/*
 * Driver for the MasterKit MA901 USB FM radio. This device plugs
 * into the USB port and an analog audio input or headphones, so this thing
 * only deals with initialization, frequency setting, volume.
 *
 * Copyright (c) 2012 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.
 */

#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>

#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@gmail.com>"
#define DRIVER_DESC "Masterkit MA901 USB FM radio driver"
#define DRIVER_VERSION "0.0.1"

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

#define USB_MA901_VENDOR  0x16c0
#define USB_MA901_PRODUCT 0x05df

/* dev_warn macro with driver name */
#define MA901_DRIVER_NAME "radio-ma901"
#define ma901radio_dev_warn(dev, fmt, arg...)                           \
                dev_warn(dev, MA901_DRIVER_NAME " - " fmt, ##arg)

#define ma901radio_dev_err(dev, fmt, arg...) \
                dev_err(dev, MA901_DRIVER_NAME " - " fmt, ##arg)

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

#define FREQ_MIN  87.5
#define FREQ_MAX 108.0
#define FREQ_MUL 16000

#define MA901_VOLUME_MAX 16
#define MA901_VOLUME_MIN 0

/* Commands that device should understand
 * List isn't full and will be updated with implementation of new functions
 */
#define MA901_RADIO_SET_FREQ            0x03
#define MA901_RADIO_SET_VOLUME          0x04
#define MA901_RADIO_SET_MONO_STEREO     0x05

/* Comfortable defines for ma901radio_set_stereo */
#define MA901_WANT_STEREO               0x50
#define MA901_WANT_MONO                 0xd0

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

/* Data for one (physical) device */
struct ma901radio_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;
        u16 volume;
        int stereo;
        bool muted;
};

static inline struct ma901radio_device *to_ma901radio_dev(struct v4l2_device *v4l2_dev)
{
        return container_of(v4l2_dev, struct ma901radio_device, v4l2_dev);
}

/* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
static int ma901radio_set_freq(struct ma901radio_device *radio, int freq)
{
        unsigned int freq_send = 0x300 + (freq >> 5) / 25;
        int retval;

        radio->buffer[0] = 0x0a;
        radio->buffer[1] = MA901_RADIO_SET_FREQ;
        radio->buffer[2] = ((freq_send >> 8) & 0xff) + 0x80;
        radio->buffer[3] = freq_send & 0xff;
        radio->buffer[4] = 0x00;
        radio->buffer[5] = 0x00;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

        retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
                                9, 0x21, 0x0300, 0,
                                radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);
        if (retval < 0)
                return retval;

        radio->curfreq = freq;
        return 0;
}

static int ma901radio_set_volume(struct ma901radio_device *radio, u16 vol_to_set)
{
        int retval;

        radio->buffer[0] = 0x0a;
        radio->buffer[1] = MA901_RADIO_SET_VOLUME;
        radio->buffer[2] = 0xc2;
        radio->buffer[3] = vol_to_set + 0x20;
        radio->buffer[4] = 0x00;
        radio->buffer[5] = 0x00;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

        retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
                                9, 0x21, 0x0300, 0,
                                radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);
        if (retval < 0)
                return retval;

        radio->volume = vol_to_set;
        return retval;
}

static int ma901_set_stereo(struct ma901radio_device *radio, u8 stereo)
{
        int retval;

        radio->buffer[0] = 0x0a;
        radio->buffer[1] = MA901_RADIO_SET_MONO_STEREO;
        radio->buffer[2] = stereo;
        radio->buffer[3] = 0x00;
        radio->buffer[4] = 0x00;
        radio->buffer[5] = 0x00;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

        retval = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
                                9, 0x21, 0x0300, 0,
                                radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

        if (retval < 0)
                return retval;

        if (stereo == MA901_WANT_STEREO)
                radio->stereo = V4L2_TUNER_MODE_STEREO;
        else
                radio->stereo = V4L2_TUNER_MODE_MONO;

        return retval;
}

/* Handle unplugging the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_ma901radio_device_release.
 */
static void usb_ma901radio_disconnect(struct usb_interface *intf)
{
        struct ma901radio_device *radio = to_ma901radio_dev(usb_get_intfdata(intf));

        mutex_lock(&radio->lock);
        video_unregister_device(&radio->vdev);
        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 ma901radio_device *radio = video_drvdata(file);

        strscpy(v->driver, "radio-ma901", sizeof(v->driver));
        strscpy(v->card, "Masterkit MA901 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;
        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 ma901radio_device *radio = video_drvdata(file);

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

        v->signal = 0;

        /* TODO: the same words like in _probe() goes here.
         * When receiving of stats will be implemented then we can call
         * ma901radio_get_stat().
         * retval = ma901radio_get_stat(radio, &is_stereo, &v->signal);
         */

        strscpy(v->name, "FM", sizeof(v->name));
        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;
        /* 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 ma901radio_device *radio = video_drvdata(file);

