/*
 * A driver for the AverMedia MR 800 USB FM radio. This device plugs
 * into both the USB and an analog audio input, so this thing
 * only deals with initialization and frequency setting, the
 * audio data has to be handled by a sound driver.
 *
 * Copyright (c) 2008 Alexey Klimov <klimov.linux@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

/*
 * Big thanks to authors and contributors of dsbr100.c and radio-si470x.c
 *
 * When work was looked pretty good, i discover this:
 * http://av-usbradio.sourceforge.net/index.php
 * http://sourceforge.net/projects/av-usbradio/
 * Latest release of theirs project was in 2005.
 * Probably, this driver could be improved through using their
 * achievements (specifications given).
 * Also, Faidon Liambotis <paravoid@debian.org> wrote nice driver for this radio
 * in 2007. He allowed to use his driver to improve current mr800 radio driver.
 * http://www.spinics.net/lists/linux-usb-devel/msg10109.html
 *
 * Version 0.01:        First working version.
 *                      It's required to blacklist AverMedia USB Radio
 *                      in usbhid/hid-quirks.c
 * Version 0.10:        A lot of cleanups and fixes: unpluging the device,
 *                      few mutex locks were added, codinstyle issues, etc.
 *                      Added stereo support. Thanks to
 *                      Douglas Schilling Landgraf <dougsland@gmail.com> and
 *                      David Ellingsworth <david@identd.dyndns.org>
 *                      for discussion, help and support.
 * Version 0.11:        Converted to v4l2_device.
 *
 * Many things to do:
 *      - Correct power management of device (suspend & resume)
 *      - Add code for scanning and smooth tuning
 *      - Add code for sensitivity value
 *      - Correct mistakes
 *      - In Japan another FREQ_MIN and FREQ_MAX
 */

/* kernel includes */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>
#include <linux/usb.h>
#include <linux/mutex.h>

/* driver and module definitions */
#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@gmail.com>"
#define DRIVER_DESC "AverMedia MR 800 USB FM radio driver"
#define DRIVER_VERSION "0.1.2"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(DRIVER_VERSION);

#define USB_AMRADIO_VENDOR 0x07ca
#define USB_AMRADIO_PRODUCT 0xb800

/* dev_warn macro with driver name */
#define MR800_DRIVER_NAME "radio-mr800"
#define amradio_dev_warn(dev, fmt, arg...)                              \
                dev_warn(dev, MR800_DRIVER_NAME " - " fmt, ##arg)

#define amradio_dev_err(dev, fmt, arg...) \
                dev_err(dev, MR800_DRIVER_NAME " - " fmt, ##arg)

/* Probably USB_TIMEOUT should be modified in module parameter */
#define BUFFER_LENGTH 8
#define USB_TIMEOUT 500

/* Frequency limits in MHz -- these are European values.  For Japanese
devices, that would be 76 and 91.  */
#define FREQ_MIN  87.5
#define FREQ_MAX 108.0
#define FREQ_MUL 16000

/*
 * Commands that device should understand
 * List isn't full and will be updated with implementation of new functions
 */
#define AMRADIO_SET_FREQ        0xa4
#define AMRADIO_GET_READY_FLAG  0xa5
#define AMRADIO_GET_SIGNAL      0xa7
#define AMRADIO_GET_FREQ        0xa8
#define AMRADIO_SET_SEARCH_UP   0xa9
#define AMRADIO_SET_SEARCH_DOWN 0xaa
#define AMRADIO_SET_MUTE        0xab
#define AMRADIO_SET_RIGHT_MUTE  0xac
#define AMRADIO_SET_LEFT_MUTE   0xad
#define AMRADIO_SET_MONO        0xae
#define AMRADIO_SET_SEARCH_LVL  0xb0
#define AMRADIO_STOP_SEARCH     0xb1

/* Comfortable defines for amradio_set_stereo */
#define WANT_STEREO             0x00
#define WANT_MONO               0x01

/* module parameter */
static int radio_nr = -1;
module_param(radio_nr, int, 0);
MODULE_PARM_DESC(radio_nr, "Radio Nr");

