drivers/gpio/max730x.c

   1 /**
   2  * drivers/gpio/max7301.c
   3  *
   4  * Copyright (C) 2006 Juergen Beisert, Pengutronix
   5  * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
   6  * Copyright (C) 2009 Wolfram Sang, Pengutronix
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
  13  * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
  14  * details
  15  * Note:
  16  * - DIN must be stable at the rising edge of clock.
  17  * - when writing:
  18  *   - always clock in 16 clocks at once
  19  *   - at DIN: D15 first, D0 last
  20  *   - D0..D7 = databyte, D8..D14 = commandbyte
  21  *   - D15 = low -> write command
  22  * - when reading
  23  *   - always clock in 16 clocks at once
  24  *   - at DIN: D15 first, D0 last
  25  *   - D0..D7 = dummy, D8..D14 = register address
  26  *   - D15 = high -> read command
  27  *   - raise CS and assert it again
  28  *   - always clock in 16 clocks at once
  29  *   - at DOUT: D15 first, D0 last
  30  *   - D0..D7 contains the data from the first cycle
  31  *
  32  * The driver exports a standard gpiochip interface
  33  */
  34
  35 #include <linux/module.h>
  36 #include <linux/init.h>
  37 #include <linux/platform_device.h>
  38 #include <linux/mutex.h>
  39 #include <linux/spi/max7301.h>
  40 #include <linux/gpio.h>
  41
  42 /*
  43  * Pin configurations, see MAX7301 datasheet page 6
  44  */
  45 #define PIN_CONFIG_MASK 0x03
  46 #define PIN_CONFIG_IN_PULLUP 0x03
  47 #define PIN_CONFIG_IN_WO_PULLUP 0x02
  48 #define PIN_CONFIG_OUT 0x01
  49
  50 #define PIN_NUMBER 28
  51
  52 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
  53 {
  54         struct max7301 *ts = container_of(chip, struct max7301, chip);
  55         u8 *config;
  56         u8 offset_bits;
  57         int ret;
  58
  59         /* First 4 pins are unused in the controller */
  60         offset += 4;
  61         offset_bits = (offset & 3) << 1;
  62
  63         config = &ts->port_config[offset >> 2];
  64
  65         mutex_lock(&ts->lock);
  66
  67         /* Standard GPIO API doesn't support pull-ups, has to be extended.
  68          * Hard-coding no pollup for now. */
  69         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
  70                            | (PIN_CONFIG_IN_WO_PULLUP << offset_bits);
  71
  72         ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
  73
  74         mutex_unlock(&ts->lock);
  75
  76         return ret;
  77 }
  78
  79 static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
  80 {
  81         if (value) {
  82                 ts->out_level |= 1 << offset;
  83                 return ts->write(ts->dev, 0x20 + offset, 0x01);
  84         } else {
  85                 ts->out_level &= ~(1 << offset);
  86                 return ts->write(ts->dev, 0x20 + offset, 0x00);
  87         }
  88 }
  89
  90 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
  91                                     int value)
  92 {
  93         struct max7301 *ts = container_of(chip, struct max7301, chip);
  94         u8 *config;
  95         u8 offset_bits;
  96         int ret;
  97
  98         /* First 4 pins are unused in the controller */
  99         offset += 4;
 100         offset_bits = (offset & 3) << 1;
 101
 102         config = &ts->port_config[offset >> 2];
 103
 104         mutex_lock(&ts->lock);
 105
 106         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
 107                            | (PIN_CONFIG_OUT << offset_bits);
 108
 109         ret = __max7301_set(ts, offset, value);
 110
 111         if (!ret)
 112                 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
 113
 114         mutex_unlock(&ts->lock);
 115
 116         return ret;
 117 }
 118
 119 static int max7301_get(struct gpio_chip *chip, unsigned offset)
 120 {
 121         struct max7301 *ts = container_of(chip, struct max7301, chip);
 122         int config, level = -EINVAL;
 123
 124         /* First 4 pins are unused in the controller */
