drivers/media/radio/radio-si470x.c

/*
 *  drivers/media/radio/radio-si470x.c
 *
 *  Driver for USB radios for the Silicon Labs Si470x FM Radio Receivers:
 *   - Silicon Labs USB FM Radio Reference Design
 *   - ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF)
 *   - KWorld USB FM Radio SnapMusic Mobile 700 (FM700)
 *   - Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear)
 *
 *  Copyright (c) 2009 Tobias Lorenz <tobias.lorenz@gmx.net>
 *
 * 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:
 * 2008-01-12	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.0
 *		- First working version
 * 2008-01-13	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.1
 *		- Improved error handling, every function now returns errno
 *		- Improved multi user access (start/mute/stop)
 *		- Channel doesn't get lost anymore after start/mute/stop
 *		- RDS support added (polling mode via interrupt EP 1)
 *		- marked default module parameters with *value*
 *		- switched from bit structs to bit masks
 *		- header file cleaned and integrated
 * 2008-01-14	Tobias Lorenz <tobias.lorenz@gmx.net>
 * 		Version 1.0.2
 * 		- hex values are now lower case
 * 		- commented USB ID for ADS/Tech moved on todo list
 * 		- blacklisted si470x in hid-quirks.c
 * 		- rds buffer handling functions integrated into *_work, *_read
 * 		- rds_command in si470x_poll exchanged against simple retval
 * 		- check for firmware version 15
 * 		- code order and prototypes still remain the same
 * 		- spacing and bottom of band codes remain the same
 * 2008-01-16	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.3
 * 		- code reordered to avoid function prototypes
 *		- switch/case defaults are now more user-friendly
 *		- unified comment style
 *		- applied all checkpatch.pl v1.12 suggestions
 *		  except the warning about the too long lines with bit comments
 *		- renamed FMRADIO to RADIO to cut line length (checkpatch.pl)
 * 2008-01-22	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.4
 *		- avoid poss. locking when doing copy_to_user which may sleep
 *		- RDS is automatically activated on read now
 *		- code cleaned of unnecessary rds_commands
 *		- USB Vendor/Product ID for ADS/Tech FM Radio Receiver verified
 *		  (thanks to Guillaume RAMOUSSE)
 * 2008-01-27	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.5
 *		- number of seek_retries changed to tune_timeout
 *		- fixed problem with incomplete tune operations by own buffers
 *		- optimization of variables and printf types
 *		- improved error logging
 * 2008-01-31	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Oliver Neukum <oliver@neukum.org>
 *		Version 1.0.6
 *		- fixed coverity checker warnings in *_usb_driver_disconnect
 *		- probe()/open() race by correct ordering in probe()
 *		- DMA coherency rules by separate allocation of all buffers
 *		- use of endianness macros
 *		- abuse of spinlock, replaced by mutex
 *		- racy handling of timer in disconnect,
 *		  replaced by delayed_work
 *		- racy interruptible_sleep_on(),
 *		  replaced with wait_event_interruptible()
 *		- handle signals in read()
 * 2008-02-08	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Oliver Neukum <oliver@neukum.org>
 *		Version 1.0.7
 *		- usb autosuspend support
 *		- unplugging fixed
 * 2008-05-07	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.8
 *		- hardware frequency seek support
 *		- afc indication
 *		- more safety checks, let si470x_get_freq return errno
 *		- vidioc behavior corrected according to v4l2 spec
 * 2008-10-20	Alexey Klimov <klimov.linux@gmail.com>
 * 		- add support for KWorld USB FM Radio FM700
 * 		- blacklisted KWorld radio in hid-core.c and hid-ids.h
 * 2008-12-03	Mark Lord <mlord@pobox.com>
 *		- add support for DealExtreme USB Radio
 * 2009-01-31	Bob Ross <pigiron@gmx.com>
 *		- correction of stereo detection/setting
 *		- correction of signal strength indicator scaling
 * 2009-01-31	Rick Bronson <rick@efn.org>
 *		Tobias Lorenz <tobias.lorenz@gmx.net>
 *		- add LED status output
 *		- get HW/SW version from scratchpad
 * 2009-06-16   Edouard Lafargue <edouard@lafargue.name>
 *		Version 1.0.10
 *		- add support for interrupt mode for RDS endpoint,
 *                instead of polling.
 *                Improves RDS reception significantly
 *
 * ToDo:
 * - add firmware download/update support
 */


