/*
   * Copyright (c) 2012 Hans Verkuil <hverkuil@xs4all.nl>
   *
   * 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
   */
  
  /* 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 <media/v4l2-ctrls.h>
  #include <media/v4l2-event.h>
  #include <linux/usb.h>
  #include <linux/mutex.h>
  
  /* driver and module definitions */
  MODULE_AUTHOR("Hans Verkuil <hverkuil@xs4all.nl>");
  MODULE_DESCRIPTION("Keene FM Transmitter driver");
  MODULE_LICENSE("GPL");
  
  /* Actually, it advertises itself as a Logitech */
  #define USB_KEENE_VENDOR 0x046d
  #define USB_KEENE_PRODUCT 0x0a0e
  
  /* Probably USB_TIMEOUT should be modified in module parameter */
  #define BUFFER_LENGTH 8
  #define USB_TIMEOUT 500
  
  /* Frequency limits in MHz */
  #define FREQ_MIN  76U
  #define FREQ_MAX 108U
  #define FREQ_MUL 16000U
  
  /* USB Device ID List */
  static struct usb_device_id usb_keene_device_table[] = {
  	{USB_DEVICE_AND_INTERFACE_INFO(USB_KEENE_VENDOR, USB_KEENE_PRODUCT,
  							USB_CLASS_HID, 0, 0) },
  	{ }						/* Terminating entry */
  };
  
  MODULE_DEVICE_TABLE(usb, usb_keene_device_table);
  
  struct keene_device {
  	struct usb_device *usbdev;
  	struct usb_interface *intf;
  	struct video_device vdev;
  	struct v4l2_device v4l2_dev;
  	struct v4l2_ctrl_handler hdl;
  	struct mutex lock;
  
  	u8 *buffer;
  	unsigned curfreq;
  	u8 tx;
  	u8 pa;
  	bool stereo;
  	bool muted;
  	bool preemph_75_us;
  };
  
  static inline struct keene_device *to_keene_dev(struct v4l2_device *v4l2_dev)
  {
  	return container_of(v4l2_dev, struct keene_device, v4l2_dev);
  }
  
  /* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
  static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
  {
  	unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
  	int ret;
  
  	radio->buffer[0] = 0x00;
  	radio->buffer[1] = 0x50;
  	radio->buffer[2] = (freq_send >> 8) & 0xff;
  	radio->buffer[3] = freq_send & 0xff;
  	radio->buffer[4] = radio->pa;
  	/* If bit 4 is set, then tune to the frequency.
  	   If bit 3 is set, then unmute; if bit 2 is set, then mute.
  	   If bit 1 is set, then enter idle mode; if bit 0 is set,
  	   then enter transmit mode.
  	 */
  	radio->buffer[5] = (radio->muted ? 4 : 8) | (play ? 1 : 2) |
  							(freq ? 0x10 : 0);
  	radio->buffer[6] = 0x00;
  	radio->buffer[7] = 0x00;
  
  	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
  		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);
  
  	if (ret < 0) {
  		dev_warn(&radio->vdev.dev, "%s failed (%d)
  ", __func__, ret);
  		return ret;
  	}
  	if (freq)
  		radio->curfreq = freq;
  	return 0;
  }
  
  /* Set TX, stereo and preemphasis mode (50 us vs 75 us). */
  static int keene_cmd_set(struct keene_device *radio)
  {
  	int ret;
  
  	radio->buffer[0] = 0x00;
  	radio->buffer[1] = 0x51;
  	radio->buffer[2] = radio->tx;
  	/* If bit 0 is set, then transmit mono, otherwise stereo.
  	   If bit 2 is set, then enable 75 us preemphasis, otherwise
  	   it is 50 us. */
  	radio->buffer[3] = (radio->stereo ? 0 : 1) | (radio->preemph_75_us ? 4 : 0);
  	radio->buffer[4] = 0x00;
  	radio->buffer[5] = 0x00;
  	radio->buffer[6] = 0x00;
  	radio->buffer[7] = 0x00;
  
  	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
  		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);
  
  	if (ret < 0) {
  		dev_warn(&radio->vdev.dev, "%s failed (%d)
  ", __func__, ret);
  		return ret;
  	}
  	return 0;
  }
  
