diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-74x164.txt | 4 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt | 20 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-xlp.txt | 3 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio.txt | 26 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/wd,mbl-gpio.txt | 38 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt (renamed from Documentation/devicetree/bindings/gpio/gpio-poweroff.txt) | 0 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/power/reset/gpio-restart.txt (renamed from Documentation/devicetree/bindings/gpio/gpio-restart.txt) | 0 | ||||
| -rw-r--r-- | Documentation/gpio/driver.txt | 97 |
8 files changed, 184 insertions, 4 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio-74x164.txt b/Documentation/devicetree/bindings/gpio/gpio-74x164.txt index cc2608021f26..ce1b2231bf5d 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-74x164.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-74x164.txt @@ -1,7 +1,9 @@ * Generic 8-bits shift register GPIO driver Required properties: -- compatible : Should be "fairchild,74hc595" +- compatible: Should contain one of the following: + "fairchild,74hc595" + "nxp,74lvc594" - reg : chip select number - gpio-controller : Marks the device node as a gpio controller. - #gpio-cells : Should be two. The first cell is the pin number and diff --git a/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt b/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt index 120bc4971cf3..4b6cc632ca5c 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt @@ -1,9 +1,10 @@ -* Freescale MPC512x/MPC8xxx/Layerscape GPIO controller +* Freescale MPC512x/MPC8xxx/QorIQ/Layerscape GPIO controller Required properties: - compatible : Should be "fsl,<soc>-gpio" The following <soc>s are known to be supported: - mpc5121, mpc5125, mpc8349, mpc8572, mpc8610, pq3, qoriq. + mpc5121, mpc5125, mpc8349, mpc8572, mpc8610, pq3, qoriq, + ls1021a, ls1043a, ls2080a. - reg : Address and length of the register set for the device - interrupts : Should be the port interrupt shared by all 32 pins. - #gpio-cells : Should be two. The first cell is the pin number and @@ -15,7 +16,7 @@ Optional properties: - little-endian : GPIO registers are used as little endian. If not present registers are used as big endian by default. -Example: +Example of gpio-controller node for a mpc5125 SoC: gpio0: gpio@1100 { compatible = "fsl,mpc5125-gpio"; @@ -24,3 +25,16 @@ gpio0: gpio@1100 { interrupts = <78 0x8>; status = "okay"; }; + +Example of gpio-controller node for a ls2080a SoC: + +gpio0: gpio@2300000 { + compatible = "fsl,ls2080a-gpio", "fsl,qoriq-gpio"; + reg = <0x0 0x2300000 0x0 0x10000>; + interrupts = <0 36 0x4>; /* Level high type */ + gpio-controller; + little-endian; + #gpio-cells = <2>; + interrupt-controller; + #interrupt-cells = <2>; +}; diff --git a/Documentation/devicetree/bindings/gpio/gpio-xlp.txt b/Documentation/devicetree/bindings/gpio/gpio-xlp.txt index 262ee4ddf2cb..28662d83a43e 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-xlp.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-xlp.txt @@ -3,6 +3,8 @@ Netlogic XLP Family GPIO This GPIO driver is used for following Netlogic XLP SoCs: XLP832, XLP316, XLP208, XLP980, XLP532 +This GPIO driver is also compatible with GPIO controller found on +Broadcom Vulcan ARM64. Required properties: ------------------- @@ -13,6 +15,7 @@ Required properties: - "netlogic,xlp208-gpio": For Netlogic XLP208 - "netlogic,xlp980-gpio": For Netlogic XLP980 - "netlogic,xlp532-gpio": For Netlogic XLP532 + - "brcm,vulcan-gpio": For Broadcom Vulcan ARM64 - reg: Physical base address and length of the controller's registers. - #gpio-cells: Should be two. The first cell is the pin number and the second cell is used to specify optional parameters (currently unused). diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt index 069cdf6f9dac..68d28f62a6f4 100644 --- a/Documentation/devicetree/bindings/gpio/gpio.txt +++ b/Documentation/devicetree/bindings/gpio/gpio.txt @@ -131,6 +131,13 @@ Every GPIO controller node must contain both an empty "gpio-controller" property, and a #gpio-cells integer property, which indicates the number of cells in a gpio-specifier. +Some system-on-chips (SoCs) use the concept of GPIO banks. A GPIO bank is an +instance of a hardware IP core on a silicon die, usually exposed to the +programmer