/* driver definitions */
#define DRIVER_AUTHOR "Tobias Lorenz <tobias.lorenz@gmx.net>"
#define DRIVER_NAME "radio-si470x"
#define DRIVER_KERNEL_VERSION KERNEL_VERSION(1, 0, 10)
#define DRIVER_CARD "Silicon Labs Si470x FM Radio Receiver"
#define DRIVER_DESC "USB radio driver for Si470x FM Radio Receivers"
#define DRIVER_VERSION "1.0.10"


/* kernel includes */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/input.h>
#include <linux/usb.h>
#include <linux/hid.h>
#include <linux/version.h>
#include <linux/videodev2.h>
#include <linux/mutex.h>
#include <media/v4l2-common.h>
#include <media/v4l2-ioctl.h>
#include <media/rds.h>
#include <asm/unaligned.h>


/* USB Device ID List */
static struct usb_device_id si470x_usb_driver_id_table[] = {
	/* Silicon Labs USB FM Radio Reference Design */
	{ USB_DEVICE_AND_INTERFACE_INFO(0x10c4, 0x818a, USB_CLASS_HID, 0, 0) },
	/* ADS/Tech FM Radio Receiver (formerly Instant FM Music) */
	{ USB_DEVICE_AND_INTERFACE_INFO(0x06e1, 0xa155, USB_CLASS_HID, 0, 0) },
	/* KWorld USB FM Radio SnapMusic Mobile 700 (FM700) */
	{ USB_DEVICE_AND_INTERFACE_INFO(0x1b80, 0xd700, USB_CLASS_HID, 0, 0) },
	/* Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear) */
	{ USB_DEVICE_AND_INTERFACE_INFO(0x10c5, 0x819a, USB_CLASS_HID, 0, 0) },
	/* Terminating entry */
	{ }
};
MODULE_DEVICE_TABLE(usb, si470x_usb_driver_id_table);



/**************************************************************************
 * Module Parameters
 **************************************************************************/

/* Radio Nr */
static int radio_nr = -1;
module_param(radio_nr, int, 0444);
MODULE_PARM_DESC(radio_nr, "Radio Nr");

/* Spacing (kHz) */
/* 0: 200 kHz (USA, Australia) */
/* 1: 100 kHz (Europe, Japan) */
/* 2:  50 kHz */
static unsigned short space = 2;
module_param(space, ushort, 0444);
MODULE_PARM_DESC(space, "Spacing: 0=200kHz 1=100kHz *2=50kHz*");

/* Bottom of Band (MHz) */
/* 0: 87.5 - 108 MHz (USA, Europe)*/
/* 1: 76   - 108 MHz (Japan wide band) */
/* 2: 76   -  90 MHz (Japan) */
static unsigned short band = 1;
module_param(band, ushort, 0444);
MODULE_PARM_DESC(band, "Band: 0=87.5..108MHz *1=76..108MHz* 2=76..90MHz");

/* De-emphasis */
/* 0: 75 us (USA) */
/* 1: 50 us (Europe, Australia, Japan) */
static unsigned short de = 1;
module_param(de, ushort, 0444);
MODULE_PARM_DESC(de, "De-emphasis: 0=75us *1=50us*");

/* USB timeout */
static unsigned int usb_timeout = 500;
module_param(usb_timeout, uint, 0644);
MODULE_PARM_DESC(usb_timeout, "USB timeout (ms): *500*");

