drivers/gpio/gpio-max730x.c

   1 /**
   2  * Copyright (C) 2006 Juergen Beisert, Pengutronix
   3  * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
   4  * Copyright (C) 2009 Wolfram Sang, Pengutronix
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
  11  * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
  12  * details
  13  * Note:
  14  * - DIN must be stable at the rising edge of clock.
  15  * - when writing:
  16  *   - always clock in 16 clocks at once
  17  *   - at DIN: D15 first, D0 last
  18  *   - D0..D7 = databyte, D8..D14 = commandbyte
  19  *   - D15 = low -> write command
  20  * - when reading
  21  *   - always clock in 16 clocks at once
  22  *   - at DIN: D15 first, D0 last
  23  *   - D0..D7 = dummy, D8..D14 = register address
  24  *   - D15 = high -> read command
  25  *   - raise CS and assert it again
  26  *   - always clock in 16 clocks at once
  27  *   - at DOUT: D15 first, D0 last
  28  *   - D0..D7 contains the data from the first cycle
  29  *
  30  * The driver exports a standard gpiochip interface
  31  */
  32
  33 #include <linux/module.h>
  34 #include <linux/init.h>
  35 #include <linux/platform_device.h>
  36 #include <linux/mutex.h>
  37 #include <linux/spi/max7301.h>
  38 #include <linux/gpio.h>
  39 #include <linux/slab.h>
  40
  41 /*
  42  * Pin configurations, see MAX7301 datasheet page 6
  43  */
  44 #define PIN_CONFIG_MASK 0x03
  45 #define PIN_CONFIG_IN_PULLUP 0x03
  46 #define PIN_CONFIG_IN_WO_PULLUP 0x02
  47 #define PIN_CONFIG_OUT 0x01
  48
  49 #define PIN_NUMBER 28
  50
  51 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
  52 {
  53         struct max7301 *ts = gpiochip_get_data(chip);
  54         u8 *config;
  55         u8 offset_bits, pin_config;
  56         int ret;
  57
  58         /* First 4 pins are unused in the controller */
  59         offset += 4;
  60         offset_bits = (offset & 3) << 1;
  61
  62         config = &ts->port_config[offset >> 2];
  63
  64         if (ts->input_pullup_active & BIT(offset))
  65                 pin_config = PIN_CONFIG_IN_PULLUP;
  66         else
  67                 pin_config = PIN_CONFIG_IN_WO_PULLUP;
  68
  69         mutex_lock(&ts->lock);
  70
  71         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
  72                            | (pin_config << offset_bits);
  73
  74         ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
  75
  76         mutex_unlock(&ts->lock);
  77
  78         return ret;
  79 }
  80
  81 static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
  82 {
  83         if (value) {
  84                 ts->out_level |= 1 << offset;
  85                 return ts->write(ts->dev, 0x20 + offset, 0x01);
  86         } else {
  87                 ts->out_level &= ~(1 << offset);
  88                 return ts->write(ts->dev, 0x20 + offset, 0x00);
  89         }
  90 }
  91
  92 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
  93                                     int value)
  94 {
  95         struct max7301 *ts = gpiochip_get_data(chip);
  96         u8 *config;
  97         u8 offset_bits;
  98         int ret;
  99
 100         /* First 4 pins are unused in the controller */
 101         offset += 4;
 102         offset_bits = (offset & 3) << 1;
 103
 104         config = &ts->port_config[offset >> 2];
 105
 106         mutex_lock(&ts->lock);
 107
 108         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
 109                            | (PIN_CONFIG_OUT << offset_bits);
 110
 111         ret = __max7301_set(ts, offset, value);
 112
 113         if (!ret)
 114                 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
 115
 116         mutex_unlock(&ts->lock);
 117
 118         return ret;
 119 }
 120
 121 static int max7301_get(struct gpio_chip *chip, unsigned offset)
 122 {
 123         struct max7301 *ts = gpiochip_get_data(chip);
 124         int config, level = -EINVAL;
 125
 126         /* First 4 pins are unused in the controller */
