gpio-mcp23s08.c

Go to the documentation of this file.

/*
 * MCP23S08 SPI/GPIO gpio expander driver
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/spi/spi.h>
#include <linux/spi/mcp23s08.h>
#include <linux/slab.h>
#include <asm/byteorder.h>

#define MCP_TYPE_S08    0
#define MCP_TYPE_S17    1
#define MCP_TYPE_008    2
#define MCP_TYPE_017    3

/* Registers are all 8 bits wide.
 *
 * The mcp23s17 has twice as many bits, and can be configured to work
 * with either 16 bit registers or with two adjacent 8 bit banks.
 */
#define MCP_IODIR   0x00        /* init/reset:  all ones */
#define MCP_IPOL    0x01
#define MCP_GPINTEN 0x02
#define MCP_DEFVAL  0x03
#define MCP_INTCON  0x04
#define MCP_IOCON   0x05
#   define IOCON_SEQOP  (1 << 5)
#   define IOCON_HAEN   (1 << 3)
#   define IOCON_ODR    (1 << 2)
#   define IOCON_INTPOL (1 << 1)
#define MCP_GPPU    0x06
#define MCP_INTF    0x07
#define MCP_INTCAP  0x08
#define MCP_GPIO    0x09
#define MCP_OLAT    0x0a

struct mcp23s08;

struct mcp23s08_ops {
    int (*read)(struct mcp23s08 *mcp, unsigned reg);
    int (*write)(struct mcp23s08 *mcp, unsigned reg, unsigned val);
    int (*read_regs)(struct mcp23s08 *mcp, unsigned reg,
                 u16 *vals, unsigned n);
};

struct mcp23s08 {
    u8          addr;

    u16         cache[11];
    /* lock protects the cached values */
    struct mutex        lock;

    struct gpio_chip    chip;

    const struct mcp23s08_ops   *ops;
    void            *data; /* ops specific data */
};

/* A given spi_device can represent up to eight mcp23sxx chips
 * sharing the same chipselect but using different addresses
 * (e.g. chips #0 and #3 might be populated, but not #1 or $2).
 * Driver data holds all the per-chip data.
 */
struct mcp23s08_driver_data {
    unsigned        ngpio;
    struct mcp23s08     *mcp[8];
    struct mcp23s08     chip[];
};

/*----------------------------------------------------------------------*/

#if IS_ENABLED(CONFIG_I2C)

static int mcp23008_read(struct mcp23s08 *mcp, unsigned reg)
{
    return i2c_smbus_read_byte_data(mcp->data, reg);
}

static int mcp23008_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
    return i2c_smbus_write_byte_data(mcp->data, reg, val);
}

static int
mcp23008_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
    while (n--) {
        int ret = mcp23008_read(mcp, reg++);
        if (ret < 0)
            return ret;
        *vals++ = ret;
    }

    return 0;
}

static int mcp23017_read(struct mcp23s08 *mcp, unsigned reg)
{
    return i2c_smbus_read_word_data(mcp->data, reg << 1);
}

static int mcp23017_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
    return i2c_smbus_write_word_data(mcp->data, reg << 1, val);
}

static int
mcp23017_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
    while (n--) {
        int ret = mcp23017_read(mcp, reg++);
        if (ret < 0)
            return ret;
        *vals++ = ret;
    }

    return 0;
}

static const struct mcp23s08_ops mcp23008_ops = {
    .read       = mcp23008_read,
    .write      = mcp23008_write,
    .read_regs  = mcp23008_read_regs,
};

static const struct mcp23s08_ops mcp23017_ops = {
    .read       = mcp23017_read,
    .write      = mcp23017_write,
    .read_regs  = mcp23017_read_regs,
};

