/*
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 * 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://kerneltrap.org/mailarchive/linux-usb-devel/2007/10/11/342492
 *
 * 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 <linux/usb.h>
#include <linux/version.h>      /* for KERNEL_VERSION MACRO */
#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 "0.11"
#define RADIO_VERSION KERNEL_VERSION(0, 1, 1)

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

#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 isnt full and will be updated with implementation of new functions
 */
#define AMRADIO_SET_FREQ        0xa4
#define AMRADIO_SET_MUTE        0xab
#define AMRADIO_SET_MONO        0xae

/* Comfortable defines for amradio_set_mute */
#define AMRADIO_START           0x00
#define AMRADIO_STOP            0x01

/* 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");

static int usb_amradio_probe(struct usb_interface *intf,
                             const struct usb_device_id *id);
static void usb_amradio_disconnect(struct usb_interface *intf);
static int usb_amradio_open(struct file *file);
static int usb_amradio_close(struct file *file);
static int usb_amradio_suspend(struct usb_interface *intf,
                                pm_message_t message);
static int usb_amradio_resume(struct usb_interface *intf);

/* 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 videodev;
        struct v4l2_device v4l2_dev;

        unsigned char *buffer;
        struct mutex lock;      /* buffer locking */
        int curfreq;
        int stereo;
        int muted;
        int initialized;
};

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

/* USB Device ID List */
static 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,
        .supports_autosuspend   = 1,
};

/* switch on/off the radio. Send 8 bytes to device */
static int amradio_set_mute(struct amradio_device *radio, char argument)
{
        int retval;
        int size;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x55;
        radio->buffer[2] = 0xaa;
        radio->buffer[3] = 0x00;
        radio->buffer[4] = AMRADIO_SET_MUTE;
        radio->buffer[5] = argument;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

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

        if (retval < 0 || size != BUFFER_LENGTH) {
                amradio_dev_warn(&radio->videodev.dev, "set mute failed\n");
                return retval;
        }

        radio->muted = argument;

        return retval;
}

/* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
static int amradio_setfreq(struct amradio_device *radio, int freq)
{
        int retval;
        int size;
        unsigned short freq_send = 0x10 + (freq >> 3) / 25;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x55;
        radio->buffer[2] = 0xaa;
        radio->buffer[3] = 0x03;
        radio->buffer[4] = AMRADIO_SET_FREQ;
        radio->buffer[5] = 0x00;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x08;

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

        if (retval < 0 || size != BUFFER_LENGTH)
                goto out_err;

        /* frequency is calculated from freq_send and placed in first 2 bytes */
        radio->buffer[0] = (freq_send >> 8) & 0xff;
        radio->buffer[1] = freq_send & 0xff;
        radio->buffer[2] = 0x01;
        radio->buffer[3] = 0x00;
        radio->buffer[4] = 0x00;
        /* 5 and 6 bytes of buffer already = 0x00 */
        radio->buffer[7] = 0x00;

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

        if (retval < 0 || size != BUFFER_LENGTH)
                goto out_err;

        radio->curfreq = freq;
        goto out;

out_err:
        amradio_dev_warn(&radio->videodev.dev, "set frequency failed\n");
out:
        return retval;
}

static int amradio_set_stereo(struct amradio_device *radio, char argument)
{
        int retval;
        int size;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x55;
        radio->buffer[2] = 0xaa;
        radio->buffer[3] = 0x00;
        radio->buffer[4] = AMRADIO_SET_MONO;
        radio->buffer[5] = argument;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

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

        if (retval < 0 || size != BUFFER_LENGTH) {
                amradio_dev_warn(&radio->videodev.dev, "set stereo failed\n");
                return retval;
        }

        if (argument == WANT_STEREO)
                radio->stereo = 1;
        else
                radio->stereo = 0;

        return retval;
}

/* 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);
        /* increase the device node's refcount */
        get_device(&radio->videodev.dev);
        v4l2_device_disconnect(&radio->v4l2_dev);
        video_unregister_device(&radio->videodev);
        mutex_unlock(&radio->lock);
        /* decrease the device node's refcount, allowing it to be released */
        put_device(&radio->videodev.dev);
}

