drivers/gpio/gpio-max730x.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /**
   3  * Copyright (C) 2006 Juergen Beisert, Pengutronix
   4  * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
   5  * Copyright (C) 2009 Wolfram Sang, Pengutronix
   6  *
   7  * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
   8  * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
   9  * details
  10  * Note:
  11  * - DIN must be stable at the rising edge of clock.
  12  * - when writing:
  13  *   - always clock in 16 clocks at once
  14  *   - at DIN: D15 first, D0 last
  15  *   - D0..D7 = databyte, D8..D14 = commandbyte
  16  *   - D15 = low -> write command
  17  * - when reading
  18  *   - always clock in 16 clocks at once
  19  *   - at DIN: D15 first, D0 last
  20  *   - D0..D7 = dummy, D8..D14 = register address
  21  *   - D15 = high -> read command
  22  *   - raise CS and assert it again
  23  *   - always clock in 16 clocks at once
  24  *   - at DOUT: D15 first, D0 last
  25  *   - D0..D7 contains the data from the first cycle
  26  *
  27  * The driver exports a standard gpiochip interface
  28  */
  29
  30 #include <linux/module.h>
  31 #include <linux/init.h>
  32 #include <linux/platform_device.h>
  33 #include <linux/mutex.h>
  34 #include <linux/spi/max7301.h>
  35 #include <linux/gpio/driver.h>
  36 #include <linux/slab.h>
  37
  38 /*
  39  * Pin configurations, see MAX7301 datasheet page 6
  40  */
  41 #define PIN_CONFIG_MASK 0x03
  42 #define PIN_CONFIG_IN_PULLUP 0x03
  43 #define PIN_CONFIG_IN_WO_PULLUP 0x02
  44 #define PIN_CONFIG_OUT 0x01
  45
  46 #define PIN_NUMBER 28
  47
  48 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
  49 {
  50         struct max7301 *ts = gpiochip_get_data(chip);
  51         u8 *config;
  52         u8 offset_bits, pin_config;
  53         int ret;
  54
  55         /* First 4 pins are unused in the controller */
  56         offset += 4;
  57         offset_bits = (offset & 3) << 1;
  58
  59         config = &ts->port_config[offset >> 2];
  60
  61         if (ts->input_pullup_active & BIT(offset))
  62                 pin_config = PIN_CONFIG_IN_PULLUP;
  63         else
  64                 pin_config = PIN_CONFIG_IN_WO_PULLUP;
  65
  66         mutex_lock(&ts->lock);
  67
  68         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
  69                            | (pin_config << offset_bits);
  70
  71         ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
  72
  73         mutex_unlock(&ts->lock);
  74
  75         return ret;
  76 }
  77
  78 static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
  79 {
  80         if (value) {
  81                 ts->out_level |= 1 << offset;
  82                 return ts->write(ts->dev, 0x20 + offset, 0x01);
  83         } else {
  84                 ts->out_level &= ~(1 << offset);
  85                 return ts->write(ts->dev, 0x20 + offset, 0x00);
  86         }
  87 }
  88
  89 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
  90                                     int value)
  91 {
  92         struct max7301 *ts = gpiochip_get_data(chip);
  93         u8 *config;
  94         u8 offset_bits;
  95         int ret;
  96
  97         /* First 4 pins are unused in the controller */
  98         offset += 4;
  99         offset_bits = (offset & 3) << 1;
 100
 101         config = &ts->port_config[offset >> 2];
 102
 103         mutex_lock(&ts->lock);
 104
 105         *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
 106                            | (PIN_CONFIG_OUT << offset_bits);
 107
 108         ret = __max7301_set(ts, offset, value);
 109
 110         if (!ret)
 111                 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
 112
 113         mutex_unlock(&ts->lock);
 114
 115         return ret;
 116 }
 117
 118 static int max7301_get(struct gpio_chip *chip, unsigned offset)
 119 {
 120         struct max7301 *ts = gpiochip_get_data(chip);
 121         int config, level = -EINVAL;
 122
