diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-gpio | 3 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt | 35 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-etraxfs.txt | 3 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt | 22 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt | 1 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/zx296702-gpio.txt | 24 | ||||
| -rw-r--r-- | Documentation/gpio/00-INDEX | 3 | ||||
| -rw-r--r-- | Documentation/gpio/drivers-on-gpio.txt | 95 | ||||
| -rw-r--r-- | Documentation/gpio/sysfs.txt | 9 |
9 files changed, 181 insertions, 14 deletions
diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio index 80f4c94c7bef..55ffa2df1c10 100644 --- a/Documentation/ABI/testing/sysfs-gpio +++ b/Documentation/ABI/testing/sysfs-gpio @@ -16,7 +16,8 @@ Description: /sys/class/gpio /export ... asks the kernel to export a GPIO to userspace /unexport ... to return a GPIO to the kernel - /gpioN ... for each exported GPIO #N + /gpioN ... for each exported GPIO #N OR + /<LINE-NAME> ... for a properly named GPIO line /value ... always readable, writes fail for input GPIOs /direction ... r/w as: in, out (default low); write: high, low /edge ... r/w as: none, falling, rising, both diff --git a/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt b/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt index 435f1bcca341..b405b4410bfb 100644 --- a/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt +++ b/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt @@ -33,6 +33,13 @@ Optional properties: - interrupt-parent: phandle of the parent interrupt controller +- interrupts-extended: + Alternate form of specifying interrupts and parents that allows for + multiple parents. This takes precedence over 'interrupts' and + 'interrupt-parent'. Wakeup-capable GPIO controllers often route their + wakeup interrupt lines through a different interrupt controller than the + primary interrupt line, making this property necessary. + - #interrupt-cells: Should be <2>. The first cell is the GPIO number, the second should specify flags. The following subset of flags is supported: @@ -47,19 +54,33 @@ Optional properties: - interrupt-controller: Marks the device node as an interrupt controller -- interrupt-names: - The name of the IRQ resource used by this controller +- wakeup-source: + GPIOs for this controller can be used as a wakeup source Example: upg_gio: gpio@f040a700 { - #gpio-cells = <0x2>; - #interrupt-cells = <0x2>; + #gpio-cells = <2>; + #interrupt-cells = <2>; compatible = "brcm,bcm7445-gpio", "brcm,brcmstb-gpio"; gpio-controller; interrupt-controller; reg = <0xf040a700 0x80>; - interrupt-parent = <0xf>; + interrupt-parent = <&irq0_intc>; + interrupts = <0x6>; + brcm,gpio-bank-widths = <32 32 32 24>; + }; + + upg_gio_aon: gpio@f04172c0 { + #gpio-cells = <2>; + #interrupt-cells = <2>; + compatible = "brcm,bcm7445-gpio", "brcm,brcmstb-gpio"; + gpio-controller; + interrupt-controller; + reg = <0xf04172c0 0x40>; + interrupt-parent = <&irq0_aon_intc>; interrupts = <0x6>; - interrupt-names = "upg_gio"; - brcm,gpio-bank-widths = <0x20 0x20 0x20 0x18>; + interrupts-extended = <&irq0_aon_intc 0x6>, + <&aon_pm_l2_intc 0x5>; + wakeup-source; + brcm,gpio-bank-widths = <18 4>; }; diff --git a/Documentation/devicetree/bindings/gpio/gpio-etraxfs.txt b/Documentation/devicetree/bindings/gpio/gpio-etraxfs.txt index abf4db736c6e..170194af3027 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-etraxfs.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-etraxfs.txt @@ -2,8 +2,9 @@ Axis ETRAX FS General I/O controller bindings Required properties: -- compatible: +- compatible: one of: - "axis,etraxfs-gio" + - "axis,artpec3-gio" - reg: Physical base address and length of the controller's registers. - #gpio-cells: Should be 3 - The first cell is the gpio offset number. diff --git a/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt b/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt new file mode 100644 index 000000000000..805ddcd79a57 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-mpc8xxx.txt @@ -0,0 +1,22 @@ +* Freescale MPC512x/MPC8xxx 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 +- 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 + the second cell is used to specify the gpio polarity: + 0 = active high + 1 = active low + +Example: + +gpio0: gpio@1100 { + compatible = "fsl,mpc5125-gpio"; + #gpio-cells = <2>; + reg = <0x1100 0x080>; + interrupts = <78 0x8>; + status = "okay"; +}; diff --git a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt index 38fb86f28ba2..f60e2f477e93 100644 --- a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt +++ b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt @@ -9,6 +9,7 @@ Required Properties: - "renesas,gpio-r8a7791": for R8A7791 (R-Car M2-W) compatible GPIO controller. - "renesas,gpio-r8a7793": for R8A7793 (R-Car M2-N) compatible GPIO controller. - "renesas,gpio-r8a7794": for R8A7794 (R-Car E2) compatible GPIO controller. + - "renesas,gpio-r8a7795": for R8A7795 (R-Car H3) compatible GPIO controller. - "renesas,gpio-rcar": for generic R-Car GPIO controller. - reg: Base address and length of each memory resource used by the GPIO diff --git a/Documentation/devicetree/bindings/gpio/zx296702-gpio.txt b/Documentation/devicetree/bindings/gpio/zx296702-gpio.txt new file mode 100644 index 000000000000..0dab156fcf41 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/zx296702-gpio.txt @@ -0,0 +1,24 @@ +ZTE ZX296702 GPIO controller + +Required properties: +- compatible : "zte,zx296702-gpio" +- #gpio-cells : Should be two. The first cell is the pin number and the + second cell is used to specify optional parameters: + - bit 0 specifies polarity (0 for normal, 1 for inverted) +- gpio-controller : Marks the device node as a GPIO controller. +- interrupts : Interrupt mapping for GPIO IRQ. +- gpio-ranges : Interaction with the PINCTRL subsystem. + +gpio1: gpio@b008040 { + compatible = "zte,zx296702-gpio"; + reg = <0xb008040 0x40>; + gpio-controller; + #gpio-cells = <2>; + gpio-ranges = < &pmx0 0 54 2 &pmx0 2 59 14>; + interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>; + interrupt-parent = <&intc>; + interrupt-controller; + #interrupt-cells = <2>; + clock-names = "gpio_pclk"; + clocks = <&lsp0clk ZX296702_GPIO_CLK>; +}; diff --git a/Documentation/gpio/00-INDEX b/Documentation/gpio/00-INDEX index 1de43ae46ae6..179beb234f98 100644 --- a/Documentation/gpio/00-INDEX +++ b/Documentation/gpio/00-INDEX @@ -6,6 +6,9 @@ consumer.txt - How to obtain and use GPIOs in a driver driver.txt - How to write a GPIO driver +drivers-on-gpio.txt: + - Drivers in other subsystems that can use GPIO to provide more + complex functionality. board.txt - How to assign GPIOs to a consumer device and a function sysfs.txt diff --git a/Documentation/gpio/drivers-on-gpio.txt b/Documentation/gpio/drivers-on-gpio.txt new file mode 100644 index 000000000000..f6121328630f --- /dev/null +++ b/Documentation/gpio/drivers-on-gpio.txt @@ -0,0 +1,95 @@ +Subsystem drivers using GPIO +============================ + +Note that standard kernel drivers exist for common GPIO tasks and will provide +the right in-kernel and userspace APIs/ABIs for the job, and that these +drivers can quite easily interconnect with other kernel subsystems using +hardware descriptions such as device tree or ACPI: + +- leds-gpio: drivers/leds/leds-gpio.c will handle LEDs connected to GPIO + lines, giving you the LED sysfs interface + +- ledtrig-gpio: drivers/leds/trigger/ledtrig-gpio.c will provide a LED trigger, + i.e. a LED will turn on/off in response to a GPIO line going high or low + (and that LED may in turn use the leds-gpio as per above). + +- gpio-keys: drivers/input/keyboard/gpio_keys.c is used when your GPIO line + can generate interrupts in response to a key press. Also supports debounce. + +- gpio-keys-polled: drivers/input/keyboard/gpio_keys_polled.c is used when your + GPIO line cannot generate interrupts, so it needs to be periodically polled + by a timer. + +- gpio_mouse: drivers/input/mouse/gpio_mouse.c is used to provide a mouse with + up to three buttons by simply using GPIOs and no mouse port. You can cut the + mouse cable and connect the wires to GPIO lines or solder a mouse connector + to the lines for a more permanent solution of this type. + +- gpio-beeper: drivers/input/misc/gpio-beeper.c is used to provide a beep from + an external speaker connected to a GPIO line. + +- gpio-tilt-polled: drivers/input/misc/gpio_tilt_polled.c provides tilt + detection switches using GPIO, which is useful for your homebrewn pinball + machine if for nothing else. It can detect different tilt angles of the + monitored object. + +- extcon-gpio: drivers/extcon/extcon-gpio.c is used when you need to read an + external connector status, such as a headset line for an audio driver or an + HDMI connector. It will provide a better userspace sysfs interface than GPIO. + +- restart-gpio: drivers/power/gpio-restart.c is used to restart/reboot the + system by pulling a GPIO line and will register a restart handler so + userspace can issue the right system call to restart the system. + +- poweroff-gpio: drivers/power/gpio-poweroff.c is used to power the system down + by pulling a GPIO line and will register a pm_power_off() callback so that + userspace can issue the right system call to power down the system. + +- gpio-gate-clock: drivers/clk/clk-gpio-gate.c is used to control a gated clock + (off/on) that uses a GPIO, and integrated with the clock subsystem. + +- i2c-gpio: drivers/i2c/busses/i2c-gpio.c is used to drive an I2C bus + (two wires, SDA and SCL lines) by hammering (bitbang) two GPIO lines. It will + appear as any other I2C bus to the system and makes it possible to connect + drivers for the I2C devices on the bus like any other I2C bus driver. + +- spi_gpio: drivers/spi/spi-gpio.c is used to drive an SPI bus (variable number + of wires, atleast SCK and optionally MISO, MOSI and chip select lines) using + GPIO hammering (bitbang). It will appear as any other SPI bus on the system + and makes it possible to connect drivers for SPI devices on the bus like + any other SPI bus driver. For example any MMC/SD card can then be connected + to this SPI by using the mmc_spi host from the MMC/SD card subsystem. + +- w1-gpio: drivers/w1/masters/w1-gpio.c is used to drive a one-wire bus using + a GPIO line, integrating with the W1 subsystem and handling devices on + the bus like any other W1 device. + +- gpio-fan: drivers/hwmon/gpio-fan.c is used to control a fan for cooling the + system, connected to a GPIO line (and optionally a GPIO alarm line), + presenting all the right in-kernel and sysfs interfaces to make your system + not overheat. + +- gpio-regulator: drivers/regulator/gpio-regulator.c is used to control a + regulator providing a certain voltage by pulling a GPIO line, integrating + with the regulator subsystem and giving you all the right interfaces. + +- gpio-wdt: drivers/watchdog/gpio_wdt.c is used to provide a watchdog timer + that will periodically "ping" a hardware connected to a GPIO line by toggling + it from 1-to-0-to-1. If that hardware does not recieve its "ping" + periodically, it will reset the system. + +- gpio-nand: drivers/mtd/nand/gpio.c is used to connect a NAND flash chip to + a set of simple GPIO lines: RDY, NCE, ALE, CLE, NWP. It interacts with the + NAND flash MTD subsystem and provides chip access and partition parsing like + any other NAND driving hardware. + +Apart from this there are special GPIO drivers in subsystems like MMC/SD to +read card detect and write protect GPIO lines, and in the TTY serial subsystem +to emulate MCTRL (modem control) signals CTS/RTS by using two GPIO lines. The +MTD NOR flash has add-ons for extra GPIO lines too, though the address bus is +usually connected directly to the flash. + +Use those instead of talking directly to the GPIOs using sysfs; they integrate +with kernel frameworks better than your userspace code could. Needless to say, +just using the apropriate kernel drivers will simplify and speed up your +embedded hacking in particular by providing ready-made components. diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt index 535b6a8a7a7c..0700b55637f5 100644 --- a/Documentation/gpio/sysfs.txt +++ b/Documentation/gpio/sysfs.txt @@ -20,11 +20,10 @@ userspace GPIO can be used to determine system configuration data that standard kernels won't know about. And for some tasks, simple userspace GPIO drivers could be all that the system really needs. -Note that standard kernel drivers exist for common "LEDs and Buttons" -GPIO tasks: "leds-gpio" and "gpio_keys", respectively. Use those -instead of talking directly to the GPIOs; they integrate with kernel -frameworks better than your userspace code could. - +DO NOT ABUSE SYFS TO CONTROL HARDWARE THAT HAS PROPER KERNEL DRIVERS. +PLEASE READ THE DOCUMENT NAMED "drivers-on-gpio.txt" IN THIS DOCUMENTATION +DIRECTORY TO AVOID REINVENTING KERNEL WHEELS IN USERSPACE. I MEAN IT. +REALLY. Paths in Sysfs -------------- |