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

        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->version = RADIO_VERSION;
        v->capabilities = V4L2_CAP_TUNER;
        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 = file->private_data;
        int retval;

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

/* TODO: Add function which look is signal stereo or not
 *      amradio_getstat(radio);
 */

/* we call amradio_set_stereo to set radio->stereo
 * Honestly, amradio_getstat should cover this in future and
 * amradio_set_stereo shouldn't be here
 */
        retval = amradio_set_stereo(radio, WANT_STEREO);

        strcpy(v->name, "FM");
        v->type = V4L2_TUNER_RADIO;
        v->rangelow = FREQ_MIN * FREQ_MUL;
        v->rangehigh = FREQ_MAX * FREQ_MUL;
        v->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO;
        v->capability = V4L2_TUNER_CAP_LOW;
        if (radio->stereo)
                v->audmode = V4L2_TUNER_MODE_STEREO;
        else
                v->audmode = V4L2_TUNER_MODE_MONO;
        v->signal = 0xffff;     /* Can't get the signal strength, sad.. */
        v->afc = 0; /* Don't know what is this */

        return retval;
}

/* vidioc_s_tuner - set tuner attributes */
static int vidioc_s_tuner(struct file *file, void *priv,
                                struct v4l2_tuner *v)
{
        struct amradio_device *radio = file->private_data;
        int retval = -EINVAL;

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

        /* mono/stereo selector */
        switch (v->audmode) {
        case V4L2_TUNER_MODE_MONO:
                retval = amradio_set_stereo(radio, WANT_MONO);
                break;
        case V4L2_TUNER_MODE_STEREO:
                retval = amradio_set_stereo(radio, WANT_STEREO);
                break;
        }

        return retval;
}

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

        if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
                return -EINVAL;
        return amradio_setfreq(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 = file->private_data;

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

        return 0;
}

/* vidioc_queryctrl - enumerate control items */
static int vidioc_queryctrl(struct file *file, void *priv,
                                struct v4l2_queryctrl *qc)
{
        switch (qc->id) {
        case V4L2_CID_AUDIO_MUTE:
                return v4l2_ctrl_query_fill(qc, 0, 1, 1, 1);
        }

        return -EINVAL;
}

/* vidioc_g_ctrl - get the value of a control */
static int vidioc_g_ctrl(struct file *file, void *priv,
                                struct v4l2_control *ctrl)
{
        struct amradio_device *radio = file->private_data;

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                ctrl->value = radio->muted;
                return 0;
        }

        return -EINVAL;
}

/* vidioc_s_ctrl - set the value of a control */
static int vidioc_s_ctrl(struct file *file, void *priv,
                                struct v4l2_control *ctrl)
{
        struct amradio_device *radio = file->private_data;
        int retval = -EINVAL;

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                if (ctrl->value)
                        retval = amradio_set_mute(radio, AMRADIO_STOP);
                else
                        retval = amradio_set_mute(radio, AMRADIO_START);

                break;
        }

        return retval;
}

/* vidioc_g_audio - get audio attributes */
static int vidioc_g_audio(struct file *file, void *priv,
                                struct v4l2_audio *a)
{
        if (a->index > 1)
                return -EINVAL;

        strcpy(a->name, "Radio");
        a->capability = V4L2_AUDCAP_STEREO;
        return 0;
}

/* vidioc_s_audio - set audio attributes  */
static int vidioc_s_audio(struct file *file, void *priv,
                                        struct v4l2_audio *a)
{
        if (a->index != 0)
                return -EINVAL;
        return 0;
}