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

        /* mono/stereo selector */
        switch (v->audmode) {
        case V4L2_TUNER_MODE_MONO:
                return ma901_set_stereo(radio, MA901_WANT_MONO);
        default:
                return ma901_set_stereo(radio, MA901_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 ma901radio_device *radio = video_drvdata(file);

        if (f->tuner != 0)
                return -EINVAL;

        return ma901radio_set_freq(radio, clamp_t(unsigned, f->frequency,
                                FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL));
}

/* vidioc_g_frequency - get tuner radio frequency */
static int vidioc_g_frequency(struct file *file, void *priv,
                                struct v4l2_frequency *f)
{
        struct ma901radio_device *radio = video_drvdata(file);

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

        return 0;
}

static int usb_ma901radio_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct ma901radio_device *radio =
                container_of(ctrl->handler, struct ma901radio_device, hdl);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_VOLUME:     /* set volume */
                return ma901radio_set_volume(radio, (u16)ctrl->val);
        }

        return -EINVAL;
}

/* TODO: Should we really need to implement suspend and resume functions?
 * Radio has it's own memory and will continue playing if power is present
 * on usb port and on resume it will start to play again based on freq, volume
 * values in device memory.
 */
static int usb_ma901radio_suspend(struct usb_interface *intf, pm_message_t message)
{
        return 0;
}

static int usb_ma901radio_resume(struct usb_interface *intf)
{
        return 0;
}

static const struct v4l2_ctrl_ops usb_ma901radio_ctrl_ops = {
        .s_ctrl = usb_ma901radio_s_ctrl,
};

/* File system interface */
static const struct v4l2_file_operations usb_ma901radio_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_ma901radio_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_log_status  = v4l2_ctrl_log_status,
        .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
        .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};

static void usb_ma901radio_release(struct v4l2_device *v4l2_dev)
{
        struct ma901radio_device *radio = to_ma901radio_dev(v4l2_dev);

        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_ma901radio_probe(struct usb_interface *intf,
                                const struct usb_device_id *id)
{
        struct usb_device *dev = interface_to_usbdev(intf);
        struct ma901radio_device *radio;
        int retval = 0;

        /* Masterkit MA901 usb radio has the same USB ID as many others
         * Atmel V-USB devices. Let's make additional checks to be sure
         * that this is our device.
         */

        if (dev->product && dev->manufacturer &&
                (strncmp(dev->product, "MA901", 5) != 0
                || strncmp(dev->manufacturer, "www.masterkit.ru", 16) != 0))
                return -ENODEV;

        radio = kzalloc(sizeof(struct ma901radio_device), GFP_KERNEL);
        if (!radio) {
                dev_err(&intf->dev, "kzalloc for ma901radio_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);

        /* TODO:It looks like this radio doesn't have mute/unmute control
         * and windows program just emulate it using volume control.
         * Let's plan to do the same in this driver.
         *
         * v4l2_ctrl_new_std(&radio->hdl, &usb_ma901radio_ctrl_ops,
         *                V4L2_CID_AUDIO_MUTE, 0, 1, 1, 1);
         */

        v4l2_ctrl_new_std(&radio->hdl, &usb_ma901radio_ctrl_ops,
                          V4L2_CID_AUDIO_VOLUME, MA901_VOLUME_MIN,
                          MA901_VOLUME_MAX, 1, MA901_VOLUME_MAX);

        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_ma901radio_release;
        strscpy(radio->vdev.name, radio->v4l2_dev.name,
                sizeof(radio->vdev.name));
        radio->vdev.v4l2_dev = &radio->v4l2_dev;
        radio->vdev.fops = &usb_ma901radio_fops;
        radio->vdev.ioctl_ops = &usb_ma901radio_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 = 95.21 * FREQ_MUL;

        video_set_drvdata(&radio->vdev, radio);

        /* TODO: we can get some statistics (freq, volume) from device
         * but it's not implemented yet. After insertion in usb-port radio
         * setups frequency and starts playing without any initialization.
         * So we don't call usb_ma901radio_init/get_stat() here.
         * retval = usb_ma901radio_init(radio);
         */

        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_ma901radio_device_table[] = {
        { USB_DEVICE_AND_INTERFACE_INFO(USB_MA901_VENDOR, USB_MA901_PRODUCT,
                                                        USB_CLASS_HID, 0, 0) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_ma901radio_device_table);

/* USB subsystem interface */
static struct usb_driver usb_ma901radio_driver = {
        .name                   = MA901_DRIVER_NAME,
        .probe                  = usb_ma901radio_probe,
        .disconnect             = usb_ma901radio_disconnect,
        .suspend                = usb_ma901radio_suspend,
        .resume                 = usb_ma901radio_resume,
        .reset_resume           = usb_ma901radio_resume,
        .id_table               = usb_ma901radio_device_table,
};

module_usb_driver(usb_ma901radio_driver);