linux/drivers/gpio/gpio-74x164.c
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   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
  20struct gen_74x164_chip {
  21        struct spi_device       *spi;
  22        struct gpio_chip        gpio_chip;
  23        struct mutex            lock;
  24        u8                      port_config;
  25};
  26
  27static 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
  32static 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
  38static 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
  50static 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
  65static 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
  72static 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
 125exit_destroy:
 126        dev_set_drvdata(&spi->dev, NULL);
 127        mutex_destroy(&chip->lock);
 128        kfree(chip);
 129        return ret;
 130}
 131
 132static 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
 154static 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
 163static int __init gen_74x164_init(void)
 164{
 165        return spi_register_driver(&gen_74x164_driver);
 166}
 167subsys_initcall(gen_74x164_init);
 168
 169static void __exit gen_74x164_exit(void)
 170{
 171        spi_unregister_driver(&gen_74x164_driver);
 172}
 173module_exit(gen_74x164_exit);
 174
 175MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 176MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
 177MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
 178MODULE_LICENSE("GPL v2");
 179
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