redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

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>
hifive-unleashed-5.1
Mika Westerberg 2014-10-29 15:41:01 +01:00 committed by Rafael J. Wysocki
parent f60e707490
commit 0d9a693cc8
4 changed files with 146 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
Documentation/acpi/gpio-properties.txt 100644
View File

@ -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.

78
drivers/gpio/gpiolib-acpi.c
View File

@ -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);
}

30
drivers/gpio/gpiolib.c
View File

@ -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]);
}
if (info.gpioint && info.active_low)
desc = acpi_get_gpiod_by_index(adev, propname, idx, &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.active_low)
*flags |= GPIO_ACTIVE_LOW;
return desc;

7
drivers/gpio/gpiolib.h
View File

@ -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);
}