[PATCH v4 08/63] Documentation: ACPI: move gpio-properties.txt to firmware-guide/acpi and convert to reST
Mauro Carvalho Chehab
mchehab+samsung at kernel.org
Wed Apr 24 06:55:15 AEST 2019
Em Wed, 24 Apr 2019 00:28:37 +0800
Changbin Du <changbin.du at gmail.com> escreveu:
> This converts the plain text documentation to reStructuredText format and
> add it to Sphinx TOC tree. No essential content change.
>
> Signed-off-by: Changbin Du <changbin.du at gmail.com>
> ---
> .../acpi/gpio-properties.rst} | 78 +++++++++++--------
> Documentation/firmware-guide/acpi/index.rst | 1 +
> MAINTAINERS | 2 +-
> 3 files changed, 46 insertions(+), 35 deletions(-)
> rename Documentation/{acpi/gpio-properties.txt => firmware-guide/acpi/gpio-properties.rst} (81%)
>
> diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/firmware-guide/acpi/gpio-properties.rst
> similarity index 81%
> rename from Documentation/acpi/gpio-properties.txt
> rename to Documentation/firmware-guide/acpi/gpio-properties.rst
> index 88c65cb5bf0a..89c636963544 100644
> --- a/Documentation/acpi/gpio-properties.txt
> +++ b/Documentation/firmware-guide/acpi/gpio-properties.rst
> @@ -1,5 +1,8 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +======================================
> _DSD Device Properties Related to GPIO
> ---------------------------------------
> +======================================
>
> With the release of ACPI 5.1, the _DSD configuration object finally
> allows names to be given to GPIOs (and other things as well) returned
> @@ -8,7 +11,7 @@ the corresponding GPIO, which is pretty error prone (it depends on
> the _CRS output ordering, for example).
>
> With _DSD we can now query GPIOs using a name instead of an integer
> -index, like the ASL example below shows:
> +index, like the ASL example below shows::
>
> // Bluetooth device with reset and shutdown GPIOs
> Device (BTH)
> @@ -34,15 +37,19 @@ index, like the ASL example below shows:
> })
> }
>
> -The format of the supported GPIO property is:
> +The format of the supported GPIO property is::
>
> Package () { "name", Package () { ref, index, pin, active_low }}
>
> - ref - The device that has _CRS containing GpioIo()/GpioInt() resources,
> - typically this is the device itself (BTH in our case).
> - index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
> - pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
> - active_low - If 1 the GPIO is marked as active_low.
> +ref
> + The device that has _CRS containing GpioIo()/GpioInt() resources,
> + typically this is the device itself (BTH in our case).
> +index
> + Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
> +pin
> + Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
> +active_low
> + If 1 the GPIO is marked as active_low.
>
> Since ACPI GpioIo() resource does not have a field saying whether it is
> active low or high, the "active_low" argument can be used here. Setting
> @@ -55,7 +62,7 @@ It is possible to leave holes in the array of GPIOs. This is useful in
> cases like with SPI host controllers where some chip selects may be
> implemented as GPIOs and some as native signals. For example a SPI host
> controller can have chip selects 0 and 2 implemented as GPIOs and 1 as
> -native:
> +native::
>
> Package () {
> "cs-gpios",
> @@ -67,7 +74,7 @@ native:
> }
>
> Other supported properties
> ---------------------------
> +==========================
>
> Following Device Tree compatible device properties are also supported by
> _DSD device properties for GPIO controllers:
> @@ -78,7 +85,7 @@ _DSD device properties for GPIO controllers:
> - input
> - line-name
>
> -Example:
> +Example::
>
> Name (_DSD, Package () {
> // _DSD Hierarchical Properties Extension UUID
> @@ -100,7 +107,7 @@ Example:
>
> - gpio-line-names
>
> -Example:
> +Example::
>
> Package () {
> "gpio-line-names",
> @@ -114,7 +121,7 @@ See Documentation/devicetree/bindings/gpio/gpio.txt for more information
> about these properties.
>
> ACPI GPIO Mappings Provided by Drivers
> ---------------------------------------
> +======================================
>
> There are systems in which the ACPI tables do not contain _DSD but provide _CRS
> with GpioIo()/GpioInt() resources and device drivers still need to work with
> @@ -139,16 +146,16 @@ line in that resource starting from zero, and the active-low flag for that line,
> respectively, in analogy with the _DSD GPIO property format specified above.