/* Data for one (physical) device */
struct amradio_device {
        /* reference to USB and video device */
        struct usb_device *usbdev;
        struct usb_interface *intf;
        struct video_device vdev;
        struct v4l2_device v4l2_dev;
        struct v4l2_ctrl_handler hdl;

        u8 *buffer;
        struct mutex lock;      /* buffer locking */
        int curfreq;
        int stereo;
        int muted;
};

static inline struct amradio_device *to_amradio_dev(struct v4l2_device *v4l2_dev)
{
        return container_of(v4l2_dev, struct amradio_device, v4l2_dev);
}

static int amradio_send_cmd(struct amradio_device *radio, u8 cmd, u8 arg,
                u8 *extra, u8 extralen, bool reply)
{
        int retval;
        int size;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x55;
        radio->buffer[2] = 0xaa;
        radio->buffer[3] = extralen;
        radio->buffer[4] = cmd;
        radio->buffer[5] = arg;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = extra || reply ? 8 : 0;

        retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
                radio->buffer, BUFFER_LENGTH, &size, USB_TIMEOUT);

        if (retval < 0 || size != BUFFER_LENGTH) {
                if (video_is_registered(&radio->vdev))
                        amradio_dev_warn(&radio->vdev.dev,
                                        "cmd %02x failed\n", cmd);
                return retval ? retval : -EIO;
        }
        if (!extra && !reply)
                return 0;

        if (extra) {
                memcpy(radio->buffer, extra, extralen);
                memset(radio->buffer + extralen, 0, 8 - extralen);
                retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
                        radio->buffer, BUFFER_LENGTH, &size, USB_TIMEOUT);
        } else {
                memset(radio->buffer, 0, 8);
                retval = usb_bulk_msg(radio->usbdev, usb_rcvbulkpipe(radio->usbdev, 0x81),
                        radio->buffer, BUFFER_LENGTH, &size, USB_TIMEOUT);
        }
        if (retval == 0 && size == BUFFER_LENGTH)
                return 0;
        if (video_is_registered(&radio->vdev) && cmd != AMRADIO_GET_READY_FLAG)
                amradio_dev_warn(&radio->vdev.dev, "follow-up to cmd %02x failed\n", cmd);
        return retval ? retval : -EIO;
}

/* switch on/off the radio. Send 8 bytes to device */
static int amradio_set_mute(struct amradio_device *radio, bool mute)
{
        int ret = amradio_send_cmd(radio,
                        AMRADIO_SET_MUTE, mute, NULL, 0, false);

        if (!ret)
                radio->muted = mute;
        return ret;
}

/* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
static int amradio_set_freq(struct amradio_device *radio, int freq)
{
        unsigned short freq_send;
        u8 buf[3];
        int retval;

        /* we need to be sure that frequency isn't out of range */
        freq = clamp_t(unsigned, freq, FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL);
        freq_send = 0x10 + (freq >> 3) / 25;

        /* frequency is calculated from freq_send and placed in first 2 bytes */
        buf[0] = (freq_send >> 8) & 0xff;
        buf[1] = freq_send & 0xff;
        buf[2] = 0x01;

        retval = amradio_send_cmd(radio, AMRADIO_SET_FREQ, 0, buf, 3, false);
        if (retval)
                return retval;
        radio->curfreq = freq;
        msleep(40);
        return 0;
}

static int amradio_set_stereo(struct amradio_device *radio, bool stereo)
{
        int ret = amradio_send_cmd(radio,
                        AMRADIO_SET_MONO, !stereo, NULL, 0, false);

        if (!ret)
                radio->stereo = stereo;
        return ret;
}

static int amradio_get_stat(struct amradio_device *radio, bool *is_stereo, u32 *signal)
{
        int ret = amradio_send_cmd(radio,
                        AMRADIO_GET_SIGNAL, 0, NULL, 0, true);

        if (ret)
                return ret;
        *is_stereo = radio->buffer[2] >> 7;
        *signal = (radio->buffer[3] & 0xf0) << 8;
        return 0;
}

