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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-10-21 13:33:59 +0200
committerMarcel Ziswiler <marcel.ziswiler@toradex.com>2015-09-18 13:54:16 +0200
commit52b6ef5a0d1db3519a15266fcf81745f0f1fa3a6 (patch)
tree003738248ddbdb66c011ab56dc532ea9877045be /drivers
parent6651a2015a20c52d0b45e89b379f66b614222d28 (diff)
gpio: Support for unified device properties interface
Some drivers need to deal with only firmware representation of its GPIOs. An example would be a GPIO button array driver where each button is described as a separate firmware node in device tree. Typically these child nodes do not have physical representation in the Linux device model. In order to help device drivers to handle such firmware child nodes we add dev[m]_get_named_gpiod_from_child() that takes a child firmware node pointer as its second argument (the first one is the parent device itself), finds the GPIO using whatever is the underlying firmware method, and requests the GPIO properly. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Alexandre Courbot <acourbot@nvidia.com> Acked-by: Grant Likely <grant.likely@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> (cherry picked from commit 40b7318319281b1bdec804f6435f26cadd329c13)
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpio/devres.c32
-rw-r--r--drivers/gpio/gpiolib.c55
2 files changed, 87 insertions, 0 deletions
diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 954b9f6b0ef8..13dbd3dfc33a 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -109,6 +109,38 @@ struct gpio_desc *__must_check __devm_gpiod_get_index(struct device *dev,
EXPORT_SYMBOL(__devm_gpiod_get_index);
/**
+ * devm_get_gpiod_from_child - get a GPIO descriptor from a device's child node
+ * @dev: GPIO consumer
+ * @child: firmware node (child of @dev)
+ *
+ * GPIO descriptors returned from this function are automatically disposed on
+ * driver detach.
+ */
+struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
+ struct fwnode_handle *child)
+{
+ struct gpio_desc **dr;
+ struct gpio_desc *desc;
+
+ dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
+ GFP_KERNEL);
+ if (!dr)
+ return ERR_PTR(-ENOMEM);
+
+ desc = fwnode_get_named_gpiod(child, "gpios");
+ if (IS_ERR(desc)) {
+ devres_free(dr);
+ return desc;
+ }
+
+ *dr = desc;
+ devres_add(dev, dr);
+
+ return desc;
+}
+EXPORT_SYMBOL(devm_get_gpiod_from_child);
+
+/**
* devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional()
* @dev: GPIO consumer
* @con_id: function within the GPIO consumer
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 15e452c98981..1a7ef2c576e8 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2536,6 +2536,61 @@ struct gpio_desc *__must_check __gpiod_get_index(struct device *dev,
EXPORT_SYMBOL_GPL(__gpiod_get_index);
/**
+ * fwnode_get_named_gpiod - obtain a GPIO from firmware node
+ * @fwnode: handle of the firmware node
+ * @propname: name of the firmware property representing the GPIO
+ *
+ * This function can be used for drivers that get their configuration
+ * from firmware.
+ *
+ * Function properly finds the corresponding GPIO using whatever is the
+ * underlying firmware interface and then makes sure that the GPIO
+ * descriptor is requested before it is returned to the caller.
+ *
+ * In case of error an ERR_PTR() is returned.
+ */
+struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
+ const char *propname)
+{
+ struct gpio_desc *desc = ERR_PTR(-ENODEV);
+ bool active_low = false;
+ int ret;
+
+ if (!fwnode)
+ return ERR_PTR(-EINVAL);
+
+ if (is_of_node(fwnode)) {
+ enum of_gpio_flags flags;
+
+ desc = of_get_named_gpiod_flags(of_node(fwnode), propname, 0,
+ &flags);
+ if (!IS_ERR(desc))
+ active_low = flags & OF_GPIO_ACTIVE_LOW;
+ } else if (is_acpi_node(fwnode)) {
+ struct acpi_gpio_info info;
+
+ desc = acpi_get_gpiod_by_index(acpi_node(fwnode), propname, 0,
+ &info);
+ if (!IS_ERR(desc))
+ active_low = info.active_low;
+ }
+
+ if (IS_ERR(desc))
+ return desc;
+
+ ret = gpiod_request(desc, NULL);
+ if (ret)
+ return ERR_PTR(ret);
+
+ /* Only value flag can be set from both DT and ACPI is active_low */
+ if (active_low)
+ set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+
+ return desc;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_named_gpiod);
+
+/**
* gpiod_get_index_optional - obtain an optional GPIO from a multi-index GPIO
* function
* @dev: GPIO consumer, can be NULL for system-global GPIOs