/* 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.
   *
   * 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
  */
  
  #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
  ",
  			__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
  ",
  			__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
  ",
  			__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
  ",
  				__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
  ");
  	mutex_unlock(&radio->v4l2_lock);
  
  	dev_info(&intf->dev, "going into suspend..
  ");
  	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
  ");
  	mutex_unlock(&radio->v4l2_lock);
  
  	dev_info(&intf->dev, "coming out of suspend..
  ");
  	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
  ");
  		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
  ");
  		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;
  	set_bit(V4L2_FL_USE_FH_PRIO, &radio->videodev.flags);
  
  	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
  ");
  
  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 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);