Merge tag 'irq-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:
 "Updates to the interrupt core and driver subsystems:

  Core changes:

   - The usual set of small fixes and improvements all over the place,
     but nothing stands out

  MSI changes:

   - Further consolidation of the PCI/MSI interrupt chip code

   - Make MSI sysfs code independent of PCI/MSI and expose the MSI
     interrupts of platform devices in the same way as PCI exposes them.

  Driver changes:

   - Support for ARM GICv3 EPPI partitions

   - Treewide conversion to generic_handle_domain_irq() for all chained
     interrupt controllers

   - Conversion to bitmap_zalloc() throughout the irq chip drivers

   - The usual set of small fixes and improvements"

* tag 'irq-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
  platform-msi: Add ABI to show msi_irqs of platform devices
  genirq/msi: Move MSI sysfs handling from PCI to MSI core
  genirq/cpuhotplug: Demote debug printk to KERN_DEBUG
  irqchip/qcom-pdc: Trim unused levels of the interrupt hierarchy
  irqdomain: Export irq_domain_disconnect_hierarchy()
  irqchip/gic-v3: Fix priority comparison when non-secure priorities are used
  irqchip/apple-aic: Fix irq_disable from within irq handlers
  pinctrl/rockchip: drop the gpio related codes
  gpio/rockchip: drop irq_gc_lock/irq_gc_unlock for irq set type
  gpio/rockchip: support next version gpio controller
  gpio/rockchip: use struct rockchip_gpio_regs for gpio controller
  gpio/rockchip: add driver for rockchip gpio
  dt-bindings: gpio: change items restriction of clock for rockchip,gpio-bank
  pinctrl/rockchip: add pinctrl device to gpio bank struct
  pinctrl/rockchip: separate struct rockchip_pin_bank to a head file
  pinctrl/rockchip: always enable clock for gpio controller
  genirq: Fix kernel doc indentation
  EDAC/altera: Convert to generic_handle_domain_irq()
  powerpc: Bulk conversion to generic_handle_domain_irq()
  nios2: Bulk conversion to generic_handle_domain_irq()
  ...

1 files changed, 25 insertions, 3 deletions

diff --git a/Documentation/core-api/irq/irq-domain.rst b/Documentation/core-api/irq/irq-domain.rst
index 53283b3729a1..6979b4af2c1f 100644
--- a/Documentation/core-api/irq/irq-domain.rst
+++ b/Documentation/core-api/irq/irq-domain.rst
@@ -55,8 +55,24 @@ exist then it will allocate a new Linux irq_desc, associate it with
 the hwirq, and call the .map() callback so the driver can perform any
 required hardware setup.
 
-When an interrupt is received, irq_find_mapping() function should
-be used to find the Linux IRQ number from the hwirq number.
+Once a mapping has been established, it can be retrieved or used via a
+variety of methods:
+
+- irq_resolve_mapping() returns a pointer to the irq_desc structure
+  for a given domain and hwirq number, and NULL if there was no
+  mapping.
+- irq_find_mapping() returns a Linux IRQ number for a given domain and
+  hwirq number, and 0 if there was no mapping
+- irq_linear_revmap() is now identical to irq_find_mapping(), and is
+  deprecated
+- generic_handle_domain_irq() handles an interrupt described by a
+  domain and a hwirq number
+- handle_domain_irq() does the same thing for root interrupt
+  controllers and deals with the set_irq_reg()/irq_enter() sequences
+  that most architecture requires
+
+Note that irq domain lookups must happen in contexts that are
+compatible with a RCU read-side critical section.
 
 The irq_create_mapping() function must be called *atleast once*
 before any call to irq_find_mapping(), lest the descriptor will not
@@ -137,7 +153,9 @@ required.  Calling irq_create_direct_mapping() will allocate a Linux
 IRQ number and call the .map() callback so that driver can program the
 Linux IRQ number into the hardware.
 
-Most drivers cannot use this mapping.
+Most drivers cannot use this mapping, and it is now gated on the
+CONFIG_IRQ_DOMAIN_NOMAP option. Please refrain from introducing new
+users of this API.
 
 Legacy
 ------
@@ -157,6 +175,10 @@ for IRQ numbers that are passed to struct device registrations.  In that
 case the Linux IRQ numbers cannot be dynamically assigned and the legacy
 mapping should be used.
 
+As the name implies, the *_legacy() functions are deprecated and only
+exist to ease the support of ancient platforms. No new users should be
+added.
+
 The legacy map assumes a contiguous range of IRQ numbers has already
 been allocated for the controller and that the IRQ number can be
 calculated by adding a fixed offset to the hwirq number, and