// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2005 Simtec Electronics
 *      Ben Dooks <ben@simtec.co.uk>
 *
 * Simtec Generic I2C Controller
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>

struct simtec_i2c_data {
        struct resource         *ioarea;
        void __iomem            *reg;
        struct i2c_adapter       adap;
        struct i2c_algo_bit_data bit;
};

#define CMD_SET_SDA     (1<<2)
#define CMD_SET_SCL     (1<<3)

#define STATE_SDA       (1<<0)
#define STATE_SCL       (1<<1)

/* i2c bit-bus functions */

static void simtec_i2c_setsda(void *pw, int state)
{
        struct simtec_i2c_data *pd = pw;
        writeb(CMD_SET_SDA | (state ? STATE_SDA : 0), pd->reg);
}

static void simtec_i2c_setscl(void *pw, int state)
{
        struct simtec_i2c_data *pd = pw;
        writeb(CMD_SET_SCL | (state ? STATE_SCL : 0), pd->reg);
}

static int simtec_i2c_getsda(void *pw)
{
        struct simtec_i2c_data *pd = pw;
        return readb(pd->reg) & STATE_SDA ? 1 : 0;
}

static int simtec_i2c_getscl(void *pw)
{
        struct simtec_i2c_data *pd = pw;
        return readb(pd->reg) & STATE_SCL ? 1 : 0;
}

/* device registration */

static int simtec_i2c_probe(struct platform_device *dev)
{
        struct simtec_i2c_data *pd;
        struct resource *res;
        int size;
        int ret;

        pd = kzalloc_obj(struct simtec_i2c_data);
        if (pd == NULL)
                return -ENOMEM;

        platform_set_drvdata(dev, pd);

        res = platform_get_resource(dev, IORESOURCE_MEM, 0);
        if (res == NULL) {
                dev_err(&dev->dev, "cannot find IO resource\n");
                ret = -ENOENT;
                goto err;
        }

        size = resource_size(res);

        pd->ioarea = request_mem_region(res->start, size, dev->name);
        if (pd->ioarea == NULL) {
                dev_err(&dev->dev, "cannot request IO\n");
                ret = -ENXIO;
                goto err;
        }

        pd->reg = ioremap(res->start, size);
        if (pd->reg == NULL) {
                dev_err(&dev->dev, "cannot map IO\n");
                ret = -ENXIO;
                goto err_res;
        }

        /* setup the private data */

        pd->adap.owner = THIS_MODULE;
        pd->adap.algo_data = &pd->bit;
        pd->adap.dev.parent = &dev->dev;

        strscpy(pd->adap.name, "Simtec I2C", sizeof(pd->adap.name));

        pd->bit.data = pd;
        pd->bit.setsda = simtec_i2c_setsda;
        pd->bit.setscl = simtec_i2c_setscl;
        pd->bit.getsda = simtec_i2c_getsda;
        pd->bit.getscl = simtec_i2c_getscl;
        pd->bit.timeout = HZ;
        pd->bit.udelay = 20;

        ret = i2c_bit_add_bus(&pd->adap);
        if (ret)
                goto err_all;

        return 0;

 err_all:
        iounmap(pd->reg);

 err_res:
        release_mem_region(pd->ioarea->start, size);

 err:
        kfree(pd);
        return ret;
}

static void simtec_i2c_remove(struct platform_device *dev)
{
        struct simtec_i2c_data *pd = platform_get_drvdata(dev);

        i2c_del_adapter(&pd->adap);

        iounmap(pd->reg);
        release_mem_region(pd->ioarea->start, resource_size(pd->ioarea));
        kfree(pd);
}

/* device driver */

static struct platform_driver simtec_i2c_driver = {
        .driver         = {
                .name           = "simtec-i2c",
        },
        .probe          = simtec_i2c_probe,
        .remove         = simtec_i2c_remove,
};

module_platform_driver(simtec_i2c_driver);

MODULE_DESCRIPTION("Simtec Generic I2C Bus driver");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:simtec-i2c");