// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Nano River Technologies viperboard i2c controller driver
 *
 *  (C) 2012 by Lemonage GmbH
 *  Author: Lars Poeschel <poeschel@lemonage.de>
 *  All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string_choices.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>

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

#include <linux/mfd/viperboard.h>

struct vprbrd_i2c {
        struct i2c_adapter i2c;
        u8 bus_freq_param;
};

/* i2c bus frequency module parameter */
static u8 i2c_bus_param;
static unsigned int i2c_bus_freq = 100;
module_param(i2c_bus_freq, int, 0);
MODULE_PARM_DESC(i2c_bus_freq,
        "i2c bus frequency in khz (default is 100) valid values: 10, 100, 200, 400, 1000, 3000, 6000");

static int vprbrd_i2c_status(struct i2c_adapter *i2c,
        struct vprbrd_i2c_status *status, bool prev_error)
{
        u16 bytes_xfer;
        int ret;
        struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;

        /* check for protocol error */
        bytes_xfer = sizeof(struct vprbrd_i2c_status);

        ret = usb_control_msg(vb->usb_dev, usb_rcvctrlpipe(vb->usb_dev, 0),
                VPRBRD_USB_REQUEST_I2C, VPRBRD_USB_TYPE_IN, 0x0000, 0x0000,
                status, bytes_xfer, VPRBRD_USB_TIMEOUT_MS);

        if (ret != bytes_xfer)
                prev_error = true;

        if (prev_error) {
                dev_err(&i2c->dev, "failure in usb communication\n");
                return -EREMOTEIO;
        }

        dev_dbg(&i2c->dev, "  status = %d\n", status->status);
        if (status->status != 0x00) {
                dev_err(&i2c->dev, "failure: i2c protocol error\n");
                return -EPROTO;
        }
        return 0;
}

static int vprbrd_i2c_receive(struct usb_device *usb_dev,
        struct vprbrd_i2c_read_msg *rmsg, int bytes_xfer)
{
        int ret, bytes_actual;
        int error = 0;

        /* send the read request */
        ret = usb_bulk_msg(usb_dev,
                usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), rmsg,
                sizeof(struct vprbrd_i2c_read_hdr), &bytes_actual,
                VPRBRD_USB_TIMEOUT_MS);

        if ((ret < 0)
                || (bytes_actual != sizeof(struct vprbrd_i2c_read_hdr))) {
                dev_err(&usb_dev->dev, "failure transmitting usb\n");
                error = -EREMOTEIO;
        }

        /* read the actual data */
        ret = usb_bulk_msg(usb_dev,
                usb_rcvbulkpipe(usb_dev, VPRBRD_EP_IN), rmsg,
                bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);

        if ((ret < 0) || (bytes_xfer != bytes_actual)) {
                dev_err(&usb_dev->dev, "failure receiving usb\n");
                error = -EREMOTEIO;
        }
        return error;
}

static int vprbrd_i2c_addr(struct usb_device *usb_dev,
        struct vprbrd_i2c_addr_msg *amsg)
{
        int ret, bytes_actual;

        ret = usb_bulk_msg(usb_dev,
                usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), amsg,
                sizeof(struct vprbrd_i2c_addr_msg), &bytes_actual,
                VPRBRD_USB_TIMEOUT_MS);

        if ((ret < 0) ||
                        (sizeof(struct vprbrd_i2c_addr_msg) != bytes_actual)) {
                dev_err(&usb_dev->dev, "failure transmitting usb\n");
                return -EREMOTEIO;
        }
        return 0;
}

static int vprbrd_i2c_read(struct vprbrd *vb, struct i2c_msg *msg)
{
        int ret;
        u16 remain_len, len1, len2, start = 0x0000;
        struct vprbrd_i2c_read_msg *rmsg =
                (struct vprbrd_i2c_read_msg *)vb->buf;

