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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-10-17 14:16:00 +0200
committerGraeme Gregory <graeme.gregory@linaro.org>2014-11-06 11:57:47 +0000
commit409a20d06cf1837090d591536e666df87136c4ec (patch)
tree1819be0c263a2c885ebcd6151c4280dba11f9b35
parent3381badecaf39479c04be77f250b70368df3ed8c (diff)
downloadleg-kernel-409a20d06cf1837090d591536e666df87136c4ec.tar.gz
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> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--drivers/gpio/devres.c36
-rw-r--r--drivers/gpio/gpiolib.c56
-rw-r--r--include/linux/gpio/consumer.h8
3 files changed, 100 insertions, 0 deletions
diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 954b9f6b0ef8..8e1d1a3ea007 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -109,6 +109,42 @@ struct gpio_desc *__must_check __devm_gpiod_get_index(struct device *dev,
EXPORT_SYMBOL(__devm_gpiod_get_index);
/**
+ * devm_get_named_gpiod_from_child - managed dev_get_named_gpiod_from_child()
+ * @dev: GPIO consumer
+ * @child: firmware node (child of @dev)
+ * @propname: name of the firmware property
+ * @index: index of the GPIO in the property value in case of many
+ *
+ * GPIO descriptors returned from this function are automatically disposed on
+ * driver detach.
+ */
+struct gpio_desc *devm_get_named_gpiod_from_child(struct device *dev,
+ struct fwnode_handle *child,
+ const char *propname,
+ int index)
+{
+ 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, propname, index);
+ if (IS_ERR(desc)) {
+ devres_free(dr);
+ return desc;
+ }
+
+ *dr = desc;
+ devres_add(dev, dr);
+
+ return desc;
+}
+EXPORT_SYMBOL(devm_get_named_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 94eb0a6ee37d..b098c7e0183c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1735,6 +1735,62 @@ 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
+ * @idx: index of the GPIO in the property value in case of many
+ *
+ * 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, int index)
+{
+ 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,
+ index, &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,
+ index, &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
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 12f146fa6604..b255ab44f3d3 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -94,6 +94,14 @@ int gpiod_to_irq(const struct gpio_desc *desc);
struct gpio_desc *gpio_to_desc(unsigned gpio);
int desc_to_gpio(const struct gpio_desc *desc);
+/* Child properties interface */
+struct fwnode_handle;
+
+struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
+ const char *propname, int index);
+struct gpio_desc *devm_get_named_gpiod_from_child(struct device *dev,
+ struct fwnode_handle *child,
+ const char *propname, int index);
#else /* CONFIG_GPIOLIB */
static inline struct gpio_desc *__must_check __gpiod_get(struct device *dev,