gpio-sx150x.c

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/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/i2c/sx150x.h>

#define NO_UPDATE_PENDING   -1

struct sx150x_device_data {
    u8 reg_pullup;
    u8 reg_pulldn;
    u8 reg_drain;
    u8 reg_polarity;
    u8 reg_dir;
    u8 reg_data;
    u8 reg_irq_mask;
    u8 reg_irq_src;
    u8 reg_sense;
    u8 reg_clock;
    u8 reg_misc;
    u8 reg_reset;
    u8 ngpios;
};

struct sx150x_chip {
    struct gpio_chip                 gpio_chip;
    struct i2c_client               *client;
    const struct sx150x_device_data *dev_cfg;
    int                              irq_summary;
    int                              irq_base;
    int              irq_update;
    u32                              irq_sense;
    u32              irq_masked;
    u32              dev_sense;
    u32              dev_masked;
    struct irq_chip                  irq_chip;
    struct mutex                     lock;
};

static const struct sx150x_device_data sx150x_devices[] = {
    [0] = { /* sx1508q */
        .reg_pullup   = 0x03,
        .reg_pulldn   = 0x04,
        .reg_drain    = 0x05,
        .reg_polarity = 0x06,
        .reg_dir      = 0x07,
        .reg_data     = 0x08,
        .reg_irq_mask = 0x09,
        .reg_irq_src  = 0x0c,
        .reg_sense    = 0x0b,
        .reg_clock    = 0x0f,
        .reg_misc     = 0x10,
        .reg_reset    = 0x7d,
        .ngpios       = 8
    },
    [1] = { /* sx1509q */
        .reg_pullup   = 0x07,
        .reg_pulldn   = 0x09,
        .reg_drain    = 0x0b,
        .reg_polarity = 0x0d,
        .reg_dir      = 0x0f,
        .reg_data     = 0x11,
        .reg_irq_mask = 0x13,
        .reg_irq_src  = 0x19,
        .reg_sense    = 0x17,
        .reg_clock    = 0x1e,
        .reg_misc     = 0x1f,
        .reg_reset    = 0x7d,
        .ngpios       = 16
    },
};

static const struct i2c_device_id sx150x_id[] = {
    {"sx1508q", 0},
    {"sx1509q", 1},
    {}
};
MODULE_DEVICE_TABLE(i2c, sx150x_id);

static s32 sx150x_i2c_write(struct i2c_client *client, u8 reg, u8 val)
{
    s32 err = i2c_smbus_write_byte_data(client, reg, val);

    if (err < 0)
        dev_warn(&client->dev,
            "i2c write fail: can't write %02x to %02x: %d\n",
            val, reg, err);
    return err;
}

static s32 sx150x_i2c_read(struct i2c_client *client, u8 reg, u8 *val)
{
    s32 err = i2c_smbus_read_byte_data(client, reg);

    if (err >= 0)
        *val = err;
    else
        dev_warn(&client->dev,
            "i2c read fail: can't read from %02x: %d\n",
            reg, err);
    return err;
}

static inline bool offset_is_oscio(struct sx150x_chip *chip, unsigned offset)
{
    return (chip->dev_cfg->ngpios == offset);
}

/*
 * These utility functions solve the common problem of locating and setting
 * configuration bits.  Configuration bits are grouped into registers
 * whose indexes increase downwards.  For example, with eight-bit registers,
 * sixteen gpios would have their config bits grouped in the following order:
 * REGISTER N-1 [ f e d c b a 9 8 ]
 *          N   [ 7 6 5 4 3 2 1 0 ]
 *
 * For multi-bit configurations, the pattern gets wider:
 * REGISTER N-3 [ f f e e d d c c ]
 *          N-2 [ b b a a 9 9 8 8 ]
 *          N-1 [ 7 7 6 6 5 5 4 4 ]
 *          N   [ 3 3 2 2 1 1 0 0 ]
 *
 * Given the address of the starting register 'N', the index of the gpio
 * whose configuration we seek to change, and the width in bits of that
 * configuration, these functions allow us to locate the correct
 * register and mask the correct bits.
 */
static inline void sx150x_find_cfg(u8 offset, u8 width,
                u8 *reg, u8 *mask, u8 *shift)
{
    *reg   -= offset * width / 8;
    *mask   = (1 << width) - 1;
    *shift  = (offset * width) % 8;
    *mask <<= *shift;
}

