drivers/gpio/74x164.c

   1 /*
   2  *  74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
   3  *
   4  *  Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
   5  *  Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/mutex.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/spi/74x164.h>
  16 #include <linux/gpio.h>
  17 #include <linux/slab.h>
  18
  19 #define GEN_74X164_GPIO_COUNT   8
  20
  21
  22 struct gen_74x164_chip {
  23         struct spi_device       *spi;
  24         struct gpio_chip        gpio_chip;
  25         struct mutex            lock;
  26         u8                      port_config;
  27 };
  28
  29 static void gen_74x164_set_value(struct gpio_chip *, unsigned, int);
  30
  31 static struct gen_74x164_chip *gpio_to_chip(struct gpio_chip *gc)
  32 {
  33         return container_of(gc, struct gen_74x164_chip, gpio_chip);
  34 }
  35
  36 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
  37 {
  38         return spi_write(chip->spi,
  39                          &chip->port_config, sizeof(chip->port_config));
  40 }
  41
  42 static int gen_74x164_direction_output(struct gpio_chip *gc,
  43                 unsigned offset, int val)
  44 {
  45         gen_74x164_set_value(gc, offset, val);
  46         return 0;
  47 }
  48
  49 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
  50 {
  51         struct gen_74x164_chip *chip = gpio_to_chip(gc);
  52         int ret;
  53
  54         mutex_lock(&chip->lock);
  55         ret = (chip->port_config >> offset) & 0x1;
  56         mutex_unlock(&chip->lock);
  57
  58         return ret;
  59 }
  60
  61 static void gen_74x164_set_value(struct gpio_chip *gc,
  62                 unsigned offset, int val)
  63 {
  64         struct gen_74x164_chip *chip = gpio_to_chip(gc);
  65
  66         mutex_lock(&chip->lock);
  67         if (val)
  68                 chip->port_config |= (1 << offset);
  69         else
  70                 chip->port_config &= ~(1 << offset);
  71
  72         __gen_74x164_write_config(chip);
  73         mutex_unlock(&chip->lock);
  74 }
  75
  76 static int __devinit gen_74x164_probe(struct spi_device *spi)
  77 {
  78         struct gen_74x164_chip *chip;
  79         struct gen_74x164_chip_platform_data *pdata;
  80         int ret;
  81
  82         pdata = spi->dev.platform_data;
  83         if (!pdata || !pdata->base) {
  84                 dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  85                 return -EINVAL;
  86         }
  87
  88         /*
  89          * bits_per_word cannot be configured in platform data
  90          */
  91         spi->bits_per_word = 8;
  92
  93         ret = spi_setup(spi);
  94         if (ret < 0)
  95                 return ret;
  96
  97         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  98         if (!chip)
  99                 return -ENOMEM;
 100
 101         mutex_init(&chip->lock);
 102
 103         dev_set_drvdata(&spi->dev, chip);
 104
 105         chip->spi = spi;
 106
 107         chip->gpio_chip.label = GEN_74X164_DRIVER_NAME,
 108                 chip->gpio_chip.direction_output = gen_74x164_direction_output;
 109         chip->gpio_chip.get = gen_74x164_get_value;
 110         chip->gpio_chip.set = gen_74x164_set_value;
 111         chip->gpio_chip.base = pdata->base;
 112         chip->gpio_chip.ngpio = GEN_74X164_GPIO_COUNT;
 113         chip->gpio_chip.can_sleep = 1;
 114         chip->gpio_chip.dev = &spi->dev;
 115         chip->gpio_chip.owner = THIS_MODULE;
 116
 117         ret = __gen_74x164_write_config(chip);
 118         if (ret) {
 119                 dev_err(&spi->dev, "Failed writing: %d\n", ret);
 120                 goto exit_destroy;
 121         }
 122
 123         ret = gpiochip_add(&chip->gpio_chip);
 124         if (ret)
 125                 goto exit_destroy;
 126
 127         return ret;
 128
 129 exit_destroy:
 130         dev_set_drvdata(&spi->dev, NULL);
 131         mutex_destroy(&chip->lock);
 132         kfree(chip);
 133         return ret;
 134 }
 135
 136 static int gen_74x164_remove(struct spi_device *spi)
 137 {
 138         struct gen_74x164_chip *chip;
 139         int ret;
 140
 141         chip = dev_get_drvdata(&spi->dev);
 142         if (chip == NULL)
 143                 return -ENODEV;
 144
 145         dev_set_drvdata(&spi->dev, NULL);
 146
 147         ret = gpiochip_remove(&chip->gpio_chip);
 148         if (!ret) {
 149                 mutex_destroy(&chip->lock);
 150                 kfree(chip);
 151         } else
 152                 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 153                                 ret);
 154
 155         return ret;
 156 }
 157
 158 static struct spi_driver gen_74x164_driver = {
 159         .driver = {
 160                 .name           = GEN_74X164_DRIVER_NAME,
 161                 .owner          = THIS_MODULE,
 162         },
 163         .probe          = gen_74x164_probe,
 164         .remove         = __devexit_p(gen_74x164_remove),
 165 };
 166
 167 static int __init gen_74x164_init(void)
 168 {
 169         return spi_register_driver(&gen_74x164_driver);
 170 }
 171 subsys_initcall(gen_74x164_init);
 172
 173 static void __exit gen_74x164_exit(void)
 174 {
 175         spi_unregister_driver(&gen_74x164_driver);
 176 }
 177 module_exit(gen_74x164_exit);
 178
 179 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 180 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
 181 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
 182 MODULE_LICENSE("GPL v2");