// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2006 Juergen Beisert, Pengutronix
 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
 * Copyright (C) 2009 Wolfram Sang, Pengutronix
 *
 * Check max730x.c for further details.
 */

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

/* A write to the MAX7301 means one message with one transfer */
static int max7301_spi_write(struct device *dev, unsigned int reg,
                                unsigned int val)
{
        struct spi_device *spi = to_spi_device(dev);
        u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);

        return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);
}

/* A read from the MAX7301 means two transfers; here, one message each */

static int max7301_spi_read(struct device *dev, unsigned int reg)
{
        int ret;
        u16 word;
        struct spi_device *spi = to_spi_device(dev);

        word = 0x8000 | (reg << 8);
        ret = spi_write_then_read(spi, &word, sizeof(word), &word,
                                  sizeof(word));
        if (ret)
                return ret;
        return word & 0xff;
}

static int max7301_probe(struct spi_device *spi)
{
        struct max7301 *ts;
        int ret;

        /* bits_per_word cannot be configured in platform data */
        spi->bits_per_word = 16;
        ret = spi_setup(spi);
        if (ret < 0)
                return ret;

        ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
        if (!ts)
                return -ENOMEM;

        ts->read = max7301_spi_read;
        ts->write = max7301_spi_write;
        ts->dev = &spi->dev;

        ret = __max730x_probe(ts);
        return ret;
}

static void max7301_remove(struct spi_device *spi)
{
        __max730x_remove(&spi->dev);
}

static const struct spi_device_id max7301_id[] = {
        { "max7301", 0 },
        { }
};
MODULE_DEVICE_TABLE(spi, max7301_id);

static struct spi_driver max7301_driver = {
        .driver = {
                .name = "max7301",
        },
        .probe = max7301_probe,
        .remove = max7301_remove,
        .id_table = max7301_id,
};

static int __init max7301_init(void)
{
        return spi_register_driver(&max7301_driver);
}
/* register after spi postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(max7301_init);

static void __exit max7301_exit(void)
{
        spi_unregister_driver(&max7301_driver);
}
module_exit(max7301_exit);

MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MAX7301 GPIO-Expander");