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 <mika.westerberg@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mika Westerberg
Rafael J. Wysocki
Родитель
f60e707490
Коммит
0d9a693cc8
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@ -0,0 +1,52 @@
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_DSD Device Properties Related to GPIO
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--------------------------------------
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With the release of ACPI 5.1 and the _DSD configuration objecte names
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can finally be given to GPIOs (and other things as well) returned by
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_CRS. Previously, we were only able to use an integer index to find
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the corresponding GPIO, which is pretty error prone (it depends on
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the _CRS output ordering, for example).
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With _DSD we can now query GPIOs using a name instead of an integer
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index, like the ASL example below shows:
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// Bluetooth device with reset and shutdown GPIOs
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Device (BTH)
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{
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Name (_HID, ...)
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Name (_CRS, ResourceTemplate ()
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{
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GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
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"\\_SB.GPO0", 0, ResourceConsumer) {15}
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GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
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"\\_SB.GPO0", 0, ResourceConsumer) {27, 31}
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})
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Name (_DSD, Package ()
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{
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package ()
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{
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Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }},
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Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }},
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}
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})
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}
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The format of the supported GPIO property is:
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Package () { "name", Package () { ref, index, pin, active_low }}
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ref - The device that has _CRS containing GpioIo()/GpioInt() resources,
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typically this is the device itself (BTH in our case).
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index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
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pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
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active_low - If 1 the GPIO is marked as active_low.
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Since ACPI GpioIo() resource does not have a field saying whether it is
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active low or high, the "active_low" argument can be used here. Setting
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it to 1 marks the GPIO as active low.
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In our Bluetooth example the "reset-gpio" refers to the second GpioIo()
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resource, second pin in that resource with the GPIO number of 31.
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@ -290,6 +290,7 @@ void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
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struct acpi_gpio_lookup {
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struct acpi_gpio_info info;
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int index;
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int pin_index;
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struct gpio_desc *desc;
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int n;
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};
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@ -303,13 +304,24 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
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if (lookup->n++ == lookup->index && !lookup->desc) {
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const struct acpi_resource_gpio *agpio = &ares->data.gpio;
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int pin_index = lookup->pin_index;
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if (pin_index >= agpio->pin_table_length)
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return 1;
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lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,
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agpio->pin_table[0]);
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agpio->pin_table[pin_index]);
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lookup->info.gpioint =
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agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
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lookup->info.active_low =
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agpio->polarity == ACPI_ACTIVE_LOW;
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/*
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* ActiveLow is only specified for GpioInt resource. If
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* GpioIo is used then the only way to set the flag is
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* to use _DSD "gpios" property.
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*/
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if (lookup->info.gpioint)
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lookup->info.active_low =
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agpio->polarity == ACPI_ACTIVE_LOW;
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}
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return 1;
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@ -317,40 +329,75 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data)
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/**
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* acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources
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* @dev: pointer to a device to get GPIO from
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* @adev: pointer to a ACPI device to get GPIO from
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* @propname: Property name of the GPIO (optional)
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* @index: index of GpioIo/GpioInt resource (starting from %0)
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* @info: info pointer to fill in (optional)
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*
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* Function goes through ACPI resources for @dev and based on @index looks
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* Function goes through ACPI resources for @adev and based on @index looks
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* up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor,
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* and returns it. @index matches GpioIo/GpioInt resources only so if there
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* are total %3 GPIO resources, the index goes from %0 to %2.
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*
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* If @propname is specified the GPIO is looked using device property. In
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* that case @index is used to select the GPIO entry in the property value
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* (in case of multiple).
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*
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* If the GPIO cannot be translated or there is an error an ERR_PTR is
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* returned.
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*
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* Note: if the GPIO resource has multiple entries in the pin list, this
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* function only returns the first.
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*/
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struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
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struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
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const char *propname, int index,
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struct acpi_gpio_info *info)
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{
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struct acpi_gpio_lookup lookup;
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struct list_head resource_list;
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struct acpi_device *adev;
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acpi_handle handle;
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bool active_low = false;
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int ret;
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if (!dev)
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return ERR_PTR(-EINVAL);
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handle = ACPI_HANDLE(dev);
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if (!handle || acpi_bus_get_device(handle, &adev))
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if (!adev)
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return ERR_PTR(-ENODEV);
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memset(&lookup, 0, sizeof(lookup));
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lookup.index = index;
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if (propname) {
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struct acpi_reference_args args;
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dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname);
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memset(&args, 0, sizeof(args));
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ret = acpi_dev_get_property_reference(adev, propname, NULL,
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index, &args);
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if (ret)
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return ERR_PTR(ret);
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/*
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* The property was found and resolved so need to
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* lookup the GPIO based on returned args instead.
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*/
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adev = args.adev;
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if (args.nargs >= 2) {
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lookup.index = args.args[0];
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lookup.pin_index = args.args[1];
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/*
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* 3rd argument, if present is used to
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* specify active_low.
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*/
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if (args.nargs >= 3)
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active_low = !!args.args[2];
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}
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dev_dbg(&adev->dev, "GPIO: _DSD returned %s %zd %llu %llu %llu\n",
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dev_name(&adev->dev), args.nargs,
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args.args[0], args.args[1], args.args[2]);
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} else {
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dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index);
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}
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INIT_LIST_HEAD(&resource_list);
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ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
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&lookup);
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@ -359,8 +406,11 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
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acpi_dev_free_resource_list(&resource_list);
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if (lookup.desc && info)
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if (lookup.desc && info) {
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*info = lookup.info;
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if (active_low)
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info->active_low = active_low;
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}
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return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);
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}
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@ -1505,14 +1505,36 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id,
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unsigned int idx,
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enum gpio_lookup_flags *flags)
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{
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static const char * const suffixes[] = { "gpios", "gpio" };
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struct acpi_device *adev = ACPI_COMPANION(dev);
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struct acpi_gpio_info info;
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struct gpio_desc *desc;
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char propname[32];
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int i;
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desc = acpi_get_gpiod_by_index(dev, idx, &info);
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if (IS_ERR(desc))
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return desc;
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/* Try first from _DSD */
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for (i = 0; i < ARRAY_SIZE(suffixes); i++) {
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if (con_id && strcmp(con_id, "gpios")) {
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snprintf(propname, sizeof(propname), "%s-%s",
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con_id, suffixes[i]);
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} else {
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snprintf(propname, sizeof(propname), "%s",
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suffixes[i]);
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}
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if (info.gpioint && info.active_low)
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desc = acpi_get_gpiod_by_index(adev, propname, idx, &info);
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if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))
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break;
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}
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/* Then from plain _CRS GPIOs */
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if (IS_ERR(desc)) {
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desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
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if (IS_ERR(desc))
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return desc;
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}
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if (info.active_low)
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*flags |= GPIO_ACTIVE_LOW;
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return desc;
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@ -34,7 +34,8 @@ void acpi_gpiochip_remove(struct gpio_chip *chip);
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void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);
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void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);
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struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
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struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
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const char *propname, int index,
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struct acpi_gpio_info *info);
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#else
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static inline void acpi_gpiochip_add(struct gpio_chip *chip) { }
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@ -47,8 +48,8 @@ static inline void
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acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }
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static inline struct gpio_desc *
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acpi_get_gpiod_by_index(struct device *dev, int index,
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struct acpi_gpio_info *info)
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acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname,
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int index, struct acpi_gpio_info *info)
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{
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return ERR_PTR(-ENOSYS);
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}
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