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_state() */ 83 enum { 84 GPIOF_INPUT = 0, 85 GPIOF_OUTPUT, 86 GPIOF_UNKNOWN, 87 }; 88 89 struct device; 90 91 /** 92 * struct struct dm_gpio_ops - Driver model GPIO operations 93 * 94 * Refer to functions above for description. These function largely copy 95 * the old API. 96 * 97 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the 98 * new DM GPIO API, this should be really easy to flip over to the Linux 99 * GPIO API-alike interface. 100 * 101 * Akso it would be useful to standardise additional functions like 102 * pullup, slew rate and drive strength. 103 * 104 * gpio_request)( and gpio_free() are optional - if NULL then they will 105 * not be called. 106 * 107 * Note that @offset is the offset from the base GPIO of the device. So 108 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO, 109 * where o is the number of GPIO lines controlled by the device. A device 110 * is typically used to control a single bank of GPIOs. Within complex 111 * SoCs there may be many banks and therefore many devices all referring 112 * to the different IO addresses within the SoC. 113 * 114 * The uclass combines all GPIO devices togther to provide a consistent 115 * numbering from 0 to n-1, where n is the number of GPIOs in total across 116 * all devices. Be careful not to confuse offset with gpio in the parameters. 117 */ 118 struct dm_gpio_ops { 119 int (*request)(struct device *dev, unsigned offset, const char *label); 120 int (*free)(struct device *dev, unsigned offset); 121 int (*direction_input)(struct device *dev, unsigned offset); 122 int (*direction_output)(struct device *dev, unsigned offset, 123 int value); 124 int (*get_value)(struct device *dev, unsigned offset); 125 int (*set_value)(struct device *dev, unsigned offset, int value); 126 int (*get_function)(struct device *dev, unsigned offset); 127 int (*get_state)(struct device *dev, unsigned offset, char *state, 128 int maxlen); 129 }; 130 131 /** 132 * struct gpio_dev_priv - information about a device used by the uclass 133 * 134 * The uclass combines all active GPIO devices into a unified numbering 135 * scheme. To do this it maintains some private information aobut each 136 * device. 137 * 138 * To implement driver model support in your GPIO driver, add a probe 139 * handler, and set @gpio_count and @bank_name correctly in that handler. 140 * This tells the uclass the name of the GPIO bank and the number of GPIOs 141 * it contains. 142 * 143 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called 144 * 'A0', 'A1', etc. 145 * @gpio_count: Number of GPIOs in this device 146 * @gpio_base: Base GPIO number for this device. For the first active device 147 * this will be 0; the numbering for others will follow sequentially so that 148 * @gpio_base for device 1 will equal the number of GPIOs in device 0. 149 */ 150 struct gpio_dev_priv { 151 const char *bank_name; 152 unsigned gpio_count; 153 unsigned gpio_base; 154 }; 155 156 /* Access the GPIO operations for a device */ 157 #define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops) 158 159 /** 160 * gpio_get_bank_info - Return information about a GPIO bank/device 161 * 162 * This looks up a device and returns both its GPIO base name and the number 163 * of GPIOs it controls. 164 * 165 * @dev: Device to look up 166 * @offset_count: Returns number of GPIOs within this bank 167 * @return bank name of this device 168 */ 169 const char *gpio_get_bank_info(struct device *dev, int *offset_count); 170 171 /** 172 * gpio_lookup_name - Look up a GPIO name and return its details 173 * 174 * This is used to convert a named GPIO into a device, offset and GPIO 175 * number. 176 * 177 * @name: GPIO name to look up 178 * @devp: Returns pointer to device which contains this GPIO 179 * @offsetp: Returns the offset number within this device 180 * @gpiop: Returns the absolute GPIO number, numbered from 0 181 */ 182 int gpio_lookup_name(const char *name, struct device **devp, 183 unsigned int *offsetp, unsigned int *gpiop); 184 185 #endif /* _ASM_GENERIC_GPIO_H_ */ 186