From 0d9a693cc8619b28f0eeb689a554647d42848fde Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Wed, 29 Oct 2014 15:41:01 +0100 Subject: gpio / ACPI: Add support for _DSD device properties 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 Acked-by: Linus Walleij Acked-by: Grant Likely Signed-off-by: Rafael J. Wysocki --- drivers/gpio/gpiolib-acpi.c | 78 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 64 insertions(+), 14 deletions(-) (limited to 'drivers/gpio/gpiolib-acpi.c') diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c index 05c6275da224..8aa6ca473748 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); } -- cgit v1.2.3