// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Driver for the Auvitek AU0828 USB bridge
 *
 *  Copyright (c) 2008 Steven Toth <stoth@linuxtv.org>
 */

#include "au0828.h"

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/io.h>

#include "media/tuner.h"
#include <media/v4l2-common.h>

static int i2c_scan;
module_param(i2c_scan, int, 0444);
MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

#define I2C_WAIT_DELAY 25
#define I2C_WAIT_RETRY 1000

static inline int i2c_slave_did_read_ack(struct i2c_adapter *i2c_adap)
{
        struct au0828_dev *dev = i2c_adap->algo_data;
        return au0828_read(dev, AU0828_I2C_STATUS_201) &
                AU0828_I2C_STATUS_NO_READ_ACK ? 0 : 1;
}

static int i2c_wait_read_ack(struct i2c_adapter *i2c_adap)
{
        int count;

        for (count = 0; count < I2C_WAIT_RETRY; count++) {
                if (!i2c_slave_did_read_ack(i2c_adap))
                        break;
                udelay(I2C_WAIT_DELAY);
        }

        if (I2C_WAIT_RETRY == count)
                return 0;

        return 1;
}

static inline int i2c_is_read_busy(struct i2c_adapter *i2c_adap)
{
        struct au0828_dev *dev = i2c_adap->algo_data;
        return au0828_read(dev, AU0828_I2C_STATUS_201) &
                AU0828_I2C_STATUS_READ_DONE ? 0 : 1;
}

static int i2c_wait_read_done(struct i2c_adapter *i2c_adap)
{
        int count;

        for (count = 0; count < I2C_WAIT_RETRY; count++) {
                if (!i2c_is_read_busy(i2c_adap))
                        break;
                udelay(I2C_WAIT_DELAY);
        }

        if (I2C_WAIT_RETRY == count)
                return 0;

        return 1;
}

static inline int i2c_is_write_done(struct i2c_adapter *i2c_adap)
{
        struct au0828_dev *dev = i2c_adap->algo_data;
        return au0828_read(dev, AU0828_I2C_STATUS_201) &
                AU0828_I2C_STATUS_WRITE_DONE ? 1 : 0;
}

static int i2c_wait_write_done(struct i2c_adapter *i2c_adap)
{
        int count;

        for (count = 0; count < I2C_WAIT_RETRY; count++) {
                if (i2c_is_write_done(i2c_adap))
                        break;
                udelay(I2C_WAIT_DELAY);
        }

        if (I2C_WAIT_RETRY == count)
                return 0;

        return 1;
}

static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
{
        struct au0828_dev *dev = i2c_adap->algo_data;
        return au0828_read(dev, AU0828_I2C_STATUS_201) &
                AU0828_I2C_STATUS_BUSY ? 1 : 0;
}

static int i2c_wait_done(struct i2c_adapter *i2c_adap)
{
        int count;

        for (count = 0; count < I2C_WAIT_RETRY; count++) {
                if (!i2c_is_busy(i2c_adap))
                        break;
                udelay(I2C_WAIT_DELAY);
        }

        if (I2C_WAIT_RETRY == count)
                return 0;

        return 1;
}

/* FIXME: Implement join handling correctly */
static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
        const struct i2c_msg *msg, int joined_rlen)
{
        int i, strobe = 0;
        struct au0828_dev *dev = i2c_adap->algo_data;
        u8 i2c_speed = dev->board.i2c_clk_divider;

        dprintk(4, "%s()\n", __func__);

        au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

        if (((dev->board.tuner_type == TUNER_XC5000) ||
             (dev->board.tuner_type == TUNER_XC5000C)) &&
            (dev->board.tuner_addr == msg->addr)) {
                /*
                 * Due to I2C clock stretch, we need to use a lower speed
                 * on xc5000 for commands. However, firmware transfer can
                 * speed up to 400 KHz.
                 */
                if (msg->len == 64)
                        i2c_speed = AU0828_I2C_CLK_250KHZ;
                else
                        i2c_speed = AU0828_I2C_CLK_20KHZ;
        }
        /* Set the I2C clock */
        au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

        /* Hardware needs 8 bit addresses */
        au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

        dprintk(4, "SEND: %02x\n", msg->addr);

        /* Deal with i2c_scan */
        if (msg->len == 0) {
                /* The analog tuner detection code makes use of the SMBUS_QUICK
                   message (which involves a zero length i2c write).  To avoid
                   checking the status register when we didn't strobe out any
                   actual bytes to the bus, just do a read check.  This is
                   consistent with how I saw i2c device checking done in the
                   USB trace of the Windows driver */
                au0828_write(dev, AU0828_I2C_TRIGGER_200,
                             AU0828_I2C_TRIGGER_READ);

                if (!i2c_wait_done(i2c_adap))
                        return -EIO;

                if (i2c_wait_read_ack(i2c_adap))
                        return -EIO;

                return 0;
        }

        for (i = 0; i < msg->len;) {

                dprintk(4, " %02x\n", msg->buf[i]);

                au0828_write(dev, AU0828_I2C_WRITE_FIFO_205, msg->buf[i]);

                strobe++;
                i++;

                if ((strobe >= 4) || (i >= msg->len)) {

                        /* Strobe the byte into the bus */
                        if (i < msg->len)
                                au0828_write(dev, AU0828_I2C_TRIGGER_200,
                                             AU0828_I2C_TRIGGER_WRITE |
                                             AU0828_I2C_TRIGGER_HOLD);
                        else
                                au0828_write(dev, AU0828_I2C_TRIGGER_200,
                                             AU0828_I2C_TRIGGER_WRITE);

                        /* Reset strobe trigger */
                        strobe = 0;