/* Handle unplugging the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_amradio_device_release.
 */
static void usb_amradio_disconnect(struct usb_interface *intf)
{
        struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

        mutex_lock(&radio->lock);
        video_unregister_device(&radio->vdev);
        amradio_set_mute(radio, true);
        usb_set_intfdata(intf, NULL);
        v4l2_device_disconnect(&radio->v4l2_dev);
        mutex_unlock(&radio->lock);
        v4l2_device_put(&radio->v4l2_dev);
}

/* vidioc_querycap - query device capabilities */
static int vidioc_querycap(struct file *file, void *priv,
                                        struct v4l2_capability *v)
{
        struct amradio_device *radio = video_drvdata(file);

        strlcpy(v->driver, "radio-mr800", sizeof(v->driver));
        strlcpy(v->card, "AverMedia MR 800 USB FM Radio", sizeof(v->card));
        usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
        v->device_caps = V4L2_CAP_RADIO | V4L2_CAP_TUNER |
                                        V4L2_CAP_HW_FREQ_SEEK;
        v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;
        return 0;
}

/* vidioc_g_tuner - get tuner attributes */
static int vidioc_g_tuner(struct file *file, void *priv,
                                struct v4l2_tuner *v)
{
        struct amradio_device *radio = video_drvdata(file);
        bool is_stereo = false;
        int retval;

        if (v->index > 0)
                return -EINVAL;

        v->signal = 0;
        retval = amradio_get_stat(radio, &is_stereo, &v->signal);
        if (retval)
                return retval;

        strcpy(v->name, "FM");
        v->type = V4L2_TUNER_RADIO;
        v->rangelow = FREQ_MIN * FREQ_MUL;
        v->rangehigh = FREQ_MAX * FREQ_MUL;
        v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO |
                V4L2_TUNER_CAP_HWSEEK_WRAP;
        v->rxsubchans = is_stereo ? V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
        v->audmode = radio->stereo ?
                V4L2_TUNER_MODE_STEREO : V4L2_TUNER_MODE_MONO;
        return 0;
}

/* vidioc_s_tuner - set tuner attributes */
static int vidioc_s_tuner(struct file *file, void *priv,
                                const struct v4l2_tuner *v)
{
        struct amradio_device *radio = video_drvdata(file);

        if (v->index > 0)
                return -EINVAL;

        /* mono/stereo selector */
        switch (v->audmode) {
        case V4L2_TUNER_MODE_MONO:
                return amradio_set_stereo(radio, WANT_MONO);
        default:
                return amradio_set_stereo(radio, WANT_STEREO);
        }
}

/* vidioc_s_frequency - set tuner radio frequency */
static int vidioc_s_frequency(struct file *file, void *priv,
                                const struct v4l2_frequency *f)
{
        struct amradio_device *radio = video_drvdata(file);

        if (f->tuner != 0)
                return -EINVAL;
        return amradio_set_freq(radio, f->frequency);
}

/* vidioc_g_frequency - get tuner radio frequency */
static int vidioc_g_frequency(struct file *file, void *priv,
                                struct v4l2_frequency *f)
{
        struct amradio_device *radio = video_drvdata(file);

        if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
                return -EINVAL;
        f->type = V4L2_TUNER_RADIO;
        f->frequency = radio->curfreq;

        return 0;
}

static int vidioc_s_hw_freq_seek(struct file *file, void *priv,
                const struct v4l2_hw_freq_seek *seek)
{
        static u8 buf[8] = {
                0x3d, 0x32, 0x0f, 0x08, 0x3d, 0x32, 0x0f, 0x08
        };
        struct amradio_device *radio = video_drvdata(file);
        unsigned long timeout;
        int retval;

        if (seek->tuner != 0 || !seek->wrap_around)
                return -EINVAL;

        if (file->f_flags & O_NONBLOCK)
                return -EWOULDBLOCK;