/* Tune timeout */
static unsigned int tune_timeout = 3000;
module_param(tune_timeout, uint, 0644);
MODULE_PARM_DESC(tune_timeout, "Tune timeout: *3000*");

/* Seek timeout */
static unsigned int seek_timeout = 5000;
module_param(seek_timeout, uint, 0644);
MODULE_PARM_DESC(seek_timeout, "Seek timeout: *5000*");

/* RDS buffer blocks */
static unsigned int rds_buf = 100;
module_param(rds_buf, uint, 0444);
MODULE_PARM_DESC(rds_buf, "RDS buffer entries: *100*");

/* RDS maximum block errors */
static unsigned short max_rds_errors = 1;
/* 0 means   0  errors requiring correction */
/* 1 means 1-2  errors requiring correction (used by original USBRadio.exe) */
/* 2 means 3-5  errors requiring correction */
/* 3 means   6+ errors or errors in checkword, correction not possible */
module_param(max_rds_errors, ushort, 0644);
MODULE_PARM_DESC(max_rds_errors, "RDS maximum block errors: *1*");


/**************************************************************************
 * Register Definitions
 **************************************************************************/
#define RADIO_REGISTER_SIZE	2	/* 16 register bit width */
#define RADIO_REGISTER_NUM	16	/* DEVICEID   ... RDSD */
#define RDS_REGISTER_NUM	6	/* STATUSRSSI ... RDSD */

#define DEVICEID		0	/* Device ID */
#define DEVICEID_PN		0xf000	/* bits 15..12: Part Number */
#define DEVICEID_MFGID		0x0fff	/* bits 11..00: Manufacturer ID */

#define CHIPID			1	/* Chip ID */
#define CHIPID_REV		0xfc00	/* bits 15..10: Chip Version */
#define CHIPID_DEV		0x0200	/* bits 09..09: Device */
#define CHIPID_FIRMWARE		0x01ff	/* bits 08..00: Firmware Version */

#define POWERCFG		2	/* Power Configuration */
#define POWERCFG_DSMUTE		0x8000	/* bits 15..15: Softmute Disable */
#define POWERCFG_DMUTE		0x4000	/* bits 14..14: Mute Disable */
#define POWERCFG_MONO		0x2000	/* bits 13..13: Mono Select */
#define POWERCFG_RDSM		0x0800	/* bits 11..11: RDS Mode (Si4701 only) */
#define POWERCFG_SKMODE		0x0400	/* bits 10..10: Seek Mode */
#define POWERCFG_SEEKUP		0x0200	/* bits 09..09: Seek Direction */
#define POWERCFG_SEEK		0x0100	/* bits 08..08: Seek */
#define POWERCFG_DISABLE	0x0040	/* bits 06..06: Powerup Disable */
#define POWERCFG_ENABLE		0x0001	/* bits 00..00: Powerup Enable */

#define CHANNEL			3	/* Channel */
#define CHANNEL_TUNE		0x8000	/* bits 15..15: Tune */
#define CHANNEL_CHAN		0x03ff	/* bits 09..00: Channel Select */

#define SYSCONFIG1		4	/* System Configuration 1 */
#define SYSCONFIG1_RDSIEN	0x8000	/* bits 15..15: RDS Interrupt Enable (Si4701 only) */
#define SYSCONFIG1_STCIEN	0x4000	/* bits 14..14: Seek/Tune Complete Interrupt Enable */
#define SYSCONFIG1_RDS		0x1000	/* bits 12..12: RDS Enable (Si4701 only) */
#define SYSCONFIG1_DE		0x0800	/* bits 11..11: De-emphasis (0=75us 1=50us) */
#define SYSCONFIG1_AGCD		0x0400	/* bits 10..10: AGC Disable */
#define SYSCONFIG1_BLNDADJ	0x00c0	/* bits 07..06: Stereo/Mono Blend Level Adjustment */
#define SYSCONFIG1_GPIO3	0x0030	/* bits 05..04: General Purpose I/O 3 */
#define SYSCONFIG1_GPIO2	0x000c	/* bits 03..02: General Purpose I/O 2 */
#define SYSCONFIG1_GPIO1	0x0003	/* bits 01..00: General Purpose I/O 1 */