as a coherent range of I/O addresses. Usually each such bank is +exposed in the device tree as an individual gpio-controller node, reflecting +the fact that the hardware was synthesized by reusing the same IP block a +few times over. + Optionally, a GPIO controller may have a "ngpios" property. This property indicates the number of in-use slots of available slots for GPIOs. The typical example is something like this: the hardware register is 32 bits @@ -145,6 +152,21 @@ additional bitmask is needed to specify which GPIOs are actually in use, and which are dummies. The bindings for this case has not yet been specified, but should be specified if/when such hardware appears. +Optionally, a GPIO controller may have a "gpio-line-names" property. This is +an array of strings defining the names of the GPIO lines going out of the +GPIO controller. This name should be the most meaningful producer name +for the system, such as a rail name indicating the usage. Package names +such as pin name are discouraged: such lines have opaque names (since they +are by definition generic purpose) and such names are usually not very +helpful. For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are +reasonable line names as they describe what the line is used for. "GPIO0" +is not a good name to give to a GPIO line. Placeholders are discouraged: +rather use the "" (blank string) if the use of the GPIO line is undefined +in your design. The names are assigned starting from line offset 0 from +left to right from the passed array. An incomplete array (where the number +of passed named are less than ngpios) will still be used up until the last +provided valid line index. + Example: gpio-controller@00000000 { @@ -153,6 +175,10 @@ gpio-controller@00000000 { gpio-controller; #gpio-cells = <2>; ngpios = <18>; + gpio-line-names = "MMC-CD", "MMC-WP", "VDD eth", "RST eth", "LED R", + "LED G", "LED B", "Col A", "Col B", "Col C", "Col D", + "Row A", "Row B", "Row C", "Row D", "NMI button", + "poweroff", "reset"; } The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism diff --git a/Documentation/devicetree/bindings/gpio/wd,mbl-gpio.txt b/Documentation/devicetree/bindings/gpio/wd,mbl-gpio.txt new file mode 100644 index 000000000000..038c3a6a1f4d --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/wd,mbl-gpio.txt @@ -0,0 +1,38 @@ +Bindings for the Western Digital's MyBook Live memory-mapped GPIO controllers. + +The Western Digital MyBook Live has two memory-mapped GPIO controllers. +Both GPIO controller only have a single 8-bit data register, where GPIO +state can be read and/or written. + +Required properties: + - compatible: should be "wd,mbl-gpio" + - reg-names: must contain + "dat" - data register + - reg: address + size pairs describing the GPIO register sets; + order must correspond with the order of entries in reg-names + - #gpio-cells: must be set to 2. The first cell is the pin number and + the second cell is used to specify the gpio polarity: + 0 = active high + 1 = active low + - gpio-controller: Marks the device node as a gpio controller. + +Optional properties: + - no-output: GPIOs are read-only. + +Examples: + gpio0: gpio0@e0000000 { + compatible = "wd,mbl-gpio"; + reg-names = "dat"; + reg = <0xe0000000 0x1>; + #gpio-cells = <2>; + gpio-controller; + }; + + gpio1: gpio1@e0100000 { + compatible = "wd,mbl-gpio"; + reg-names = "dat"; + reg = <0xe0100000 0x1>; + #gpio-cells = <2>; + gpio-controller; + no-output; + }; diff --git a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt b/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt index d4eab9227ea4..d4eab9227ea4 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt +++ b/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt diff --git a/Documentation/devicetree/bindings/gpio/gpio-restart.txt b/Documentation/devicetree/bindings/power/reset/gpio-restart.txt index af3701bc15c4..af3701bc15c4 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-restart.txt +++ b/Documentation/devicetree/bindings/power/reset/gpio-restart.txt diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt index bbeec415f406..6cb35a78eff4 100644 --- a/Documentation/gpio/driver.txt +++ b/Documentation/gpio/driver.txt @@ -68,6 +68,103 @@ control callbacks) if it is expected to call GPIO APIs from atomic context on -RT (inside hard IRQ handlers and similar contexts). Normally this should not be required. + +GPIOs with open