#endif /* CONFIG_I2C */

/*----------------------------------------------------------------------*/

#ifdef CONFIG_SPI_MASTER

static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
{
    u8  tx[2], rx[1];
    int status;

    tx[0] = mcp->addr | 0x01;
    tx[1] = reg;
    status = spi_write_then_read(mcp->data, tx, sizeof tx, rx, sizeof rx);
    return (status < 0) ? status : rx[0];
}

static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
    u8  tx[3];

    tx[0] = mcp->addr;
    tx[1] = reg;
    tx[2] = val;
    return spi_write_then_read(mcp->data, tx, sizeof tx, NULL, 0);
}

static int
mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
    u8  tx[2], *tmp;
    int status;

    if ((n + reg) > sizeof mcp->cache)
        return -EINVAL;
    tx[0] = mcp->addr | 0x01;
    tx[1] = reg;

    tmp = (u8 *)vals;
    status = spi_write_then_read(mcp->data, tx, sizeof tx, tmp, n);
    if (status >= 0) {
        while (n--)
            vals[n] = tmp[n]; /* expand to 16bit */
    }
    return status;
}

static int mcp23s17_read(struct mcp23s08 *mcp, unsigned reg)
{
    u8  tx[2], rx[2];
    int status;

    tx[0] = mcp->addr | 0x01;
    tx[1] = reg << 1;
    status = spi_write_then_read(mcp->data, tx, sizeof tx, rx, sizeof rx);
    return (status < 0) ? status : (rx[0] | (rx[1] << 8));
}

static int mcp23s17_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
{
    u8  tx[4];

    tx[0] = mcp->addr;
    tx[1] = reg << 1;
    tx[2] = val;
    tx[3] = val >> 8;
    return spi_write_then_read(mcp->data, tx, sizeof tx, NULL, 0);
}

static int
mcp23s17_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
{
    u8  tx[2];
    int status;

    if ((n + reg) > sizeof mcp->cache)
        return -EINVAL;
    tx[0] = mcp->addr | 0x01;
    tx[1] = reg << 1;

    status = spi_write_then_read(mcp->data, tx, sizeof tx,
                     (u8 *)vals, n * 2);
    if (status >= 0) {
        while (n--)
            vals[n] = __le16_to_cpu((__le16)vals[n]);
    }

    return status;
}

static const struct mcp23s08_ops mcp23s08_ops = {
    .read       = mcp23s08_read,
    .write      = mcp23s08_write,
    .read_regs  = mcp23s08_read_regs,
};

static const struct mcp23s08_ops mcp23s17_ops = {
    .read       = mcp23s17_read,
    .write      = mcp23s17_write,
    .read_regs  = mcp23s17_read_regs,
};

#endif /* CONFIG_SPI_MASTER */

/*----------------------------------------------------------------------*/

static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
{
    struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
    int status;

    mutex_lock(&mcp->lock);
    mcp->cache[MCP_IODIR] |= (1 << offset);
    status = mcp->ops->write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
    mutex_unlock(&mcp->lock);
    return status;
}

static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
{
    struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
    int status;

    mutex_lock(&mcp->lock);

    /* REVISIT reading this clears any IRQ ... */
    status = mcp->ops->read(mcp, MCP_GPIO);
    if (status < 0)
        status = 0;
    else {
        mcp->cache[MCP_GPIO] = status;
        status = !!(status & (1 << offset));
    }
    mutex_unlock(&mcp->lock);
    return status;
}

static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
{
    unsigned olat = mcp->cache[MCP_OLAT];

    if (value)
        olat |= mask;
    else
        olat &= ~mask;
    mcp->cache[MCP_OLAT] = olat;
    return mcp->ops->write(mcp, MCP_OLAT, olat);
}

static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
{
    struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
    unsigned mask = 1 << offset;

    mutex_lock(&mcp->lock);
    __mcp23s08_set(mcp, mask, value);
    mutex_unlock(&mcp->lock);
}

static int
mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
{
    struct mcp23s08 *mcp = container_of(chip, struct mcp23s08, chip);
    unsigned mask = 1 << offset;
    int status;

    mutex_lock(&mcp->lock);
    status = __mcp23s08_set(mcp, mask, value);
    if (status == 0) {
        mcp->cache[MCP_IODIR] &= ~mask;
        status = mcp->ops->write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
    }
    mutex_unlock(&mcp->lock);
    return status;
}