#define SYSCONFIG2		5	/* System Configuration 2 */
#define SYSCONFIG2_SEEKTH	0xff00	/* bits 15..08: RSSI Seek Threshold */
#define SYSCONFIG2_BAND		0x0080	/* bits 07..06: Band Select */
#define SYSCONFIG2_SPACE	0x0030	/* bits 05..04: Channel Spacing */
#define SYSCONFIG2_VOLUME	0x000f	/* bits 03..00: Volume */

#define SYSCONFIG3		6	/* System Configuration 3 */
#define SYSCONFIG3_SMUTER	0xc000	/* bits 15..14: Softmute Attack/Recover Rate */
#define SYSCONFIG3_SMUTEA	0x3000	/* bits 13..12: Softmute Attenuation */
#define SYSCONFIG3_SKSNR	0x00f0	/* bits 07..04: Seek SNR Threshold */
#define SYSCONFIG3_SKCNT	0x000f	/* bits 03..00: Seek FM Impulse Detection Threshold */

#define TEST1			7	/* Test 1 */
#define TEST1_AHIZEN		0x4000	/* bits 14..14: Audio High-Z Enable */

#define TEST2			8	/* Test 2 */
/* TEST2 only contains reserved bits */

#define BOOTCONFIG		9	/* Boot Configuration */
/* BOOTCONFIG only contains reserved bits */

#define STATUSRSSI		10	/* Status RSSI */
#define STATUSRSSI_RDSR		0x8000	/* bits 15..15: RDS Ready (Si4701 only) */
#define STATUSRSSI_STC		0x4000	/* bits 14..14: Seek/Tune Complete */
#define STATUSRSSI_SF		0x2000	/* bits 13..13: Seek Fail/Band Limit */
#define STATUSRSSI_AFCRL	0x1000	/* bits 12..12: AFC Rail */
#define STATUSRSSI_RDSS		0x0800	/* bits 11..11: RDS Synchronized (Si4701 only) */
#define STATUSRSSI_BLERA	0x0600	/* bits 10..09: RDS Block A Errors (Si4701 only) */
#define STATUSRSSI_ST		0x0100	/* bits 08..08: Stereo Indicator */
#define STATUSRSSI_RSSI		0x00ff	/* bits 07..00: RSSI (Received Signal Strength Indicator) */

#define READCHAN		11	/* Read Channel */
#define READCHAN_BLERB		0xc000	/* bits 15..14: RDS Block D Errors (Si4701 only) */
#define READCHAN_BLERC		0x3000	/* bits 13..12: RDS Block C Errors (Si4701 only) */
#define READCHAN_BLERD		0x0c00	/* bits 11..10: RDS Block B Errors (Si4701 only) */
#define READCHAN_READCHAN	0x03ff	/* bits 09..00: Read Channel */

#define RDSA			12	/* RDSA */
#define RDSA_RDSA		0xffff	/* bits 15..00: RDS Block A Data (Si4701 only) */

#define RDSB			13	/* RDSB */
#define RDSB_RDSB		0xffff	/* bits 15..00: RDS Block B Data (Si4701 only) */

#define RDSC			14	/* RDSC */
#define RDSC_RDSC		0xffff	/* bits 15..00: RDS Block C Data (Si4701 only) */

#define RDSD			15	/* RDSD */
#define RDSD_RDSD		0xffff	/* bits 15..00: RDS Block D Data (Si4701 only) */



/**************************************************************************
 * USB HID Reports
 **************************************************************************/