drain/source support +------------------------------------ + +Open drain (CMOS) or open collector (TTL) means the line is not actively driven +high: instead you provide the drain/collector as output, so when the transistor +is not open, it will present a high-impedance (tristate) to the external rail. + + + CMOS CONFIGURATION TTL CONFIGURATION + + ||--- out +--- out + in ----|| |/ + ||--+ in ----| + | |\ + GND GND + +This configuration is normally used as a way to achieve one of two things: + +- Level-shifting: to reach a logical level higher than that of the silicon + where the output resides. + +- inverse wire-OR on an I/O line, for example a GPIO line, making it possible + for any driving stage on the line to drive it low even if any other output + to the same line is simultaneously driving it high. A special case of this + is driving the SCL and SCA lines of an I2C bus, which is by definition a + wire-OR bus. + +Both usecases require that the line be equipped with a pull-up resistor. This +resistor will make the line tend to high level unless one of the transistors on +the rail actively pulls it down. + +The level on the line will go as high as the VDD on the pull-up resistor, which +may be higher than the level supported by the transistor, achieveing a +level-shift to the higher VDD. + +Integrated electronics often have an output driver stage in the form of a CMOS +"totem-pole" with one N-MOS and one P-MOS transistor where one of them drives +the line high and one of them drives the line low. This is called a push-pull +output. The "totem-pole" looks like so: + + VDD + | + OD ||--+ + +--/ ---o|| P-MOS-FET + | ||--+ +IN --+ +----- out + | ||--+ + +--/ ----|| N-MOS-FET + OS ||--+ + | + GND + +The desired output signal (e.g. coming directly from some GPIO output register) +arrives at IN. The switches named "OD" and "OS" are normally closed, creating +a push-pull circuit. + +Consider the little "switches" named "OD" and "OS" that enable/disable the +P-MOS or N-MOS transistor right after the split of the input. As you can see, +either transistor will go totally numb if this switch is open. The totem-pole +is then halved and give high impedance instead of actively driving the line +high or low respectively. That is usually how software-controlled open +drain/source works. + +Some GPIO hardware come in open drain / open source configuration. Some are +hard-wired lines that will only support open drain or open source no matter +what: there is only one transistor there. Some are software-configurable: +by flipping a bit in a register the output can be configured as open drain +or open source, in practice by flicking open the switches labeled "OD" and "OS" +in the drawing above. + +By disabling the P-MOS transistor, the output can be driven between GND and +high impedance (open drain), and by disabling the N-MOS transistor, the output +can be driven between VDD and high impedance (open source). In the first case, +a pull-up resistor is needed on the outgoing rail to complete the circuit, and +in the second case, a pull-down resistor is needed on the rail. + +Hardware that supports open drain or open source or both, can implement a +special callback in the gpio_chip: .set_single_ended() that takes an enum flag +telling whether to configure the line as open drain, open source or push-pull. +This will happen in response to the GPIO_OPEN_DRAIN or GPIO_OPEN_SOURCE flag +set in the machine file, or coming from other hardware descriptions. + +If this state can not be configured in hardware, i.e. if the GPIO hardware does +not support open drain/open source in hardware, the GPIO library will instead +use a trick: when a line is set as output, if the line is flagged as open +drain, and the IN output value is low, it will be driven low as usual. But +if the IN output value is set to high, it will instead *NOT* be driven high, +instead it will be switched to input, as input mode is high impedance, thus +achieveing an "open drain emulation" of sorts: electrically the behaviour will +be identical, with the exception of possible hardware glitches when switching +the mode of the line. + +For open source configuration the same principle is used, just that instead +of actively driving the line low, it is set to input. + + GPIO drivers providing IRQs --------------------------- It is custom that GPIO drivers (GPIO chips) are also providing interrupts, |