1000 0 0 0 0>; + device_type = "pci"; + phys = <&usbphy 0 0>; + phy-names = "usb"; + }; + }; + +Example board setup: + +&pci0 { + status = "okay"; + pinctrl-0 = <&usb0_pins>; + pinctrl-names = "default"; +}; diff --git a/drivers/pci/host/pci-rcar-gen2.c b/drivers/pci/host/pci-rcar-gen2.c index 4fe349dcaf59..3ef854f5a5b5 100644 --- a/drivers/pci/host/pci-rcar-gen2.c +++ b/drivers/pci/host/pci-rcar-gen2.c @@ -99,6 +99,7 @@ struct rcar_pci_priv { struct resource io_res; struct resource mem_res; struct resource *cfg_res; + unsigned busnr; int irq; unsigned long window_size; }; @@ -318,8 +319,8 @@ static int rcar_pci_setup(int nr, struct pci_sys_data *sys) pci_add_resource(&sys->resources, &priv->io_res); pci_add_resource(&sys->resources, &priv->mem_res); - /* Setup bus number based on platform device id */ - sys->busnr = to_platform_device(priv->dev)->id; + /* Setup bus number based on platform device id / of bus-range */ + sys->busnr = priv->busnr; return 1; } @@ -372,6 +373,23 @@ static int rcar_pci_probe(struct platform_device *pdev) priv->window_size = SZ_1G; + if (pdev->dev.of_node) { + struct resource busnr; + int ret; + + ret = of_pci_parse_bus_range(pdev->dev.of_node, &busnr); + if (ret < 0) { + dev_err(&pdev->dev, "failed to parse bus-range\n"); + return ret; + } + + priv->busnr = busnr.start; + if (busnr.end != busnr.start) + dev_warn(&pdev->dev, "only one bus number supported\n"); + } else { + priv->busnr = pdev->id; + } + hw_private[0] = priv; memset(&hw, 0, sizeof(hw)); hw.nr_controllers = ARRAY_SIZE(hw_private); @@ -383,11 +401,20 @@ static int rcar_pci_probe(struct platform_device *pdev) return 0; } +static struct of_device_id rcar_pci_of_match[] = { + { .compatible = "renesas,pci-r8a7790", }, + { .compatible = "renesas,pci-r8a7791", }, + { }, +}; + +MODULE_DEVICE_TABLE(of, rcar_pci_of_match); + static struct platform_driver rcar_pci_driver = { .driver = { .name = "pci-rcar-gen2", .owner = THIS_MODULE, .suppress_bind_attrs = true, + .of_match_table = rcar_pci_of_match, }, .probe = rcar_pci_probe, }; -- cgit v1.2.3-58-ga151 From 782a985d7af26db39e86070d28f987cad21313c0 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 20 May 2014 08:53:21 -0600 Subject: PCI: Introduce new device binding path using pci_dev.driver_override The driver_override field allows us to specify the driver for a device rather than relying on the driver to provide a positive match of the device. This shortcuts the existing process of looking up the vendor and device ID, adding them to the driver new_id, binding the device, then removing the ID, but it also provides a couple advantages. First, the above existing process allows the driver to bind to any device matching the new_id for the window where it's enabled. This is often not desired, such as the case of trying to bind a single device to a meta driver like pci-stub or vfio-pci. Using driver_override we can do this deterministically using: echo pci-stub > /sys/bus/pci/devices/0000:03:00.0/driver_override echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind echo 0000:03:00.0 > /sys/bus/pci/drivers_probe Previously we could not invoke drivers_probe after adding a device to new_id for a driver as we get non-deterministic behavior whether the driver we intend or the standard driver will claim the device. Now it becomes a deterministic process, only the driver matching driver_override will probe the device. To return the device to the standard driver, we simply clear the driver_override and reprobe the device: echo > /sys/bus/pci/devices/0000:03:00.0/driver_override echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind echo 0000:03:00.0 > /sys/bus/pci/drivers_probe Another advantage to this approach is that we can specify a driver override to force a specific binding or prevent any binding. For instance when an IOMMU group is exposed to userspace through VFIO we require that all devices within that group are owned by VFIO. However, devices can be hot-added into an IOMMU group, in which case we want to prevent the device from binding to any