static s32 sx150x_write_cfg(struct sx150x_chip *chip,
            u8 offset, u8 width, u8 reg, u8 val)
{
    u8  mask;
    u8  data;
    u8  shift;
    s32 err;

    sx150x_find_cfg(offset, width, &reg, &mask, &shift);
    err = sx150x_i2c_read(chip->client, reg, &data);
    if (err < 0)
        return err;

    data &= ~mask;
    data |= (val << shift) & mask;
    return sx150x_i2c_write(chip->client, reg, data);
}

static int sx150x_get_io(struct sx150x_chip *chip, unsigned offset)
{
    u8  reg = chip->dev_cfg->reg_data;
    u8  mask;
    u8  data;
    u8  shift;
    s32 err;

    sx150x_find_cfg(offset, 1, &reg, &mask, &shift);
    err = sx150x_i2c_read(chip->client, reg, &data);
    if (err >= 0)
        err = (data & mask) != 0 ? 1 : 0;

    return err;
}

static void sx150x_set_oscio(struct sx150x_chip *chip, int val)
{
    sx150x_i2c_write(chip->client,
            chip->dev_cfg->reg_clock,
            (val ? 0x1f : 0x10));
}

static void sx150x_set_io(struct sx150x_chip *chip, unsigned offset, int val)
{
    sx150x_write_cfg(chip,
            offset,
            1,
            chip->dev_cfg->reg_data,
            (val ? 1 : 0));
}

static int sx150x_io_input(struct sx150x_chip *chip, unsigned offset)
{
    return sx150x_write_cfg(chip,
                offset,
                1,
                chip->dev_cfg->reg_dir,
                1);
}

static int sx150x_io_output(struct sx150x_chip *chip, unsigned offset, int val)
{
    int err;

    err = sx150x_write_cfg(chip,
            offset,
            1,
            chip->dev_cfg->reg_data,
            (val ? 1 : 0));
    if (err >= 0)
        err = sx150x_write_cfg(chip,
                offset,
                1,
                chip->dev_cfg->reg_dir,
                0);
    return err;
}

static int sx150x_gpio_get(struct gpio_chip *gc, unsigned offset)
{
    struct sx150x_chip *chip;
    int status = -EINVAL;

    chip = container_of(gc, struct sx150x_chip, gpio_chip);

    if (!offset_is_oscio(chip, offset)) {
        mutex_lock(&chip->lock);
        status = sx150x_get_io(chip, offset);
        mutex_unlock(&chip->lock);
    }

    return status;
}

static void sx150x_gpio_set(struct gpio_chip *gc, unsigned offset, int val)
{
    struct sx150x_chip *chip;

    chip = container_of(gc, struct sx150x_chip, gpio_chip);

    mutex_lock(&chip->lock);
    if (offset_is_oscio(chip, offset))
        sx150x_set_oscio(chip, val);
    else
        sx150x_set_io(chip, offset, val);
    mutex_unlock(&chip->lock);
}

static int sx150x_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
{
    struct sx150x_chip *chip;
    int status = -EINVAL;

    chip = container_of(gc, struct sx150x_chip, gpio_chip);

    if (!offset_is_oscio(chip, offset)) {
        mutex_lock(&chip->lock);
        status = sx150x_io_input(chip, offset);
        mutex_unlock(&chip->lock);
    }
    return status;
}

static int sx150x_gpio_direction_output(struct gpio_chip *gc,
                    unsigned offset,
                    int val)
{
    struct sx150x_chip *chip;
    int status = 0;

    chip = container_of(gc, struct sx150x_chip, gpio_chip);

