gpio-max730x.c

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#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/spi/max7301.h>
#include <linux/gpio.h>
#include <linux/slab.h>

/*
 * Pin configurations, see MAX7301 datasheet page 6
 */
#define PIN_CONFIG_MASK 0x03
#define PIN_CONFIG_IN_PULLUP 0x03
#define PIN_CONFIG_IN_WO_PULLUP 0x02
#define PIN_CONFIG_OUT 0x01

#define PIN_NUMBER 28

static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
{
    struct max7301 *ts = container_of(chip, struct max7301, chip);
    u8 *config;
    u8 offset_bits, pin_config;
    int ret;

    /* First 4 pins are unused in the controller */
    offset += 4;
    offset_bits = (offset & 3) << 1;

    config = &ts->port_config[offset >> 2];

    if (ts->input_pullup_active & BIT(offset))
        pin_config = PIN_CONFIG_IN_PULLUP;
    else
        pin_config = PIN_CONFIG_IN_WO_PULLUP;

    mutex_lock(&ts->lock);

    *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
               | (pin_config << offset_bits);

    ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);

    mutex_unlock(&ts->lock);

    return ret;
}

static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
{
    if (value) {
        ts->out_level |= 1 << offset;
        return ts->write(ts->dev, 0x20 + offset, 0x01);
    } else {
        ts->out_level &= ~(1 << offset);
        return ts->write(ts->dev, 0x20 + offset, 0x00);
    }
}

static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
                    int value)
{
    struct max7301 *ts = container_of(chip, struct max7301, chip);
    u8 *config;
    u8 offset_bits;
    int ret;

    /* First 4 pins are unused in the controller */
    offset += 4;
    offset_bits = (offset & 3) << 1;

    config = &ts->port_config[offset >> 2];

    mutex_lock(&ts->lock);

    *config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
               | (PIN_CONFIG_OUT << offset_bits);

    ret = __max7301_set(ts, offset, value);

    if (!ret)
        ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);

    mutex_unlock(&ts->lock);

    return ret;
}

static int max7301_get(struct gpio_chip *chip, unsigned offset)
{
    struct max7301 *ts = container_of(chip, struct max7301, chip);
    int config, level = -EINVAL;

    /* First 4 pins are unused in the controller */
    offset += 4;

    mutex_lock(&ts->lock);

    config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
            & PIN_CONFIG_MASK;

    switch (config) {
    case PIN_CONFIG_OUT:
        /* Output: return cached level */
        level =  !!(ts->out_level & (1 << offset));
        break;
    case PIN_CONFIG_IN_WO_PULLUP:
    case PIN_CONFIG_IN_PULLUP:
        /* Input: read out */
        level = ts->read(ts->dev, 0x20 + offset) & 0x01;
    }
    mutex_unlock(&ts->lock);

    return level;
}

static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
{
    struct max7301 *ts = container_of(chip, struct max7301, chip);

    /* First 4 pins are unused in the controller */
    offset += 4;

    mutex_lock(&ts->lock);

    __max7301_set(ts, offset, value);

    mutex_unlock(&ts->lock);
}

int __devinit __max730x_probe(struct max7301 *ts)
{
    struct device *dev = ts->dev;
    struct max7301_platform_data *pdata;
    int i, ret;

    pdata = dev->platform_data;
    if (!pdata || !pdata->base) {
        dev_err(dev, "incorrect or missing platform data\n");
        return -EINVAL;
    }

    mutex_init(&ts->lock);
    dev_set_drvdata(dev, ts);

    /* Power up the chip and disable IRQ output */
    ts->write(dev, 0x04, 0x01);

    ts->input_pullup_active = pdata->input_pullup_active;
    ts->chip.label = dev->driver->name;

    ts->chip.direction_input = max7301_direction_input;
    ts->chip.get = max7301_get;
    ts->chip.direction_output = max7301_direction_output;
    ts->chip.set = max7301_set;

    ts->chip.base = pdata->base;
    ts->chip.ngpio = PIN_NUMBER;
    ts->chip.can_sleep = 1;
    ts->chip.dev = dev;
    ts->chip.owner = THIS_MODULE;

    /*
     * initialize pullups according to platform data and cache the
     * register values for later use.
     */
    for (i = 1; i < 8; i++) {
        int j;
        /*
         * initialize port_config with "0xAA", which means
         * input with internal pullup disabled. This is needed
         * to avoid writing zeros (in the inner for loop),
         * which is not allowed according to the datasheet.
         */
        ts->port_config[i] = 0xAA;
        for (j = 0; j < 4; j++) {
            int offset = (i - 1) * 4 + j;
            ret = max7301_direction_input(&ts->chip, offset);
            if (ret)
                goto exit_destroy;
        }
    }

    ret = gpiochip_add(&ts->chip);
    if (ret)
        goto exit_destroy;

    return ret;

exit_destroy:
    dev_set_drvdata(dev, NULL);
    mutex_destroy(&ts->lock);
    return ret;
}
EXPORT_SYMBOL_GPL(__max730x_probe);

int __devexit __max730x_remove(struct device *dev)
{
    struct max7301 *ts = dev_get_drvdata(dev);
    int ret;

    if (ts == NULL)
        return -ENODEV;

    dev_set_drvdata(dev, NULL);

    /* Power down the chip and disable IRQ output */
    ts->write(dev, 0x04, 0x00);

    ret = gpiochip_remove(&ts->chip);
    if (!ret) {
        mutex_destroy(&ts->lock);
        kfree(ts);
    } else
        dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);

    return ret;
}
EXPORT_SYMBOL_GPL(__max730x_remove);

MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");