driver (override driver = "none") or perhaps have it automatically bind to vfio-pci. With driver_override it's a simple matter for this field to be set internally when the device is first discovered to prevent driver matches. Signed-off-by: Alex Williamson Signed-off-by: Bjorn Helgaas Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Alexander Graf Acked-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-bus-pci | 21 +++++++++++++++++ drivers/pci/pci-driver.c | 25 ++++++++++++++++++--- drivers/pci/pci-sysfs.c | 40 +++++++++++++++++++++++++++++++++ drivers/pci/probe.c | 1 + include/linux/pci.h | 1 + 5 files changed, 85 insertions(+), 3 deletions(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index a3c5a6685036..898ddc4440e6 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -250,3 +250,24 @@ Description: valid. For example, writing a 2 to this file when sriov_numvfs is not 0 and not 2 already will return an error. Writing a 10 when the value of sriov_totalvfs is 8 will return an error. + +What: /sys/bus/pci/devices/.../driver_override +Date: April 2014 +Contact: Alex Williamson +Description: + This file allows the driver for a device to be specified which + will override standard static and dynamic ID matching. When + specified, only a driver with a name matching the value written + to driver_override will have an opportunity to bind to the + device. The override is specified by writing a string to the + driver_override file (echo pci-stub > driver_override) and + may be cleared with an empty string (echo > driver_override). + This returns the device to standard matching rules binding. + Writing to driver_override does not automatically unbind the + device from its current driver or make any attempt to + automatically load the specified driver. If no driver with a + matching name is currently loaded in the kernel, the device + will not bind to any driver. This also allows devices to + opt-out of driver binding using a driver_override name such as + "none". Only a single driver may be specified in the override, + there is no support for parsing delimiters. diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index d911e0c1f359..4393c12e9135 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -216,6 +216,13 @@ const struct pci_device_id *pci_match_id(const struct pci_device_id *ids, return NULL; } +static const struct pci_device_id pci_device_id_any = { + .vendor = PCI_ANY_ID, + .device = PCI_ANY_ID, + .subvendor = PCI_ANY_ID, + .subdevice = PCI_ANY_ID, +}; + /** * pci_match_device - Tell if a PCI device structure has a matching PCI device id structure * @drv: the PCI driver to match against @@ -229,18 +236,30 @@ static const struct pci_device_id *pci_match_device(struct pci_driver *drv, struct pci_dev *dev) { struct pci_dynid *dynid; + const struct pci_device_id *found_id = NULL; + + /* When driver_override is set, only bind to the matching driver */ + if (dev->driver_override && strcmp(dev->driver_override, drv->name)) + return NULL; /* Look at the dynamic ids first, before the static ones */ spin_lock(&drv->dynids.lock); list_for_each_entry(dynid, &drv->dynids.list, node) { if (pci_match_one_device(&dynid->id, dev)) { - spin_unlock(&drv->dynids.lock); - return &dynid->id; + found_id = &dynid->id; + break; } } spin_unlock(&drv->dynids.lock); - return pci_match_id(drv->id_table, dev); + if (!found_id) + found_id = pci_match_id(drv->id_table, dev); + + /* driver_override will always match, send a dummy id */ + if (!found_id && dev->driver_override) + found_id = &pci_device_id_any; + + return found_id; } struct drv_dev_and_id { diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 4e0acefb7565..faa4ab554d68 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -499,6 +499,45 @@ static struct device_attribute sriov_numvfs_attr = sriov_numvfs_show, sriov_numvfs_store); #endif /* CONFIG_PCI_IOV */ +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pci_dev *pdev = to_pci_dev(dev); + char *driver_override, *old = pdev->driver_override, *cp; + + if (count > PATH_MAX) + return -EINVAL; + + driver_override = kstrndup(buf, count, GFP_KERNEL); + if (!driver_override) + return -ENOMEM; + + cp = strchr(driver_override, '\n'); + if (cp) + *cp = '\0'; + + if (strlen(driver_override)) { + pdev->driver_override = driver_override; + } else { + kfree(driver_override); + pdev->driver_override = NULL; + } + + kfree(old); + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pci_dev *pdev = to_pci_dev(dev); + + return sprintf(buf, "%s\n", pdev->driver_override); +} +static DEVICE_ATTR_RW(driver_override); + static struct attribute *pci_dev_attrs[] = { &dev_attr_resource.attr, &dev_attr_vendor.attr, @@ -521,6 +560,7 @@ static struct attribute *pci_dev_attrs[] = { #if defined(CONFIG_PM_RUNTIME) && defined(CONFIG_ACPI) &dev_attr_d3cold_allowed.attr, #endif + &dev_attr_driver_override.attr, NULL, }; diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ef09f5f2fe6c..54268de45f59 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1215,6 +1215,7 @@ static void pci_release_dev(struct device *dev) pci_release_of_node(pci_dev); pcibios_release_device(pci_dev); pci_bus_put(pci_dev->bus); + kfree(pci_dev->driver_override); kfree(pci_dev); } diff --git a/include/linux/pci.h b/include/linux/pci.h index aab57b4abe7f..b72af276f591 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -365,6 +365,7 @@ struct pci_dev { #endif phys_addr_t rom; /* Physical address of ROM if it's not from the BAR */ size_t romlen; /* Length of ROM if it's not from the BAR */ + char *driver_override; /* Driver name to force a match */ }; static inline struct pci_dev *pci_physfn(struct pci_dev *dev) -- cgit v1.2.3-58-ga151 From ce292991d88b77160f348fb8a3a2cf6e78f4b456 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 22 Nov 2013 16:14:41 +0000 Subject: PCI: generic: Add generic PCI host controller driver Add support for a generic PCI host controller, such as a firmware-initialised device with static windows or an emulation by something such as kvmtool. The controller itself has no configuration registers and has its address spaces described entirely by the device-tree (using the bindings from ePAPR). Both CAM and ECAM are supported for Config Space accesses. Add corresponding documentation for the DT binding. [bhelgaas: currently uses the ARM-specific pci_common_init_dev() interface] Signed-off-by: Will Deacon Signed-off-by: Bjorn Helgaas Reviewed-by: Liviu Dudau --- .../devicetree/bindings/pci/host-generic-pci.txt | 100 ++++++ drivers/pci/host/Kconfig | 7 + drivers/pci/host/Makefile | 1 + drivers/pci/host/pci-host-generic.c | 388 +++++++++++++++++++++ 4 files changed, 496 insertions(+) create mode 100644 Documentation/devicetree/bindings/pci/host-generic-pci.txt create mode 100644 drivers/pci/host/pci-host-generic.c (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/pci/host-generic-pci.txt b/Documentation/devicetree/bindings/pci/host-generic-pci.txt new file mode 100644 index 000000000000..f0b0436807b4 --- /dev/null +++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt @@ -0,0 +1,100 @@ +* Generic PCI host controller + +Firmware-initialised PCI host controllers and PCI emulations, such as the +virtio-pci implementations found in kvmtool and other para-virtualised +systems, do not require driver support for complexities such as regulator +and clock management. In fact, the controller may not even require the +configuration of a control interface by the operating system, instead +presenting a set of fixed windows describing a subset of IO, Memory and +Configuration Spaces. + +Such a controller can be described purely in terms of the standardized device +tree bindings communicated in pci.txt: + + +Properties of the host controller node: + +- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic" + depending on the layout of configuration space (CAM vs + ECAM respectively). + +- device_type : Must be "pci". + +- ranges : As described in IEEE Std 1275-1994, but must provide + at least a definition of non-prefetchable memory. One + or both of prefetchable Memory and IO Space may also + be provided. + +- bus-range : Optional property (also described in IEEE Std 1275-1994) + to indicate the range of bus numbers for this controller. + If absent, defaults to <0 255> (i.e. all buses). + +- #address-cells : Must be 3. + +- #size-cells : Must be 2. + +- reg : The Configuration Space base address and size, as accessed + from the parent bus. + + +Properties of the /chosen node: + +- linux,pci-probe-only + : Optional property which takes a single-cell argument. + If '0', then Linux will assign devices in its usual manner, + otherwise it will not try to assign devices and instead use + them as they are configured already. + +Configuration Space is assumed to be memory-mapped (as opposed to being +accessed via an ioport) and laid out with a direct correspondence to the +geography of a PCI bus address by concatenating the various components to +form an offset. + +For CAM, this 24-bit offset is: + + cfg_offset(bus, device, function, register) = + bus << 16 | device << 11 | function << 8 | register + +Whilst ECAM extends this by 4 bits to accomodate 4k of function space: + + cfg_offset(bus, device, function, register) = + bus << 20 | device << 15 | function << 12 | register + +Interrupt mapping is exactly as described in `Open Firmware Recommended +Practice: Interrupt Mapping' and requires the following properties: + +- #interrupt-cells : Must be 1 + +- interrupt-map : + +- interrupt-map-mask : + + +Example: + +pci { + compatible = "pci-host-cam-generic" + device_type = "pci"; + #address-cells = <3>; + #size-cells = <2>; + bus-range = <0x0 0x1>; + + // CPU_PHYSICAL(2) SIZE(2) + reg = <0x0 0x40000000 0x0 0x1000000>; + + // BUS_ADDRESS(3) CPU_PHYSICAL(2) SIZE(2) + ranges = <0x01000000 0x0 0x01000000 0x0 0x01000000 0x0 0x00010000>, + <0x02000000 0x0 0x41000000 0x0 0x41000000 0x0 0x3f000000>; + + + #interrupt-cells = <0x1>; + + // PCI_DEVICE(3) INT#(1) CONTROLLER(PHANDLE) CONTROLLER_DATA(3) + interrupt-map = < 0x0 0x0 0x0 0x1 &gic 0x0 0x4 0x1 + 0x800 0x0 0x0 0x1 &gic 0x0 0x5 0x1 + 0x1000 0x0 0x0 0x1 &gic 0x0 0x6 0x1 + 0x1800 0x0 0x0 0x1 &gic 0x0 0x7 0x1>; + + // PCI_DEVICE(3) INT#(1) + interrupt-map-mask = <0xf800 0x0 0x0 0x7>; +} diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig index a6f67ec8882f..32d446effbb3 100644 --- a/drivers/pci/host/Kconfig +++ b/drivers/pci/host/Kconfig @@ -33,4 +33,11 @@ config PCI_RCAR_GEN2 There are 3 internal PCI controllers available with a single built-in EHCI/OHCI host controller present on each one. +config PCI_HOST_GENERIC + bool "Generic PCI host controller" + depends on ARM && OF + help + Say Y here if you want to support a simple generic PCI host + controller, such as the one emulated by kvmtool. + endmenu diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile index 13fb3333aa05..bd1bf1ab4ac8 100644 --- a/drivers/pci/host/Makefile +++ b/drivers/pci/host/Makefile @@ -4,3 +4,4 @@ obj-$(CONFIG_PCI_IMX6) += pci-imx6.o obj-$(CONFIG_PCI_MVEBU) += pci-mvebu.o obj-$(CONFIG_PCI_TEGRA) += pci-tegra.o obj-$(CONFIG_PCI_RCAR_GEN2) += pci-rcar-gen2.o +obj-$(CONFIG_PCI_HOST_GENERIC) += pci-host-generic.o diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c new file mode 100644 index 000000000000..44fe6aa6a43f --- /dev/null +++ b/drivers/pci/host/pci-host-generic.c @@ -0,0 +1,388 @@ +/* + * Simple, generic PCI host controller driver targetting firmware-initialised + * systems and virtual machines (e.g. the PCI emulation provided by kvmtool). + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + * + * Copyright (C) 2014 ARM Limited + * + * Author: Will Deacon + */ + +#include +#include +#include +#include +#include + +struct gen_pci_cfg_bus_ops { + u32 bus_shift; + void __iomem *(*map_bus)(struct pci_bus *, unsigned int, int); +}; + +struct gen_pci_cfg_windows { + struct resource res; + struct resource bus_range; + void __iomem **win; + + const struct gen_pci_cfg_bus_ops *ops; +}; + +struct gen_pci { + struct pci_host_bridge host; + struct gen_pci_cfg_windows cfg; + struct list_head resources; +}; + +static void __iomem *gen_pci_map_cfg_bus_cam(struct pci_bus *bus, + unsigned int devfn, + int where) +{ + struct pci_sys_data *sys = bus->sysdata; + struct gen_pci *pci = sys->private_data; + resource_size_t idx = bus->number - pci->cfg.bus_range.start; + + return pci->cfg.win[idx] + ((devfn << 8) | where); +} + +static struct gen_pci_cfg_bus_ops gen_pci_cfg_cam_bus_ops = { + .bus_shift = 16, + .map_bus = gen_pci_map_cfg_bus_cam, +}; + +static void __iomem *gen_pci_map_cfg_bus_ecam(struct pci_bus *bus, + unsigned int devfn, + int where) +{ + struct pci_sys_data *sys = bus->sysdata; + struct gen_pci *pci = sys->private_data; + resource_size_t idx = bus->number - pci->cfg.bus_range.start; + + return pci->cfg.win[idx] + ((devfn << 12) | where); +} + +static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = { + .bus_shift = 20, + .map_bus = gen_pci_map_cfg_bus_ecam, +}; + +static int gen_pci_config_read(struct pci_bus *bus, unsigned int devfn, + int where, int size, u32 *val) +{ + void __iomem *addr; + struct pci_sys_data *sys = bus->sysdata; + struct gen_pci *pci = sys->private_data; + + addr = pci->cfg.ops->map_bus(bus, devfn, where); + + switch (size) { + case 1: + *val = readb(addr); + break; + case 2: + *val = readw(addr); + break; + default: + *val = readl(addr); + } + + return PCIBIOS_SUCCESSFUL; +} + +static int gen_pci_config_write(struct pci_bus *bus, unsigned int devfn, + int where, int size, u32 val) +{ + void __iomem *addr; + struct pci_sys_data *sys = bus->sysdata; + struct gen_pci *pci = sys->private_data; + + addr = pci->cfg.ops->map_bus(bus, devfn, where); + + switch (size) { + case 1: + writeb(val, addr); + break; + case 2: + writew(val, addr); + break; + default: + writel(val, addr); + } + + return PCIBIOS_SUCCESSFUL; +} + +static struct pci_ops gen_pci_ops = { + .read = gen_pci_config_read, + .write = gen_pci_config_write, +}; + +static const struct of_device_id gen_pci_of_match[] = { + { .compatible = "pci-host-cam-generic", + .data = &gen_pci_cfg_cam_bus_ops }, + + { .compatible = "pci-host-ecam-generic", + .data = &gen_pci_cfg_ecam_bus_ops }, + + { }, +}; +MODULE_DEVICE_TABLE(of, gen_pci_of_match); + +static int gen_pci_calc_io_offset(struct device *dev, + struct of_pci_range *range, + struct resource *res, + resource_size_t *offset) +{ + static atomic_t wins = ATOMIC_INIT(0); + int err, idx, max_win; + unsigned int window; + + if (!PAGE_ALIGNED(range->cpu_addr)) + return -EINVAL; + + max_win = (IO_SPACE_LIMIT + 1) / SZ_64K; + idx = atomic_inc_return(&wins); + if (idx > max_win) + return -ENOSPC; + + window = (idx - 1) * SZ_64K; + err = pci_ioremap_io(window, range->cpu_addr); + if (err) + return err; + + of_pci_range_to_resource(range, dev->of_node, res); + res->start = window; + res->end = res->start + range->size - 1; + *offset = window - range->pci_addr; + return 0; +} + +static int gen_pci_calc_mem_offset(struct device *dev, + struct of_pci_range *range, + struct resource *res, + resource_size_t *offset) +{ + of_pci_range_to_resource(range, dev->of_node, res); + *offset = range->cpu_addr - range->pci_addr; + return 0; +} + +static void gen_pci_release_of_pci_ranges(struct gen_pci *pci) +{ + struct pci_host_bridge_window *win; + + list_for_each_entry(win, &pci->resources, list) + release_resource(win->res); + + pci_free_resource_list(&pci->resources); +} + +static int gen_pci_parse_request_of_pci_ranges(struct gen_pci *pci) +{ + struct of_pci_range range; + struct of_pci_range_parser parser; + int err, res_valid = 0; + struct device *dev = pci->host.dev.parent; + struct device_node *np = dev->of_node; + + if (of_pci_range_parser_init(&parser, np)) { + dev_err(dev, "missing \"ranges\" property\n"); + return -EINVAL; + } + + for_each_of_pci_range(&parser, &range) { + struct resource *parent, *res; + resource_size_t offset; + u32 restype = range.flags & IORESOURCE_TYPE_BITS; + + res = devm_kmalloc(dev, sizeof(*res), GFP_KERNEL); + if (!res) { + err = -ENOMEM; + goto out_release_res; + } + + switch (restype) { + case IORESOURCE_IO: + parent = &ioport_resource; + err = gen_pci_calc_io_offset(dev, &range, res, &offset); + break; + case IORESOURCE_MEM: + parent = &iomem_resource; + err = gen_pci_calc_mem_offset(dev, &range, res, &offset); + res_valid |= !