        remain_len = msg->len;
        rmsg->header.cmd = VPRBRD_I2C_CMD_READ;
        while (remain_len > 0) {
                rmsg->header.addr = cpu_to_le16(start + 0x4000);
                if (remain_len <= 255) {
                        len1 = remain_len;
                        len2 = 0x00;
                        rmsg->header.len0 = remain_len;
                        rmsg->header.len1 = 0x00;
                        rmsg->header.len2 = 0x00;
                        rmsg->header.len3 = 0x00;
                        rmsg->header.len4 = 0x00;
                        rmsg->header.len5 = 0x00;
                        remain_len = 0;
                } else if (remain_len <= 510) {
                        len1 = remain_len;
                        len2 = 0x00;
                        rmsg->header.len0 = remain_len - 255;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0x00;
                        rmsg->header.len3 = 0x00;
                        rmsg->header.len4 = 0x00;
                        rmsg->header.len5 = 0x00;
                        remain_len = 0;
                } else if (remain_len <= 512) {
                        len1 = remain_len;
                        len2 = 0x00;
                        rmsg->header.len0 = remain_len - 510;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0xff;
                        rmsg->header.len3 = 0x00;
                        rmsg->header.len4 = 0x00;
                        rmsg->header.len5 = 0x00;
                        remain_len = 0;
                } else if (remain_len <= 767) {
                        len1 = 512;
                        len2 = remain_len - 512;
                        rmsg->header.len0 = 0x02;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0xff;
                        rmsg->header.len3 = remain_len - 512;
                        rmsg->header.len4 = 0x00;
                        rmsg->header.len5 = 0x00;
                        remain_len = 0;
                } else if (remain_len <= 1022) {
                        len1 = 512;
                        len2 = remain_len - 512;
                        rmsg->header.len0 = 0x02;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0xff;
                        rmsg->header.len3 = remain_len - 767;
                        rmsg->header.len4 = 0xff;
                        rmsg->header.len5 = 0x00;
                        remain_len = 0;
                } else if (remain_len <= 1024) {
                        len1 = 512;
                        len2 = remain_len - 512;
                        rmsg->header.len0 = 0x02;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0xff;
                        rmsg->header.len3 = remain_len - 1022;
                        rmsg->header.len4 = 0xff;
                        rmsg->header.len5 = 0xff;
                        remain_len = 0;
                } else {
                        len1 = 512;
                        len2 = 512;
                        rmsg->header.len0 = 0x02;
                        rmsg->header.len1 = 0xff;
                        rmsg->header.len2 = 0xff;
                        rmsg->header.len3 = 0x02;
                        rmsg->header.len4 = 0xff;
                        rmsg->header.len5 = 0xff;
                        remain_len -= 1024;
                        start += 1024;
                }
                rmsg->header.tf1 = cpu_to_le16(len1);
                rmsg->header.tf2 = cpu_to_le16(len2);

                /* first read transfer */
                ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len1);
                if (ret < 0)
                        return ret;
                /* copy the received data */
                memcpy(msg->buf + start, rmsg, len1);

                /* second read transfer if necessary */
                if (len2 > 0) {
                        ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len2);
                        if (ret < 0)
                                return ret;
                        /* copy the received data */
                        memcpy(msg->buf + start + 512, rmsg, len2);
                }
        }
        return 0;
}

static int vprbrd_i2c_write(struct vprbrd *vb, struct i2c_msg *msg)
{
        int ret, bytes_actual;
        u16 remain_len, bytes_xfer,
                start = 0x0000;
        struct vprbrd_i2c_write_msg *wmsg =
                (struct vprbrd_i2c_write_msg *)vb->buf;