/* Reports 1-16 give direct read/write access to the 16 Si470x registers */
/* with the (REPORT_ID - 1) corresponding to the register address across USB */
/* endpoint 0 using GET_REPORT and SET_REPORT */
#define REGISTER_REPORT_SIZE	(RADIO_REGISTER_SIZE + 1)
#define REGISTER_REPORT(reg)	((reg) + 1)

/* Report 17 gives direct read/write access to the entire Si470x register */
/* map across endpoint 0 using GET_REPORT and SET_REPORT */
#define ENTIRE_REPORT_SIZE	(RADIO_REGISTER_NUM * RADIO_REGISTER_SIZE + 1)
#define ENTIRE_REPORT		17

/* Report 18 is used to send the lowest 6 Si470x registers up the HID */
/* interrupt endpoint 1 to Windows every 20 milliseconds for status */
#define RDS_REPORT_SIZE		(RDS_REGISTER_NUM * RADIO_REGISTER_SIZE + 1)
#define RDS_REPORT		18

/* Report 19: LED state */
#define LED_REPORT_SIZE		3
#define LED_REPORT		19

/* Report 19: stream */
#define STREAM_REPORT_SIZE	3
#define STREAM_REPORT		19

/* Report 20: scratch */
#define SCRATCH_PAGE_SIZE	63
#define SCRATCH_REPORT_SIZE	(SCRATCH_PAGE_SIZE + 1)
#define SCRATCH_REPORT		20

/* Reports 19-22: flash upgrade of the C8051F321 */
#define WRITE_REPORT_SIZE	4
#define WRITE_REPORT		19
#define FLASH_REPORT_SIZE	64
#define FLASH_REPORT		20
#define CRC_REPORT_SIZE		3
#define CRC_REPORT		21
#define RESPONSE_REPORT_SIZE	2
#define RESPONSE_REPORT		22

/* Report 23: currently unused, but can accept 60 byte reports on the HID */
/* interrupt out endpoint 2 every 1 millisecond */
#define UNUSED_REPORT		23



/**************************************************************************
 * Software/Hardware Versions
 **************************************************************************/
#define RADIO_SW_VERSION_NOT_BOOTLOADABLE	6
#define RADIO_SW_VERSION			7
#define RADIO_SW_VERSION_CURRENT		15
#define RADIO_HW_VERSION			1

#define SCRATCH_PAGE_SW_VERSION	1
#define SCRATCH_PAGE_HW_VERSION	2



/**************************************************************************
 * LED State Definitions
 **************************************************************************/
#define LED_COMMAND		0x35

#define NO_CHANGE_LED		0x00
#define ALL_COLOR_LED		0x01	/* streaming state */
#define BLINK_GREEN_LED		0x02	/* connect state */
#define BLINK_RED_LED		0x04
#define BLINK_ORANGE_LED	0x10	/* disconnect state */
#define SOLID_GREEN_LED		0x20	/* tuning/seeking state */
#define SOLID_RED_LED		0x40	/* bootload state */
#define SOLID_ORANGE_LED	0x80



/**************************************************************************
 * Stream State Definitions
 **************************************************************************/
#define STREAM_COMMAND	0x36
#define STREAM_VIDPID	0x00
#define STREAM_AUDIO	0xff



/**************************************************************************
 * Bootloader / Flash Commands
 **************************************************************************/

/* unique id sent to bootloader and required to put into a bootload state */
#define UNIQUE_BL_ID		0x34

/* mask for the flash data */
#define FLASH_DATA_MASK		0x55

/* bootloader commands */
#define GET_SW_VERSION_COMMAND	0x00
#define SET_PAGE_COMMAND	0x01
#define ERASE_PAGE_COMMAND	0x02
#define WRITE_PAGE_COMMAND	0x03
#define CRC_ON_PAGE_COMMAND	0x04
#define READ_FLASH_BYTE_COMMAND	0x05
#define RESET_DEVICE_COMMAND	0x06
#define GET_HW_VERSION_COMMAND	0x07
#define BLANK			0xff

/* bootloader command responses */
#define COMMAND_OK		0x01
#define COMMAND_FAILED		0x02
#define COMMAND_PENDING		0x03



/**************************************************************************
 * General Driver Definitions
 **************************************************************************/

/*
 * si470x_device - private data
 */
struct si470x_device {
	/* reference to USB and video device */
	struct usb_device *usbdev;
	struct usb_interface *intf;
	struct video_device *videodev;

	/* Interrupt endpoint handling */
	char *int_in_buffer;
	struct usb_endpoint_descriptor *int_in_endpoint;
	struct urb *int_in_urb;
	int int_in_running;

	/* driver management */
	unsigned int users;
	unsigned char disconnected;
	struct mutex disconnect_lock;

	/* Silabs internal registers (0..15) */
	unsigned short registers[RADIO_REGISTER_NUM];

	/* RDS receive buffer */
	wait_queue_head_t read_queue;
	struct mutex lock;		/* buffer locking */
	unsigned char *buffer;		/* size is always multiple of three */
	unsigned int buf_size;
	unsigned int rd_index;
	unsigned int wr_index;

	/* scratch page */
	unsigned char software_version;
	unsigned char hardware_version;
};


/*
 * The frequency is set in units of 62.5 Hz when using V4L2_TUNER_CAP_LOW,
 * 62.5 kHz otherwise.
 * The tuner is able to have a channel spacing of 50, 100 or 200 kHz.
 * tuner->capability is therefore set to V4L2_TUNER_CAP_LOW
 * The FREQ_MUL is then: 1 MHz / 62.5 Hz = 16000
 */
#define FREQ_MUL (1000000 / 62.5)



/**************************************************************************
 * General Driver Functions - REGISTER_REPORTs
 **************************************************************************/

/*
 * si470x_get_report - receive a HID report
 */
static int si470x_get_report(struct si470x_device *radio, void *buf, int size)
{
	unsigned char *report = (unsigned char *) buf;
	int retval;

	retval = usb_control_msg(radio->usbdev,
		usb_rcvctrlpipe(radio->usbdev, 0),
		HID_REQ_GET_REPORT,
		USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
		report[0], 2,
		buf, size, usb_timeout);

	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": si470x_get_report: usb_control_msg returned %d\n",
			retval);
	return retval;
}


/*
 * si470x_set_report - send a HID report
 */
static int si470x_set_report(struct si470x_device *radio, void *buf, int size)
{
	unsigned char *report = (unsigned char *) buf;
	int retval;

	retval = usb_control_msg(radio->usbdev,
		usb_sndctrlpipe(radio->usbdev, 0),
		HID_REQ_SET_REPORT,
		USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
		report[0], 2,
		buf, size, usb_timeout);

	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": si470x_set_report: usb_control_msg returned %d\n",
			retval);
	return retval;
}


/*
 * si470x_get_register - read register
 */
static int si470x_get_register(struct si470x_device *radio, int regnr)
{
	unsigned char buf[REGISTER_REPORT_SIZE];
	int retval;

	buf[0] = REGISTER_REPORT(regnr);

	retval = si470x_get_report(radio, (void *) &buf, sizeof(buf));

	if (retval >= 0)
		radio->registers[regnr] = get_unaligned_be16(&buf[1]);

	return (retval < 0) ? -EINVAL : 0;
}


/*
 * si470x_set_register - write register
 */
static int si470x_set_register(struct si470x_device *radio, int regnr)
{
	unsigned char buf[REGISTER_REPORT_SIZE];
	int retval;

	buf[0] = REGISTER_REPORT(regnr);
	put_unaligned_be16(radio->registers[regnr], &buf[1]);

	retval = si470x_set_report(radio, (void *) &buf, sizeof(buf));

	return (retval < 0) ? -EINVAL : 0;
}


/*
 * si470x_set_chan - set the channel
 */
static int si470x_set_chan(struct si470x_device *radio, unsigned short chan)
{
	int retval;
	unsigned long timeout;
	bool timed_out = 0;

