path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 09:40:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 10:09:12 -0800
commit8e5096607280d4e103389bfe8f8b7decbf538ff6 (patch)
tree60352a466e96c7b36d41263d7590ee79e0aaff35 /Documentation
parent02d0a752460ea5dab34ce36c9ddc9c682e846a0d (diff)
parentde755c330512364d3396c7da0c20b1c20b3b08b2 (diff)
Merge tag 'gpio-v3.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull GPIO tree bulk changes from Linus Walleij: "A big set this merge window, as we have much going on in this subsystem. The changes to other subsystems (notably a slew of ARM machines as I am doing away with their custom APIs) have all been ACKed to the extent possible. Major changes this time: - Some core improvements and cleanups to the new GPIO descriptor API. This seems to be working now so we can start the exodus to this API, moving gradually away from the global GPIO numberspace. - Incremental improvements to the ACPI GPIO core, and move the few GPIO ACPI clients we have to the GPIO descriptor API right *now* before we go any further. We actually managed to contain this *before* we started to litter the kernel with yet another hackish global numberspace for the ACPI GPIOs, which is a big win. - The RFkill GPIO driver and all platforms using it have been migrated to use the GPIO descriptors rather than fixed number assignments. Tegra machine has been migrated as part of this. - New drivers for MOXA ART, Xtensa GPIO32 and SMSC SCH311x. Those should be really good examples of how I expect a nice GPIO driver to look these days. - Do away with custom GPIO implementations on a major part of the ARM machines: ks8695, lpc32xx, mv78xx0. Make a first step towards the same in the horribly convoluted Samsung S3C include forest. We expect to continue to clean this up as we move forward. - Flag GPIO lines used for IRQ on adnp, bcm-kona, em, intel-mid and lynxpoint. This makes the GPIOlib core aware that a certain GPIO line is used for IRQs and can then enforce some semantics such as disallowing a GPIO line marked as in use for IRQ to be switched to output mode. - Drop all use of irq_set_chip_and_handler_name(). The name provided in these cases were just unhelpful tags like "mux" or "demux". - Extend the MCP23s08 driver to handle interrupts. - Minor incremental improvements for rcar, lynxpoint, em 74x164 and msm drivers. - Some non-urgent bug fixes here and there, duplicate #includes and that usual kind of cleanups" Fix up broken Kconfig file manually to make this all compile. * tag 'gpio-v3.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (71 commits) gpio: mcp23s08: fix casting caused build warning gpio: mcp23s08: depend on OF_GPIO gpio: mcp23s08: Add irq functionality for i2c chips ARM: S5P[v210|c100|64x0]: Fix build error gpio: pxa: clamp gpio get value to [0,1] ARM: s3c24xx: explicit dependency on <plat/gpio-cfg.h> ARM: S3C[24|64]xx: move includes back under <mach/> scope Documentation / ACPI: update to GPIO descriptor API gpio / ACPI: get rid of acpi_gpio.h gpio / ACPI: register to ACPI events automatically mmc: sdhci-acpi: convert to use GPIO descriptor API ARM: s3c24xx: fix build error gpio: f7188x: set can_sleep attribute gpio: samsung: Update documentation gpio: samsung: Remove hardware.h inclusion gpio: xtensa: depend on HAVE_XTENSA_GPIO32 gpio: clps711x: Enable driver compilation with COMPILE_TEST gpio: clps711x: Use of_match_ptr() net: rfkill: gpio: convert to descriptor-based GPIO interface leds: s3c24xx: Fix build failure ...
Diffstat (limited to 'Documentation')
7 files changed, 78 insertions, 55 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index b994bcb32b92..2a1519b87177 100644
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -293,36 +293,13 @@ the device to the driver. For example:
These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
specifies the path to the controller. In order to use these GPIOs in Linux
-we need to translate them to the Linux GPIO numbers.
+we need to translate them to the corresponding Linux GPIO descriptors.