>
> For the example Bluetooth device discussed previously the data structures in
> -question would look like this:
> +question would look like this::
>
> -static const struct acpi_gpio_params reset_gpio = { 1, 1, false };
> -static const struct acpi_gpio_params shutdown_gpio = { 0, 0, false };
> + static const struct acpi_gpio_params reset_gpio = { 1, 1, false };
> + static const struct acpi_gpio_params shutdown_gpio = { 0, 0, false };
>
> -static const struct acpi_gpio_mapping bluetooth_acpi_gpios[] = {
> - { "reset-gpios", &reset_gpio, 1 },
> - { "shutdown-gpios", &shutdown_gpio, 1 },
> - { },
> -};
> + static const struct acpi_gpio_mapping bluetooth_acpi_gpios[] = {
> + { "reset-gpios", &reset_gpio, 1 },
> + { "shutdown-gpios", &shutdown_gpio, 1 },
> + { },
> + };
>
> Next, the mapping table needs to be passed as the second argument to
> acpi_dev_add_driver_gpios() that will register it with the ACPI device object
> @@ -158,12 +165,12 @@ calling acpi_dev_remove_driver_gpios() on the ACPI device object where that
> table was previously registered.
>
> Using the _CRS fallback
> ------------------------
> +=======================
>
> If a device does not have _DSD or the driver does not create ACPI GPIO
> mapping, the Linux GPIO framework refuses to return any GPIOs. This is
> because the driver does not know what it actually gets. For example if we
> -have a device like below:
> +have a device like below::
>
> Device (BTH)
> {
> @@ -177,7 +184,7 @@ have a device like below:
> })
> }
>
> -The driver might expect to get the right GPIO when it does:
> +The driver might expect to get the right GPIO when it does:：
Hmm... there is a small typo here:
": :" -> "::"
For the conversion itself, after correcting the above typo:
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung at kernel.org>
>
> desc = gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>
> @@ -193,22 +200,25 @@ the ACPI GPIO mapping tables are hardly linked to ACPI ID and certain
> objects, as listed in the above chapter, of the device in question.
>
> Getting GPIO descriptor
> ------------------------
> +=======================
> +
> +There are two main approaches to get GPIO resource from ACPI::
>
> -There are two main approaches to get GPIO resource from ACPI:
> - desc = gpiod_get(dev, connection_id, flags);
> - desc = gpiod_get_index(dev, connection_id, index, flags);
> + desc = gpiod_get(dev, connection_id, flags);
> + desc = gpiod_get_index(dev, connection_id, index, flags);
>
> We may consider two different cases here, i.e. when connection ID is
> provided and otherwise.
>
> -Case 1:
> - desc = gpiod_get(dev, "non-null-connection-id", flags);
> - desc = gpiod_get_index(dev, "non-null-connection-id", index, flags);
> +Case 1::
> +
> + desc = gpiod_get(dev, "non-null-connection-id", flags);
> + desc = gpiod_get_index(dev, "non-null-connection-id", index, flags);
> +
> +Case 2::
>
> -Case 2:
> - desc = gpiod_get(dev, NULL, flags);
> - desc = gpiod_get_index(dev, NULL, index, flags);
> + desc = gpiod_get(dev, NULL, flags);
> + desc = gpiod_get_index(dev, NULL, index, flags);
>
> Case 1 assumes that corresponding ACPI device description must have
> defined device properties and will prevent to getting any GPIO resources
> diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst
> index 0e05b843521c..61d67763851b 100644
> --- a/Documentation/firmware-guide/acpi/index.rst
> +++ b/Documentation/firmware-guide/acpi/index.rst
> @@ -11,3 +11,4 @@ ACPI Support
> enumeration
> osi
> DSD-properties-rules
> + gpio-properties
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 09f43f1bdd15..87f930bf32ad 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6593,7 +6593,7 @@ M: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> L: linux-gpio at vger.kernel.org
> L: linux-acpi at vger.kernel.org
> S: Maintained
> -F: Documentation/acpi/gpio-properties.txt
> +F: Documentation/firmware-guide/acpi/gpio-properties.rst
> F: drivers/gpio/gpiolib-acpi.c
>
> GPIO IR Transmitter
Thanks,
Mauro
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