/*----------------------------------------------------------------------*/

#ifdef CONFIG_DEBUG_FS

#include <linux/seq_file.h>

/*
 * This shows more info than the generic gpio dump code:
 * pullups, deglitching, open drain drive.
 */
static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
    struct mcp23s08 *mcp;
    char        bank;
    int     t;
    unsigned    mask;

    mcp = container_of(chip, struct mcp23s08, chip);

    /* NOTE: we only handle one bank for now ... */
    bank = '0' + ((mcp->addr >> 1) & 0x7);

    mutex_lock(&mcp->lock);
    t = mcp->ops->read_regs(mcp, 0, mcp->cache, ARRAY_SIZE(mcp->cache));
    if (t < 0) {
        seq_printf(s, " I/O ERROR %d\n", t);
        goto done;
    }

    for (t = 0, mask = 1; t < chip->ngpio; t++, mask <<= 1) {
        const char  *label;

        label = gpiochip_is_requested(chip, t);
        if (!label)
            continue;

        seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
            chip->base + t, bank, t, label,
            (mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
            (mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
            (mcp->cache[MCP_GPPU] & mask) ? "up" : "  ");
        /* NOTE:  ignoring the irq-related registers */
        seq_printf(s, "\n");
    }
done:
    mutex_unlock(&mcp->lock);
}

#else
#define mcp23s08_dbg_show   NULL
#endif

/*----------------------------------------------------------------------*/

static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
                  void *data, unsigned addr,
                  unsigned type, unsigned base, unsigned pullups)
{
    int status;

    mutex_init(&mcp->lock);

    mcp->data = data;
    mcp->addr = addr;

    mcp->chip.direction_input = mcp23s08_direction_input;
    mcp->chip.get = mcp23s08_get;
    mcp->chip.direction_output = mcp23s08_direction_output;
    mcp->chip.set = mcp23s08_set;
    mcp->chip.dbg_show = mcp23s08_dbg_show;

    switch (type) {
#ifdef CONFIG_SPI_MASTER
    case MCP_TYPE_S08:
        mcp->ops = &mcp23s08_ops;
        mcp->chip.ngpio = 8;
        mcp->chip.label = "mcp23s08";
        break;

    case MCP_TYPE_S17:
        mcp->ops = &mcp23s17_ops;
        mcp->chip.ngpio = 16;
        mcp->chip.label = "mcp23s17";
        break;
#endif /* CONFIG_SPI_MASTER */

#if IS_ENABLED(CONFIG_I2C)
    case MCP_TYPE_008:
        mcp->ops = &mcp23008_ops;
        mcp->chip.ngpio = 8;
        mcp->chip.label = "mcp23008";
        break;

    case MCP_TYPE_017:
        mcp->ops = &mcp23017_ops;
        mcp->chip.ngpio = 16;
        mcp->chip.label = "mcp23017";
        break;
#endif /* CONFIG_I2C */

    default:
        dev_err(dev, "invalid device type (%d)\n", type);
        return -EINVAL;
    }

    mcp->chip.base = base;
    mcp->chip.can_sleep = 1;
    mcp->chip.dev = dev;
    mcp->chip.owner = THIS_MODULE;

    /* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
     * and MCP_IOCON.HAEN = 1, so we work with all chips.
     */
    status = mcp->ops->read(mcp, MCP_IOCON);
    if (status < 0)
        goto fail;
    if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN)) {
        /* mcp23s17 has IOCON twice, make sure they are in sync */
        status &= ~(IOCON_SEQOP | (IOCON_SEQOP << 8));
        status |= IOCON_HAEN | (IOCON_HAEN << 8);
        status = mcp->ops->write(mcp, MCP_IOCON, status);
        if (status < 0)
            goto fail;
    }

