// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for RobotFuzz OSIF
 *
 * Copyright (c) 2013 Andrew Lunn <andrew@lunn.ch>
 * Copyright (c) 2007 Barry Carter <Barry.Carter@robotfuzz.com>
 *
 * Based on the i2c-tiny-usb by
 *
 * Copyright (C) 2006 Til Harbaum (Till@Harbaum.org)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/usb.h>

#define OSIFI2C_READ            20
#define OSIFI2C_WRITE           21
#define OSIFI2C_STOP            22
#define OSIFI2C_STATUS          23
#define OSIFI2C_SET_BIT_RATE    24

#define STATUS_ADDRESS_ACK      0
#define STATUS_ADDRESS_NAK      2

struct osif_priv {
        struct usb_device *usb_dev;
        struct usb_interface *interface;
        struct i2c_adapter adapter;
        unsigned char status;
};

static int osif_usb_read(struct i2c_adapter *adapter, int cmd,
                         int value, int index, void *data, int len)
{
        struct osif_priv *priv = adapter->algo_data;

        return usb_control_msg(priv->usb_dev, usb_rcvctrlpipe(priv->usb_dev, 0),
                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
                               USB_DIR_IN, value, index, data, len, 2000);
}

static int osif_usb_write(struct i2c_adapter *adapter, int cmd,
                          int value, int index, void *data, int len)
{

        struct osif_priv *priv = adapter->algo_data;

        return usb_control_msg(priv->usb_dev, usb_sndctrlpipe(priv->usb_dev, 0),
                               cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                               value, index, data, len, 2000);
}

static int osif_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
                         int num)
{
        struct osif_priv *priv = adapter->algo_data;
        struct i2c_msg *pmsg;
        int ret;
        int i;

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

                if (pmsg->flags & I2C_M_RD) {
                        ret = osif_usb_read(adapter, OSIFI2C_READ,
                                            pmsg->flags, pmsg->addr,
                                            pmsg->buf, pmsg->len);
                        if (ret != pmsg->len) {
                                dev_err(&adapter->dev, "failure reading data\n");
                                return -EREMOTEIO;
                        }
                } else {
                        ret = osif_usb_write(adapter, OSIFI2C_WRITE,
                                             pmsg->flags, pmsg->addr,
                                             pmsg->buf, pmsg->len);
                        if (ret != pmsg->len) {
                                dev_err(&adapter->dev, "failure writing data\n");
                                return -EREMOTEIO;
                        }
                }

                ret = osif_usb_write(adapter, OSIFI2C_STOP, 0, 0, NULL, 0);
                if (ret) {
                        dev_err(&adapter->dev, "failure sending STOP\n");
                        return -EREMOTEIO;
                }

                /* read status */
                ret = osif_usb_read(adapter, OSIFI2C_STATUS, 0, 0,
                                    &priv->status, 1);
                if (ret != 1) {
                        dev_err(&adapter->dev, "failure reading status\n");
                        return -EREMOTEIO;
                }

                if (priv->status != STATUS_ADDRESS_ACK) {
                        dev_dbg(&adapter->dev, "status = %d\n", priv->status);
                        return -EREMOTEIO;
                }
        }

        return i;
}

static u32 osif_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

/* prevent invalid 0-length usb_control_msg */
static const struct i2c_adapter_quirks osif_quirks = {
        .flags = I2C_AQ_NO_ZERO_LEN_READ,
};

static const struct i2c_algorithm osif_algorithm = {
        .xfer = osif_xfer,
        .functionality = osif_func,
};

#define USB_OSIF_VENDOR_ID      0x1964
#define USB_OSIF_PRODUCT_ID     0x0001

static const struct usb_device_id osif_table[] = {
        { USB_DEVICE(USB_OSIF_VENDOR_ID, USB_OSIF_PRODUCT_ID) },
        { }
};
MODULE_DEVICE_TABLE(usb, osif_table);

static int osif_probe(struct usb_interface *interface,
                             const struct usb_device_id *id)
{
        int ret;
        struct osif_priv *priv;
        u16 version;

        priv = devm_kzalloc(&interface->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->usb_dev = interface_to_usbdev(interface);
        priv->interface = interface;

        usb_set_intfdata(interface, priv);

        priv->adapter.owner = THIS_MODULE;
        priv->adapter.class = I2C_CLASS_HWMON;
        priv->adapter.quirks = &osif_quirks;
        priv->adapter.algo = &osif_algorithm;
        priv->adapter.algo_data = priv;
        snprintf(priv->adapter.name, sizeof(priv->adapter.name),
                 "OSIF at bus %03d device %03d",
                 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);

        /*
         * Set bus frequency. The frequency is:
         * 120,000,000 / ( 16 + 2 * div * 4^prescale).
         * Using dev = 52, prescale = 0 give 100KHz */
        ret = osif_usb_write(&priv->adapter, OSIFI2C_SET_BIT_RATE, 52, 0,
                            NULL, 0);
        if (ret) {
                dev_err(&interface->dev, "failure sending bit rate");
                return ret;
        }

        i2c_add_adapter(&(priv->adapter));

        version = le16_to_cpu(priv->usb_dev->descriptor.bcdDevice);
        dev_info(&interface->dev,
                 "version %x.%02x found at bus %03d address %03d",
                 version >> 8, version & 0xff,
                 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);

        return 0;
}

static void osif_disconnect(struct usb_interface *interface)
{
        struct osif_priv *priv = usb_get_intfdata(interface);

        i2c_del_adapter(&(priv->adapter));
        usb_set_intfdata(interface, NULL);
}

static struct usb_driver osif_driver = {
        .name           = "RobotFuzz Open Source InterFace, OSIF",
        .probe          = osif_probe,
        .disconnect     = osif_disconnect,
        .id_table       = osif_table,
};

module_usb_driver(osif_driver);

MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
MODULE_AUTHOR("Barry Carter <barry.carter@robotfuzz.com>");
MODULE_DESCRIPTION("RobotFuzz OSIF driver");
MODULE_LICENSE("GPL v2");