linux/drivers/gpio/gpio-max730x.c
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   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
  51static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
  52{
  53        struct max7301 *ts = container_of(chip, struct max7301, 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
  81static 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
  92static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
  93                                    int value)
  94{
  95        struct max7301 *ts = container_of(chip, struct max7301, 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
 121static int max7301_get(struct gpio_chip *chip, unsigned offset)
 122{
 123        struct max7301 *ts = container_of(chip, struct max7301, 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
 149static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
 150{
 151        struct max7301 *ts = container_of(chip, struct max7301, 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
 163int __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->platform_data;
 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 = 1;
 192        ts->chip.dev = dev;
 193        ts->chip.owner = THIS_MODULE;
 194
 195        /*
 196         * initialize pullups according to platform data and cache the
 197         * register values for later use.
 198         */
 199        for (i = 1; i < 8; i++) {
 200                int j;
 201                /*
 202                 * initialize port_config with "0xAA", which means
 203                 * input with internal pullup disabled. This is needed
 204                 * to avoid writing zeros (in the inner for loop),
 205                 * which is not allowed according to the datasheet.
 206                 */
 207                ts->port_config[i] = 0xAA;
 208                for (j = 0; j < 4; j++) {
 209                        int offset = (i - 1) * 4 + j;
 210                        ret = max7301_direction_input(&ts->chip, offset);
 211                        if (ret)
 212                                goto exit_destroy;
 213                }
 214        }
 215
 216        ret = gpiochip_add(&ts->chip);
 217        if (ret)
 218                goto exit_destroy;
 219
 220        return ret;
 221
 222exit_destroy:
 223        dev_set_drvdata(dev, NULL);
 224        mutex_destroy(&ts->lock);
 225        return ret;
 226}
 227EXPORT_SYMBOL_GPL(__max730x_probe);
 228
 229int __max730x_remove(struct device *dev)
 230{
 231        struct max7301 *ts = dev_get_drvdata(dev);
 232        int ret;
 233
 234        if (ts == NULL)
 235                return -ENODEV;
 236
 237        dev_set_drvdata(dev, NULL);
 238
 239        /* Power down the chip and disable IRQ output */
 240        ts->write(dev, 0x04, 0x00);
 241
 242        ret = gpiochip_remove(&ts->chip);
 243        if (!ret) {
 244                mutex_destroy(&ts->lock);
 245                kfree(ts);
 246        } else
 247                dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
 248
 249        return ret;
 250}
 251EXPORT_SYMBOL_GPL(__max730x_remove);
 252
 253MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
 254MODULE_LICENSE("GPL v2");
 255MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
 256
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