    /* configure ~100K pullups */
    status = mcp->ops->write(mcp, MCP_GPPU, pullups);
    if (status < 0)
        goto fail;

    status = mcp->ops->read_regs(mcp, 0, mcp->cache, ARRAY_SIZE(mcp->cache));
    if (status < 0)
        goto fail;

    /* disable inverter on input */
    if (mcp->cache[MCP_IPOL] != 0) {
        mcp->cache[MCP_IPOL] = 0;
        status = mcp->ops->write(mcp, MCP_IPOL, 0);
        if (status < 0)
            goto fail;
    }

    /* disable irqs */
    if (mcp->cache[MCP_GPINTEN] != 0) {
        mcp->cache[MCP_GPINTEN] = 0;
        status = mcp->ops->write(mcp, MCP_GPINTEN, 0);
        if (status < 0)
            goto fail;
    }

    status = gpiochip_add(&mcp->chip);
fail:
    if (status < 0)
        dev_dbg(dev, "can't setup chip %d, --> %d\n",
            addr, status);
    return status;
}

/*----------------------------------------------------------------------*/

#if IS_ENABLED(CONFIG_I2C)

static int __devinit mcp230xx_probe(struct i2c_client *client,
                    const struct i2c_device_id *id)
{
    struct mcp23s08_platform_data *pdata;
    struct mcp23s08 *mcp;
    int status;

    pdata = client->dev.platform_data;
    if (!pdata || !gpio_is_valid(pdata->base)) {
        dev_dbg(&client->dev, "invalid or missing platform data\n");
        return -EINVAL;
    }

    mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
    if (!mcp)
        return -ENOMEM;

    status = mcp23s08_probe_one(mcp, &client->dev, client, client->addr,
                    id->driver_data, pdata->base,
                    pdata->chip[0].pullups);
    if (status)
        goto fail;

    i2c_set_clientdata(client, mcp);

    return 0;

fail:
    kfree(mcp);

    return status;
}

static int __devexit mcp230xx_remove(struct i2c_client *client)
{
    struct mcp23s08 *mcp = i2c_get_clientdata(client);
    int status;

    status = gpiochip_remove(&mcp->chip);
    if (status == 0)
        kfree(mcp);

    return status;
}

static const struct i2c_device_id mcp230xx_id[] = {
    { "mcp23008", MCP_TYPE_008 },
    { "mcp23017", MCP_TYPE_017 },
    { },
};
MODULE_DEVICE_TABLE(i2c, mcp230xx_id);

static struct i2c_driver mcp230xx_driver = {
    .driver = {
        .name   = "mcp230xx",
        .owner  = THIS_MODULE,
    },
    .probe      = mcp230xx_probe,
    .remove     = __devexit_p(mcp230xx_remove),
    .id_table   = mcp230xx_id,
};

static int __init mcp23s08_i2c_init(void)
{
    return i2c_add_driver(&mcp230xx_driver);
}

static void mcp23s08_i2c_exit(void)
{
    i2c_del_driver(&mcp230xx_driver);
}

#else

static int __init mcp23s08_i2c_init(void) { return 0; }
static void mcp23s08_i2c_exit(void) { }

