/* A driver for the D-Link DSB-R100 USB radio.  The R100 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

 Copyright (c) 2000 Markus Demleitner <msdemlei@tucana.harvard.edu>

 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

 History:

 Version 0.25:
        PSL and Markus: Cleanup, radio now doesn't stop on device close
        
 Version 0.24:
        Markus: Hope I got these silly VIDEO_TUNER_LOW issues finally
        right.  Some minor cleanup, improved standalone compilation

 Version 0.23:
        Markus: Sign extension bug fixed by declaring transfer_buffer unsigned

 Version 0.22:
        Markus: Some (brown bag) cleanup in what VIDIOCSTUNER returns, 
        thanks to Mike Cox for pointing the problem out.

 Version 0.21:
        Markus: Minor cleanup, warnings if something goes wrong, lame attempt
        to adhere to Documentation/CodingStyle

 Version 0.2: 
        Brad Hards <bradh@dynamite.com.au>: Fixes to make it work as non-module
        Markus: Copyright clarification

 Version 0.01: Markus: initial release

*/


#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/videodev.h>
#include <linux/usb.h>
#include <linux/smp_lock.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.25"
#define DRIVER_AUTHOR "Markus Demleitner <msdemlei@tucana.harvard.edu>"
#define DRIVER_DESC "D-Link DSB-R100 USB FM radio driver"

#define DSB100_VENDOR 0x04b4
#define DSB100_PRODUCT 0x1002

#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

static void *usb_dsbr100_probe(struct usb_device *dev, unsigned int ifnum,
                         const struct usb_device_id *id);
static void usb_dsbr100_disconnect(struct usb_device *dev, void *ptr);
static int usb_dsbr100_ioctl(struct video_device *dev, unsigned int cmd, 
        void *arg);
static int usb_dsbr100_open(struct video_device *dev, int flags);
static void usb_dsbr100_close(struct video_device *dev);

static int radio_nr = -1;
MODULE_PARM(radio_nr, "i");

typedef struct
{       struct urb readurb, writeurb;
        struct usb_device *dev;
        unsigned char transfer_buffer[TB_LEN];
        int curfreq;
        int stereo;
        int ifnum;
} usb_dsbr100;

/* D-Link DSB-R100 and D-Link DRU-R100 are very similar products, 
 * both works with this driver. I don't know about any difference.
 * */

static struct video_device usb_dsbr100_radio =
{
        name:           "D-Link DSB R-100 USB FM radio",
        type:           VID_TYPE_TUNER,
        hardware:       VID_HARDWARE_AZTECH,
        open:           usb_dsbr100_open,
        close:          usb_dsbr100_close,
        ioctl:          usb_dsbr100_ioctl,
};

static int users = 0;

static struct usb_device_id usb_dsbr100_table [] = {
        { USB_DEVICE(DSB100_VENDOR, DSB100_PRODUCT) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, usb_dsbr100_table);

static struct usb_driver usb_dsbr100_driver = {
        name:           "dsbr100",
        probe:          usb_dsbr100_probe,
        disconnect:     usb_dsbr100_disconnect,
        fops:           NULL,
        minor:          0,
        id_table:       usb_dsbr100_table,
};


static int dsbr100_start(usb_dsbr100 *radio)
{
        if (usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x00, 0xC0, 0x00, 0xC7, radio->transfer_buffer, 8, 300)<0 ||
            usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x02, 0xC0, 0x01, 0x00, radio->transfer_buffer, 8, 300)<0)
                return -1;
        return (radio->transfer_buffer)[0];
}


static int dsbr100_stop(usb_dsbr100 *radio)
{
        if (usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x00, 0xC0, 0x16, 0x1C, radio->transfer_buffer, 8, 300)<0 ||
            usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x02, 0xC0, 0x00, 0x00, radio->transfer_buffer, 8, 300)<0)
                return -1;
        return (radio->transfer_buffer)[0];
}


static int dsbr100_setfreq(usb_dsbr100 *radio, int freq)
{
        int rfreq = (freq/16*80)/1000+856;
        if (usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x01, 0xC0, (rfreq>>8)&0x00ff, rfreq&0xff, 
                radio->transfer_buffer, 8, 300)<0 ||
            usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x00, 0xC0, 0x96, 0xB7, radio->transfer_buffer, 8, 300)<0 ||
            usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x00, 0xC0, 0x00, 0x24, radio->transfer_buffer, 8, 300)<0) {
                radio->stereo = -1;
                return -1;
        }
        radio->stereo = ! ((radio->transfer_buffer)[0]&0x01);
        return (radio->transfer_buffer)[0];
}

static void dsbr100_getstat(usb_dsbr100 *radio)
{
        if (usb_control_msg(radio->dev, usb_rcvctrlpipe(radio->dev, 0),
                0x00, 0xC0, 0x00 , 0x24, radio->transfer_buffer, 8, 300)<0)
                radio->stereo = -1;
        else
                radio->stereo = ! (radio->transfer_buffer[0]&0x01);
}


static void *usb_dsbr100_probe(struct usb_device *dev, unsigned int ifnum,
                         const struct usb_device_id *id)
{
        usb_dsbr100 *radio;

        if (!(radio = kmalloc(sizeof(usb_dsbr100), GFP_KERNEL)))
                return NULL;
        usb_dsbr100_radio.priv = radio;
        radio->dev = dev;
        radio->ifnum = ifnum;
        radio->curfreq = FREQ_MIN*FREQ_MUL;
        return (void*)radio;
}

