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 #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  */
  48 struct 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
  55 static int mc33880_write_config(struct mc33880 *mc)
  56 {
  57         return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
  58 }
  59
  60
  61 static 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
  72 static 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
  83 static int mc33880_probe(struct spi_device *spi)
  84 {
  85         struct mc33880 *mc;
  86         struct mc33880_platform_data *pdata;
  87         int ret;
  88
  89         pdata = dev_get_platdata(&spi->dev);
  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 = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL);
 105         if (!mc)
 106                 return -ENOMEM;
 107
 108         mutex_init(&mc->lock);
 109
 110         spi_set_drvdata(spi, 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 = true;
 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                 dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n",
 134                         ret);
 135                 goto exit_destroy;
 136         }
 137
 138         ret = gpiochip_add(&mc->chip);
 139         if (ret)
 140                 goto exit_destroy;
 141
 142         return ret;
 143
 144 exit_destroy:
 145         mutex_destroy(&mc->lock);
 146         return ret;
 147 }
 148
 149 static int mc33880_remove(struct spi_device *spi)
 150 {
 151         struct mc33880 *mc;
 152         int ret;
 153
 154         mc = spi_get_drvdata(spi);
 155         if (mc == NULL)
 156                 return -ENODEV;
 157
 158         ret = gpiochip_remove(&mc->chip);
 159         if (!ret)
 160                 mutex_destroy(&mc->lock);
 161         else
 162                 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
 163                         ret);
 164
 165         return ret;
 166 }
 167
 168 static struct spi_driver mc33880_driver = {
 169         .driver = {
 170                 .name           = DRIVER_NAME,
 171                 .owner          = THIS_MODULE,
 172         },
 173         .probe          = mc33880_probe,
 174         .remove         = mc33880_remove,
 175 };
 176
 177 static int __init mc33880_init(void)
 178 {
 179         return spi_register_driver(&mc33880_driver);
 180 }
 181 /* register after spi postcore initcall and before
 182  * subsys initcalls that may rely on these GPIOs
 183  */
 184 subsys_initcall(mc33880_init);
 185
 186 static void __exit mc33880_exit(void)
 187 {
 188         spi_unregister_driver(&mc33880_driver);
 189 }
 190 module_exit(mc33880_exit);
 191
 192 MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
 193 MODULE_LICENSE("GPL v2");
 194