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 { 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 * struct struct dm_gpio_ops - Driver model GPIO operations 100 * 101 * Refer to functions above for description. These function largely copy 102 * the old API. 103 * 104 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the 105 * new DM GPIO API, this should be really easy to flip over to the Linux 106 * GPIO API-alike interface. 107 * 108 * Also it would be useful to standardise additional functions like 109 * pullup, slew rate and drive strength. 110 * 111 * gpio_request)( and gpio_free() are optional - if NULL then they will 112 * not be called. 113 * 114 * Note that @offset is the offset from the base GPIO of the device. So 115 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO, 116 * where o is the number of GPIO lines controlled by the device. A device 117 * is typically used to control a single bank of GPIOs. Within complex 118 * SoCs there may be many banks and therefore many devices all referring 119 * to the different IO addresses within the SoC. 120 * 121 * The uclass combines all GPIO devices together to provide a consistent 122 * numbering from 0 to n-1, where n is the number of GPIOs in total across 123 * all devices. Be careful not to confuse offset with gpio in the parameters. 124 */ 125 struct dm_gpio_ops { 126 int (*request)(struct udevice *dev, unsigned offset, const char *label); 127 int (*free)(struct udevice *dev, unsigned offset); 128 int (*direction_input)(struct udevice *dev, unsigned offset); 129 int (*direction_output)(struct udevice *dev, unsigned offset, 130 int value); 131 int (*get_value)(struct udevice *dev, unsigned offset); 132 int (*set_value)(struct udevice *dev, unsigned offset, int value); 133 /** 134 * get_function() Get the GPIO function 135 * 136 * @dev: Device to check 137 * @offset: GPIO offset within that device 138 * @return current function - GPIOF_... 139 */ 140 int (*get_function)(struct udevice *dev, unsigned offset); 141 int (*get_state)(struct udevice *dev, unsigned offset, char *state, 142 int maxlen); 143 }; 144 145 /** 146 * struct gpio_dev_priv - information about a device used by the uclass 147 * 148 * The uclass combines all active GPIO devices into a unified numbering 149 * scheme. To do this it maintains some private information about each 150 * device. 151 * 152 * To implement driver model support in your GPIO driver, add a probe 153 * handler, and set @gpio_count and @bank_name correctly in that handler. 154 * This tells the uclass the name of the GPIO bank and the number of GPIOs 155 * it contains. 156 * 157 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called 158 * 'A0', 'A1', etc. 159 * @gpio_count: Number of GPIOs in this device 160 * @gpio_base: Base GPIO number for this device. For the first active device 161 * this will be 0; the numbering for others will follow sequentially so that 162 * @gpio_base for device 1 will equal the number of GPIOs in device 0. 163 * @name: Array of pointers to the name for each GPIO in this bank. The 164 * value of the pointer will be NULL if the GPIO has not been claimed. 165 */ 166 struct gpio_dev_priv { 167 const char *bank_name; 168 unsigned gpio_count; 169 unsigned gpio_base; 170 char **name; 171 }; 172 173 /* Access the GPIO operations for a device */ 174 #define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops) 175 176 /** 177 * gpio_get_bank_info - Return information about a GPIO bank/device 178 * 179 * This looks up a device and returns both its GPIO base name and the number 180 * of GPIOs it controls. 181 * 182 * @dev: Device to look up 183 * @offset_count: Returns number of GPIOs within this bank 184 * @return bank name of this device 185 */ 186 const char *gpio_get_bank_info(struct udevice *dev, int *offset_count); 187 188 /** 189 * gpio_lookup_name - Look up a GPIO name and return its details 190 * 191 * This is used to convert a named GPIO into a device, offset and GPIO 192 * number. 193 * 194 * @name: GPIO name to look up 195 * @devp: Returns pointer to device which contains this GPIO 196 * @offsetp: Returns the offset number within this device 197 * @gpiop: Returns the absolute GPIO number, numbered from 0 198 */ 199 int gpio_lookup_name(const char *name, struct udevice **devp, 200 unsigned int *offsetp, unsigned int *gpiop); 201 202 #endif /* _ASM_GENERIC_GPIO_H_ */ 203