drivers/gpio/gpio-lp3943.c

   1 /*
   2  * TI/National Semiconductor LP3943 GPIO driver
   3  *
   4  * Copyright 2013 Texas Instruments
   5  *
   6  * Author: Milo Kim <milo.kim@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; version 2.
  11  */
  12
  13 #include <linux/bitops.h>
  14 #include <linux/err.h>
  15 #include <linux/gpio.h>
  16 #include <linux/i2c.h>
  17 #include <linux/mfd/lp3943.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/slab.h>
  21
  22 enum lp3943_gpios {
  23         LP3943_GPIO1,
  24         LP3943_GPIO2,
  25         LP3943_GPIO3,
  26         LP3943_GPIO4,
  27         LP3943_GPIO5,
  28         LP3943_GPIO6,
  29         LP3943_GPIO7,
  30         LP3943_GPIO8,
  31         LP3943_GPIO9,
  32         LP3943_GPIO10,
  33         LP3943_GPIO11,
  34         LP3943_GPIO12,
  35         LP3943_GPIO13,
  36         LP3943_GPIO14,
  37         LP3943_GPIO15,
  38         LP3943_GPIO16,
  39         LP3943_MAX_GPIO,
  40 };
  41
  42 struct lp3943_gpio {
  43         struct gpio_chip chip;
  44         struct lp3943 *lp3943;
  45         u16 input_mask;         /* 1 = GPIO is input direction, 0 = output */
  46 };
  47
  48 static inline struct lp3943_gpio *to_lp3943_gpio(struct gpio_chip *_chip)
  49 {
  50         return container_of(_chip, struct lp3943_gpio, chip);
  51 }
  52
  53 static int lp3943_gpio_request(struct gpio_chip *chip, unsigned offset)
  54 {
  55         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
  56         struct lp3943 *lp3943 = lp3943_gpio->lp3943;
  57
  58         /* Return an error if the pin is already assigned */
  59         if (test_and_set_bit(offset, &lp3943->pin_used))
  60                 return -EBUSY;
  61
  62         return 0;
  63 }
  64
  65 static void lp3943_gpio_free(struct gpio_chip *chip, unsigned offset)
  66 {
  67         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
  68         struct lp3943 *lp3943 = lp3943_gpio->lp3943;
  69
  70         clear_bit(offset, &lp3943->pin_used);
  71 }
  72
  73 static int lp3943_gpio_set_mode(struct lp3943_gpio *lp3943_gpio, u8 offset,
  74                                 u8 val)
  75 {
  76         struct lp3943 *lp3943 = lp3943_gpio->lp3943;
  77         const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
  78
  79         return lp3943_update_bits(lp3943, mux[offset].reg, mux[offset].mask,
  80                                   val << mux[offset].shift);
  81 }
  82
  83 static int lp3943_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  84 {
  85         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
  86
  87         lp3943_gpio->input_mask |= BIT(offset);
  88
  89         return lp3943_gpio_set_mode(lp3943_gpio, offset, LP3943_GPIO_IN);
  90 }
  91
  92 static int lp3943_get_gpio_in_status(struct lp3943_gpio *lp3943_gpio,
  93                                      struct gpio_chip *chip, unsigned offset)
  94 {
  95         u8 addr, read;
  96         int err;
  97
  98         switch (offset) {
  99         case LP3943_GPIO1 ... LP3943_GPIO8:
 100                 addr = LP3943_REG_GPIO_A;
 101                 break;
 102         case LP3943_GPIO9 ... LP3943_GPIO16:
 103                 addr = LP3943_REG_GPIO_B;
 104                 offset = offset - 8;
 105                 break;
 106         default:
 107                 return -EINVAL;
 108         }
 109
 110         err = lp3943_read_byte(lp3943_gpio->lp3943, addr, &read);
 111         if (err)
 112                 return err;
 113
 114         return !!(read & BIT(offset));
 115 }
 116
 117 static int lp3943_get_gpio_out_status(struct lp3943_gpio *lp3943_gpio,
 118                                       struct gpio_chip *chip, unsigned offset)
 119 {
 120         struct lp3943 *lp3943 = lp3943_gpio->lp3943;
 121         const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
 122         u8 read;
 123         int err;
 124
 125         err = lp3943_read_byte(lp3943, mux[offset].reg, &read);
 126         if (err)
 127                 return err;
 128
 129         read = (read & mux[offset].mask) >> mux[offset].shift;
 130
 131         if (read == LP3943_GPIO_OUT_HIGH)
 132                 return 1;
 133         else if (read == LP3943_GPIO_OUT_LOW)
 134                 return 0;
 135         else
 136                 return -EINVAL;
 137 }
 138
 139 static int lp3943_gpio_get(struct gpio_chip *chip, unsigned offset)
 140 {
 141         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 142
 143         /*
 144          * Limitation:
 145          *   LP3943 doesn't have the GPIO direction register. It provides
 146          *   only input and output status registers.
