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 * @param gp GPIO number 33 * @param label User label for this GPIO 34 * @return 0 if ok, -1 on error 35 */ 36 int gpio_request(unsigned gpio, const char *label); 37 38 /** 39 * Stop using the GPIO. This function should not alter pin configuration. 40 * 41 * @param gpio GPIO number 42 * @return 0 if ok, -1 on error 43 */ 44 int gpio_free(unsigned gpio); 45 46 /** 47 * Make a GPIO an input. 48 * 49 * @param gpio GPIO number 50 * @return 0 if ok, -1 on error 51 */ 52 int gpio_direction_input(unsigned gpio); 53 54 /** 55 * Make a GPIO an output, and set its value. 56 * 57 * @param gpio GPIO number 58 * @param value GPIO value (0 for low or 1 for high) 59 * @return 0 if ok, -1 on error 60 */ 61 int gpio_direction_output(unsigned gpio, int value); 62 63 /** 64 * Get a GPIO's value. This will work whether the GPIO is an input 65 * or an output. 66 * 67 * @param gpio GPIO number 68 * @return 0 if low, 1 if high, -1 on error 69 */ 70 int gpio_get_value(unsigned gpio); 71 72 /** 73 * Set an output GPIO's value. The GPIO must already be an output or 74 * this function may have no effect. 75 * 76 * @param gpio GPIO number 77 * @param value GPIO value (0 for low or 1 for high) 78 * @return 0 if ok, -1 on error 79 */ 80 int gpio_set_value(unsigned gpio, int value); 81 82 /* State of a GPIO, as reported by get_function() */ 83 enum { 84 GPIOF_INPUT = 0, 85 GPIOF_OUTPUT, 86 GPIOF_UNUSED, /* Not claimed */ 87 GPIOF_UNKNOWN, /* Not known */ 88 GPIOF_FUNC, /* Not used as a GPIO */ 89 90 GPIOF_COUNT, 91 }; 92 93 struct udevice; 94 95 /** 96 * struct struct dm_gpio_ops - Driver model GPIO operations 97 * 98 * Refer to functions above for description. These function largely copy 99 * the old API. 100 * 101 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the 102 * new DM GPIO API, this should be really easy to flip over to the Linux 103 * GPIO API-alike interface. 104 * 105 * Akso it would be useful to standardise additional functions like 106 * pullup, slew rate and drive strength. 107 * 108 * gpio_request)( and gpio_free() are optional - if NULL then they will 109 * not be called. 110 * 111 * Note that @offset is the offset from the base GPIO of the device. So 112 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO, 113 * where o is the number of GPIO lines controlled by the device. A device 114 * is typically used to control a single bank of GPIOs. Within complex 115 * SoCs there may be many banks and therefore many devices all referring 116 * to the different IO addresses within the SoC. 117 * 118 * The uclass combines all GPIO devices togther to provide a consistent 119 * numbering from 0 to n-1, where n is the number of GPIOs in total across 120 * all devices. Be careful not to confuse offset with gpio in the parameters. 121 */ 122 struct dm_gpio_ops { 123 int (*request)(struct udevice *dev, unsigned offset, const char *label); 124 int (*free)(struct udevice *dev, unsigned offset); 125 int (*direction_input)(struct udevice *dev, unsigned offset); 126 int (*direction_output)(struct udevice *dev, unsigned offset, 127 int value); 128 int (*get_value)(struct udevice *dev, unsigned offset); 129 int (*set_value)(struct udevice *dev, unsigned offset, int value); 130 /** 131 * get_function() Get the GPIO function 132 * 133 * @dev: Device to check 134 * @offset: GPIO offset within that device 135 * @return current function - GPIOF_... 136 */ 137 int (*get_function)(struct udevice *dev, unsigned offset); 138 int (*get_state)(struct udevice *dev, unsigned offset, char *state, 139 int maxlen); 140 }; 141 142 /** 143 * struct gpio_dev_priv - information about a device used by the uclass 144 * 145 * The uclass combines all active GPIO devices into a unified numbering 146 * scheme. To do this it maintains some private information aobut each 147 * device. 148 * 149 * To implement driver model support in your GPIO driver, add a probe 150 * handler, and set @gpio_count and @bank_name correctly in that handler. 151 * This tells the uclass the name of the GPIO bank and the number of GPIOs 152 * it contains. 153 * 154 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called 155 * 'A0', 'A1', etc. 156 * @gpio_count: Number of GPIOs in this device 157 * @gpio_base: Base GPIO number for this device. For the first active device 158 * this will be 0; the numbering for others will follow sequentially so that 159 * @gpio_base for device 1 will equal the number of GPIOs in device 0. 160 */ 161 struct gpio_dev_priv { 162 const char *bank_name; 163 unsigned gpio_count; 164 unsigned gpio_base; 165 }; 166 167 /* Access the GPIO operations for a device */ 168 #define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops) 169 170 /** 171 * gpio_get_bank_info - Return information about a GPIO bank/device 172 * 173 * This looks up a device and returns both its GPIO base name and the number 174 * of GPIOs it controls. 175 * 176 * @dev: Device to look up 177 * @offset_count: Returns number of GPIOs within this bank 178 * @return bank name of this device 179 */ 180 const char *gpio_get_bank_info(struct udevice *dev, int *offset_count); 181 182 /** 183 * gpio_lookup_name - Look up a GPIO name and return its details 184 * 185 * This is used to convert a named GPIO into a device, offset and GPIO 186 * number. 187 * 188 * @name: GPIO name to look up 189 * @devp: Returns pointer to device which contains this GPIO 190 * @offsetp: Returns the offset number within this device 191 * @gpiop: Returns the absolute GPIO number, numbered from 0 192 */ 193 int gpio_lookup_name(const char *name, struct udevice **devp, 194 unsigned int *offsetp, unsigned int *gpiop); 195 196 #endif /* _ASM_GENERIC_GPIO_H_ */ 197