include/asm-generic/gpio.h

   1 /*
   2  * Copyright (c) 2011 The Chromium OS Authors.
   3  * Copyright (c) 2011, NVIDIA Corp. All rights reserved.
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #ifndef _ASM_GENERIC_GPIO_H_
   8 #define _ASM_GENERIC_GPIO_H_
   9
  10 /*
  11  * Generic GPIO API for U-Boot
  12  *
  13  * GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
  14  * by the SOC/architecture.
  15  *
  16  * Each GPIO can be an input or output. If an input then its value can
  17  * be read as 0 or 1. If an output then its value can be set to 0 or 1.
  18  * If you try to write an input then the value is undefined. If you try
  19  * to read an output, barring something very unusual,  you will get
  20  * back the value of the output that you previously set.
  21  *
  22  * In some cases the operation may fail, for example if the GPIO number
  23  * is out of range, or the GPIO is not available because its pin is
  24  * being used by another function. In that case, functions may return
  25  * an error value of -1.
  26  */
  27
  28 /**
  29  * Request a GPIO. This should be called before any of the other functions
  30  * are used on this GPIO.
  31  *
  32  * Note: With driver model, the label is allocated so there is no need for
  33  * the caller to preserve it.
  34  *
  35  * @param gp    GPIO number
  36  * @param label User label for this GPIO
  37  * @return 0 if ok, -1 on error
  38  */
  39 int gpio_request(unsigned gpio, const char *label);
  40
  41 /**
  42  * Stop using the GPIO.  This function should not alter pin configuration.
  43  *
  44  * @param gpio  GPIO number
  45  * @return 0 if ok, -1 on error
  46  */
  47 int gpio_free(unsigned gpio);
  48
  49 /**
  50  * Make a GPIO an input.
  51  *
  52  * @param gpio  GPIO number
  53  * @return 0 if ok, -1 on error
  54  */
  55 int gpio_direction_input(unsigned gpio);
  56
  57 /**
  58  * Make a GPIO an output, and set its value.
  59  *
  60  * @param gpio  GPIO number
  61  * @param value GPIO value (0 for low or 1 for high)
  62  * @return 0 if ok, -1 on error
  63  */
  64 int gpio_direction_output(unsigned gpio, int value);
  65
  66 /**
  67  * Get a GPIO's value. This will work whether the GPIO is an input
  68  * or an output.
  69  *
  70  * @param gpio  GPIO number
  71  * @return 0 if low, 1 if high, -1 on error
  72  */
  73 int gpio_get_value(unsigned gpio);
  74
  75 /**
  76  * Set an output GPIO's value. The GPIO must already be an output or
  77  * this function may have no effect.
  78  *
  79  * @param gpio  GPIO number
  80  * @param value GPIO value (0 for low or 1 for high)
  81  * @return 0 if ok, -1 on error
  82  */
  83 int gpio_set_value(unsigned gpio, int value);
  84
  85 /* State of a GPIO, as reported by get_function() */
  86 enum gpio_func_t {
  87         GPIOF_INPUT = 0,
  88         GPIOF_OUTPUT,
  89         GPIOF_UNUSED,           /* Not claimed */
  90         GPIOF_UNKNOWN,          /* Not known */
  91         GPIOF_FUNC,             /* Not used as a GPIO */
  92
  93         GPIOF_COUNT,
  94 };
  95
  96 struct udevice;
  97
  98 /**
  99  * gpio_get_status() - get the current GPIO status as a string
 100  *
 101  * Obtain the current GPIO status as a string which can be presented to the
 102  * user. A typical string is:
 103  *
 104  * "b4:  in: 1 [x] sdmmc_cd"
 105  *
 106  * which means this is GPIO bank b, offset 4, currently set to input, current
 107  * value 1, [x] means that it is requested and the owner is 'sdmmc_cd'
 108  *
 109  * @dev:        Device to check
 110  * @offset:     Offset of device GPIO to check
 111  * @buf:        Place to put string
 112  * @buffsize:   Size of string including \0
 113  */
 114 int gpio_get_status(struct udevice *dev, int offset, char *buf, int buffsize);
 115
 116 /**
 117  * gpio_get_function() - get the current function for a GPIO pin
 118  *
 119  * Note this returns GPIOF_UNUSED if the GPIO is not requested.
 120  *
 121  * @dev:        Device to check
 122  * @offset:     Offset of device GPIO to check
 123  * @namep:      If non-NULL, this is set to the nane given when the GPIO
 124  *              was requested, or -1 if it has not been requested
 125  * @return  -ENODATA if the driver returned an unknown function,
 126  * -ENODEV if the device is not active, -EINVAL if the offset is invalid.
 127  * GPIOF_UNUSED if the GPIO has not been requested. Otherwise returns the
 128  * function from enum gpio_func_t.
 129  */
 130 int gpio_get_function(struct udevice *dev, int offset, const char **namep);
 131
 132 /**
 133  * gpio_get_raw_function() - get the current raw function for a GPIO pin
 134  *
 135  * Note this does not return GPIOF_UNUSED - it will always return the GPIO
 136  * driver's view of a pin function, even if it is not correctly set up.