-In a simple case of just getting the Linux GPIO number from device
-resources one can use acpi_get_gpio_by_index() helper function. It takes
-pointer to the device and index of the GpioIo/GpioInt descriptor in the
-device resources list. For example:
+There is a standard GPIO API for that and is documented in
- int gpio_irq, gpio_power;
- int ret;
- gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
- if (gpio_irq < 0)
- /* handle error */
- gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
- if (gpio_power < 0)
- /* handle error */
- /* Now we can use the GPIO numbers */
-Other GpioIo parameters must be converted first by the driver to be
-suitable to the gpiolib before passing them.
-In case of GpioInt resource an additional call to gpio_to_irq() must be
-done before calling request_irq().
-Note that the above API is ACPI specific and not recommended for drivers
-that need to support non-ACPI systems. The recommended way is to use
-the descriptor based GPIO interfaces. The above example looks like this
-when converted to the GPIO desc:
+In the above example we can get the corresponding two GPIO descriptors with
+a code like this:
#include <linux/gpio/consumer.h>
@@ -339,4 +316,5 @@ when converted to the GPIO desc:
/* Now we can use the GPIO descriptors */
-See also Documentation/gpio.txt.
+There are also devm_* versions of these functions which release the
+descriptors once the device is released.
diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt
index 8b46c79679c4..0ebd7e2244d0 100644
--- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt
+++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt
@@ -85,21 +85,10 @@ between the calls.
- See arch/arm/mach-s3c2410/include/mach/regs-gpio.h for the list
+ See arch/arm/mach-s3c24xx/include/mach/regs-gpio.h for the list
of GPIO pins, and the configuration values for them. This
is included by using #include <mach/regs-gpio.h>
- The GPIO management functions are defined in the hardware
- header arch/arm/mach-s3c2410/include/mach/hardware.h which can be
- included by #include <mach/hardware.h>
- A useful amount of documentation can be found in the hardware
- header on how the GPIO functions (and others) work.
- Whilst a number of these functions do make some checks on what
- is passed to them, for speed of use, they may not always ensure
- that the user supplied data to them is correct.
PIN Numbers
diff --git a/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt
index daa30174bcc1..3ddc7ccfe5f3 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-mcp23s08.txt
@@ -38,12 +38,38 @@ Required device specific properties (only for SPI chips):
- spi-max-frequency = The maximum frequency this chip is able to handle
-Example I2C:
+Optional properties:
+- #interrupt-cells : Should be two.
+ - first cell is the pin number
+ - second cell is used to specify flags.
+- interrupt-controller: Marks the device node as a interrupt controller.
+NOTE: The interrupt functionality is only supported for i2c versions of the
+chips. The spi chips can also do the interrupts, but this is not supported by
+the linux driver yet.
+Optional device specific properties:
+- microchip,irq-mirror: Sets the mirror flag in the IOCON register. Devices
+ with two interrupt outputs (these are the devices ending with 17 and
+ those that have 16 IOs) have two IO banks: IO 0-7 form bank 1 and
+ IO 8-15 are bank 2. These chips have two different interrupt outputs:
+ One for bank 1 and another for bank 2. If irq-mirror is set, both
+ interrupts are generated regardless of the bank that an input change
+ occured on. If it is not set, the interrupt are only generated for the
+ bank they belong to.
+ On devices with only one interrupt output this property is useless.
+Example I2C (with interrupt):
gpiom1: gpio@20 {
compatible = "microchip,mcp23017";
#gpio-cells = <2>;
reg = <0x20>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <17 IRQ_TYPE_LEVEL_LOW>;
+ interrupt-controller;
+ #interrupt-cells=<2>;
+ microchip,irq-mirror;
Example SPI:
diff --git a/Documentation/devicetree/bindings/gpio/moxa,moxart-gpio.txt b/Documentation/devicetree/bindings/gpio/moxa,moxart-gpio.txt
new file mode 100644
index 000000000000..f8e8f185a3db
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/moxa,moxart-gpio.txt
@@ -0,0 +1,19 @@
+MOXA ART GPIO Controller
+Required properties:
+- #gpio-cells : Should be 2, The first cell is the pin number,
+ the second cell is used to specify polarity:
+ 0 = active high
+ 1 = active low
+- compatible : Must be "moxa,moxart-gpio"
+- reg : Should contain registers location and length
+ gpio: gpio@98700000 {
+ gpio-controller;
+ #gpio-cells = <2>;
+ compatible = "moxa,moxart-gpio";
+ reg = <0x98700000 0xC>;
+ };
diff --git a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
index 8655df9440d5..f61cef74a212 100644
--- a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
+++ b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
@@ -2,10 +2,11 @@
Required Properties:
- - compatible: should be one of the following.