static void usb_dsbr100_disconnect(struct usb_device *dev, void *ptr)
{
        usb_dsbr100 *radio=ptr;

        lock_kernel();
        if (users) {
                unlock_kernel();
                return;
        }
        kfree(radio);
        usb_dsbr100_radio.priv = NULL;
        unlock_kernel();
}

static int usb_dsbr100_ioctl(struct video_device *dev, unsigned int cmd, 
        void *arg)
{
        usb_dsbr100 *radio=dev->priv;

        if (!radio)
                return -EINVAL;

        switch(cmd)
        {
                case VIDIOCGCAP: {
                        struct video_capability v;
                        v.type=VID_TYPE_TUNER;
                        v.channels=1;
                        v.audios=1;
                        v.maxwidth=0;
                        v.maxheight=0;
                        v.minwidth=0;
                        v.minheight=0;
                        strcpy(v.name, "D-Link R-100 USB FM Radio");
                        if(copy_to_user(arg, &v, sizeof(v)))
                                return -EFAULT;
                        return 0;
                }
                case VIDIOCGTUNER: {
                        struct video_tuner v;
                        dsbr100_getstat(radio);
                        if(copy_from_user(&v, arg, sizeof(v))!=0) 
                                return -EFAULT;
                        if(v.tuner)     /* Only 1 tuner */ 
                                return -EINVAL;
                        v.rangelow = FREQ_MIN*FREQ_MUL;
                        v.rangehigh = FREQ_MAX*FREQ_MUL;
                        v.flags = VIDEO_TUNER_LOW;
                        v.mode = VIDEO_MODE_AUTO;
                        v.signal = radio->stereo*0x7000;
                                /* Don't know how to get signal strength */
                        v.flags |= VIDEO_TUNER_STEREO_ON*radio->stereo;
                        strcpy(v.name, "DSB R-100");
                        if(copy_to_user(arg, &v, sizeof(v)))
                                return -EFAULT;
                        return 0;
                }
                case VIDIOCSTUNER: {
                        struct video_tuner v;
                        if(copy_from_user(&v, arg, sizeof(v)))
                                return -EFAULT;
                        if(v.tuner!=0)
                                return -EINVAL;
                        /* Only 1 tuner so no setting needed ! */
                        return 0;
                }
                case VIDIOCGFREQ: 
                        if (radio->curfreq==-1)
                                return -EINVAL;
                        if(copy_to_user(arg, &(radio->curfreq), 
                                sizeof(radio->curfreq)))
                                return -EFAULT;
                        return 0;

                case VIDIOCSFREQ:
                        if(copy_from_user(&(radio->curfreq), arg,
                                sizeof(radio->curfreq)))
                                return -EFAULT;
                        if (dsbr100_setfreq(radio, radio->curfreq)==-1)
                                warn("set frequency failed");
                        return 0;

                case VIDIOCGAUDIO: {
                        struct video_audio v;
                        memset(&v, 0, sizeof(v));
                        v.flags|=VIDEO_AUDIO_MUTABLE;
                        v.mode=VIDEO_SOUND_STEREO;
                        v.volume=1;
                        v.step=1;
                        strcpy(v.name, "Radio");
                        if(copy_to_user(arg, &v, sizeof(v)))
                                return -EFAULT;
                        return 0;                       
                }
                case VIDIOCSAUDIO: {
                        struct video_audio v;
                        if(copy_from_user(&v, arg, sizeof(v))) 
                                return -EFAULT; 
                        if(v.audio) 
                                return -EINVAL;

                        if(v.flags&VIDEO_AUDIO_MUTE) {
                                if (dsbr100_stop(radio)==-1)
                                        warn("radio did not respond properly");
                        }
                        else
                                if (dsbr100_start(radio)==-1)
                                        warn("radio did not respond properly");
                        return 0;
                }
                default:
                        return -ENOIOCTLCMD;
        }
}


static int usb_dsbr100_open(struct video_device *dev, int flags)
{
        usb_dsbr100 *radio=dev->priv;

        if (! radio) {
                warn("radio not initialised");
                return -EAGAIN;
        }
        if(users)
        {
                warn("radio in use");
                return -EBUSY;
        }
        users++;
        MOD_INC_USE_COUNT;
        if (dsbr100_start(radio)<0)
                warn("radio did not start up properly");
        dsbr100_setfreq(radio, radio->curfreq);
        return 0;
}

static void usb_dsbr100_close(struct video_device *dev)
{
        usb_dsbr100 *radio=dev->priv;

        if (!radio)
                return;
        users--;
        MOD_DEC_USE_COUNT;
}

static int __init dsbr100_init(void)
{
        usb_dsbr100_radio.priv = NULL;
        usb_register(&usb_dsbr100_driver);
        if (video_register_device(&usb_dsbr100_radio, VFL_TYPE_RADIO, 
                radio_nr)==-1) {        
                warn("couldn't register video device");
                return -EINVAL;
        }
        info(DRIVER_VERSION ":" DRIVER_DESC);
        return 0;
}

static void __exit dsbr100_exit(void)
{
        usb_dsbr100 *radio=usb_dsbr100_radio.priv;

        if (radio)
                dsbr100_stop(radio);
        video_unregister_device(&usb_dsbr100_radio);
        usb_deregister(&usb_dsbr100_driver);
}

module_init (dsbr100_init);
module_exit (dsbr100_exit);

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