                        if (!i2c_wait_write_done(i2c_adap))
                                return -EIO;

                }

        }
        if (!i2c_wait_done(i2c_adap))
                return -EIO;

        dprintk(4, "\n");

        return msg->len;
}

/* FIXME: Implement join handling correctly */
static int i2c_readbytes(struct i2c_adapter *i2c_adap,
        const struct i2c_msg *msg, int joined)
{
        struct au0828_dev *dev = i2c_adap->algo_data;
        u8 i2c_speed = dev->board.i2c_clk_divider;
        int i;

        dprintk(4, "%s()\n", __func__);

        au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

        /*
         * Due to xc5000c clock stretch, we cannot use full speed at
         * readings from xc5000, as otherwise they'll fail.
         */
        if (((dev->board.tuner_type == TUNER_XC5000) ||
             (dev->board.tuner_type == TUNER_XC5000C)) &&
            (dev->board.tuner_addr == msg->addr))
                i2c_speed = AU0828_I2C_CLK_20KHZ;

        /* Set the I2C clock */
        au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

        /* Hardware needs 8 bit addresses */
        au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

        dprintk(4, " RECV:\n");

        /* Deal with i2c_scan */
        if (msg->len == 0) {
                au0828_write(dev, AU0828_I2C_TRIGGER_200,
                             AU0828_I2C_TRIGGER_READ);

                if (i2c_wait_read_ack(i2c_adap))
                        return -EIO;
                return 0;
        }

        for (i = 0; i < msg->len;) {

                i++;

                if (i < msg->len)
                        au0828_write(dev, AU0828_I2C_TRIGGER_200,
                                     AU0828_I2C_TRIGGER_READ |
                                     AU0828_I2C_TRIGGER_HOLD);
                else
                        au0828_write(dev, AU0828_I2C_TRIGGER_200,
                                     AU0828_I2C_TRIGGER_READ);

                if (!i2c_wait_read_done(i2c_adap))
                        return -EIO;

                msg->buf[i-1] = au0828_read(dev, AU0828_I2C_READ_FIFO_209) &
                        0xff;

                dprintk(4, " %02x\n", msg->buf[i-1]);
        }
        if (!i2c_wait_done(i2c_adap))
                return -EIO;

        dprintk(4, "\n");

        return msg->len;
}

static int i2c_xfer(struct i2c_adapter *i2c_adap,
                    struct i2c_msg *msgs, int num)
{
        int i, retval = 0;

        dprintk(4, "%s(num = %d)\n", __func__, num);

        for (i = 0; i < num; i++) {
                dprintk(4, "%s(num = %d) addr = 0x%02x  len = 0x%x\n",
                        __func__, num, msgs[i].addr, msgs[i].len);
                if (msgs[i].flags & I2C_M_RD) {
                        /* read */
                        retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
                } else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
                           msgs[i].addr == msgs[i + 1].addr) {
                        /* write then read from same address */
                        retval = i2c_sendbytes(i2c_adap, &msgs[i],
                                               msgs[i + 1].len);
                        if (retval < 0)
                                goto err;
                        i++;
                        retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
                } else {
                        /* write */
                        retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
                }
                if (retval < 0)
                        goto err;
        }
        return num;

err:
        return retval;
}

static u32 au0828_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C;
}

static const struct i2c_algorithm au0828_i2c_algo_template = {
        .master_xfer    = i2c_xfer,
        .functionality  = au0828_functionality,
};

/* ----------------------------------------------------------------------- */

static const struct i2c_adapter au0828_i2c_adap_template = {
        .name              = KBUILD_MODNAME,
        .owner             = THIS_MODULE,
        .algo              = &au0828_i2c_algo_template,
};

static const struct i2c_client au0828_i2c_client_template = {
        .name   = "au0828 internal",
};

static char *i2c_devs[128] = {
        [0x8e >> 1] = "au8522",
        [0xa0 >> 1] = "eeprom",
        [0xc2 >> 1] = "tuner/xc5000",
};

static void do_i2c_scan(char *name, struct i2c_client *c)
{
        unsigned char buf;
        int i, rc;

        for (i = 0; i < 128; i++) {
                c->addr = i;
                rc = i2c_master_recv(c, &buf, 0);
                if (rc < 0)
                        continue;
                pr_info("%s: i2c scan: found device @ 0x%x  [%s]\n",
                       name, i << 1, i2c_devs[i] ? i2c_devs[i] : "???");
        }
}

/* init + register i2c adapter */
int au0828_i2c_register(struct au0828_dev *dev)
{
        dprintk(1, "%s()\n", __func__);

        dev->i2c_adap = au0828_i2c_adap_template;
        dev->i2c_algo = au0828_i2c_algo_template;
        dev->i2c_client = au0828_i2c_client_template;

        dev->i2c_adap.dev.parent = &dev->usbdev->dev;

        strscpy(dev->i2c_adap.name, KBUILD_MODNAME,
                sizeof(dev->i2c_adap.name));

        dev->i2c_adap.algo = &dev->i2c_algo;
        dev->i2c_adap.algo_data = dev;
#ifdef CONFIG_VIDEO_AU0828_V4L2
        i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
#else
        i2c_set_adapdata(&dev->i2c_adap, dev);
#endif
        i2c_add_adapter(&dev->i2c_adap);

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

        if (0 == dev->i2c_rc) {
                pr_info("i2c bus registered\n");
                if (i2c_scan)
                        do_i2c_scan(KBUILD_MODNAME, &dev->i2c_client);
        } else
                pr_info("i2c bus register FAILED\n");

        return dev->i2c_rc;
}

int au0828_i2c_unregister(struct au0828_dev *dev)
{
        i2c_del_adapter(&dev->i2c_adap);
        return 0;
}