/*
   * 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.
   *
   * 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 <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);
  
  	strlcpy(v->driver, "radio-ma901", sizeof(v->driver));
  	strlcpy(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);
  	 */
  
  	strcpy(v->name, "FM");
  	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
  ");
  		retval = -ENOMEM;
  		goto err;
  	}
  
  	radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);
  	if (!radio->buffer) {
  		dev_err(&intf->dev, "kmalloc for radio->buffer failed
  ");
  		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
  ");
  		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
  ");
  		goto err_ctrl;
  	}
  	mutex_init(&radio->lock);
  
  	radio->v4l2_dev.ctrl_handler = &radio->hdl;
  	radio->v4l2_dev.release = usb_ma901radio_release;
  	strlcpy(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
  ");
  		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 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);