    if (!offset_is_oscio(chip, offset)) {
        mutex_lock(&chip->lock);
        status = sx150x_io_output(chip, offset, val);
        mutex_unlock(&chip->lock);
    }
    return status;
}

static int sx150x_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
{
    struct sx150x_chip *chip;

    chip = container_of(gc, struct sx150x_chip, gpio_chip);

    if (offset >= chip->dev_cfg->ngpios)
        return -EINVAL;

    if (chip->irq_base < 0)
        return -EINVAL;

    return chip->irq_base + offset;
}

static void sx150x_irq_mask(struct irq_data *d)
{
    struct sx150x_chip *chip = irq_data_get_irq_chip_data(d);
    unsigned n;

    n = d->irq - chip->irq_base;
    chip->irq_masked |= (1 << n);
    chip->irq_update = n;
}

static void sx150x_irq_unmask(struct irq_data *d)
{
    struct sx150x_chip *chip = irq_data_get_irq_chip_data(d);
    unsigned n;

    n = d->irq - chip->irq_base;
    chip->irq_masked &= ~(1 << n);
    chip->irq_update = n;
}

static int sx150x_irq_set_type(struct irq_data *d, unsigned int flow_type)
{
    struct sx150x_chip *chip = irq_data_get_irq_chip_data(d);
    unsigned n, val = 0;

    if (flow_type & (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW))
        return -EINVAL;

    n = d->irq - chip->irq_base;

    if (flow_type & IRQ_TYPE_EDGE_RISING)
        val |= 0x1;
    if (flow_type & IRQ_TYPE_EDGE_FALLING)
        val |= 0x2;

    chip->irq_sense &= ~(3UL << (n * 2));
    chip->irq_sense |= val << (n * 2);
    chip->irq_update = n;
    return 0;
}

static irqreturn_t sx150x_irq_thread_fn(int irq, void *dev_id)
{
    struct sx150x_chip *chip = (struct sx150x_chip *)dev_id;
    unsigned nhandled = 0;
    unsigned sub_irq;
    unsigned n;
    s32 err;
    u8 val;
    int i;

    for (i = (chip->dev_cfg->ngpios / 8) - 1; i >= 0; --i) {
        err = sx150x_i2c_read(chip->client,
                      chip->dev_cfg->reg_irq_src - i,
                      &val);
        if (err < 0)
            continue;

        sx150x_i2c_write(chip->client,
                chip->dev_cfg->reg_irq_src - i,
                val);
        for (n = 0; n < 8; ++n) {
            if (val & (1 << n)) {
                sub_irq = chip->irq_base + (i * 8) + n;
                handle_nested_irq(sub_irq);
                ++nhandled;
            }
        }
    }

    return (nhandled > 0 ? IRQ_HANDLED : IRQ_NONE);
}

static void sx150x_irq_bus_lock(struct irq_data *d)
{
    struct sx150x_chip *chip = irq_data_get_irq_chip_data(d);

    mutex_lock(&chip->lock);
}

static void sx150x_irq_bus_sync_unlock(struct irq_data *d)
{
    struct sx150x_chip *chip = irq_data_get_irq_chip_data(d);
    unsigned n;

    if (chip->irq_update == NO_UPDATE_PENDING)
        goto out;

    n = chip->irq_update;
    chip->irq_update = NO_UPDATE_PENDING;

    /* Avoid updates if nothing changed */
    if (chip->dev_sense == chip->irq_sense &&
        chip->dev_sense == chip->irq_masked)
        goto out;

    chip->dev_sense = chip->irq_sense;
    chip->dev_masked = chip->irq_masked;

    if (chip->irq_masked & (1 << n)) {
        sx150x_write_cfg(chip, n, 1, chip->dev_cfg->reg_irq_mask, 1);
        sx150x_write_cfg(chip, n, 2, chip->dev_cfg->reg_sense, 0);
    } else {
        sx150x_write_cfg(chip, n, 1, chip->dev_cfg->reg_irq_mask, 0);
        sx150x_write_cfg(chip, n, 2, chip->dev_cfg->reg_sense,
                 chip->irq_sense >> (n * 2));
    }
out:
    mutex_unlock(&chip->lock);
}

