diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-08 18:00:35 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-08 18:00:35 -0700 |
commit | 06b49ea43c0cdd22625883e555e45e66ef29e201 (patch) | |
tree | 9c72c88541e2bec5a95354504708a066fd8e50aa /Documentation | |
parent | 664fb23070ae66a023250a83870a5bae7cd0efeb (diff) | |
parent | bdc6e95e1273b5cef01590273c1a240c53ceeea0 (diff) |
Merge tag 'gpio-v3.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull GPIO update from Linus Walleij:
"This is the bulk of GPIO changes for the v3.17 development cycle, and
this time we got a lot of action going on and it will continue:
- The core GPIO library implementation has been split up in three
different files:
- gpiolib.c for the latest and greatest and shiny GPIO library code
using GPIO descriptors only
- gpiolib-legacy.c for the old integer number space API that we are
phasing out gradually
- gpiolib-sysfs.c for the sysfs interface that we are not entirely
happy with, but has to live on for ABI compatibility
- Add a flags argument to *gpiod_get* functions, with some
backward-compatibility macros to ease transitions. We should have
had the flags there from the beginning it seems, now we need to
clean up the mess. There is a plan on how to move forward here
devised by Alexandre Courbot and Mark Brown
- Split off a special <linux/gpio/machine.h> header for the board
gpio table registration, as per example from the regulator
subsystem
- Start to kill off the return value from gpiochip_remove() by
removing the __must_check attribute and removing all checks inside
the drivers/gpio directory. The rationale is: well what were we
supposed to do if there is an error code? Not much: print an error
message. And gpiolib already does that. So make this function
return void eventually
- Some cleanups of hairy gpiolib code, make some functions not to be
used outside the library private and make sure they are not
exported, remove gpiod_lock/unlock_as_irq() as the existing
function is for driver-internal use and fine as it is, delete
gpio_ensure_requested() as it is not meaningful anymore
- Support the GPIOF_ACTIVE_LOW flag from gpio_request_one() function
calls, which is logical since this is already supported when
referencing GPIOs from e.g. device trees
- Switch STMPE, intel-mid, lynxpoint and ACPI (!) to use the gpiolib
irqchip helpers cutting down on GPIO irqchip boilerplate a bit more
- New driver for the Zynq GPIO block
- The usual incremental improvements around a bunch of drivers
- Janitorial syntactic and semantic cleanups by Jingoo Han, and
Rickard Strandqvist especially"
* tag 'gpio-v3.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (37 commits)
MAINTAINERS: update GPIO include files
gpio: add missing includes in machine.h
gpio: add flags argument to gpiod_get*() functions
MAINTAINERS: Update Samsung pin control entry
gpio / ACPI: Move event handling registration to gpiolib irqchip helpers
gpio: lynxpoint: Convert to use gpiolib irqchip
gpio: split gpiod board registration into machine header
gpio: remove gpio_ensure_requested()
gpio: remove useless check in gpiolib_sysfs_init()
gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc
gpio: move gpio_ensure_requested() into legacy C file
gpio: remove gpiod_lock/unlock_as_irq()
gpio: make gpiochip_get_desc() gpiolib-private
gpio: simplify gpiochip_export()
gpio: remove export of private of_get_named_gpio_flags()
gpio: Add support for GPIOF_ACTIVE_LOW to gpio_request_one functions
gpio: zynq: Clear pending interrupt when enabling a IRQ
gpio: drop retval check enforcing from gpiochip_remove()
gpio: remove all usage of gpio_remove retval in driver/gpio
devicetree: Add Zynq GPIO devicetree bindings documentation
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-zynq.txt | 26 | ||||
-rw-r--r-- | Documentation/gpio/board.txt | 2 | ||||
-rw-r--r-- | Documentation/gpio/consumer.txt | 26 | ||||
-rw-r--r-- | Documentation/gpio/driver.txt | 25 |
4 files changed, 70 insertions, 9 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio-zynq.txt b/Documentation/devicetree/bindings/gpio/gpio-zynq.txt new file mode 100644 index 000000000000..986371a4be2c --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-zynq.txt @@ -0,0 +1,26 @@ +Xilinx Zynq GPIO controller Device Tree Bindings +------------------------------------------- + +Required properties: +- #gpio-cells : Should be two + - First cell is the GPIO line number + - Second cell is used to specify optional + parameters (unused) +- compatible : Should be "xlnx,zynq-gpio-1.0" +- clocks : Clock specifier (see clock bindings for details) +- gpio-controller : Marks the device node as a GPIO controller. +- interrupts : Interrupt specifier (see interrupt bindings for + details) +- interrupt-parent : Must be core interrupt controller +- reg : Address and length of the register set for the device + +Example: + gpio@e000a000 { + #gpio-cells = <2>; + compatible = "xlnx,zynq-gpio-1.0"; + clocks = <&clkc 42>; + gpio-controller; + interrupt-parent = <&intc>; + interrupts = <0 20 4>; + reg = <0xe000a000 0x1000>; + }; diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index ba169faad5c6..4452786225b8 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -60,7 +60,7 @@ Platform Data Finally, GPIOs can be bound to devices and functions using platform data. Board files that desire to do so need to include the following header: - #include <linux/gpio/driver.h> + #include <linux/gpio/machine.h> GPIOs are mapped by the means of tables of lookups, containing instances of the gpiod_lookup structure. Two macros are defined to help declaring such mappings: diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt index d8abfc31abbe..76546324e968 100644 --- a/Documentation/gpio/consumer.txt +++ b/Documentation/gpio/consumer.txt @@ -29,13 +29,24 @@ gpiod_get() functions. Like many other kernel subsystems, gpiod_get() takes the device that will use the GPIO and the function the requested GPIO is supposed to fulfill: - struct gpio_desc *gpiod_get(struct device *dev, const char *con_id) + struct gpio_desc *gpiod_get(struct device *dev, const char *con_id, + enum gpiod_flags flags) If a function is implemented by using several GPIOs together (e.g. a simple LED device that displays digits), an additional index argument can be specified: struct gpio_desc *gpiod_get_index(struct device *dev, - const char *con_id, unsigned int idx) + const char *con_id, unsigned int idx, + enum gpiod_flags flags) + +The flags parameter is used to optionally specify a direction and initial value +for the GPIO. Values can be: + +* GPIOD_ASIS or 0 to not initialize the GPIO at all. The direction must be set + later with one of the dedicated functions. +* GPIOD_IN to initialize the GPIO as input. +* GPIOD_OUT_LOW to initialize the GPIO as output with a value of 0. +* GPIOD_OUT_HIGH to initialize the GPIO as output with a value of 1. Both functions return either a valid GPIO descriptor, or an error code checkable with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned @@ -46,11 +57,13 @@ errors and an absence of GPIO for optional GPIO parameters. Device-managed variants of these functions are also defined: - struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id) + struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id, + enum gpiod_flags flags) struct gpio_desc *devm_gpiod_get_index(struct device *dev, const char *con_id, - unsigned int idx) + unsigned int idx, + enum gpiod_flags flags) A GPIO descriptor can be disposed of using the gpiod_put() function: @@ -67,8 +80,9 @@ Using GPIOs Setting Direction ----------------- -The first thing a driver must do with a GPIO is setting its direction. This is -done by invoking one of the gpiod_direction_*() functions: +The first thing a driver must do with a GPIO is setting its direction. If no +direction-setting flags have been given to gpiod_get*(), this is done by +invoking one of the gpiod_direction_*() functions: int gpiod_direction_input(struct gpio_desc *desc) int gpiod_direction_output(struct gpio_desc *desc, int value) diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt index fa9a0a8b3734..18790c237977 100644 --- a/Documentation/gpio/driver.txt +++ b/Documentation/gpio/driver.txt @@ -157,13 +157,34 @@ Locking IRQ usage Input GPIOs can be used as IRQ signals. When this happens, a driver is requested to mark the GPIO as being used as an IRQ: - int gpiod_lock_as_irq(struct gpio_desc *desc) + int gpio_lock_as_irq(struct gpio_chip *chip, unsigned int offset) This will prevent the use of non-irq related GPIO APIs until the GPIO IRQ lock is released: - void gpiod_unlock_as_irq(struct gpio_desc *desc) + void gpio_unlock_as_irq(struct gpio_chip *chip, unsigned int offset) When implementing an irqchip inside a GPIO driver, these two functions should typically be called in the .startup() and .shutdown() callbacks from the irqchip. + + +Requesting self-owned GPIO pins +------------------------------- + +Sometimes it is useful to allow a GPIO chip driver to request its own GPIO +descriptors through the gpiolib API. Using gpio_request() for this purpose +does not help since it pins the module to the kernel forever (it calls +try_module_get()). A GPIO driver can use the following functions instead +to request and free descriptors without being pinned to the kernel forever. + + int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label) + + void gpiochip_free_own_desc(struct gpio_desc *desc) + +Descriptors requested with gpiochip_request_own_desc() must be released with +gpiochip_free_own_desc(). + +These functions must be used with care since they do not affect module use +count. Do not use the functions to request gpio descriptors not owned by the +calling driver. |