	/* start tuning */
	radio->registers[CHANNEL] &= ~CHANNEL_CHAN;
	radio->registers[CHANNEL] |= CHANNEL_TUNE | chan;
	retval = si470x_set_register(radio, CHANNEL);
	if (retval < 0)
		goto done;

	/* wait till tune operation has completed */
	timeout = jiffies + msecs_to_jiffies(tune_timeout);
	do {
		retval = si470x_get_register(radio, STATUSRSSI);
		if (retval < 0)
			goto stop;
		timed_out = time_after(jiffies, timeout);
	} while (((radio->registers[STATUSRSSI] & STATUSRSSI_STC) == 0) &&
		(!timed_out));
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_STC) == 0)
		printk(KERN_WARNING DRIVER_NAME ": tune does not complete\n");
	if (timed_out)
		printk(KERN_WARNING DRIVER_NAME
			": tune timed out after %u ms\n", tune_timeout);

stop:
	/* stop tuning */
	radio->registers[CHANNEL] &= ~CHANNEL_TUNE;
	retval = si470x_set_register(radio, CHANNEL);

done:
	return retval;
}


/*
 * si470x_get_freq - get the frequency
 */
static int si470x_get_freq(struct si470x_device *radio, unsigned int *freq)
{
	unsigned int spacing, band_bottom;
	unsigned short chan;
	int retval;

	/* Spacing (kHz) */
	switch ((radio->registers[SYSCONFIG2] & SYSCONFIG2_SPACE) >> 4) {
	/* 0: 200 kHz (USA, Australia) */
	case 0:
		spacing = 0.200 * FREQ_MUL; break;
	/* 1: 100 kHz (Europe, Japan) */
	case 1:
		spacing = 0.100 * FREQ_MUL; break;
	/* 2:  50 kHz */
	default:
		spacing = 0.050 * FREQ_MUL; break;
	};

	/* Bottom of Band (MHz) */
	switch ((radio->registers[SYSCONFIG2] & SYSCONFIG2_BAND) >> 6) {
	/* 0: 87.5 - 108 MHz (USA, Europe) */
	case 0:
		band_bottom = 87.5 * FREQ_MUL; break;
	/* 1: 76   - 108 MHz (Japan wide band) */
	default:
		band_bottom = 76   * FREQ_MUL; break;
	/* 2: 76   -  90 MHz (Japan) */
	case 2:
		band_bottom = 76   * FREQ_MUL; break;
	};

	/* read channel */
	retval = si470x_get_register(radio, READCHAN);
	chan = radio->registers[READCHAN] & READCHAN_READCHAN;

	/* Frequency (MHz) = Spacing (kHz) x Channel + Bottom of Band (MHz) */
	*freq = chan * spacing + band_bottom;

	return retval;
}


/*
 * si470x_set_freq - set the frequency
 */
static int si470x_set_freq(struct si470x_device *radio, unsigned int freq)
{
	unsigned int spacing, band_bottom;
	unsigned short chan;

	/* Spacing (kHz) */
	switch ((radio->registers[SYSCONFIG2] & SYSCONFIG2_SPACE) >> 4) {
	/* 0: 200 kHz (USA, Australia) */
	case 0:
		spacing = 0.200 * FREQ_MUL; break;
	/* 1: 100 kHz (Europe, Japan) */
	case 1:
		spacing = 0.100 * FREQ_MUL; break;
	/* 2:  50 kHz */
	default:
		spacing = 0.050 * FREQ_MUL; break;
	};

