u-boot/include/asm-generic/gpio.h
Simon Glass 0dac4d51f5 dm: gpio: Add a driver GPIO translation method
Only the GPIO driver knows about the full GPIO device tree binding used by
a device. Add a method to allow the driver to provide this information to the
uclass, including the GPIO offset within the device and flags such as the
polarity.

Signed-off-by: Simon Glass <sjg@chromium.org>
2015-01-29 17:09:50 -07:00

317 lines
10 KiB
C

/*
* Copyright (c) 2011 The Chromium OS Authors.
* Copyright (c) 2011, NVIDIA Corp. All rights reserved.
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef _ASM_GENERIC_GPIO_H_
#define _ASM_GENERIC_GPIO_H_
/*
* Generic GPIO API for U-Boot
*
* GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
* by the SOC/architecture.
*
* Each GPIO can be an input or output. If an input then its value can
* be read as 0 or 1. If an output then its value can be set to 0 or 1.
* If you try to write an input then the value is undefined. If you try
* to read an output, barring something very unusual, you will get
* back the value of the output that you previously set.
*
* In some cases the operation may fail, for example if the GPIO number
* is out of range, or the GPIO is not available because its pin is
* being used by another function. In that case, functions may return
* an error value of -1.
*/
/**
* Request a GPIO. This should be called before any of the other functions
* are used on this GPIO.
*
* Note: With driver model, the label is allocated so there is no need for
* the caller to preserve it.
*
* @param gp GPIO number
* @param label User label for this GPIO
* @return 0 if ok, -1 on error
*/
int gpio_request(unsigned gpio, const char *label);
/**
* Stop using the GPIO. This function should not alter pin configuration.
*
* @param gpio GPIO number
* @return 0 if ok, -1 on error
*/
int gpio_free(unsigned gpio);
/**
* Make a GPIO an input.
*
* @param gpio GPIO number
* @return 0 if ok, -1 on error
*/
int gpio_direction_input(unsigned gpio);
/**
* Make a GPIO an output, and set its value.
*
* @param gpio GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_direction_output(unsigned gpio, int value);
/**
* Get a GPIO's value. This will work whether the GPIO is an input
* or an output.
*
* @param gpio GPIO number
* @return 0 if low, 1 if high, -1 on error
*/
int gpio_get_value(unsigned gpio);
/**
* Set an output GPIO's value. The GPIO must already be an output or
* this function may have no effect.
*
* @param gpio GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_set_value(unsigned gpio, int value);
/* State of a GPIO, as reported by get_function() */
enum gpio_func_t {
GPIOF_INPUT = 0,
GPIOF_OUTPUT,
GPIOF_UNUSED, /* Not claimed */
GPIOF_UNKNOWN, /* Not known */
GPIOF_FUNC, /* Not used as a GPIO */
GPIOF_COUNT,
};
struct udevice;
struct gpio_desc {
struct udevice *dev; /* Device, NULL for invalid GPIO */
unsigned long flags;
#define GPIOD_REQUESTED (1 << 0) /* Requested/claimed */
#define GPIOD_IS_OUT (1 << 1) /* GPIO is an output */
#define GPIOD_IS_IN (1 << 2) /* GPIO is an output */
#define GPIOD_ACTIVE_LOW (1 << 3) /* value has active low */
#define GPIOD_IS_OUT_ACTIVE (1 << 4) /* set output active */
uint offset; /* GPIO offset within the device */
/*
* We could consider adding the GPIO label in here. Possibly we could
* use this structure for internal GPIO information.
*/
};
/**
* gpio_get_status() - get the current GPIO status as a string
*
* Obtain the current GPIO status as a string which can be presented to the
* user. A typical string is:
*
* "b4: in: 1 [x] sdmmc_cd"
*
* which means this is GPIO bank b, offset 4, currently set to input, current
* value 1, [x] means that it is requested and the owner is 'sdmmc_cd'
*
* @dev: Device to check
* @offset: Offset of device GPIO to check
* @buf: Place to put string
* @buffsize: Size of string including \0
*/
int gpio_get_status(struct udevice *dev, int offset, char *buf, int buffsize);
/**
* gpio_get_function() - get the current function for a GPIO pin
*
* Note this returns GPIOF_UNUSED if the GPIO is not requested.
*
* @dev: Device to check
* @offset: Offset of device GPIO to check
* @namep: If non-NULL, this is set to the nane given when the GPIO
* was requested, or -1 if it has not been requested
* @return -ENODATA if the driver returned an unknown function,
* -ENODEV if the device is not active, -EINVAL if the offset is invalid.
* GPIOF_UNUSED if the GPIO has not been requested. Otherwise returns the
* function from enum gpio_func_t.
*/
int gpio_get_function(struct udevice *dev, int offset, const char **namep);
/**
* gpio_get_raw_function() - get the current raw function for a GPIO pin
*
* Note this does not return GPIOF_UNUSED - it will always return the GPIO
* driver's view of a pin function, even if it is not correctly set up.
*
* @dev: Device to check
* @offset: Offset of device GPIO to check
* @namep: If non-NULL, this is set to the nane given when the GPIO
* was requested, or -1 if it has not been requested
* @return -ENODATA if the driver returned an unknown function,
* -ENODEV if the device is not active, -EINVAL if the offset is invalid.
* Otherwise returns the function from enum gpio_func_t.
*/
int gpio_get_raw_function(struct udevice *dev, int offset, const char **namep);
/**
* gpio_requestf() - request a GPIO using a format string for the owner