 127         offset += 4;
 128
 129         mutex_lock(&ts->lock);
 130
 131         config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
 132                         & PIN_CONFIG_MASK;
 133
 134         switch (config) {
 135         case PIN_CONFIG_OUT:
 136                 /* Output: return cached level */
 137                 level =  !!(ts->out_level & (1 << offset));
 138                 break;
 139         case PIN_CONFIG_IN_WO_PULLUP:
 140         case PIN_CONFIG_IN_PULLUP:
 141                 /* Input: read out */
 142                 level = ts->read(ts->dev, 0x20 + offset) & 0x01;
 143         }
 144         mutex_unlock(&ts->lock);
 145
 146         return level;
 147 }
 148
 149 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
 150 {
 151         struct max7301 *ts = gpiochip_get_data(chip);
 152
 153         /* First 4 pins are unused in the controller */
 154         offset += 4;
 155
 156         mutex_lock(&ts->lock);
 157
 158         __max7301_set(ts, offset, value);
 159
 160         mutex_unlock(&ts->lock);
 161 }
 162
 163 int __max730x_probe(struct max7301 *ts)
 164 {
 165         struct device *dev = ts->dev;
 166         struct max7301_platform_data *pdata;
 167         int i, ret;
 168
 169         pdata = dev_get_platdata(dev);
 170
 171         mutex_init(&ts->lock);
 172         dev_set_drvdata(dev, ts);
 173
 174         /* Power up the chip and disable IRQ output */
 175         ts->write(dev, 0x04, 0x01);
 176
 177         if (pdata) {
 178                 ts->input_pullup_active = pdata->input_pullup_active;
 179                 ts->chip.base = pdata->base;
 180         } else {
 181                 ts->chip.base = -1;
 182         }
 183         ts->chip.label = dev->driver->name;
 184
 185         ts->chip.direction_input = max7301_direction_input;
 186         ts->chip.get = max7301_get;
 187         ts->chip.direction_output = max7301_direction_output;
 188         ts->chip.set = max7301_set;
 189
 190         ts->chip.ngpio = PIN_NUMBER;
 191         ts->chip.can_sleep = true;
 192         ts->chip.parent = dev;
 193         ts->chip.owner = THIS_MODULE;
 194
 195         ret = gpiochip_add_data(&ts->chip, ts);
 196         if (ret)
 197                 goto exit_destroy;
 198
 199         /*
 200          * initialize pullups according to platform data and cache the
 201          * register values for later use.
 202          */
 203         for (i = 1; i < 8; i++) {
 204                 int j;
 205                 /*
 206                  * initialize port_config with "0xAA", which means
 207                  * input with internal pullup disabled. This is needed
 208                  * to avoid writing zeros (in the inner for loop),
 209                  * which is not allowed according to the datasheet.
 210                  */
 211                 ts->port_config[i] = 0xAA;
 212                 for (j = 0; j < 4; j++) {
 213                         int offset = (i - 1) * 4 + j;
 214                         ret = max7301_direction_input(&ts->chip, offset);
 215                         if (ret)
 216                                 goto exit_destroy;
 217                 }
 218         }
 219
 220         return ret;
 221
 222 exit_destroy:
 223         mutex_destroy(&ts->lock);
 224         return ret;
 225 }
 226 EXPORT_SYMBOL_GPL(__max730x_probe);
 227
 228 int __max730x_remove(struct device *dev)
 229 {
 230         struct max7301 *ts = dev_get_drvdata(dev);
 231
 232         if (ts == NULL)
 233                 return -ENODEV;
 234
 235         /* Power down the chip and disable IRQ output */
 236         ts->write(dev, 0x04, 0x00);
 237         gpiochip_remove(&ts->chip);
 238         mutex_destroy(&ts->lock);
 239         return 0;
 240 }
 241 EXPORT_SYMBOL_GPL(__max730x_remove);
 242
 243 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
 244 MODULE_LICENSE("GPL v2");
 245 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");