static void sx150x_init_chip(struct sx150x_chip *chip,
            struct i2c_client *client,
            kernel_ulong_t driver_data,
            struct sx150x_platform_data *pdata)
{
    mutex_init(&chip->lock);

    chip->client                     = client;
    chip->dev_cfg                    = &sx150x_devices[driver_data];
    chip->gpio_chip.label            = client->name;
    chip->gpio_chip.direction_input  = sx150x_gpio_direction_input;
    chip->gpio_chip.direction_output = sx150x_gpio_direction_output;
    chip->gpio_chip.get              = sx150x_gpio_get;
    chip->gpio_chip.set              = sx150x_gpio_set;
    chip->gpio_chip.to_irq           = sx150x_gpio_to_irq;
    chip->gpio_chip.base             = pdata->gpio_base;
    chip->gpio_chip.can_sleep        = 1;
    chip->gpio_chip.ngpio            = chip->dev_cfg->ngpios;
    if (pdata->oscio_is_gpo)
        ++chip->gpio_chip.ngpio;

    chip->irq_chip.name                = client->name;
    chip->irq_chip.irq_mask            = sx150x_irq_mask;
    chip->irq_chip.irq_unmask          = sx150x_irq_unmask;
    chip->irq_chip.irq_set_type        = sx150x_irq_set_type;
    chip->irq_chip.irq_bus_lock        = sx150x_irq_bus_lock;
    chip->irq_chip.irq_bus_sync_unlock = sx150x_irq_bus_sync_unlock;
    chip->irq_summary                  = -1;
    chip->irq_base                     = -1;
    chip->irq_masked                   = ~0;
    chip->irq_sense                    = 0;
    chip->dev_masked                   = ~0;
    chip->dev_sense                    = 0;
    chip->irq_update           = NO_UPDATE_PENDING;
}

static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg)
{
    int err = 0;
    unsigned n;

    for (n = 0; err >= 0 && n < (chip->dev_cfg->ngpios / 8); ++n)
        err = sx150x_i2c_write(chip->client, base - n, cfg >> (n * 8));
    return err;
}

static int sx150x_reset(struct sx150x_chip *chip)
{
    int err;

    err = i2c_smbus_write_byte_data(chip->client,
                    chip->dev_cfg->reg_reset,
                    0x12);
    if (err < 0)
        return err;

    err = i2c_smbus_write_byte_data(chip->client,
                    chip->dev_cfg->reg_reset,
                    0x34);
    return err;
}

static int sx150x_init_hw(struct sx150x_chip *chip,
            struct sx150x_platform_data *pdata)
{
    int err = 0;

    if (pdata->reset_during_probe) {
        err = sx150x_reset(chip);
        if (err < 0)
            return err;
    }

    err = sx150x_i2c_write(chip->client,
            chip->dev_cfg->reg_misc,
            0x01);
    if (err < 0)
        return err;

    err = sx150x_init_io(chip, chip->dev_cfg->reg_pullup,
            pdata->io_pullup_ena);
    if (err < 0)
        return err;

    err = sx150x_init_io(chip, chip->dev_cfg->reg_pulldn,
            pdata->io_pulldn_ena);
    if (err < 0)
        return err;

    err = sx150x_init_io(chip, chip->dev_cfg->reg_drain,
            pdata->io_open_drain_ena);
    if (err < 0)
        return err;

    err = sx150x_init_io(chip, chip->dev_cfg->reg_polarity,
            pdata->io_polarity);
    if (err < 0)
        return err;

    if (pdata->oscio_is_gpo)
        sx150x_set_oscio(chip, 0);

    return err;
}

static int sx150x_install_irq_chip(struct sx150x_chip *chip,
                int irq_summary,
                int irq_base)
{
    int err;
    unsigned n;
    unsigned irq;