*
* This is a helper function for gpio_request(). It allows you to provide
* a printf()-format string for the GPIO owner. It calls gpio_request() with
* the string that is created
*/
int gpio_requestf(unsigned gpio, const char *fmt, ...)
__attribute__ ((format (__printf__, 2, 3)));
struct fdtdec_phandle_args;
/**
* struct struct dm_gpio_ops - Driver model GPIO operations
*
* Refer to functions above for description. These function largely copy
* the old API.
*
* This is trying to be close to Linux GPIO API. Once the U-Boot uses the
* new DM GPIO API, this should be really easy to flip over to the Linux
* GPIO API-alike interface.
*
* Also it would be useful to standardise additional functions like
* pullup, slew rate and drive strength.
*
* gpio_request)( and gpio_free() are optional - if NULL then they will
* not be called.
*
* Note that @offset is the offset from the base GPIO of the device. So
* offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
* where o is the number of GPIO lines controlled by the device. A device
* is typically used to control a single bank of GPIOs. Within complex
* SoCs there may be many banks and therefore many devices all referring
* to the different IO addresses within the SoC.
*
* The uclass combines all GPIO devices together to provide a consistent
* numbering from 0 to n-1, where n is the number of GPIOs in total across
* all devices. Be careful not to confuse offset with gpio in the parameters.
*/
struct dm_gpio_ops {
int (*request)(struct udevice *dev, unsigned offset, const char *label);
int (*free)(struct udevice *dev, unsigned offset);
int (*direction_input)(struct udevice *dev, unsigned offset);
int (*direction_output)(struct udevice *dev, unsigned offset,
int value);
int (*get_value)(struct udevice *dev, unsigned offset);
int (*set_value)(struct udevice *dev, unsigned offset, int value);
/**
* get_function() Get the GPIO function
*
* @dev: Device to check
* @offset: GPIO offset within that device
* @return current function - GPIOF_...
*/
int (*get_function)(struct udevice *dev, unsigned offset);
/**
* xlate() - Translate phandle arguments into a GPIO description
*
* This function should set up the fields in desc according to the
* information in the arguments. The uclass will have set up:
*
* @desc->dev to @dev
* @desc->flags to 0
* @desc->offset to the value of the first argument in args, if any,
* otherwise -1 (which is invalid)
*
* This method is optional so if the above defaults suit it can be
* omitted. Typical behaviour is to set up the GPIOD_ACTIVE_LOW flag
* in desc->flags.
*
* Note that @dev is passed in as a parameter to follow driver model
* uclass conventions, even though it is already available as
* desc->dev.
*
* @dev: GPIO device
* @desc: Place to put GPIO description
* @args: Arguments provided in descripion
* @return 0 if OK, -ve on error
*/
int (*xlate)(struct udevice *dev, struct gpio_desc *desc,
struct fdtdec_phandle_args *args);
};
/**
* struct gpio_dev_priv - information about a device used by the uclass
*
* The uclass combines all active GPIO devices into a unified numbering
* scheme. To do this it maintains some private information about each
* device.
*
* To implement driver model support in your GPIO driver, add a probe
* handler, and set @gpio_count and @bank_name correctly in that handler.
* This tells the uclass the name of the GPIO bank and the number of GPIOs
* it contains.
*
* @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
* 'A0', 'A1', etc.
* @gpio_count: Number of GPIOs in this device
* @gpio_base: Base GPIO number for this device. For the first active device
* this will be 0; the numbering for others will follow sequentially so that
* @gpio_base for device 1 will equal the number of GPIOs in device 0.
* @name: Array of pointers to the name for each GPIO in this bank. The
* value of the pointer will be NULL if the GPIO has not been claimed.
*/
struct gpio_dev_priv {
const char *bank_name;
unsigned gpio_count;
unsigned gpio_base;
char **name;
};
/* Access the GPIO operations for a device */
#define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops)
/**
* gpio_get_bank_info - Return information about a GPIO bank/device
*
* This looks up a device and returns both its GPIO base name and the number
* of GPIOs it controls.
*
* @dev: Device to look up
* @offset_count: Returns number of GPIOs within this bank
* @return bank name of this device
*/
const char *gpio_get_bank_info(struct udevice *dev, int *offset_count);
/**
* gpio_lookup_name - Look up a GPIO name and return its details
*
* This is used to convert a named GPIO into a device, offset and GPIO
* number.
*
* @name: GPIO name to look up
* @devp: Returns pointer to device which contains this GPIO
* @offsetp: Returns the offset number within this device
* @gpiop: Returns the absolute GPIO number, numbered from 0
*/
int gpio_lookup_name(const char *name, struct udevice **devp,
unsigned int *offsetp, unsigned int *gpiop);
/**
* get_gpios() - Turn the values of a list of GPIOs into an integer
*
* This puts the value of the first GPIO into bit 0, the second into bit 1,
* etc. then returns the resulting integer.
*
* @gpio_list: List of GPIOs to collect
* @return resulting integer value
*/
unsigned gpio_get_values_as_int(const int *gpio_list);
#endif /* _ASM_GENERIC_GPIO_H_ */