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  */
  47 struct 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
  54 static int mc33880_write_config(struct mc33880 *mc)
  55 {
  56         return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  57 }
  58
  59
  60 static 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
  71 static 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
  82 static 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
 142 exit_destroy:
 143         dev_set_drvdata(&spi->dev, NULL);
 144         mutex_destroy(&mc->lock);
 145         kfree(mc);
 146         return ret;
 147 }
 148
 149 static 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
 171 static 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
 180 static 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  */
 187 subsys_initcall(mc33880_init);
 188
 189 static void __exit mc33880_exit(void)
 190 {
 191         spi_unregister_driver(&mc33880_driver);
 192 }
 193 module_exit(mc33880_exit);
 194
 195 MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 196 MODULE_LICENSE("GPL v2");
 197