LXR linux/drivers/gpio/gpio-mc33880.c

   1/*
   2 * MC33880 high-side/low-side switch GPIO driver
   3 * Copyright (c) 2009 Intel Corporation
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17 */
  18
  19/* Supports:
  20 * Freescale MC33880 high-side/low-side switch
  21 */
  22
  23#include <linux/init.h>
  24#include <linux/mutex.h>
  25#include <linux/spi/spi.h>
  26#include <linux/spi/mc33880.h>
  27#include <linux/gpio.h>
  28#include <linux/slab.h>
  29
  30#define DRIVER_NAME "mc33880"
  31
  32/*
  33 * Pin configurations, see MAX7301 datasheet page 6
  34 */
  35#define PIN_CONFIG_MASK 0x03
  36#define PIN_CONFIG_IN_PULLUP 0x03
  37#define PIN_CONFIG_IN_WO_PULLUP 0x02
  38#define PIN_CONFIG_OUT 0x01
  39
  40#define PIN_NUMBER 8
  41
  42
  43/*
  44 * Some registers must be read back to modify.
  45 * To save time we cache them here in memory
  46 */
  47struct mc33880 {
  48        struct mutex    lock;   /* protect from simultaneous accesses */
  49        u8              port_config;
  50        struct gpio_chip chip;
  51        struct spi_device *spi;
  52};
  53
  54static int mc33880_write_config(struct mc33880 *mc)
  55{
  56        return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  57}
  58
  59
  60static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
  61{
  62        if (value)
  63                mc->port_config |= 1 << offset;
  64        else
  65                mc->port_config &= ~(1 << offset);
  66
  67        return mc33880_write_config(mc);
  68}
  69
  70
  71static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
  72{
  73        struct mc33880 *mc = container_of(chip, struct mc33880, chip);
  74
  75        mutex_lock(&mc->lock);
  76
  77        __mc33880_set(mc, offset, value);
  78
  79        mutex_unlock(&mc->lock);
  80}
  81
  82static int __devinit mc33880_probe(struct spi_device *spi)
  83{
  84        struct mc33880 *mc;
  85        struct mc33880_platform_data *pdata;
  86        int ret;
  87
  88        pdata = spi->dev.platform_data;
  89        if (!pdata || !pdata->base) {
  90                dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  91                return -EINVAL;
  92        }
  93
  94        /*
  95         * bits_per_word cannot be configured in platform data
  96         */
  97        spi->bits_per_word = 8;
  98
  99        ret = spi_setup(spi);
 100        if (ret < 0)
 101                return ret;
 102
 103        mc = kzalloc(sizeof(struct mc33880), GFP_KERNEL);
 104        if (!mc)
 105                return -ENOMEM;
 106
 107        mutex_init(&mc->lock);
 108
 109        dev_set_drvdata(&spi->dev, mc);
 110
 111        mc->spi = spi;
 112
 113        mc->chip.label = DRIVER_NAME,
 114        mc->chip.set = mc33880_set;
 115        mc->chip.base = pdata->base;
 116        mc->chip.ngpio = PIN_NUMBER;
 117        mc->chip.can_sleep = 1;
 118        mc->chip.dev = &spi->dev;
 119        mc->chip.owner = THIS_MODULE;
 120
 121        mc->port_config = 0x00;
 122        /* write twice, because during initialisation the first setting
 123         * is just for testing SPI communication, and the second is the
 124         * "real" configuration
 125         */
 126        ret = mc33880_write_config(mc);
 127        mc->port_config = 0x00;
 128        if (!ret)
 129                ret = mc33880_write_config(mc);
 130
 131        if (ret) {
 132                printk(KERN_ERR "Failed writing to " DRIVER_NAME ": %d\n", ret);
 133                goto exit_destroy;
 134        }
 135
 136        ret = gpiochip_add(&mc->chip);
 137        if (ret)
 138                goto exit_destroy;
 139
 140        return ret;
 141
 142exit_destroy:
 143        dev_set_drvdata(&spi->dev, NULL);
 144        mutex_destroy(&mc->lock);
 145        kfree(mc);
 146        return ret;
 147}
 148
 149static int __devexit mc33880_remove(struct spi_device *spi)
 150{
 151        struct mc33880 *mc;
 152        int ret;
 153
 154        mc = dev_get_drvdata(&spi->dev);
 155        if (mc == NULL)
 156                return -ENODEV;
 157
 158        dev_set_drvdata(&spi->dev, NULL);
 159
 160        ret = gpiochip_remove(&mc->chip);
 161        if (!ret) {
 162                mutex_destroy(&mc->lock);
 163                kfree(mc);
 164        } else
 165                dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 166                        ret);
 167
 168        return ret;
 169}
 170
 171static struct spi_driver mc33880_driver = {
 172        .driver = {
 173                .name           = DRIVER_NAME,
 174                .owner          = THIS_MODULE,
 175        },
 176        .probe          = mc33880_probe,
 177        .remove         = __devexit_p(mc33880_remove),
 178};
 179
 180static int __init mc33880_init(void)
 181{
 182        return spi_register_driver(&mc33880_driver);
 183}
 184/* register after spi postcore initcall and before
 185 * subsys initcalls that may rely on these GPIOs
 186 */
 187subsys_initcall(mc33880_init);
 188
 189static void __exit mc33880_exit(void)
 190{
 191        spi_unregister_driver(&mc33880_driver);
 192}
 193module_exit(mc33880_exit);
 194
 195MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 196MODULE_LICENSE("GPL v2");
 197
 198