        retval = amradio_send_cmd(radio,
                        AMRADIO_SET_SEARCH_LVL, 0, buf, 8, false);
        if (retval)
                return retval;
        amradio_set_freq(radio, radio->curfreq);
        retval = amradio_send_cmd(radio,
                seek->seek_upward ? AMRADIO_SET_SEARCH_UP : AMRADIO_SET_SEARCH_DOWN,
                0, NULL, 0, false);
        if (retval)
                return retval;
        timeout = jiffies + msecs_to_jiffies(30000);
        for (;;) {
                if (time_after(jiffies, timeout)) {
                        retval = -ENODATA;
                        break;
                }
                if (schedule_timeout_interruptible(msecs_to_jiffies(10))) {
                        retval = -ERESTARTSYS;
                        break;
                }
                retval = amradio_send_cmd(radio, AMRADIO_GET_READY_FLAG,
                                0, NULL, 0, true);
                if (retval)
                        continue;
                amradio_send_cmd(radio, AMRADIO_GET_FREQ, 0, NULL, 0, true);
                if (radio->buffer[1] || radio->buffer[2]) {
                        /* To check: sometimes radio->curfreq is set to out of range value */
                        radio->curfreq = (radio->buffer[1] << 8) | radio->buffer[2];
                        radio->curfreq = (radio->curfreq - 0x10) * 200;
                        amradio_send_cmd(radio, AMRADIO_STOP_SEARCH,
                                        0, NULL, 0, false);
                        amradio_set_freq(radio, radio->curfreq);
                        retval = 0;
                        break;
                }
        }
        amradio_send_cmd(radio, AMRADIO_STOP_SEARCH, 0, NULL, 0, false);
        amradio_set_freq(radio, radio->curfreq);
        return retval;
}

static int usb_amradio_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct amradio_device *radio =
                container_of(ctrl->handler, struct amradio_device, hdl);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                return amradio_set_mute(radio, ctrl->val);
        }

        return -EINVAL;
}

static int usb_amradio_init(struct amradio_device *radio)
{
        int retval;

        retval = amradio_set_mute(radio, true);
        if (retval)
                goto out_err;
        retval = amradio_set_stereo(radio, true);
        if (retval)
                goto out_err;
        retval = amradio_set_freq(radio, radio->curfreq);
        if (retval)
                goto out_err;
        return 0;

out_err:
        amradio_dev_err(&radio->vdev.dev, "initialization failed\n");
        return retval;
}

/* Suspend device - stop device. Need to be checked and fixed */
static int usb_amradio_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

        mutex_lock(&radio->lock);
        if (!radio->muted) {
                amradio_set_mute(radio, true);
                radio->muted = false;
        }
        mutex_unlock(&radio->lock);

        dev_info(&intf->dev, "going into suspend..\n");
        return 0;
}

/* Resume device - start device. Need to be checked and fixed */
static int usb_amradio_resume(struct usb_interface *intf)
{
        struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

        mutex_lock(&radio->lock);
        amradio_set_stereo(radio, radio->stereo);
        amradio_set_freq(radio, radio->curfreq);

        if (!radio->muted)
                amradio_set_mute(radio, false);

        mutex_unlock(&radio->lock);

        dev_info(&intf->dev, "coming out of suspend..\n");
        return 0;
}

static const struct v4l2_ctrl_ops usb_amradio_ctrl_ops = {
        .s_ctrl = usb_amradio_s_ctrl,
};

/* File system interface */
static const struct v4l2_file_operations usb_amradio_fops = {
        .owner          = THIS_MODULE,
        .open           = v4l2_fh_open,
        .release        = v4l2_fh_release,
        .poll           = v4l2_ctrl_poll,
        .unlocked_ioctl = video_ioctl2,
};

static const struct v4l2_ioctl_ops usb_amradio_ioctl_ops = {
        .vidioc_querycap    = vidioc_querycap,
        .vidioc_g_tuner     = vidioc_g_tuner,
        .vidioc_s_tuner     = vidioc_s_tuner,
        .vidioc_g_frequency = vidioc_g_frequency,
        .vidioc_s_frequency = vidioc_s_frequency,
        .vidioc_s_hw_freq_seek = vidioc_s_hw_freq_seek,
        .vidioc_log_status  = v4l2_ctrl_log_status,
        .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
        .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};

static void usb_amradio_release(struct v4l2_device *v4l2_dev)
{
        struct amradio_device *radio = to_amradio_dev(v4l2_dev);

