From: Mika Westerberg mika.westerberg@linux.intel.com
With release of ACPI 5.1 and _DSD method we can finally name GPIOs (and other things as well) returned by _CRS. Previously we were only able to use integer index to find the corresponding GPIO, which is pretty error prone if the order changes.
With _DSD we can now query GPIOs using name instead of an integer index, like the below example shows:
// Bluetooth device with reset and shutdown GPIOs Device (BTH) { Name (_HID, ...)
Name (_CRS, ResourceTemplate () { GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, "\_SB.GPO0", 0, ResourceConsumer) {15} GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, "\_SB.GPO0", 0, ResourceConsumer) {27, 31} })
Name (_DSD, Package () { ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), Package () { Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }}, Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }}, } }) }
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.
Since ACPI GpioIo() resource does not have field saying whether it is active low or high, the "active_low" argument can be used here. Setting it to 1 marks the GPIO as active low.
In our Bluetooth example the "reset-gpio" refers to the second GpioIo() resource, second pin in that resource with the GPIO number of 31.
This patch implements necessary support to gpiolib for extracting GPIOs using _DSD device properties.
Signed-off-by: Mika Westerberg mika.westerberg@linux.intel.com Acked-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com --- Documentation/acpi/gpio-properties.txt | 52 +++++++++++++++++++++++ drivers/gpio/gpiolib-acpi.c | 78 ++++++++++++++++++++++++++++------ drivers/gpio/gpiolib.c | 30 +++++++++++-- drivers/gpio/gpiolib.h | 7 +-- 4 files changed, 146 insertions(+), 21 deletions(-) create mode 100644 Documentation/acpi/gpio-properties.txt
diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt new file mode 100644 index 0000000..3e45b8b --- /dev/null +++ b/Documentation/acpi/gpio-properties.txt @@ -0,0 +1,52 @@ +_DSD Device Properties Related to GPIO +-------------------------------------- + +With the release of ACPI 5.1 and the _DSD configuration objecte names +can finally be given to GPIOs (and other things as well) returned by +_CRS. Previously, we were only able to use an integer index to find +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: + + // Bluetooth device with reset and shutdown GPIOs + Device (BTH) + { + Name (_HID, ...) + + Name (_CRS, ResourceTemplate () + { + GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, + "\_SB.GPO0", 0, ResourceConsumer) {15} + GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly, + "\_SB.GPO0", 0, ResourceConsumer) {27, 31} + }) + + Name (_DSD, Package () + { + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), + Package () + { + Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }}, + Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }}, + } + }) + } + +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. + +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 +it to 1 marks the GPIO as active low. + +In our Bluetooth example the "reset-gpio" refers to the second GpioIo() +resource, second pin in that resource with the GPIO number of 31. diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c index 05c6275..8aa6ca4 100644 --- a/drivers/gpio/gpiolib-acpi.c +++ b/drivers/gpio/gpiolib-acpi.c @@ -290,6 +290,7 @@ void acpi_gpiochip_free_interrupts(struct gpio_chip *chip) struct acpi_gpio_lookup { struct acpi_gpio_info info; int index; + int pin_index; struct gpio_desc *desc; int n; }; @@ -303,13 +304,24 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
if (lookup->n++ == lookup->index && !lookup->desc) { const struct acpi_resource_gpio *agpio = &ares->data.gpio; + int pin_index = lookup->pin_index; + + if (pin_index >= agpio->pin_table_length) + return 1;
lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr, - agpio->pin_table[0]); + agpio->pin_table[pin_index]); lookup->info.gpioint = agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT; - lookup->info.active_low = - agpio->polarity == ACPI_ACTIVE_LOW; + + /* + * ActiveLow is only specified for GpioInt resource. If + * GpioIo is used then the only way to set the flag is + * to use _DSD "gpios" property. + */ + if (lookup->info.gpioint) + lookup->info.active_low = + agpio->polarity == ACPI_ACTIVE_LOW; }
return 1; @@ -317,40 +329,75 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
/** * acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources - * @dev: pointer to a device to get GPIO from + * @adev: pointer to a ACPI device to get GPIO from + * @propname: Property name of the GPIO (optional) * @index: index of GpioIo/GpioInt resource (starting from %0) * @info: info pointer to fill in (optional) * - * Function goes through ACPI resources for @dev and based on @index looks + * Function goes through ACPI resources for @adev and based on @index looks * up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor, * and returns it. @index matches GpioIo/GpioInt resources only so if there * are total %3 GPIO resources, the index goes from %0 to %2. * + * If @propname is specified the GPIO is looked using device property. In + * that case @index is used to select the GPIO entry in the property value + * (in case of multiple). + * * If the GPIO cannot be translated or there is an error an ERR_PTR is * returned. * * Note: if the GPIO resource has multiple entries in the pin list, this * function only returns the first. */ -struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index, +struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev, + const char *propname, int index, struct acpi_gpio_info *info) { struct acpi_gpio_lookup lookup; struct list_head resource_list; - struct acpi_device *adev; - acpi_handle handle; + bool active_low = false; int ret;
- if (!dev) - return ERR_PTR(-EINVAL); - - handle = ACPI_HANDLE(dev); - if (!handle || acpi_bus_get_device(handle, &adev)) + if (!adev) return ERR_PTR(-ENODEV);
memset(&lookup, 0, sizeof(lookup)); lookup.index = index;
+ if (propname) { + struct acpi_reference_args args; + + dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname); + + memset(&args, 0, sizeof(args)); + ret = acpi_dev_get_property_reference(adev, propname, NULL, + index, &args); + if (ret) + return ERR_PTR(ret); + + /* + * The property was found and resolved so need to + * lookup the GPIO based on returned args instead. + */ + adev = args.adev; + if (args.nargs >= 2) { + lookup.index = args.args[0]; + lookup.pin_index = args.args[1]; + /* + * 3rd argument, if present is used to + * specify active_low. + */ + if (args.nargs >= 3) + active_low = !!args.args[2]; + } + + dev_dbg(&adev->dev, "GPIO: _DSD returned %s %zd %llu %llu %llu\n", + dev_name(&adev->dev), args.nargs, + args.args[0], args.args[1], args.args[2]); + } else { + dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index); + } + INIT_LIST_HEAD(&resource_list); ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio, &lookup); @@ -359,8 +406,11 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
acpi_dev_free_resource_list(&resource_list);
- if (lookup.desc && info) + if (lookup.desc && info) { *info = lookup.info; + if (active_low) + info->active_low = active_low; + }
return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT); } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index e8e98ca..94eb0a6 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1505,14 +1505,36 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id, unsigned int idx, enum gpio_lookup_flags *flags) { + static const char * const suffixes[] = { "gpios", "gpio" }; + struct acpi_device *adev = ACPI_COMPANION(dev); struct acpi_gpio_info info; struct gpio_desc *desc; + char propname[32]; + int i;
- desc = acpi_get_gpiod_by_index(dev, idx, &info); - if (IS_ERR(desc)) - return desc; + /* Try first from _DSD */ + for (i = 0; i < ARRAY_SIZE(suffixes); i++) { + if (con_id && strcmp(con_id, "gpios")) { + snprintf(propname, sizeof(propname), "%s-%s", + con_id, suffixes[i]); + } else { + snprintf(propname, sizeof(propname), "%s", + suffixes[i]); + } + + desc = acpi_get_gpiod_by_index(adev, propname, 0, &info); + if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER)) + break; + } + + /* Then from plain _CRS GPIOs */ + if (IS_ERR(desc)) { + desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info); + if (IS_ERR(desc)) + return desc; + }
- if (info.gpioint && info.active_low) + if (info.active_low) *flags |= GPIO_ACTIVE_LOW;
return desc; diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 9db2b6a..e3a5211 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -34,7 +34,8 @@ void acpi_gpiochip_remove(struct gpio_chip *chip); void acpi_gpiochip_request_interrupts(struct gpio_chip *chip); void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);
-struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index, +struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev, + const char *propname, int index, struct acpi_gpio_info *info); #else static inline void acpi_gpiochip_add(struct gpio_chip *chip) { } @@ -47,8 +48,8 @@ static inline void acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }
static inline struct gpio_desc * -acpi_get_gpiod_by_index(struct device *dev, int index, - struct acpi_gpio_info *info) +acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname, + int index, struct acpi_gpio_info *info) { return ERR_PTR(-ENOSYS); }