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dm: gpio: Add better functions to request GPIOs
At present U-Boot sort-of supports the standard way of reading GPIOs from device tree nodes, but the support is incomplete, a bit clunky and only works for GPIO bindings where #gpio-cells is 2. Add new functions to request GPIOs, taking full account of the device tree binding. These permit requesting a GPIO with a simple call like: gpio_request_by_name(dev, "cd-gpios", 0, &desc, GPIOD_IS_IN); This will request the GPIO, looking at the device's node which might be this, for example: cd-gpios = <&gpio TEGRA_GPIO(B, 3) GPIO_ACTIVE_LOW>; The GPIO will be set to input mode in this case and polarity will be honoured by the GPIO calls. It is also possible to request and free a list of GPIOs. Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
parent
0dac4d51f5
commit
3669e0e759
5 changed files with 461 additions and 4 deletions
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@ -111,6 +111,18 @@ struct gpio_desc {
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*/
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};
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/**
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* dm_gpio_is_valid() - Check if a GPIO is gpio_is_valie
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*
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* @desc: GPIO description containing device, offset and flags,
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* previously returned by gpio_request_by_name()
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* @return true if valid, false if not
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*/
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static inline bool dm_gpio_is_valid(struct gpio_desc *desc)
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{
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return desc->dev != NULL;
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}
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/**
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* gpio_get_status() - get the current GPIO status as a string
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*
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@ -313,4 +325,191 @@ int gpio_lookup_name(const char *name, struct udevice **devp,
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*/
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unsigned gpio_get_values_as_int(const int *gpio_list);
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/**
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* gpio_request_by_name() - Locate and request a GPIO by name
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*
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* This operates by looking up the given list name in the device (device
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* tree property) and requesting the GPIO for use. The property must exist
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* in @dev's node.
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*
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* Use @flags to specify whether the GPIO should be an input or output. In
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* principle this can also come from the device tree binding but most
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* bindings don't provide this information. Specifically, when the GPIO uclass
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* calls the xlate() method, it can return default flags, which are then
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* ORed with this @flags.
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*
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* If we find that requesting the GPIO is not always needed we could add a
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* new function or a new GPIOD_NO_REQUEST flag.
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*
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* At present driver model has no reference counting so if one device
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* requests a GPIO which subsequently is unbound, the @desc->dev pointer
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* will be invalid. However this will only happen if the GPIO device is
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* unbound, not if it is removed, so this seems like a reasonable limitation
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* for now. There is no real use case for unbinding drivers in normal
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* operation.
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*
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* The device tree binding is doc/device-tree-bindings/gpio/gpio.txt in
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* generate terms and each specific device may add additional details in
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* a binding file in the same directory.
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*
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* @dev: Device requesting the GPIO
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* @list_name: Name of GPIO list (e.g. "board-id-gpios")
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* @index: Index number of the GPIO in that list use request (0=first)
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* @desc: Returns GPIO description information. If there is no such
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* GPIO, dev->dev will be NULL.
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* @flags: Indicates the GPIO input/output settings (GPIOD_...)
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* @return 0 if OK, -ENOENT if the GPIO does not exist, -EINVAL if there is
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* something wrong with the list, or other -ve for another error (e.g.
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* -EBUSY if a GPIO was already requested)
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*/
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int gpio_request_by_name(struct udevice *dev, const char *list_name,
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int index, struct gpio_desc *desc, int flags);
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/**
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* gpio_request_list_by_name() - Request a list of GPIOs
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*
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* Reads all the GPIOs from a list and requetss them. See
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* gpio_request_by_name() for additional details. Lists should not be
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* misused to hold unrelated or optional GPIOs. They should only be used
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* for things like parallel data lines. A zero phandle terminates the list
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* the list.
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*
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* This function will either succeed, and request all GPIOs in the list, or
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* fail and request none (it will free already-requested GPIOs in case of
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* an error part-way through).
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*
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* @dev: Device requesting the GPIO
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* @list_name: Name of GPIO list (e.g. "board-id-gpios")
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* @desc_list: Returns a list of GPIO description information
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* @max_count: Maximum number of GPIOs to return (@desc_list must be at least
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* this big)
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* @flags: Indicates the GPIO input/output settings (GPIOD_...)
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* @return number of GPIOs requested, or -ve on error
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*/
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int gpio_request_list_by_name(struct udevice *dev, const char *list_name,
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struct gpio_desc *desc_list, int max_count,
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int flags);
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/**
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* gpio_get_list_count() - Returns the number of GPIOs in a list
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*
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* Counts the GPIOs in a list. See gpio_request_by_name() for additional
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* details.