        /* free rest memory */
        v4l2_ctrl_handler_free(&radio->hdl);
        v4l2_device_unregister(&radio->v4l2_dev);
        kfree(radio->buffer);
        kfree(radio);
}

/* check if the device is present and register with v4l and usb if it is */
static int usb_amradio_probe(struct usb_interface *intf,
                                const struct usb_device_id *id)
{
        struct amradio_device *radio;
        int retval = 0;

        radio = kzalloc(sizeof(struct amradio_device), GFP_KERNEL);

        if (!radio) {
                dev_err(&intf->dev, "kmalloc for amradio_device failed\n");
                retval = -ENOMEM;
                goto err;
        }

        radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

        if (!radio->buffer) {
                dev_err(&intf->dev, "kmalloc for radio->buffer failed\n");
                retval = -ENOMEM;
                goto err_nobuf;
        }

        retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
        if (retval < 0) {
                dev_err(&intf->dev, "couldn't register v4l2_device\n");
                goto err_v4l2;
        }

        v4l2_ctrl_handler_init(&radio->hdl, 1);
        v4l2_ctrl_new_std(&radio->hdl, &usb_amradio_ctrl_ops,
                          V4L2_CID_AUDIO_MUTE, 0, 1, 1, 1);
        if (radio->hdl.error) {
                retval = radio->hdl.error;
                dev_err(&intf->dev, "couldn't register control\n");
                goto err_ctrl;
        }
        mutex_init(&radio->lock);

        radio->v4l2_dev.ctrl_handler = &radio->hdl;
        radio->v4l2_dev.release = usb_amradio_release;
        strlcpy(radio->vdev.name, radio->v4l2_dev.name,
                sizeof(radio->vdev.name));
        radio->vdev.v4l2_dev = &radio->v4l2_dev;
        radio->vdev.fops = &usb_amradio_fops;
        radio->vdev.ioctl_ops = &usb_amradio_ioctl_ops;
        radio->vdev.release = video_device_release_empty;
        radio->vdev.lock = &radio->lock;

        radio->usbdev = interface_to_usbdev(intf);
        radio->intf = intf;
        usb_set_intfdata(intf, &radio->v4l2_dev);
        radio->curfreq = 95.16 * FREQ_MUL;

        video_set_drvdata(&radio->vdev, radio);
        retval = usb_amradio_init(radio);
        if (retval)
                goto err_vdev;

        retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO,
                                        radio_nr);
        if (retval < 0) {
                dev_err(&intf->dev, "could not register video device\n");
                goto err_vdev;
        }

        return 0;

err_vdev:
        v4l2_ctrl_handler_free(&radio->hdl);
err_ctrl:
        v4l2_device_unregister(&radio->v4l2_dev);
err_v4l2:
        kfree(radio->buffer);
err_nobuf:
        kfree(radio);
err:
        return retval;
}

/* USB Device ID List */
static const struct usb_device_id usb_amradio_device_table[] = {
        { USB_DEVICE_AND_INTERFACE_INFO(USB_AMRADIO_VENDOR, USB_AMRADIO_PRODUCT,
                                                        USB_CLASS_HID, 0, 0) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_amradio_device_table);

/* USB subsystem interface */
static struct usb_driver usb_amradio_driver = {
        .name                   = MR800_DRIVER_NAME,
        .probe                  = usb_amradio_probe,
        .disconnect             = usb_amradio_disconnect,
        .suspend                = usb_amradio_suspend,
        .resume                 = usb_amradio_resume,
        .reset_resume           = usb_amradio_resume,
        .id_table               = usb_amradio_device_table,
};

module_usb_driver(usb_amradio_driver);