// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * STK1160 driver
 *
 * Copyright (C) 2012 Ezequiel Garcia
 * <elezegarcia--a.t--gmail.com>
 *
 * Based on Easycap driver by R.M. Thomas
 *      Copyright (C) 2010 R.M. Thomas
 *      <rmthomas--a.t--sciolus.org>
 */

#include <linux/module.h>
#include <linux/usb.h>
#include <linux/i2c.h>

#include "stk1160.h"
#include "stk1160-reg.h"

static unsigned int i2c_debug;
module_param(i2c_debug, int, 0644);
MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");

#define dprintk_i2c(fmt, args...)                               \
do {                                                            \
        if (i2c_debug)                                          \
                printk(KERN_DEBUG fmt, ##args);                 \
} while (0)

static int stk1160_i2c_busy_wait(struct stk1160 *dev, u8 wait_bit_mask)
{
        unsigned long end;
        u8 flag;

        /* Wait until read/write finish bit is set */
        end = jiffies + msecs_to_jiffies(STK1160_I2C_TIMEOUT);
        while (time_is_after_jiffies(end)) {

                stk1160_read_reg(dev, STK1160_SICTL+1, &flag);
                /* read/write done? */
                if (flag & wait_bit_mask)
                        goto done;

                usleep_range(10 * USEC_PER_MSEC, 20 * USEC_PER_MSEC);
        }

        return -ETIMEDOUT;

done:
        return 0;
}

static int stk1160_i2c_write_reg(struct stk1160 *dev, u8 addr,
                u8 reg, u8 value)
{
        int rc;

        /* Set serial device address */
        rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
        if (rc < 0)
                return rc;

        /* Set i2c device register sub-address */
        rc = stk1160_write_reg(dev, STK1160_SBUSW_WA, reg);
        if (rc < 0)
                return rc;

        /* Set i2c device register value */
        rc = stk1160_write_reg(dev, STK1160_SBUSW_WD, value);
        if (rc < 0)
                return rc;

        /* Start write now */
        rc = stk1160_write_reg(dev, STK1160_SICTL, 0x01);
        if (rc < 0)
                return rc;

        rc = stk1160_i2c_busy_wait(dev, 0x04);
        if (rc < 0)
                return rc;

        return 0;
}

static int stk1160_i2c_read_reg(struct stk1160 *dev, u8 addr,
                u8 reg, u8 *value)
{
        int rc;

        /* Set serial device address */
        rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
        if (rc < 0)
                return rc;

        /* Set i2c device register sub-address */
        rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, reg);
        if (rc < 0)
                return rc;

        /* Start read now */
        rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
        if (rc < 0)
                return rc;

        rc = stk1160_i2c_busy_wait(dev, 0x01);
        if (rc < 0)
                return rc;

        rc = stk1160_read_reg(dev, STK1160_SBUSR_RD, value);
        if (rc < 0)
                return rc;

        return 0;
}

/*
 * stk1160_i2c_check_for_device()
 * check if there is a i2c_device at the supplied address
 */
static int stk1160_i2c_check_for_device(struct stk1160 *dev,
                unsigned char addr)
{
        int rc;

        /* Set serial device address */
        rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
        if (rc < 0)
                return rc;

        /* Set device sub-address, we'll chip version reg */
        rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, 0x00);
        if (rc < 0)
                return rc;

        /* Start read now */
        rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
        if (rc < 0)
                return rc;

        rc = stk1160_i2c_busy_wait(dev, 0x01);
        if (rc < 0)
                return -ENODEV;

        return 0;
}

/*
 * stk1160_i2c_xfer()
 * the main i2c transfer function
 */
static int stk1160_i2c_xfer(struct i2c_adapter *i2c_adap,
                           struct i2c_msg msgs[], int num)
{
        struct stk1160 *dev = i2c_adap->algo_data;
        int addr, rc, i;

        for (i = 0; i < num; i++) {
                addr = msgs[i].addr << 1;
                dprintk_i2c("%s: addr=%x", __func__, addr);

                if (!msgs[i].len) {
                        /* no len: check only for device presence */
                        rc = stk1160_i2c_check_for_device(dev, addr);
                        if (rc < 0) {
                                dprintk_i2c(" no device\n");
                                return rc;
                        }

                } else if (msgs[i].flags & I2C_M_RD) {
                        /* read request without preceding register selection */
                        dprintk_i2c(" subaddr not selected");
                        rc = -EOPNOTSUPP;
                        goto err;

                } else if (i + 1 < num && msgs[i].len <= 2 &&
                           (msgs[i + 1].flags & I2C_M_RD) &&
                           msgs[i].addr == msgs[i + 1].addr) {

                        if (msgs[i].len != 1 || msgs[i + 1].len != 1) {
                                dprintk_i2c(" len not supported");
                                rc = -EOPNOTSUPP;
                                goto err;
                        }

                        dprintk_i2c(" subaddr=%x", msgs[i].buf[0]);

                        rc = stk1160_i2c_read_reg(dev, addr, msgs[i].buf[0],
                                msgs[i + 1].buf);

                        dprintk_i2c(" read=%x", *msgs[i + 1].buf);

                        /* consumed two msgs, so we skip one of them */
                        i++;

                } else {
                        if (msgs[i].len != 2) {
                                dprintk_i2c(" len not supported");
                                rc = -EOPNOTSUPP;
                                goto err;
                        }

                        dprintk_i2c(" subaddr=%x write=%x",
                                msgs[i].buf[0],  msgs[i].buf[1]);

                        rc = stk1160_i2c_write_reg(dev, addr, msgs[i].buf[0],
                                msgs[i].buf[1]);
                }

                if (rc < 0)
                        goto err;
                dprintk_i2c(" OK\n");
        }

        return num;
err:
        dprintk_i2c(" ERROR: %d\n", rc);
        return num;
}

/*
 * functionality(), what da heck is this?
 */
static u32 functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm algo = {
        .master_xfer   = stk1160_i2c_xfer,
        .functionality = functionality,
};

static const struct i2c_adapter adap_template = {
        .owner = THIS_MODULE,
        .name = "stk1160",
        .algo = &algo,
};

static const struct i2c_client client_template = {
        .name = "stk1160 internal",
};

/*
 * stk1160_i2c_register()
 * register i2c bus
 */
int stk1160_i2c_register(struct stk1160 *dev)
{
        int rc;

        dev->i2c_adap = adap_template;
        dev->i2c_adap.dev.parent = dev->dev;
        strscpy(dev->i2c_adap.name, "stk1160", sizeof(dev->i2c_adap.name));
        dev->i2c_adap.algo_data = dev;

        i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);

        rc = i2c_add_adapter(&dev->i2c_adap);
        if (rc < 0) {
                stk1160_err("cannot add i2c adapter (%d)\n", rc);
                return rc;
        }

        dev->i2c_client = client_template;
        dev->i2c_client.adapter = &dev->i2c_adap;

        /* Set i2c clock divider device address */
        stk1160_write_reg(dev, STK1160_SICTL_CD,  0x0f);

        /* ??? */
        stk1160_write_reg(dev, STK1160_ASIC + 3,  0x00);

        return 0;
}

/*
 * stk1160_i2c_unregister()
 * unregister i2c_bus
 */
int stk1160_i2c_unregister(struct stk1160 *dev)
{
        i2c_del_adapter(&dev->i2c_adap);
        return 0;
}