  /* Handle unplugging the device.
   * We call video_unregister_device in any case.
   * The last function called in this procedure is
   * usb_keene_device_release.
   */
  static void usb_keene_disconnect(struct usb_interface *intf)
  {
  	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));
  
  	mutex_lock(&radio->lock);
  	usb_set_intfdata(intf, NULL);
  	video_unregister_device(&radio->vdev);
  	v4l2_device_disconnect(&radio->v4l2_dev);
  	mutex_unlock(&radio->lock);
  	v4l2_device_put(&radio->v4l2_dev);
  }
  
  static int usb_keene_suspend(struct usb_interface *intf, pm_message_t message)
  {
  	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));
  
  	return keene_cmd_main(radio, 0, false);
  }
  
  static int usb_keene_resume(struct usb_interface *intf)
  {
  	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));
  
  	mdelay(50);
  	keene_cmd_set(radio);
  	keene_cmd_main(radio, radio->curfreq, true);
  	return 0;
  }
  
  static int vidioc_querycap(struct file *file, void *priv,
  					struct v4l2_capability *v)
  {
  	struct keene_device *radio = video_drvdata(file);
  
  	strlcpy(v->driver, "radio-keene", sizeof(v->driver));
  	strlcpy(v->card, "Keene FM Transmitter", sizeof(v->card));
  	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
  	v->device_caps = V4L2_CAP_RADIO | V4L2_CAP_MODULATOR;
  	v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;
  	return 0;
  }
  
  static int vidioc_g_modulator(struct file *file, void *priv,
  				struct v4l2_modulator *v)
  {
  	struct keene_device *radio = video_drvdata(file);
  
  	if (v->index > 0)
  		return -EINVAL;
  
  	strlcpy(v->name, "FM", sizeof(v->name));
  	v->rangelow = FREQ_MIN * FREQ_MUL;
  	v->rangehigh = FREQ_MAX * FREQ_MUL;
  	v->txsubchans = radio->stereo ? V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
  	v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;
  	return 0;
  }
  
  static int vidioc_s_modulator(struct file *file, void *priv,
  				const struct v4l2_modulator *v)
  {
  	struct keene_device *radio = video_drvdata(file);
  
  	if (v->index > 0)
  		return -EINVAL;
  
  	radio->stereo = (v->txsubchans == V4L2_TUNER_SUB_STEREO);
  	return keene_cmd_set(radio);
  }
  
  static int vidioc_s_frequency(struct file *file, void *priv,
  				const struct v4l2_frequency *f)
  {
  	struct keene_device *radio = video_drvdata(file);
  	unsigned freq = f->frequency;
  
  	if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
  		return -EINVAL;
  	freq = clamp(freq, FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL);
  	return keene_cmd_main(radio, freq, true);
  }
  
  static int vidioc_g_frequency(struct file *file, void *priv,
  				struct v4l2_frequency *f)
  {
  	struct keene_device *radio = video_drvdata(file);
  
  	if (f->tuner != 0)
  		return -EINVAL;
  	f->type = V4L2_TUNER_RADIO;
  	f->frequency = radio->curfreq;
  	return 0;
  }
  
  static int keene_s_ctrl(struct v4l2_ctrl *ctrl)
  {
  	static const u8 db2tx[] = {
  	     /*	 -15,  -12,   -9,   -6,   -3,    0 dB */
  		0x03, 0x13, 0x02, 0x12, 0x22, 0x32,
  	     /*	   3,    6,    9,   12,   15,   18 dB */
  		0x21, 0x31, 0x20, 0x30, 0x40, 0x50
  	};
  	struct keene_device *radio =
  		container_of(ctrl->handler, struct keene_device, hdl);
  
  	switch (ctrl->id) {
  	case V4L2_CID_AUDIO_MUTE:
  		radio->muted = ctrl->val;
  		return keene_cmd_main(radio, 0, true);
  
  	case V4L2_CID_TUNE_POWER_LEVEL:
  		/* To go from dBuV to the register value we apply the
  		   following formula: */
  		radio->pa = (ctrl->val - 71) * 100 / 62;
  		return keene_cmd_main(radio, 0, true);
  
  	case V4L2_CID_TUNE_PREEMPHASIS:
  		radio->preemph_75_us = ctrl->val == V4L2_PREEMPHASIS_75_uS;
  		return keene_cmd_set(radio);
  
  	case V4L2_CID_AUDIO_COMPRESSION_GAIN:
  		radio->tx = db2tx[(ctrl->val - (s32)ctrl->minimum) / (s32)ctrl->step];
  		return keene_cmd_set(radio);
  	}
  	return -EINVAL;
  }
  
  /* File system interface */
  static const struct v4l2_file_operations usb_keene_fops = {
  	.owner		= THIS_MODULE,
  	.open           = v4l2_fh_open,
  	.release        = v4l2_fh_release,
  	.poll		= v4l2_ctrl_poll,
  	.unlocked_ioctl	= video_ioctl2,
  };
  
  static const struct v4l2_ctrl_ops keene_ctrl_ops = {
  	.s_ctrl = keene_s_ctrl,
  };
  
  static const struct v4l2_ioctl_ops usb_keene_ioctl_ops = {
  	.vidioc_querycap    = vidioc_querycap,
  	.vidioc_g_modulator = vidioc_g_modulator,
  	.vidioc_s_modulator = vidioc_s_modulator,
  	.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_keene_video_device_release(struct v4l2_device *v4l2_dev)
  {
  	struct keene_device *radio = to_keene_dev(v4l2_dev);
  