+ - compatible: should contain one of the following.
- "renesas,gpio-r8a7778": for R8A7778 (R-Mobile M1) compatible GPIO controller.
- "renesas,gpio-r8a7779": for R8A7779 (R-Car H1) compatible GPIO controller.
- "renesas,gpio-r8a7790": for R8A7790 (R-Car H2) compatible GPIO controller.
+ - "renesas,gpio-r8a7791": for R8A7791 (R-Car M2) 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/gpio/board.txt b/Documentation/gpio/board.txt
index 0d03506f2cc5..ba169faad5c6 100644
--- a/Documentation/gpio/board.txt
+++ b/Documentation/gpio/board.txt
@@ -72,10 +72,11 @@ where
- chip_label is the label of the gpiod_chip instance providing the GPIO
- chip_hwnum is the hardware number of the GPIO within the chip
- - dev_id is the identifier of the device that will make use of this GPIO. If
- NULL, the GPIO will be available to all devices.
+ - dev_id is the identifier of the device that will make use of this GPIO. It
+ can be NULL, in which case it will be matched for calls to gpiod_get()
+ with a NULL device.
- con_id is the name of the GPIO function from the device point of view. It
- can be NULL.
+ can be NULL, in which case it will match any function.
- idx is the index of the GPIO within the function.
- flags is defined to specify the following properties:
* GPIOF_ACTIVE_LOW - to configure the GPIO as active-low
@@ -86,18 +87,23 @@ In the future, these flags might be extended to support more properties.
Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0.
-A lookup table can then be defined as follows:
+A lookup table can then be defined as follows, with an empty entry defining its
- struct gpiod_lookup gpios_table[] = {
- GPIO_LOOKUP_IDX("gpio.0", 15, "foo.0", "led", 0, GPIO_ACTIVE_HIGH),
- GPIO_LOOKUP_IDX("gpio.0", 16, "foo.0", "led", 1, GPIO_ACTIVE_HIGH),
- GPIO_LOOKUP_IDX("gpio.0", 17, "foo.0", "led", 2, GPIO_ACTIVE_HIGH),
- GPIO_LOOKUP("gpio.0", 1, "foo.0", "power", GPIO_ACTIVE_LOW),
- };
+struct gpiod_lookup_table gpios_table = {
+ .dev_id = "foo.0",
+ .table = {
+ GPIO_LOOKUP_IDX("gpio.0", 15, "led", 0, GPIO_ACTIVE_HIGH),
+ GPIO_LOOKUP_IDX("gpio.0", 16, "led", 1, GPIO_ACTIVE_HIGH),
+ GPIO_LOOKUP_IDX("gpio.0", 17, "led", 2, GPIO_ACTIVE_HIGH),
+ GPIO_LOOKUP("gpio.0", 1, "power", GPIO_ACTIVE_LOW),
+ { },
+ },
And the table can be added by the board code as follows:
- gpiod_add_table(gpios_table, ARRAY_SIZE(gpios_table));
+ gpiod_add_lookup_table(&gpios_table);
The driver controlling "foo.0" will then be able to obtain its GPIOs as follows:
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 07c74a3765a0..e42f77d8d4ca 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -38,7 +38,11 @@ device that displays digits), an additional index argument can be specified:
const char *con_id, unsigned int idx)
Both functions return either a valid GPIO descriptor, or an error code checkable
-with IS_ERR(). They will never return a NULL pointer.
+with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
+if and only if no GPIO has been assigned to the device/function/index triplet,
+other error codes are used for cases where a GPIO has been assigned but an error
+occured while trying to acquire it. This is useful to discriminate between mere
+errors and an absence of GPIO for optional GPIO parameters.
Device-managed variants of these functions are also defined: