/* A driver for the D-Link DSB-R100 USB radio and Gemtek USB Radio 21.
 * The device plugs into both the USB and an analog audio input, so this thing
 * only deals with initialisation and frequency setting, the
 * audio data has to be handled by a sound driver.
 *
 * Major issue: I can't find out where the device reports the signal
 * strength, and indeed the windows software appearantly just looks
 * at the stereo indicator as well.  So, scanning will only find
 * stereo stations.  Sad, but I can't help it.
 *
 * Also, the windows program sends oodles of messages over to the
 * device, and I couldn't figure out their meaning.  My suspicion
 * is that they don't have any:-)
 *
 * You might find some interesting stuff about this module at
 * http://unimut.fsk.uni-heidelberg.de/unimut/demi/dsbr
 *
 * Fully tested with the Keene USB FM Transmitter and the v4l2-compliance tool.
 *
 * Copyright (c) 2000 Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
 *
 * 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 <linux/usb.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>

/*
 * Version Information
 */
MODULE_AUTHOR("Markus Demleitner <msdemlei@tucana.harvard.edu>");
MODULE_DESCRIPTION("D-Link DSB-R100 USB FM radio driver");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.1.0");

#define DSB100_VENDOR 0x04b4
#define DSB100_PRODUCT 0x1002

/* Commands the device appears to understand */
#define DSB100_TUNE 1
#define DSB100_ONOFF 2

#define TB_LEN 16

/* 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

#define v4l2_dev_to_radio(d) container_of(d, struct dsbr100_device, v4l2_dev)

static int radio_nr = -1;
module_param(radio_nr, int, 0);

/* Data for one (physical) device */
struct dsbr100_device {
        struct usb_device *usbdev;
        struct video_device videodev;
        struct v4l2_device v4l2_dev;
        struct v4l2_ctrl_handler hdl;

        u8 *transfer_buffer;
        struct mutex v4l2_lock;
        int curfreq;
        bool stereo;
        bool muted;
};

/* Low-level device interface begins here */

/* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
static int dsbr100_setfreq(struct dsbr100_device *radio, unsigned freq)
{
        unsigned f = (freq / 16 * 80) / 1000 + 856;
        int retval = 0;

        if (!radio->muted) {
                retval = usb_control_msg(radio->usbdev,
                                usb_rcvctrlpipe(radio->usbdev, 0),
                                DSB100_TUNE,
                                USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
                                (f >> 8) & 0x00ff, f & 0xff,
                                radio->transfer_buffer, 8, 300);
                if (retval >= 0)
                        mdelay(1);
        }

        if (retval >= 0) {
                radio->curfreq = freq;
                return 0;
        }
        dev_err(&radio->usbdev->dev,
                "%s - usb_control_msg returned %i, request %i\n",
                        __func__, retval, DSB100_TUNE);
        return retval;
}

/* switch on radio */
static int dsbr100_start(struct dsbr100_device *radio)
{
        int retval = usb_control_msg(radio->usbdev,
                usb_rcvctrlpipe(radio->usbdev, 0),
                DSB100_ONOFF,
                USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
                0x01, 0x00, radio->transfer_buffer, 8, 300);

        if (retval >= 0)
                return dsbr100_setfreq(radio, radio->curfreq);
        dev_err(&radio->usbdev->dev,
                "%s - usb_control_msg returned %i, request %i\n",
                        __func__, retval, DSB100_ONOFF);
        return retval;

}

/* switch off radio */
static int dsbr100_stop(struct dsbr100_device *radio)
{
        int retval = usb_control_msg(radio->usbdev,
                usb_rcvctrlpipe(radio->usbdev, 0),
                DSB100_ONOFF,
                USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
                0x00, 0x00, radio->transfer_buffer, 8, 300);

        if (retval >= 0)
                return 0;
        dev_err(&radio->usbdev->dev,
                "%s - usb_control_msg returned %i, request %i\n",
                        __func__, retval, DSB100_ONOFF);
        return retval;

}

/* return the device status.  This is, in effect, just whether it
sees a stereo signal or not.  Pity. */
static void dsbr100_getstat(struct dsbr100_device *radio)
{
        int retval = usb_control_msg(radio->usbdev,
                usb_rcvctrlpipe(radio->usbdev, 0),
                USB_REQ_GET_STATUS,
                USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
                0x00, 0x24, radio->transfer_buffer, 8, 300);

        if (retval < 0) {
                radio->stereo = false;
                dev_err(&radio->usbdev->dev,
                        "%s - usb_control_msg returned %i, request %i\n",
                                __func__, retval, USB_REQ_GET_STATUS);
        } else {
                radio->stereo = !(radio->transfer_buffer[0] & 0x01);
        }
}

static int vidioc_querycap(struct file *file, void *priv,
                                        struct v4l2_capability *v)
{
        struct dsbr100_device *radio = video_drvdata(file);

        strlcpy(v->driver, "dsbr100", sizeof(v->driver));
        strlcpy(v->card, "D-Link R-100 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;
}

static int vidioc_g_tuner(struct file *file, void *priv,
                                struct v4l2_tuner *v)
{
        struct dsbr100_device *radio = video_drvdata(file);

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

        dsbr100_getstat(radio);
        strcpy(v->name, "FM");
        v->type = V4L2_TUNER_RADIO;
        v->rangelow = FREQ_MIN * FREQ_MUL;
        v->rangehigh = FREQ_MAX * FREQ_MUL;
        v->rxsubchans = radio->stereo ? V4L2_TUNER_SUB_STEREO :
                V4L2_TUNER_SUB_MONO;
        v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;
        v->audmode = V4L2_TUNER_MODE_STEREO;
        v->signal = radio->stereo ? 0xffff : 0;     /* We can't get the signal strength */
        return 0;
}

static int vidioc_s_tuner(struct file *file, void *priv,
                                const struct v4l2_tuner *v)
{
        return v->index ? -EINVAL : 0;
}

static int vidioc_s_frequency(struct file *file, void *priv,
                                const struct v4l2_frequency *f)
{
        struct dsbr100_device *radio = video_drvdata(file);

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

        return dsbr100_setfreq(radio, clamp_t(unsigned, f->frequency,
                        FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL));
}

static int vidioc_g_frequency(struct file *file, void *priv,
                                struct v4l2_frequency *f)
{
        struct dsbr100_device *radio = video_drvdata(file);

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

static int usb_dsbr100_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct dsbr100_device *radio =
                container_of(ctrl->handler, struct dsbr100_device, hdl);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                radio->muted = ctrl->val;
                return radio->muted ? dsbr100_stop(radio) : dsbr100_start(radio);
        }
        return -EINVAL;
}


/* USB subsystem interface begins here */

/*
 * Handle unplugging of the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_dsbr100_video_device_release
 */
static void usb_dsbr100_disconnect(struct usb_interface *intf)
{
        struct dsbr100_device *radio = usb_get_intfdata(intf);

        mutex_lock(&radio->v4l2_lock);
        /*
         * Disconnect is also called on unload, and in that case we need to
         * mute the device. This call will silently fail if it is called
         * after a physical disconnect.
         */
        usb_control_msg(radio->usbdev,
                usb_rcvctrlpipe(radio->usbdev, 0),
                DSB100_ONOFF,
                USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
                0x00, 0x00, radio->transfer_buffer, 8, 300);
        usb_set_intfdata(intf, NULL);
        video_unregister_device(&radio->videodev);
        v4l2_device_disconnect(&radio->v4l2_dev);
        mutex_unlock(&radio->v4l2_lock);
        v4l2_device_put(&radio->v4l2_dev);
}


/* Suspend device - stop device. */
static int usb_dsbr100_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct dsbr100_device *radio = usb_get_intfdata(intf);

        mutex_lock(&radio->v4l2_lock);
        if (!radio->muted && dsbr100_stop(radio) < 0)
                dev_warn(&intf->dev, "dsbr100_stop failed\n");
        mutex_unlock(&radio->v4l2_lock);

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

/* Resume device - start device. */
static int usb_dsbr100_resume(struct usb_interface *intf)
{
        struct dsbr100_device *radio = usb_get_intfdata(intf);

        mutex_lock(&radio->v4l2_lock);
        if (!radio->muted && dsbr100_start(radio) < 0)
                dev_warn(&intf->dev, "dsbr100_start failed\n");
        mutex_unlock(&radio->v4l2_lock);