  	/* free rest memory */
  	v4l2_ctrl_handler_free(&radio->hdl);
  	kfree(radio->buffer);
  	kfree(radio);
  }
  
  /* check if the device is present and register with v4l and usb if it is */
  static int usb_keene_probe(struct usb_interface *intf,
  				const struct usb_device_id *id)
  {
  	struct usb_device *dev = interface_to_usbdev(intf);
  	struct keene_device *radio;
  	struct v4l2_ctrl_handler *hdl;
  	int retval = 0;
  
  	/*
  	 * The Keene FM transmitter USB device has the same USB ID as
  	 * the Logitech AudioHub Speaker, but it should ignore the hid.
  	 * Check if the name is that of the Keene device.
  	 * If not, then someone connected the AudioHub and we shouldn't
  	 * attempt to handle this driver.
  	 * For reference: the product name of the AudioHub is
  	 * "AudioHub Speaker".
  	 */
  	if (dev->product && strcmp(dev->product, "B-LINK USB Audio  "))
  		return -ENODEV;
  
  	radio = kzalloc(sizeof(struct keene_device), GFP_KERNEL);
  	if (radio)
  		radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);
  
  	if (!radio || !radio->buffer) {
  		dev_err(&intf->dev, "kmalloc for keene_device failed
  ");
  		kfree(radio);
  		retval = -ENOMEM;
  		goto err;
  	}
  
  	hdl = &radio->hdl;
  	v4l2_ctrl_handler_init(hdl, 4);
  	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_MUTE,
  			0, 1, 1, 0);
  	v4l2_ctrl_new_std_menu(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_PREEMPHASIS,
  			V4L2_PREEMPHASIS_75_uS, 1, V4L2_PREEMPHASIS_50_uS);
  	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_POWER_LEVEL,
  			84, 118, 1, 118);
  	v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_COMPRESSION_GAIN,
  			-15, 18, 3, 0);
  	radio->pa = 118;
  	radio->tx = 0x32;
  	radio->stereo = true;
  	if (hdl->error) {
  		retval = hdl->error;
  
  		v4l2_ctrl_handler_free(hdl);
  		goto err_v4l2;
  	}
  	retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
  	if (retval < 0) {
  		dev_err(&intf->dev, "couldn't register v4l2_device
  ");
  		goto err_v4l2;
  	}
  
  	mutex_init(&radio->lock);
  
  	radio->v4l2_dev.ctrl_handler = hdl;
  	radio->v4l2_dev.release = usb_keene_video_device_release;
  	strlcpy(radio->vdev.name, radio->v4l2_dev.name,
  		sizeof(radio->vdev.name));
  	radio->vdev.v4l2_dev = &radio->v4l2_dev;
  	radio->vdev.fops = &usb_keene_fops;
  	radio->vdev.ioctl_ops = &usb_keene_ioctl_ops;
  	radio->vdev.lock = &radio->lock;
  	radio->vdev.release = video_device_release_empty;
  	radio->vdev.vfl_dir = VFL_DIR_TX;
  
  	radio->usbdev = interface_to_usbdev(intf);
  	radio->intf = intf;
  	usb_set_intfdata(intf, &radio->v4l2_dev);
  
  	video_set_drvdata(&radio->vdev, radio);
  
  	/* at least 11ms is needed in order to settle hardware */
  	msleep(20);
  	keene_cmd_main(radio, 95.16 * FREQ_MUL, false);
  
  	retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
  	if (retval < 0) {
  		dev_err(&intf->dev, "could not register video device
  ");
  		goto err_vdev;
  	}
  	v4l2_ctrl_handler_setup(hdl);
  	dev_info(&intf->dev, "V4L2 device registered as %s
  ",
  			video_device_node_name(&radio->vdev));
  	return 0;
  
  err_vdev:
  	v4l2_device_unregister(&radio->v4l2_dev);
  err_v4l2:
  	kfree(radio->buffer);
  	kfree(radio);
  err:
  	return retval;
  }
  
  /* USB subsystem interface */
  static struct usb_driver usb_keene_driver = {
  	.name			= "radio-keene",
  	.probe			= usb_keene_probe,
  	.disconnect		= usb_keene_disconnect,
  	.id_table		= usb_keene_device_table,
  	.suspend		= usb_keene_suspend,
  	.resume			= usb_keene_resume,
  	.reset_resume		= usb_keene_resume,
  };
  
  module_usb_driver(usb_keene_driver);