/* vidioc_g_input - get input */
static int vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
{
        *i = 0;
        return 0;
}

/* vidioc_s_input - set input */
static int vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
        if (i != 0)
                return -EINVAL;
        return 0;
}

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

        retval = amradio_set_mute(radio, AMRADIO_STOP);
        if (retval)
                goto out_err;

        retval = amradio_set_stereo(radio, WANT_STEREO);
        if (retval)
                goto out_err;

        radio->initialized = 1;
        goto out;

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

/* open device - amradio_start() and amradio_setfreq() */
static int usb_amradio_open(struct file *file)
{
        struct amradio_device *radio = video_drvdata(file);
        int retval;

        file->private_data = radio;
        retval = usb_autopm_get_interface(radio->intf);
        if (retval)
                return retval;

        if (unlikely(!radio->initialized)) {
                retval = usb_amradio_init(radio);
                if (retval)
                        usb_autopm_put_interface(radio->intf);
        }
        return retval;
}

/*close device */
static int usb_amradio_close(struct file *file)
{
        struct amradio_device *radio = file->private_data;

        if (video_is_registered(&radio->videodev))
                usb_autopm_put_interface(radio->intf);
        return 0;
}

/* 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 && radio->initialized) {
                amradio_set_mute(radio, AMRADIO_STOP);
                radio->muted = 0;
        }
        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);
        if (unlikely(!radio->initialized))
                goto unlock;

        if (radio->stereo)
                amradio_set_stereo(radio, WANT_STEREO);
        else
                amradio_set_stereo(radio, WANT_MONO);

        amradio_setfreq(radio, radio->curfreq);

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

unlock:
        mutex_unlock(&radio->lock);

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

/* File system interface */
static const struct v4l2_file_operations usb_amradio_fops = {
        .owner          = THIS_MODULE,
        .open           = usb_amradio_open,
        .release        = usb_amradio_close,
        .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_queryctrl   = vidioc_queryctrl,
        .vidioc_g_ctrl      = vidioc_g_ctrl,
        .vidioc_s_ctrl      = vidioc_s_ctrl,
        .vidioc_g_audio     = vidioc_g_audio,
        .vidioc_s_audio     = vidioc_s_audio,
        .vidioc_g_input     = vidioc_g_input,
        .vidioc_s_input     = vidioc_s_input,
};

static void usb_amradio_video_device_release(struct video_device *videodev)
{
        struct amradio_device *radio = video_get_drvdata(videodev);

        /* free rest memory */
        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;
        }

        mutex_init(&radio->lock);

        strlcpy(radio->videodev.name, radio->v4l2_dev.name,
                sizeof(radio->videodev.name));
        radio->videodev.v4l2_dev = &radio->v4l2_dev;
        radio->videodev.fops = &usb_amradio_fops;
        radio->videodev.ioctl_ops = &usb_amradio_ioctl_ops;
        radio->videodev.release = usb_amradio_video_device_release;
        radio->videodev.lock = &radio->lock;

        radio->usbdev = interface_to_usbdev(intf);
        radio->intf = intf;
        radio->curfreq = 95.16 * FREQ_MUL;

        video_set_drvdata(&radio->videodev, radio);

        retval = video_register_device(&radio->videodev, 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_device_unregister(&radio->v4l2_dev);
err_v4l2:
        kfree(radio->buffer);
err_nobuf:
        kfree(radio);
err:
        return retval;
}

static int __init amradio_init(void)
{
        int retval = usb_register(&usb_amradio_driver);

        pr_info(KBUILD_MODNAME
                ": version " DRIVER_VERSION " " DRIVER_DESC "\n");

        if (retval)
                pr_err(KBUILD_MODNAME
                        ": usb_register failed. Error number %d\n", retval);

        return retval;
}

static void __exit amradio_exit(void)
{
        usb_deregister(&usb_amradio_driver);
}

module_init(amradio_init);
module_exit(amradio_exit);