 123         /* First 4 pins are unused in the controller */
 124         offset += 4;
 125
 126         mutex_lock(&ts->lock);
 127
 128         config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
 129                         & PIN_CONFIG_MASK;
 130
 131         switch (config) {
 132         case PIN_CONFIG_OUT:
 133                 /* Output: return cached level */
 134                 level =  !!(ts->out_level & (1 << offset));
 135                 break;
 136         case PIN_CONFIG_IN_WO_PULLUP:
 137         case PIN_CONFIG_IN_PULLUP:
 138                 /* Input: read out */
 139                 level = ts->read(ts->dev, 0x20 + offset) & 0x01;
 140         }
 141         mutex_unlock(&ts->lock);
 142
 143         return level;
 144 }
 145
 146 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
 147 {
 148         struct max7301 *ts = gpiochip_get_data(chip);
 149
 150         /* First 4 pins are unused in the controller */
 151         offset += 4;
 152
 153         mutex_lock(&ts->lock);
 154
 155         __max7301_set(ts, offset, value);
 156
 157         mutex_unlock(&ts->lock);
 158 }
 159
 160 int __max730x_probe(struct max7301 *ts)
 161 {
 162         struct device *dev = ts->dev;
 163         struct max7301_platform_data *pdata;
 164         int i, ret;
 165
 166         pdata = dev_get_platdata(dev);
 167
 168         mutex_init(&ts->lock);
 169         dev_set_drvdata(dev, ts);
 170
 171         /* Power up the chip and disable IRQ output */
 172         ts->write(dev, 0x04, 0x01);
 173
 174         if (pdata) {
 175                 ts->input_pullup_active = pdata->input_pullup_active;
 176                 ts->chip.base = pdata->base;
 177         } else {
 178                 ts->chip.base = -1;
 179         }
 180         ts->chip.label = dev->driver->name;
 181
 182         ts->chip.direction_input = max7301_direction_input;
 183         ts->chip.get = max7301_get;
 184         ts->chip.direction_output = max7301_direction_output;
 185         ts->chip.set = max7301_set;
 186
 187         ts->chip.ngpio = PIN_NUMBER;
 188         ts->chip.can_sleep = true;
 189         ts->chip.parent = dev;
 190         ts->chip.owner = THIS_MODULE;
 191
 192         ret = gpiochip_add_data(&ts->chip, ts);
 193         if (ret)
 194                 goto exit_destroy;
 195
 196         /*
 197          * initialize pullups according to platform data and cache the
 198          * register values for later use.
 199          */
 200         for (i = 1; i < 8; i++) {
 201                 int j;
 202                 /*
 203                  * initialize port_config with "0xAA", which means
 204                  * input with internal pullup disabled. This is needed
 205                  * to avoid writing zeros (in the inner for loop),
 206                  * which is not allowed according to the datasheet.
 207                  */
 208                 ts->port_config[i] = 0xAA;
 209                 for (j = 0; j < 4; j++) {
 210                         int offset = (i - 1) * 4 + j;
 211                         ret = max7301_direction_input(&ts->chip, offset);
 212                         if (ret)
 213                                 goto exit_destroy;
 214                 }
 215         }
 216
 217         return ret;
 218
 219 exit_destroy:
 220         mutex_destroy(&ts->lock);
 221         return ret;
 222 }
 223 EXPORT_SYMBOL_GPL(__max730x_probe);
 224
 225 int __max730x_remove(struct device *dev)
 226 {
 227         struct max7301 *ts = dev_get_drvdata(dev);
 228
 229         if (ts == NULL)
 230                 return -ENODEV;
 231
 232         /* Power down the chip and disable IRQ output */
 233         ts->write(dev, 0x04, 0x00);
 234         gpiochip_remove(&ts->chip);
 235         mutex_destroy(&ts->lock);
 236         return 0;
 237 }
 238 EXPORT_SYMBOL_GPL(__max730x_remove);
 239
 240 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
 241 MODULE_LICENSE("GPL v2");
 242 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");