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  */
  46 struct 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
  53 static int mc33880_write_config(struct mc33880 *mc)
  54 {
  55         return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  56 }
  57
  58
  59 static 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
  70 static 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
  81 static 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
 141 exit_destroy:
 142         dev_set_drvdata(&spi->dev, NULL);
 143         mutex_destroy(&mc->lock);
 144         kfree(mc);
 145         return ret;
 146 }
 147
 148 static 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
 170 static 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
 179 static 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  */
 186 subsys_initcall(mc33880_init);
 187
 188 static void __exit mc33880_exit(void)
 189 {
 190         spi_unregister_driver(&mc33880_driver);
 191 }
 192 module_exit(mc33880_exit);
 193
 194 MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 195 MODULE_LICENSE("GPL v2");
 196