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*
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* @dev: Device requesting the GPIO
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* @list_name: Name of GPIO list (e.g. "board-id-gpios")
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* @return number of GPIOs (0 for an empty property) or -ENOENT if the list
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* does not exist
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*/
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int gpio_get_list_count(struct udevice *dev, const char *list_name);
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/**
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* gpio_request_by_name_nodev() - request GPIOs without a device
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*
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* This is a version of gpio_request_list_by_name() that does not use a
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* device. Avoid it unless the caller is not yet using driver model
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*/
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int gpio_request_by_name_nodev(const void *blob, int node,
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const char *list_name,
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int index, struct gpio_desc *desc, int flags);
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/**
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* gpio_request_list_by_name_nodev() - request GPIOs without a device
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*
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* This is a version of gpio_request_list_by_name() that does not use a
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* device. Avoid it unless the caller is not yet using driver model
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*/
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int gpio_request_list_by_name_nodev(const void *blob, int node,
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const char *list_name,
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struct gpio_desc *desc_list, int max_count,
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int flags);
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/**
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* dm_gpio_free() - Free a single GPIO
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*
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* This frees a single GPIOs previously returned from gpio_request_by_name().
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*
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* @dev: Device which requested the GPIO
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* @desc: GPIO to free
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* @return 0 if OK, -ve on error
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*/
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int dm_gpio_free(struct udevice *dev, struct gpio_desc *desc);
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/**
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* gpio_free_list() - Free a list of GPIOs
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*
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* This frees a list of GPIOs previously returned from
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* gpio_request_list_by_name().
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*
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* @dev: Device which requested the GPIOs
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* @desc: List of GPIOs to free
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* @count: Number of GPIOs in the list
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* @return 0 if OK, -ve on error
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*/
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int gpio_free_list(struct udevice *dev, struct gpio_desc *desc, int count);
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/**
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* gpio_free_list_nodev() - free GPIOs without a device
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*
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* This is a version of gpio_free_list() that does not use a
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* device. Avoid it unless the caller is not yet using driver model
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*/
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int gpio_free_list_nodev(struct gpio_desc *desc, int count);
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/**
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* dm_gpio_get_value() - Get the value of a GPIO
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*
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* This is the driver model version of the existing gpio_get_value() function
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* and should be used instead of that.
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*
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* For now, these functions have a dm_ prefix since they conflict with
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* existing names.
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*
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* @desc: GPIO description containing device, offset and flags,
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* previously returned by gpio_request_by_name()
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* @return GPIO value (0 for inactive, 1 for active) or -ve on error
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*/
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int dm_gpio_get_value(struct gpio_desc *desc);
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int dm_gpio_set_value(struct gpio_desc *desc, int value);
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/**
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* dm_gpio_set_dir() - Set the direction for a GPIO
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*
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* This sets up the direction according tot the provided flags. It will do
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* nothing unless the direction is actually specified.
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*
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* @desc: GPIO description containing device, offset and flags,
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* previously returned by gpio_request_by_name()
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* @return 0 if OK, -ve on error
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*/
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int dm_gpio_set_dir(struct gpio_desc *desc);
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/**
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* dm_gpio_set_dir_flags() - Set direction using specific flags
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*
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* This is like dm_gpio_set_dir() except that the flags value is provided
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* instead of being used from desc->flags. This is needed because in many
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* cases the GPIO description does not include direction information.
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* Note that desc->flags is updated by this function.
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*
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* @desc: GPIO description containing device, offset and flags,
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* previously returned by gpio_request_by_name()
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* @flags: New flags to use
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* @return 0 if OK, -ve on error, in which case desc->flags is not updated
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*/
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int dm_gpio_set_dir_flags(struct gpio_desc *desc, ulong flags);
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/**
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* gpio_get_number() - Get the global GPIO number of a GPIO
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*
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* This should only be used for debugging or interest. It returns the nummber
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* that should be used for gpio_get_value() etc. to access this GPIO.
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*
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* @desc: GPIO description containing device, offset and flags,
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* previously returned by gpio_request_by_name()
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* @return GPIO number, or -ve if not found
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*/
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int gpio_get_number(struct gpio_desc *desc);
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#endif /* _ASM_GENERIC_GPIO_H_ */
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