drivers/gpio/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 #include <linux/module.h>
  19
  20 struct gen_74x164_chip {
  21         struct spi_device       *spi;
  22         struct gpio_chip        gpio_chip;
  23         struct mutex            lock;
  24         u8                      port_config;
  25 };
  26
  27 static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
  28 {
  29         return container_of(gc, struct gen_74x164_chip, gpio_chip);
  30 }
  31
  32 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
  33 {
  34         return spi_write(chip->spi,
  35                          &chip->port_config, sizeof(chip->port_config));
  36 }
  37
  38 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
  39 {
  40         struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
  41         int ret;
  42
  43         mutex_lock(&chip->lock);
  44         ret = (chip->port_config >> offset) & 0x1;
  45         mutex_unlock(&chip->lock);
  46
  47         return ret;
  48 }
  49
  50 static void gen_74x164_set_value(struct gpio_chip *gc,
  51                 unsigned offset, int val)
  52 {
  53         struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
  54
  55         mutex_lock(&chip->lock);
  56         if (val)
  57                 chip->port_config |= (1 << offset);
  58         else
  59                 chip->port_config &= ~(1 << offset);
  60
  61         __gen_74x164_write_config(chip);
  62         mutex_unlock(&chip->lock);
  63 }
  64
  65 static int gen_74x164_direction_output(struct gpio_chip *gc,
  66                 unsigned offset, int val)
  67 {
  68         gen_74x164_set_value(gc, offset, val);
  69         return 0;
  70 }
  71
  72 static int __devinit gen_74x164_probe(struct spi_device *spi)
  73 {
  74         struct gen_74x164_chip *chip;
  75         struct gen_74x164_chip_platform_data *pdata;
  76         int ret;
  77
  78         pdata = spi->dev.platform_data;
  79         if (!pdata || !pdata->base) {
  80                 dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  81                 return -EINVAL;
  82         }
  83
  84         /*
  85          * bits_per_word cannot be configured in platform data
  86          */
  87         spi->bits_per_word = 8;
  88
  89         ret = spi_setup(spi);
  90         if (ret < 0)
  91                 return ret;
  92
  93         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  94         if (!chip)
  95                 return -ENOMEM;
  96
  97         mutex_init(&chip->lock);
  98
  99         dev_set_drvdata(&spi->dev, chip);
 100
 101         chip->spi = spi;
 102
 103         chip->gpio_chip.label = spi->modalias;
 104         chip->gpio_chip.direction_output = gen_74x164_direction_output;
 105         chip->gpio_chip.get = gen_74x164_get_value;
 106         chip->gpio_chip.set = gen_74x164_set_value;
 107         chip->gpio_chip.base = pdata->base;
 108         chip->gpio_chip.ngpio = 8;
 109         chip->gpio_chip.can_sleep = 1;
 110         chip->gpio_chip.dev = &spi->dev;
 111         chip->gpio_chip.owner = THIS_MODULE;
 112
 113         ret = __gen_74x164_write_config(chip);
 114         if (ret) {
 115                 dev_err(&spi->dev, "Failed writing: %d\n", ret);
 116                 goto exit_destroy;
 117         }
 118
 119         ret = gpiochip_add(&chip->gpio_chip);
 120         if (ret)
 121                 goto exit_destroy;
 122
 123         return ret;
 124
 125 exit_destroy:
 126         dev_set_drvdata(&spi->dev, NULL);
 127         mutex_destroy(&chip->lock);
 128         kfree(chip);
 129         return ret;
 130 }
 131
 132 static int __devexit gen_74x164_remove(struct spi_device *spi)
 133 {
 134         struct gen_74x164_chip *chip;
 135         int ret;
 136
 137         chip = dev_get_drvdata(&spi->dev);
 138         if (chip == NULL)
 139                 return -ENODEV;
 140
 141         dev_set_drvdata(&spi->dev, NULL);
 142
 143         ret = gpiochip_remove(&chip->gpio_chip);
 144         if (!ret) {
 145                 mutex_destroy(&chip->lock);
 146                 kfree(chip);
 147         } else
 148                 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 149                                 ret);
 150
 151         return ret;
 152 }
 153
 154 static struct spi_driver gen_74x164_driver = {
 155         .driver = {
 156                 .name           = "74x164",
 157                 .owner          = THIS_MODULE,
 158         },
 159         .probe          = gen_74x164_probe,
 160         .remove         = __devexit_p(gen_74x164_remove),
 161 };
 162
 163 static int __init gen_74x164_init(void)
 164 {
 165         return spi_register_driver(&gen_74x164_driver);
 166 }
 167 subsys_initcall(gen_74x164_init);
 168
 169 static void __exit gen_74x164_exit(void)
 170 {
 171         spi_unregister_driver(&gen_74x164_driver);
 172 }
 173 module_exit(gen_74x164_exit);
 174
 175 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 176 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
 177 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
 178 MODULE_LICENSE("GPL v2");