linux/drivers/gpio/gpio-mc33880.c
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   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#include <linux/module.h>
  30
  31#define DRIVER_NAME "mc33880"
  32
  33/*
  34 * Pin configurations, see MAX7301 datasheet page 6
  35 */
  36#define PIN_CONFIG_MASK 0x03
  37#define PIN_CONFIG_IN_PULLUP 0x03
  38#define PIN_CONFIG_IN_WO_PULLUP 0x02
  39#define PIN_CONFIG_OUT 0x01
  40
  41#define PIN_NUMBER 8
  42
  43
  44/*
  45 * Some registers must be read back to modify.
  46 * To save time we cache them here in memory
  47 */
  48struct mc33880 {
  49        struct mutex    lock;   /* protect from simultaneous accesses */
  50        u8              port_config;
  51        struct gpio_chip chip;
  52        struct spi_device *spi;
  53};
  54
  55static int mc33880_write_config(struct mc33880 *mc)
  56{
  57        return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  58}
  59
  60
  61static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
  62{
  63        if (value)
  64                mc->port_config |= 1 << offset;
  65        else
  66                mc->port_config &= ~(1 << offset);
  67
  68        return mc33880_write_config(mc);
  69}
  70
  71
  72static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
  73{
  74        struct mc33880 *mc = container_of(chip, struct mc33880, chip);
  75
  76        mutex_lock(&mc->lock);
  77
  78        __mc33880_set(mc, offset, value);
  79
  80        mutex_unlock(&mc->lock);
  81}
  82
  83static int mc33880_probe(struct spi_device *spi)
  84{
  85        struct mc33880 *mc;
  86        struct mc33880_platform_data *pdata;
  87        int ret;
  88
  89        pdata = spi->dev.platform_data;
  90        if (!pdata || !pdata->base) {
  91                dev_dbg(&spi->dev, "incorrect or missing platform data\n");
  92                return -EINVAL;
  93        }
  94
  95        /*
  96         * bits_per_word cannot be configured in platform data
  97         */
  98        spi->bits_per_word = 8;
  99
 100        ret = spi_setup(spi);
 101        if (ret < 0)
 102                return ret;
 103
 104        mc = kzalloc(sizeof(struct mc33880), GFP_KERNEL);
 105        if (!mc)
 106                return -ENOMEM;
 107
 108        mutex_init(&mc->lock);
 109
 110        dev_set_drvdata(&spi->dev, mc);
 111
 112        mc->spi = spi;
 113
 114        mc->chip.label = DRIVER_NAME,
 115        mc->chip.set = mc33880_set;
 116        mc->chip.base = pdata->base;
 117        mc->chip.ngpio = PIN_NUMBER;
 118        mc->chip.can_sleep = 1;
 119        mc->chip.dev = &spi->dev;
 120        mc->chip.owner = THIS_MODULE;
 121
 122        mc->port_config = 0x00;
 123        /* write twice, because during initialisation the first setting
 124         * is just for testing SPI communication, and the second is the
 125         * "real" configuration
 126         */
 127        ret = mc33880_write_config(mc);
 128        mc->port_config = 0x00;
 129        if (!ret)
 130                ret = mc33880_write_config(mc);
 131
 132        if (ret) {
 133                printk(KERN_ERR "Failed writing to " DRIVER_NAME ": %d\n", ret);
 134                goto exit_destroy;
 135        }
 136
 137        ret = gpiochip_add(&mc->chip);
 138        if (ret)
 139                goto exit_destroy;
 140
 141        return ret;
 142
 143exit_destroy:
 144        dev_set_drvdata(&spi->dev, NULL);
 145        mutex_destroy(&mc->lock);
 146        kfree(mc);
 147        return ret;
 148}
 149
 150static int mc33880_remove(struct spi_device *spi)
 151{
 152        struct mc33880 *mc;
 153        int ret;
 154
 155        mc = dev_get_drvdata(&spi->dev);
 156        if (mc == NULL)
 157                return -ENODEV;
 158
 159        dev_set_drvdata(&spi->dev, NULL);
 160
 161        ret = gpiochip_remove(&mc->chip);
 162        if (!ret) {
 163                mutex_destroy(&mc->lock);
 164                kfree(mc);
 165        } else
 166                dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 167                        ret);
 168
 169        return ret;
 170}
 171
 172static struct spi_driver mc33880_driver = {
 173        .driver = {
 174                .name           = DRIVER_NAME,
 175                .owner          = THIS_MODULE,
 176        },
 177        .probe          = mc33880_probe,
 178        .remove         = mc33880_remove,
 179};
 180
 181static int __init mc33880_init(void)
 182{
 183        return spi_register_driver(&mc33880_driver);
 184}
 185/* register after spi postcore initcall and before
 186 * subsys initcalls that may rely on these GPIOs
 187 */
 188subsys_initcall(mc33880_init);
 189
 190static void __exit mc33880_exit(void)
 191{
 192        spi_unregister_driver(&mc33880_driver);
 193}
 194module_exit(mc33880_exit);
 195
 196MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 197MODULE_LICENSE("GPL v2");
 198
 199
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