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