        remain_len = msg->len;
        wmsg->header.cmd = VPRBRD_I2C_CMD_WRITE;
        wmsg->header.last = 0x00;
        wmsg->header.chan = 0x00;
        wmsg->header.spi = 0x0000;
        while (remain_len > 0) {
                wmsg->header.addr = cpu_to_le16(start + 0x4000);
                if (remain_len > 503) {
                        wmsg->header.len1 = 0xff;
                        wmsg->header.len2 = 0xf8;
                        remain_len -= 503;
                        bytes_xfer = 503 + sizeof(struct vprbrd_i2c_write_hdr);
                        start += 503;
                } else if (remain_len > 255) {
                        wmsg->header.len1 = 0xff;
                        wmsg->header.len2 = (remain_len - 255);
                        bytes_xfer = remain_len +
                                sizeof(struct vprbrd_i2c_write_hdr);
                        remain_len = 0;
                } else {
                        wmsg->header.len1 = remain_len;
                        wmsg->header.len2 = 0x00;
                        bytes_xfer = remain_len +
                                sizeof(struct vprbrd_i2c_write_hdr);
                        remain_len = 0;
                }
                memcpy(wmsg->data, msg->buf + start,
                        bytes_xfer - sizeof(struct vprbrd_i2c_write_hdr));

                ret = usb_bulk_msg(vb->usb_dev,
                        usb_sndbulkpipe(vb->usb_dev,
                        VPRBRD_EP_OUT), wmsg,
                        bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
                if ((ret < 0) || (bytes_xfer != bytes_actual))
                        return -EREMOTEIO;
        }
        return 0;
}

static int vprbrd_i2c_xfer(struct i2c_adapter *i2c, struct i2c_msg *msgs,
                int num)
{
        struct i2c_msg *pmsg;
        int i, ret,
                error = 0;
        struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
        struct vprbrd_i2c_addr_msg *amsg =
                (struct vprbrd_i2c_addr_msg *)vb->buf;
        struct vprbrd_i2c_status *smsg = (struct vprbrd_i2c_status *)vb->buf;

        for (i = 0 ; i < num ; i++) {
                pmsg = &msgs[i];

                dev_dbg(&i2c->dev,
                        "  %d: %s (flags %d) %d bytes to 0x%02x\n",
                        i, str_read_write(pmsg->flags & I2C_M_RD),
                        pmsg->flags, pmsg->len, pmsg->addr);

                mutex_lock(&vb->lock);
                /* directly send the message */
                if (pmsg->flags & I2C_M_RD) {
                        /* read data */
                        amsg->cmd = VPRBRD_I2C_CMD_ADDR;
                        amsg->unknown2 = 0x00;
                        amsg->unknown3 = 0x00;
                        amsg->addr = pmsg->addr;
                        amsg->unknown1 = 0x01;
                        amsg->len = cpu_to_le16(pmsg->len);
                        /* send the addr and len, we're interested to board */
                        ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
                        if (ret < 0)
                                error = ret;

                        ret = vprbrd_i2c_read(vb, pmsg);
                        if (ret < 0)
                                error = ret;

                        ret = vprbrd_i2c_status(i2c, smsg, error);
                        if (ret < 0)
                                error = ret;
                        /* in case of protocol error, return the error */
                        if (error < 0)
                                goto error;
                } else {
                        /* write data */
                        ret = vprbrd_i2c_write(vb, pmsg);

                        amsg->cmd = VPRBRD_I2C_CMD_ADDR;
                        amsg->unknown2 = 0x00;
                        amsg->unknown3 = 0x00;
                        amsg->addr = pmsg->addr;
                        amsg->unknown1 = 0x00;
                        amsg->len = cpu_to_le16(pmsg->len);
                        /* send the addr, the data goes to to board */
                        ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
                        if (ret < 0)
                                error = ret;

                        ret = vprbrd_i2c_status(i2c, smsg, error);
                        if (ret < 0)
                                error = ret;

                        if (error < 0)
                                goto error;
                }
                mutex_unlock(&vb->lock);
        }
        return num;
error:
        mutex_unlock(&vb->lock);
        return error;
}

static u32 vprbrd_i2c_func(struct i2c_adapter *i2c)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

/* This is the actual algorithm we define */
static const struct i2c_algorithm vprbrd_algorithm = {
        .xfer = vprbrd_i2c_xfer,
        .functionality = vprbrd_i2c_func,
};

static const struct i2c_adapter_quirks vprbrd_quirks = {
        .max_read_len = 2048,
        .max_write_len = 2048,
};

static int vprbrd_i2c_probe(struct platform_device *pdev)
{
        struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
        struct vprbrd_i2c *vb_i2c;
        int ret;
        int pipe;

        vb_i2c = devm_kzalloc(&pdev->dev, sizeof(*vb_i2c), GFP_KERNEL);
        if (vb_i2c == NULL)
                return -ENOMEM;