#endif /* CONFIG_I2C */

/*----------------------------------------------------------------------*/

#ifdef CONFIG_SPI_MASTER

static int mcp23s08_probe(struct spi_device *spi)
{
    struct mcp23s08_platform_data   *pdata;
    unsigned            addr;
    unsigned            chips = 0;
    struct mcp23s08_driver_data *data;
    int             status, type;
    unsigned            base;

    type = spi_get_device_id(spi)->driver_data;

    pdata = spi->dev.platform_data;
    if (!pdata || !gpio_is_valid(pdata->base)) {
        dev_dbg(&spi->dev, "invalid or missing platform data\n");
        return -EINVAL;
    }

    for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
        if (!pdata->chip[addr].is_present)
            continue;
        chips++;
        if ((type == MCP_TYPE_S08) && (addr > 3)) {
            dev_err(&spi->dev,
                "mcp23s08 only supports address 0..3\n");
            return -EINVAL;
        }
    }
    if (!chips)
        return -ENODEV;

    data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
            GFP_KERNEL);
    if (!data)
        return -ENOMEM;
    spi_set_drvdata(spi, data);

    base = pdata->base;
    for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
        if (!pdata->chip[addr].is_present)
            continue;
        chips--;
        data->mcp[addr] = &data->chip[chips];
        status = mcp23s08_probe_one(data->mcp[addr], &spi->dev, spi,
                        0x40 | (addr << 1), type, base,
                        pdata->chip[addr].pullups);
        if (status < 0)
            goto fail;

        base += (type == MCP_TYPE_S17) ? 16 : 8;
    }
    data->ngpio = base - pdata->base;

    /* NOTE:  these chips have a relatively sane IRQ framework, with
     * per-signal masking and level/edge triggering.  It's not yet
     * handled here...
     */

    return 0;

fail:
    for (addr = 0; addr < ARRAY_SIZE(data->mcp); addr++) {
        int tmp;

        if (!data->mcp[addr])
            continue;
        tmp = gpiochip_remove(&data->mcp[addr]->chip);
        if (tmp < 0)
            dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
    }
    kfree(data);
    return status;
}

static int mcp23s08_remove(struct spi_device *spi)
{
    struct mcp23s08_driver_data *data = spi_get_drvdata(spi);
    unsigned            addr;
    int             status = 0;

    for (addr = 0; addr < ARRAY_SIZE(data->mcp); addr++) {
        int tmp;

        if (!data->mcp[addr])
            continue;

        tmp = gpiochip_remove(&data->mcp[addr]->chip);
        if (tmp < 0) {
            dev_err(&spi->dev, "%s --> %d\n", "remove", tmp);
            status = tmp;
        }
    }
    if (status == 0)
        kfree(data);
    return status;
}

static const struct spi_device_id mcp23s08_ids[] = {
    { "mcp23s08", MCP_TYPE_S08 },
    { "mcp23s17", MCP_TYPE_S17 },
    { },
};
MODULE_DEVICE_TABLE(spi, mcp23s08_ids);

static struct spi_driver mcp23s08_driver = {
    .probe      = mcp23s08_probe,
    .remove     = mcp23s08_remove,
    .id_table   = mcp23s08_ids,
    .driver = {
        .name   = "mcp23s08",
        .owner  = THIS_MODULE,
    },
};

static int __init mcp23s08_spi_init(void)
{
    return spi_register_driver(&mcp23s08_driver);
}

static void mcp23s08_spi_exit(void)
{
    spi_unregister_driver(&mcp23s08_driver);
}

#else

static int __init mcp23s08_spi_init(void) { return 0; }
static void mcp23s08_spi_exit(void) { }

#endif /* CONFIG_SPI_MASTER */

/*----------------------------------------------------------------------*/

static int __init mcp23s08_init(void)
{
    int ret;

    ret = mcp23s08_spi_init();
    if (ret)
        goto spi_fail;

    ret = mcp23s08_i2c_init();
    if (ret)
        goto i2c_fail;

    return 0;

 i2c_fail:
    mcp23s08_spi_exit();
 spi_fail:
    return ret;
}
/* register after spi/i2c postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(mcp23s08_init);

static void __exit mcp23s08_exit(void)
{
    mcp23s08_spi_exit();
    mcp23s08_i2c_exit();
}
module_exit(mcp23s08_exit);

MODULE_LICENSE("GPL");