(res->flags & IORESOURCE_PREFETCH || err); + break; + default: + err = -EINVAL; + continue; + } + + if (err) { + dev_warn(dev, + "error %d: failed to add resource [type 0x%x, %lld bytes]\n", + err, restype, range.size); + continue; + } + + err = request_resource(parent, res); + if (err) + goto out_release_res; + + pci_add_resource_offset(&pci->resources, res, offset); + } + + if (!res_valid) { + dev_err(dev, "non-prefetchable memory resource required\n"); + err = -EINVAL; + goto out_release_res; + } + + return 0; + +out_release_res: + gen_pci_release_of_pci_ranges(pci); + return err; +} + +static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci) +{ + int err; + u8 bus_max; + resource_size_t busn; + struct resource *bus_range; + struct device *dev = pci->host.dev.parent; + struct device_node *np = dev->of_node; + + if (of_pci_parse_bus_range(np, &pci->cfg.bus_range)) + pci->cfg.bus_range = (struct resource) { + .name = np->name, + .start = 0, + .end = 0xff, + .flags = IORESOURCE_BUS, + }; + + err = of_address_to_resource(np, 0, &pci->cfg.res); + if (err) { + dev_err(dev, "missing \"reg\" property\n"); + return err; + } + + pci->cfg.win = devm_kcalloc(dev, resource_size(&pci->cfg.bus_range), + sizeof(*pci->cfg.win), GFP_KERNEL); + if (!pci->cfg.win) + return -ENOMEM; + + /* Limit the bus-range to fit within reg */ + bus_max = pci->cfg.bus_range.start + + (resource_size(&pci->cfg.res) >> pci->cfg.ops->bus_shift) - 1; + pci->cfg.bus_range.end = min_t(resource_size_t, pci->cfg.bus_range.end, + bus_max); + + /* Map our Configuration Space windows */ + if (!devm_request_mem_region(dev, pci->cfg.res.start, + resource_size(&pci->cfg.res), + "Configuration Space")) + return -ENOMEM; + + bus_range = &pci->cfg.bus_range; + for (busn = bus_range->start; busn <= bus_range->end; ++busn) { + u32 idx = busn - bus_range->start; + u32 sz = 1 << pci->cfg.ops->bus_shift; + + pci->cfg.win[idx] = devm_ioremap(dev, + pci->cfg.res.start + busn * sz, + sz); + if (!pci->cfg.win[idx]) + return -ENOMEM; + } + + /* Register bus resource */ + pci_add_resource(&pci->resources, bus_range); + return 0; +} + +static int gen_pci_setup(int nr, struct pci_sys_data *sys) +{ + struct gen_pci *pci = sys->private_data; + list_splice_init(&pci->resources, &sys->resources); + return 1; +} + +static int gen_pci_probe(struct platform_device *pdev) +{ + int err; + const char *type; + const struct of_device_id *of_id; + const int *prop; + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL); + struct hw_pci hw = { + .nr_controllers = 1, + .private_data = (void **)&pci, + .setup = gen_pci_setup, + .map_irq = of_irq_parse_and_map_pci, + .ops = &gen_pci_ops, + }; + + if (!pci) + return -ENOMEM; + + type = of_get_property(np, "device_type", NULL); + if (!type || strcmp(type, "pci")) { + dev_err(dev, "invalid \"device_type\" %s\n", type); + return -EINVAL; + } + + prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL); + if (prop) { + if (*prop) + pci_add_flags(PCI_PROBE_ONLY); + else + pci_clear_flags(PCI_PROBE_ONLY); + } + + of_id = of_match_node(gen_pci_of_match, np); + pci->cfg.ops = of_id->data; + pci->host.dev.parent = dev; + INIT_LIST_HEAD(&pci->host.windows); + INIT_LIST_HEAD(&pci->resources); + + /* Parse our PCI ranges and request their resources */ + err = gen_pci_parse_request_of_pci_ranges(pci); + if (err) + return err; + + /* Parse and map our Configuration Space windows */ + err = gen_pci_parse_map_cfg_windows(pci); + if (err) { + gen_pci_release_of_pci_ranges(pci); + return err; + } + + pci_common_init_dev(dev, &hw); + return 0; +} + +static struct platform_driver gen_pci_driver = { + .driver = { + .name = "pci-host-generic", + .owner = THIS_MODULE, + .of_match_table = gen_pci_of_match, + }, + .probe = gen_pci_probe, +}; +module_platform_driver(gen_pci_driver); + +MODULE_DESCRIPTION("Generic PCI host driver"); +MODULE_AUTHOR("Will Deacon "); +MODULE_LICENSE("GPLv2"); -- cgit v1.2.3-58-ga151