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

/* free data structures */
static void usb_dsbr100_release(struct v4l2_device *v4l2_dev)
{
        struct dsbr100_device *radio = v4l2_dev_to_radio(v4l2_dev);

        v4l2_ctrl_handler_free(&radio->hdl);
        v4l2_device_unregister(&radio->v4l2_dev);
        kfree(radio->transfer_buffer);
        kfree(radio);
}

static const struct v4l2_ctrl_ops usb_dsbr100_ctrl_ops = {
        .s_ctrl = usb_dsbr100_s_ctrl,
};

/* File system interface */
static const struct v4l2_file_operations usb_dsbr100_fops = {
        .owner          = THIS_MODULE,
        .unlocked_ioctl = video_ioctl2,
        .open           = v4l2_fh_open,
        .release        = v4l2_fh_release,
        .poll           = v4l2_ctrl_poll,
};

static const struct v4l2_ioctl_ops usb_dsbr100_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,
};

/* check if the device is present and register with v4l and usb if it is */
static int usb_dsbr100_probe(struct usb_interface *intf,
                                const struct usb_device_id *id)
{
        struct dsbr100_device *radio;
        struct v4l2_device *v4l2_dev;
        int retval;

        radio = kzalloc(sizeof(struct dsbr100_device), GFP_KERNEL);

        if (!radio)
                return -ENOMEM;

        radio->transfer_buffer = kmalloc(TB_LEN, GFP_KERNEL);

        if (!(radio->transfer_buffer)) {
                kfree(radio);
                return -ENOMEM;
        }

        v4l2_dev = &radio->v4l2_dev;
        v4l2_dev->release = usb_dsbr100_release;

        retval = v4l2_device_register(&intf->dev, v4l2_dev);
        if (retval < 0) {
                v4l2_err(v4l2_dev, "couldn't register v4l2_device\n");
                goto err_reg_dev;
        }

        v4l2_ctrl_handler_init(&radio->hdl, 1);
        v4l2_ctrl_new_std(&radio->hdl, &usb_dsbr100_ctrl_ops,
                          V4L2_CID_AUDIO_MUTE, 0, 1, 1, 1);
        if (radio->hdl.error) {
                retval = radio->hdl.error;
                v4l2_err(v4l2_dev, "couldn't register control\n");
                goto err_reg_ctrl;
        }
        mutex_init(&radio->v4l2_lock);
        strlcpy(radio->videodev.name, v4l2_dev->name, sizeof(radio->videodev.name));
        radio->videodev.v4l2_dev = v4l2_dev;
        radio->videodev.fops = &usb_dsbr100_fops;
        radio->videodev.ioctl_ops = &usb_dsbr100_ioctl_ops;
        radio->videodev.release = video_device_release_empty;
        radio->videodev.lock = &radio->v4l2_lock;
        radio->videodev.ctrl_handler = &radio->hdl;

        radio->usbdev = interface_to_usbdev(intf);
        radio->curfreq = FREQ_MIN * FREQ_MUL;
        radio->muted = true;

        video_set_drvdata(&radio->videodev, radio);
        usb_set_intfdata(intf, radio);

        retval = video_register_device(&radio->videodev, VFL_TYPE_RADIO, radio_nr);
        if (retval == 0)
                return 0;
        v4l2_err(v4l2_dev, "couldn't register video device\n");

err_reg_ctrl:
        v4l2_ctrl_handler_free(&radio->hdl);
        v4l2_device_unregister(v4l2_dev);
err_reg_dev:
        kfree(radio->transfer_buffer);
        kfree(radio);
        return retval;
}

static const struct usb_device_id usb_dsbr100_device_table[] = {
        { USB_DEVICE(DSB100_VENDOR, DSB100_PRODUCT) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_dsbr100_device_table);

/* USB subsystem interface */
static struct usb_driver usb_dsbr100_driver = {
        .name                   = "dsbr100",
        .probe                  = usb_dsbr100_probe,
        .disconnect             = usb_dsbr100_disconnect,
        .id_table               = usb_dsbr100_device_table,
        .suspend                = usb_dsbr100_suspend,
        .resume                 = usb_dsbr100_resume,
        .reset_resume           = usb_dsbr100_resume,
};

module_usb_driver(usb_dsbr100_driver);