    chip->irq_summary = irq_summary;
    chip->irq_base    = irq_base;

    for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
        irq = irq_base + n;
        irq_set_chip_data(irq, chip);
        irq_set_chip_and_handler(irq, &chip->irq_chip, handle_edge_irq);
        irq_set_nested_thread(irq, 1);
#ifdef CONFIG_ARM
        set_irq_flags(irq, IRQF_VALID);
#else
        irq_set_noprobe(irq);
#endif
    }

    err = request_threaded_irq(irq_summary,
                NULL,
                sx150x_irq_thread_fn,
                IRQF_SHARED | IRQF_TRIGGER_FALLING,
                chip->irq_chip.name,
                chip);
    if (err < 0) {
        chip->irq_summary = -1;
        chip->irq_base    = -1;
    }

    return err;
}

static void sx150x_remove_irq_chip(struct sx150x_chip *chip)
{
    unsigned n;
    unsigned irq;

    free_irq(chip->irq_summary, chip);

    for (n = 0; n < chip->dev_cfg->ngpios; ++n) {
        irq = chip->irq_base + n;
        irq_set_chip_and_handler(irq, NULL, NULL);
    }
}

static int __devinit sx150x_probe(struct i2c_client *client,
                const struct i2c_device_id *id)
{
    static const u32 i2c_funcs = I2C_FUNC_SMBUS_BYTE_DATA |
                     I2C_FUNC_SMBUS_WRITE_WORD_DATA;
    struct sx150x_platform_data *pdata;
    struct sx150x_chip *chip;
    int rc;

    pdata = client->dev.platform_data;
    if (!pdata)
        return -EINVAL;

    if (!i2c_check_functionality(client->adapter, i2c_funcs))
        return -ENOSYS;

    chip = kzalloc(sizeof(struct sx150x_chip), GFP_KERNEL);
    if (!chip)
        return -ENOMEM;

    sx150x_init_chip(chip, client, id->driver_data, pdata);
    rc = sx150x_init_hw(chip, pdata);
    if (rc < 0)
        goto probe_fail_pre_gpiochip_add;

    rc = gpiochip_add(&chip->gpio_chip);
    if (rc < 0)
        goto probe_fail_pre_gpiochip_add;

    if (pdata->irq_summary >= 0) {
        rc = sx150x_install_irq_chip(chip,
                    pdata->irq_summary,
                    pdata->irq_base);
        if (rc < 0)
            goto probe_fail_post_gpiochip_add;
    }

    i2c_set_clientdata(client, chip);

    return 0;
probe_fail_post_gpiochip_add:
    WARN_ON(gpiochip_remove(&chip->gpio_chip) < 0);
probe_fail_pre_gpiochip_add:
    kfree(chip);
    return rc;
}

static int __devexit sx150x_remove(struct i2c_client *client)
{
    struct sx150x_chip *chip;
    int rc;

    chip = i2c_get_clientdata(client);
    rc = gpiochip_remove(&chip->gpio_chip);
    if (rc < 0)
        return rc;

    if (chip->irq_summary >= 0)
        sx150x_remove_irq_chip(chip);

    kfree(chip);

    return 0;
}

static struct i2c_driver sx150x_driver = {
    .driver = {
        .name = "sx150x",
        .owner = THIS_MODULE
    },
    .probe    = sx150x_probe,
    .remove   = __devexit_p(sx150x_remove),
    .id_table = sx150x_id,
};

static int __init sx150x_init(void)
{
    return i2c_add_driver(&sx150x_driver);
}
subsys_initcall(sx150x_init);

static void __exit sx150x_exit(void)
{
    return i2c_del_driver(&sx150x_driver);
}
module_exit(sx150x_exit);

MODULE_AUTHOR("Gregory Bean <[email protected]>");
MODULE_DESCRIPTION("Driver for Semtech SX150X I2C GPIO Expanders");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("i2c:sx150x");