 147          *   So, direction info is required to handle the 'get' operation.
 148          *   This variable is updated whenever the direction is changed and
 149          *   it is used here.
 150          */
 151
 152         if (lp3943_gpio->input_mask & BIT(offset))
 153                 return lp3943_get_gpio_in_status(lp3943_gpio, chip, offset);
 154         else
 155                 return lp3943_get_gpio_out_status(lp3943_gpio, chip, offset);
 156 }
 157
 158 static void lp3943_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 159 {
 160         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 161         u8 data;
 162
 163         if (value)
 164                 data = LP3943_GPIO_OUT_HIGH;
 165         else
 166                 data = LP3943_GPIO_OUT_LOW;
 167
 168         lp3943_gpio_set_mode(lp3943_gpio, offset, data);
 169 }
 170
 171 static int lp3943_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 172                                         int value)
 173 {
 174         struct lp3943_gpio *lp3943_gpio = to_lp3943_gpio(chip);
 175
 176         lp3943_gpio_set(chip, offset, value);
 177         lp3943_gpio->input_mask &= ~BIT(offset);
 178
 179         return 0;
 180 }
 181
 182 static const struct gpio_chip lp3943_gpio_chip = {
 183         .label                  = "lp3943",
 184         .owner                  = THIS_MODULE,
 185         .request                = lp3943_gpio_request,
 186         .free                   = lp3943_gpio_free,
 187         .direction_input        = lp3943_gpio_direction_input,
 188         .get                    = lp3943_gpio_get,
 189         .direction_output       = lp3943_gpio_direction_output,
 190         .set                    = lp3943_gpio_set,
 191         .base                   = -1,
 192         .ngpio                  = LP3943_MAX_GPIO,
 193         .can_sleep              = 1,
 194 };
 195
 196 static int lp3943_gpio_probe(struct platform_device *pdev)
 197 {
 198         struct lp3943 *lp3943 = dev_get_drvdata(pdev->dev.parent);
 199         struct lp3943_gpio *lp3943_gpio;
 200
 201         lp3943_gpio = devm_kzalloc(&pdev->dev, sizeof(*lp3943_gpio),
 202                                 GFP_KERNEL);
 203         if (!lp3943_gpio)
 204                 return -ENOMEM;
 205
 206         lp3943_gpio->lp3943 = lp3943;
 207         lp3943_gpio->chip = lp3943_gpio_chip;
 208         lp3943_gpio->chip.dev = &pdev->dev;
 209
 210         platform_set_drvdata(pdev, lp3943_gpio);
 211
 212         return gpiochip_add(&lp3943_gpio->chip);
 213 }
 214
 215 static int lp3943_gpio_remove(struct platform_device *pdev)
 216 {
 217         struct lp3943_gpio *lp3943_gpio = platform_get_drvdata(pdev);
 218
 219         gpiochip_remove(&lp3943_gpio->chip);
 220         return 0;
 221 }
 222
 223 static const struct of_device_id lp3943_gpio_of_match[] = {
 224         { .compatible = "ti,lp3943-gpio", },
 225         { }
 226 };
 227 MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);
 228
 229 static struct platform_driver lp3943_gpio_driver = {
 230         .probe = lp3943_gpio_probe,
 231         .remove = lp3943_gpio_remove,
 232         .driver = {
 233                 .name = "lp3943-gpio",
 234                 .of_match_table = lp3943_gpio_of_match,
 235         },
 236 };
 237 module_platform_driver(lp3943_gpio_driver);
 238
 239 MODULE_DESCRIPTION("LP3943 GPIO driver");
 240 MODULE_ALIAS("platform:lp3943-gpio");
 241 MODULE_AUTHOR("Milo Kim");
 242 MODULE_LICENSE("GPL");