LXR linux/drivers/gpio/mc33880.c

   1/*
   2 * mc33880.c 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
  29#define DRIVER_NAME "mc33880"
  30
  31/*
  32 * Pin configurations, see MAX7301 datasheet page 6
  33 */
  34#define PIN_CONFIG_MASK 0x03
  35#define PIN_CONFIG_IN_PULLUP 0x03
  36#define PIN_CONFIG_IN_WO_PULLUP 0x02
  37#define PIN_CONFIG_OUT 0x01
  38
  39#define PIN_NUMBER 8
  40
  41
  42/*
  43 * Some registers must be read back to modify.
  44 * To save time we cache them here in memory
  45 */
  46struct mc33880 {
  47        struct mutex    lock;   /* protect from simultanous accesses */
  48        u8              port_config;
  49        struct gpio_chip chip;
  50        struct spi_device *spi;
  51};
  52
  53static int mc33880_write_config(struct mc33880 *mc)
  54{
  55        return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  56}
  57
  58
  59static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
  60{
  61        if (value)
  62                mc->port_config |= 1 << offset;
  63        else
  64                mc->port_config &= ~(1 << offset);
  65
  66        return mc33880_write_config(mc);
  67}
  68
  69
  70static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
  71{
  72        struct mc33880 *mc = container_of(chip, struct mc33880, chip);
  73
  74        mutex_lock(&mc->lock);
  75
  76        __mc33880_set(mc, offset, value);
  77
  78        mutex_unlock(&mc->lock);
  79}
  80
  81static int __devinit mc33880_probe(struct spi_device *spi)
  82{
  83        struct mc33880 *mc;
  84        struct mc33880_platform_data *pdata;
  85        int ret;
  86
  87        pdata = spi->dev.platform_data;
  88        if (!pdata || !pdata->base) {
  89                dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  90                return -EINVAL;
  91        }
  92
  93        /*
  94         * bits_per_word cannot be configured in platform data
  95         */
  96        spi->bits_per_word = 8;
  97
  98        ret = spi_setup(spi);
  99        if (ret < 0)
 100                return ret;
 101
 102        mc = kzalloc(sizeof(struct mc33880), GFP_KERNEL);
 103        if (!mc)
 104                return -ENOMEM;
 105
 106        mutex_init(&mc->lock);
 107
 108        dev_set_drvdata(&spi->dev, mc);
 109
 110        mc->spi = spi;
 111
 112        mc->chip.label = DRIVER_NAME,
 113        mc->chip.set = mc33880_set;
 114        mc->chip.base = pdata->base;
 115        mc->chip.ngpio = PIN_NUMBER;
 116        mc->chip.can_sleep = 1;
 117        mc->chip.dev = &spi->dev;
 118        mc->chip.owner = THIS_MODULE;
 119
 120        mc->port_config = 0x00;
 121        /* write twice, because during initialisation the first setting
 122         * is just for testing SPI communication, and the second is the
 123         * "real" configuration
 124         */
 125        ret = mc33880_write_config(mc);
 126        mc->port_config = 0x00;
 127        if (!ret)
 128                ret = mc33880_write_config(mc);
 129
 130        if (ret) {
 131                printk(KERN_ERR "Failed writing to " DRIVER_NAME ": %d\n", ret);
 132                goto exit_destroy;
 133        }
 134
 135        ret = gpiochip_add(&mc->chip);
 136        if (ret)
 137                goto exit_destroy;
 138
 139        return ret;
 140
 141exit_destroy:
 142        dev_set_drvdata(&spi->dev, NULL);
 143        mutex_destroy(&mc->lock);
 144        kfree(mc);
 145        return ret;
 146}
 147
 148static int mc33880_remove(struct spi_device *spi)
 149{
 150        struct mc33880 *mc;
 151        int ret;
 152
 153        mc = dev_get_drvdata(&spi->dev);
 154        if (mc == NULL)
 155                return -ENODEV;
 156
 157        dev_set_drvdata(&spi->dev, NULL);
 158
 159        ret = gpiochip_remove(&mc->chip);
 160        if (!ret) {
 161                mutex_destroy(&mc->lock);
 162                kfree(mc);
 163        } else
 164                dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 165                        ret);
 166
 167        return ret;
 168}
 169
 170static struct spi_driver mc33880_driver = {
 171        .driver = {
 172                .name           = DRIVER_NAME,
 173                .owner          = THIS_MODULE,
 174        },
 175        .probe          = mc33880_probe,
 176        .remove         = __devexit_p(mc33880_remove),
 177};
 178
 179static int __init mc33880_init(void)
 180{
 181        return spi_register_driver(&mc33880_driver);
 182}
 183/* register after spi postcore initcall and before
 184 * subsys initcalls that may rely on these GPIOs
 185 */
 186subsys_initcall(mc33880_init);
 187
 188static void __exit mc33880_exit(void)
 189{
 190        spi_unregister_driver(&mc33880_driver);
 191}
 192module_exit(mc33880_exit);
 193
 194MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 195MODULE_LICENSE("GPL v2");
 196
 197