mc13xxx-spi.c

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/*
 * Copyright 2009-2010 Pengutronix
 * Uwe Kleine-Koenig <[email protected]>
 *
 * loosely based on an earlier driver that has
 * Copyright 2009 Pengutronix, Sascha Hauer <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the
 * Free Software Foundation.
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/mfd/core.h>
#include <linux/mfd/mc13xxx.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/err.h>
#include <linux/spi/spi.h>

#include "mc13xxx.h"

static const struct spi_device_id mc13xxx_device_id[] = {
    {
        .name = "mc13783",
        .driver_data = MC13XXX_ID_MC13783,
    }, {
        .name = "mc13892",
        .driver_data = MC13XXX_ID_MC13892,
    }, {
        /* sentinel */
    }
};
MODULE_DEVICE_TABLE(spi, mc13xxx_device_id);

static const struct of_device_id mc13xxx_dt_ids[] = {
    { .compatible = "fsl,mc13783", .data = (void *) MC13XXX_ID_MC13783, },
    { .compatible = "fsl,mc13892", .data = (void *) MC13XXX_ID_MC13892, },
    { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mc13xxx_dt_ids);

static struct regmap_config mc13xxx_regmap_spi_config = {
    .reg_bits = 7,
    .pad_bits = 1,
    .val_bits = 24,
    .write_flag_mask = 0x80,

    .max_register = MC13XXX_NUMREGS,

    .cache_type = REGCACHE_NONE,
    .use_single_rw = 1,
};

static int mc13xxx_spi_read(void *context, const void *reg, size_t reg_size,
                void *val, size_t val_size)
{
    unsigned char w[4] = { *((unsigned char *) reg), 0, 0, 0};
    unsigned char r[4];
    unsigned char *p = val;
    struct device *dev = context;
    struct spi_device *spi = to_spi_device(dev);
    struct spi_transfer t = {
        .tx_buf = w,
        .rx_buf = r,
        .len = 4,
    };

    struct spi_message m;
    int ret;

    if (val_size != 3 || reg_size != 1)
        return -ENOTSUPP;

    spi_message_init(&m);
    spi_message_add_tail(&t, &m);
    ret = spi_sync(spi, &m);

    memcpy(p, &r[1], 3);

    return ret;
}

static int mc13xxx_spi_write(void *context, const void *data, size_t count)
{
    struct device *dev = context;
    struct spi_device *spi = to_spi_device(dev);

    if (count != 4)
        return -ENOTSUPP;

    return spi_write(spi, data, count);
}

/*
 * We cannot use regmap-spi generic bus implementation here.
 * The MC13783 chip will get corrupted if CS signal is deasserted
 * and on i.Mx31 SoC (the target SoC for MC13783 PMIC) the SPI controller
 * has the following errata (DSPhl22960):
 * "The CSPI negates SS when the FIFO becomes empty with
 * SSCTL= 0. Software cannot guarantee that the FIFO will not
 * drain because of higher priority interrupts and the
 * non-realtime characteristics of the operating system. As a
 * result, the SS will negate before all of the data has been
 * transferred to/from the peripheral."
 * We workaround this by accessing the SPI controller with a
 * single transfert.
 */

static struct regmap_bus regmap_mc13xxx_bus = {
    .write = mc13xxx_spi_write,
    .read = mc13xxx_spi_read,
};

static int mc13xxx_spi_probe(struct spi_device *spi)
{
    struct mc13xxx *mc13xxx;
    struct mc13xxx_platform_data *pdata = dev_get_platdata(&spi->dev);
    int ret;

    mc13xxx = devm_kzalloc(&spi->dev, sizeof(*mc13xxx), GFP_KERNEL);
    if (!mc13xxx)
        return -ENOMEM;

    dev_set_drvdata(&spi->dev, mc13xxx);
    spi->mode = SPI_MODE_0 | SPI_CS_HIGH;

    mc13xxx->dev = &spi->dev;
    mutex_init(&mc13xxx->lock);

    mc13xxx->regmap = devm_regmap_init(&spi->dev, &regmap_mc13xxx_bus,
                       &spi->dev,
                       &mc13xxx_regmap_spi_config);
    if (IS_ERR(mc13xxx->regmap)) {
        ret = PTR_ERR(mc13xxx->regmap);
        dev_err(mc13xxx->dev, "Failed to initialize register map: %d\n",
                ret);
        dev_set_drvdata(&spi->dev, NULL);
        return ret;
    }

    ret = mc13xxx_common_init(mc13xxx, pdata, spi->irq);

    if (ret) {
        dev_set_drvdata(&spi->dev, NULL);
    } else {
        const struct spi_device_id *devid =
            spi_get_device_id(spi);
        if (!devid || devid->driver_data != mc13xxx->ictype)
            dev_warn(mc13xxx->dev,
                "device id doesn't match auto detection!\n");
    }

    return ret;
}

static int __devexit mc13xxx_spi_remove(struct spi_device *spi)
{
    struct mc13xxx *mc13xxx = dev_get_drvdata(&spi->dev);

    mc13xxx_common_cleanup(mc13xxx);

    return 0;
}

static struct spi_driver mc13xxx_spi_driver = {
    .id_table = mc13xxx_device_id,
    .driver = {
        .name = "mc13xxx",
        .owner = THIS_MODULE,
        .of_match_table = mc13xxx_dt_ids,
    },
    .probe = mc13xxx_spi_probe,
    .remove = __devexit_p(mc13xxx_spi_remove),
};

static int __init mc13xxx_init(void)
{
    return spi_register_driver(&mc13xxx_spi_driver);
}
subsys_initcall(mc13xxx_init);

static void __exit mc13xxx_exit(void)
{
    spi_unregister_driver(&mc13xxx_spi_driver);
}
module_exit(mc13xxx_exit);

MODULE_DESCRIPTION("Core driver for Freescale MC13XXX PMIC");
MODULE_AUTHOR("Uwe Kleine-Koenig <[email protected]>");
MODULE_LICENSE("GPL v2");