 125         offset += 4;
 126
 127         mutex_lock(&ts->lock);
 128
 129         config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
 130                         & PIN_CONFIG_MASK;
 131
 132         switch (config) {
 133         case PIN_CONFIG_OUT:
 134                 /* Output: return cached level */
 135                 level =  !!(ts->out_level & (1 << offset));
 136                 break;
 137         case PIN_CONFIG_IN_WO_PULLUP:
 138         case PIN_CONFIG_IN_PULLUP:
 139                 /* Input: read out */
 140                 level = ts->read(ts->dev, 0x20 + offset) & 0x01;
 141         }
 142         mutex_unlock(&ts->lock);
 143
 144         return level;
 145 }
 146
 147 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
 148 {
 149         struct max7301 *ts = container_of(chip, struct max7301, chip);
 150
 151         /* First 4 pins are unused in the controller */
 152         offset += 4;
 153
 154         mutex_lock(&ts->lock);
 155
 156         __max7301_set(ts, offset, value);
 157
 158         mutex_unlock(&ts->lock);
 159 }
 160
 161 int __devinit __max730x_probe(struct max7301 *ts)
 162 {
 163         struct device *dev = ts->dev;
 164         struct max7301_platform_data *pdata;
 165         int i, ret;
 166
 167         pdata = dev->platform_data;
 168         if (!pdata || !pdata->base) {
 169                 dev_err(dev, "incorrect or missing platform data\n");
 170                 return -EINVAL;
 171         }
 172
 173         mutex_init(&ts->lock);
 174         dev_set_drvdata(dev, ts);
 175
 176         /* Power up the chip and disable IRQ output */
 177         ts->write(dev, 0x04, 0x01);
 178
 179         ts->chip.label = dev->driver->name;
 180
 181         ts->chip.direction_input = max7301_direction_input;
 182         ts->chip.get = max7301_get;
 183         ts->chip.direction_output = max7301_direction_output;
 184         ts->chip.set = max7301_set;
 185
 186         ts->chip.base = pdata->base;
 187         ts->chip.ngpio = PIN_NUMBER;
 188         ts->chip.can_sleep = 1;
 189         ts->chip.dev = dev;
 190         ts->chip.owner = THIS_MODULE;
 191
 192         /*
 193          * tristate all pins in hardware and cache the
 194          * register values for later use.
 195          */
 196         for (i = 1; i < 8; i++) {
 197                 int j;
 198                 /* 0xAA means input with internal pullup disabled */
 199                 ts->write(dev, 0x08 + i, 0xAA);
 200                 ts->port_config[i] = 0xAA;
 201                 for (j = 0; j < 4; j++) {
 202                         int offset = (i - 1) * 4 + j;
 203                         ret = max7301_direction_input(&ts->chip, offset);
 204                         if (ret)
 205                                 goto exit_destroy;
 206                 }
 207         }
 208
 209         ret = gpiochip_add(&ts->chip);
 210         if (ret)
 211                 goto exit_destroy;
 212
 213         return ret;
 214
 215 exit_destroy:
 216         dev_set_drvdata(dev, NULL);
 217         mutex_destroy(&ts->lock);
 218         return ret;
 219 }
 220 EXPORT_SYMBOL_GPL(__max730x_probe);
 221
 222 int __devexit __max730x_remove(struct device *dev)
 223 {
 224         struct max7301 *ts = dev_get_drvdata(dev);
 225         int ret;
 226
 227         if (ts == NULL)
 228                 return -ENODEV;
 229
 230         dev_set_drvdata(dev, NULL);
 231
 232         /* Power down the chip and disable IRQ output */
 233         ts->write(dev, 0x04, 0x00);
 234
 235         ret = gpiochip_remove(&ts->chip);
 236         if (!ret) {
 237                 mutex_destroy(&ts->lock);
 238                 kfree(ts);
 239         } else
 240                 dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
 241
 242         return ret;
 243 }
 244 EXPORT_SYMBOL_GPL(__max730x_remove);
 245
 246 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
 247 MODULE_LICENSE("GPL v2");
 248 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");