 137  *
 138  * @dev:        Device to check
 139  * @offset:     Offset of device GPIO to check
 140  * @namep:      If non-NULL, this is set to the nane given when the GPIO
 141  *              was requested, or -1 if it has not been requested
 142  * @return  -ENODATA if the driver returned an unknown function,
 143  * -ENODEV if the device is not active, -EINVAL if the offset is invalid.
 144  * Otherwise returns the function from enum gpio_func_t.
 145  */
 146 int gpio_get_raw_function(struct udevice *dev, int offset, const char **namep);
 147
 148 /**
 149  * gpio_requestf() - request a GPIO using a format string for the owner
 150  *
 151  * This is a helper function for gpio_request(). It allows you to provide
 152  * a printf()-format string for the GPIO owner. It calls gpio_request() with
 153  * the string that is created
 154  */
 155 int gpio_requestf(unsigned gpio, const char *fmt, ...)
 156                 __attribute__ ((format (__printf__, 2, 3)));
 157
 158 /**
 159  * struct struct dm_gpio_ops - Driver model GPIO operations
 160  *
 161  * Refer to functions above for description. These function largely copy
 162  * the old API.
 163  *
 164  * This is trying to be close to Linux GPIO API. Once the U-Boot uses the
 165  * new DM GPIO API, this should be really easy to flip over to the Linux
 166  * GPIO API-alike interface.
 167  *
 168  * Also it would be useful to standardise additional functions like
 169  * pullup, slew rate and drive strength.
 170  *
 171  * gpio_request)( and gpio_free() are optional - if NULL then they will
 172  * not be called.
 173  *
 174  * Note that @offset is the offset from the base GPIO of the device. So
 175  * offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
 176  * where o is the number of GPIO lines controlled by the device. A device
 177  * is typically used to control a single bank of GPIOs. Within complex
 178  * SoCs there may be many banks and therefore many devices all referring
 179  * to the different IO addresses within the SoC.
 180  *
 181  * The uclass combines all GPIO devices together to provide a consistent
 182  * numbering from 0 to n-1, where n is the number of GPIOs in total across
 183  * all devices. Be careful not to confuse offset with gpio in the parameters.
 184  */
 185 struct dm_gpio_ops {
 186         int (*request)(struct udevice *dev, unsigned offset, const char *label);
 187         int (*free)(struct udevice *dev, unsigned offset);
 188         int (*direction_input)(struct udevice *dev, unsigned offset);
 189         int (*direction_output)(struct udevice *dev, unsigned offset,
 190                                 int value);
 191         int (*get_value)(struct udevice *dev, unsigned offset);
 192         int (*set_value)(struct udevice *dev, unsigned offset, int value);
 193         /**
 194          * get_function() Get the GPIO function
 195          *
 196          * @dev:     Device to check
 197          * @offset:  GPIO offset within that device
 198          * @return current function - GPIOF_...
 199          */
 200         int (*get_function)(struct udevice *dev, unsigned offset);
 201 };
 202
 203 /**
 204  * struct gpio_dev_priv - information about a device used by the uclass
 205  *
 206  * The uclass combines all active GPIO devices into a unified numbering
 207  * scheme. To do this it maintains some private information about each
 208  * device.
 209  *
 210  * To implement driver model support in your GPIO driver, add a probe
 211  * handler, and set @gpio_count and @bank_name correctly in that handler.
 212  * This tells the uclass the name of the GPIO bank and the number of GPIOs
 213  * it contains.
 214  *
 215  * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
 216  * 'A0', 'A1', etc.
 217  * @gpio_count: Number of GPIOs in this device
 218  * @gpio_base: Base GPIO number for this device. For the first active device
 219  * this will be 0; the numbering for others will follow sequentially so that
 220  * @gpio_base for device 1 will equal the number of GPIOs in device 0.
 221  * @name: Array of pointers to the name for each GPIO in this bank. The
 222  * value of the pointer will be NULL if the GPIO has not been claimed.
 223  */
 224 struct gpio_dev_priv {
 225         const char *bank_name;
 226         unsigned gpio_count;
 227         unsigned gpio_base;
 228         char **name;
 229 };
 230
 231 /* Access the GPIO operations for a device */
 232 #define gpio_get_ops(dev)       ((struct dm_gpio_ops *)(dev)->driver->ops)
 233
 234 /**
 235  * gpio_get_bank_info - Return information about a GPIO bank/device
 236  *
 237  * This looks up a device and returns both its GPIO base name and the number
 238  * of GPIOs it controls.
 239  *
 240  * @dev: Device to look up
 241  * @offset_count: Returns number of GPIOs within this bank
 242  * @return bank name of this device
 243  */
 244 const char *gpio_get_bank_info(struct udevice *dev, int *offset_count);
 245
 246 /**
 247  * gpio_lookup_name - Look up a GPIO name and return its details
 248  *
 249  * This is used to convert a named GPIO into a device, offset and GPIO
 250  * number.
 251  *
 252  * @name: GPIO name to look up
 253  * @devp: Returns pointer to device which contains this GPIO
 254  * @offsetp: Returns the offset number within this device
 255  * @gpiop: Returns the absolute GPIO number, numbered from 0
 256  */
 257 int gpio_lookup_name(const char *name, struct udevice **devp,
 258                      unsigned int *offsetp, unsigned int *gpiop);
 259
 260 int name_to_gpio(const char *name);
 261
 262 #endif  /* _ASM_GENERIC_GPIO_H_ */