        /* setup i2c adapter description */
        vb_i2c->i2c.owner = THIS_MODULE;
        vb_i2c->i2c.class = I2C_CLASS_HWMON;
        vb_i2c->i2c.algo = &vprbrd_algorithm;
        vb_i2c->i2c.quirks = &vprbrd_quirks;
        vb_i2c->i2c.algo_data = vb;
        /* save the param in usb capabable memory */
        vb_i2c->bus_freq_param = i2c_bus_param;

        snprintf(vb_i2c->i2c.name, sizeof(vb_i2c->i2c.name),
                 "viperboard at bus %03d device %03d",
                 vb->usb_dev->bus->busnum, vb->usb_dev->devnum);

        /* setting the bus frequency */
        if ((i2c_bus_param <= VPRBRD_I2C_FREQ_10KHZ)
                && (i2c_bus_param >= VPRBRD_I2C_FREQ_6MHZ)) {
                pipe = usb_sndctrlpipe(vb->usb_dev, 0);
                ret = usb_control_msg(vb->usb_dev, pipe,
                        VPRBRD_USB_REQUEST_I2C_FREQ, VPRBRD_USB_TYPE_OUT,
                        0x0000, 0x0000, &vb_i2c->bus_freq_param, 1,
                        VPRBRD_USB_TIMEOUT_MS);
                if (ret != 1)
                        return dev_err_probe(&pdev->dev, -EIO,
                                             "failure setting i2c_bus_freq to %d\n",
                                             i2c_bus_freq);
        } else {
                return dev_err_probe(&pdev->dev, -EIO,
                                     "invalid i2c_bus_freq setting:%d\n", i2c_bus_freq);
        }

        vb_i2c->i2c.dev.parent = &pdev->dev;

        /* attach to i2c layer */
        i2c_add_adapter(&vb_i2c->i2c);

        platform_set_drvdata(pdev, vb_i2c);

        return 0;
}

static void vprbrd_i2c_remove(struct platform_device *pdev)
{
        struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);

        i2c_del_adapter(&vb_i2c->i2c);
}

static struct platform_driver vprbrd_i2c_driver = {
        .driver.name    = "viperboard-i2c",
        .probe          = vprbrd_i2c_probe,
        .remove         = vprbrd_i2c_remove,
};

static int __init vprbrd_i2c_init(void)
{
        switch (i2c_bus_freq) {
        case 6000:
                i2c_bus_param = VPRBRD_I2C_FREQ_6MHZ;
                break;
        case 3000:
                i2c_bus_param = VPRBRD_I2C_FREQ_3MHZ;
                break;
        case 1000:
                i2c_bus_param = VPRBRD_I2C_FREQ_1MHZ;
                break;
        case 400:
                i2c_bus_param = VPRBRD_I2C_FREQ_400KHZ;
                break;
        case 200:
                i2c_bus_param = VPRBRD_I2C_FREQ_200KHZ;
                break;
        case 100:
                i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
                break;
        case 10:
                i2c_bus_param = VPRBRD_I2C_FREQ_10KHZ;
                break;
        default:
                pr_warn("invalid i2c_bus_freq (%d)\n", i2c_bus_freq);
                i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
        }

        return platform_driver_register(&vprbrd_i2c_driver);
}
subsys_initcall(vprbrd_i2c_init);

static void __exit vprbrd_i2c_exit(void)
{
        platform_driver_unregister(&vprbrd_i2c_driver);
}
module_exit(vprbrd_i2c_exit);

MODULE_AUTHOR("Lars Poeschel <poeschel@lemonage.de>");
MODULE_DESCRIPTION("I2C controller driver for Nano River Techs Viperboard");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:viperboard-i2c");