[PATCH v3 05/15] gpio / ACPI: Add support for _DSD device properties

Rafael J. Wysocki
2014-10-01T02:12:41Z

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>
---
drivers/gpio/gpiolib-acpi.c | 78 ++++++++++++++++++++++++++++++++++++--------
drivers/gpio/gpiolib.c | 30 ++++++++++++++--
drivers/gpio/gpiolib.h | 7 ++-
3 files changed, 94 insertions(+), 21 deletions(-)

Index: linux-pm/drivers/gpio/gpiolib-acpi.c
===================================================================
--- linux-pm.orig/drivers/gpio/gpiolib-acpi.c
+++ linux-pm/drivers/gpio/gpiolib-acpi.c
@@ -293,6 +293,7 @@ void acpi_gpiochip_free_interrupts(struc
struct acpi_gpio_lookup {
struct acpi_gpio_info info;
int index;
+ int pin_index;
struct gpio_desc *desc;
int n;
};
@@ -306,13 +307,24 @@ static int acpi_find_gpio(struct acpi_re

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;
@@ -320,40 +332,75 @@ static int acpi_find_gpio(struct acpi_re

/**
* 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);
@@ -362,8 +409,11 @@ struct gpio_desc *acpi_get_gpiod_by_inde

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);
}
Index: linux-pm/drivers/gpio/gpiolib.c
===================================================================
--- linux-pm.orig/drivers/gpio/gpiolib.c
+++ linux-pm/drivers/gpio/gpiolib.c
@@ -1487,14 +1487,36 @@ static struct gpio_desc *acpi_find_gpio(
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, 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.active_low)
*flags |= GPIO_ACTIVE_LOW;

return desc;
Index: linux-pm/drivers/gpio/gpiolib.h
===================================================================
--- linux-pm.orig/drivers/gpio/gpiolib.h
+++ linux-pm/drivers/gpio/gpiolib.h
@@ -34,7 +34,8 @@ void acpi_gpiochip_remove(struct gpio_ch
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);
}