	/* Bottom of Band (MHz) */
	switch ((radio->registers[SYSCONFIG2] & SYSCONFIG2_BAND) >> 6) {
	/* 0: 87.5 - 108 MHz (USA, Europe) */
	case 0:
		band_bottom = 87.5 * FREQ_MUL; break;
	/* 1: 76   - 108 MHz (Japan wide band) */
	default:
		band_bottom = 76   * FREQ_MUL; break;
	/* 2: 76   -  90 MHz (Japan) */
	case 2:
		band_bottom = 76   * FREQ_MUL; break;
	};

	/* Chan = [ Freq (Mhz) - Bottom of Band (MHz) ] / Spacing (kHz) */
	chan = (freq - band_bottom) / spacing;

	return si470x_set_chan(radio, chan);
}


/*
 * si470x_set_seek - set seek
 */
static int si470x_set_seek(struct si470x_device *radio,
		unsigned int wrap_around, unsigned int seek_upward)
{
	int retval = 0;
	unsigned long timeout;
	bool timed_out = 0;

	/* start seeking */
	radio->registers[POWERCFG] |= POWERCFG_SEEK;
	if (wrap_around == 1)
		radio->registers[POWERCFG] &= ~POWERCFG_SKMODE;
	else
		radio->registers[POWERCFG] |= POWERCFG_SKMODE;
	if (seek_upward == 1)
		radio->registers[POWERCFG] |= POWERCFG_SEEKUP;
	else
		radio->registers[POWERCFG] &= ~POWERCFG_SEEKUP;
	retval = si470x_set_register(radio, POWERCFG);
	if (retval < 0)
		goto done;

	/* wait till seek operation has completed */
	timeout = jiffies + msecs_to_jiffies(seek_timeout);
	do {
		retval = si470x_get_register(radio, STATUSRSSI);
		if (retval < 0)
			goto stop;
		timed_out = time_after(jiffies, timeout);
	} while (((radio->registers[STATUSRSSI] & STATUSRSSI_STC) == 0) &&
		(!timed_out));
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_STC) == 0)
		printk(KERN_WARNING DRIVER_NAME ": seek does not complete\n");
	if (radio->registers[STATUSRSSI] & STATUSRSSI_SF)
		printk(KERN_WARNING DRIVER_NAME
			": seek failed / band limit reached\n");
	if (timed_out)
		printk(KERN_WARNING DRIVER_NAME
			": seek timed out after %u ms\n", seek_timeout);

stop:
	/* stop seeking */
	radio->registers[POWERCFG] &= ~POWERCFG_SEEK;
	retval = si470x_set_register(radio, POWERCFG);

done:
	/* try again, if timed out */
	if ((retval == 0) && timed_out)
		retval = -EAGAIN;

	return retval;
}


/*
 * si470x_start - switch on radio
 */
static int si470x_start(struct si470x_device *radio)
{
	int retval;

	/* powercfg */
	radio->registers[POWERCFG] =
		POWERCFG_DMUTE | POWERCFG_ENABLE | POWERCFG_RDSM;
	retval = si470x_set_register(radio, POWERCFG);
	if (retval < 0)
		goto done;

	/* sysconfig 1 */
	radio->registers[SYSCONFIG1] = SYSCONFIG1_DE;
	retval = si470x_set_register(radio, SYSCONFIG1);
	if (retval < 0)
		goto done;

	/* sysconfig 2 */
	radio->registers[SYSCONFIG2] =
		(0x3f  << 8) |				/* SEEKTH */
		((band  << 6) & SYSCONFIG2_BAND)  |	/* BAND */
		((space << 4) & SYSCONFIG2_SPACE) |	/* SPACE */
		15;					/* VOLUME (max) */
	retval = si470x_set_register(radio, SYSCONFIG2);
	if (retval < 0)
		goto done;

	/* reset last channel */
	retval = si470x_set_chan(radio,
		radio->registers[CHANNEL] & CHANNEL_CHAN);

done:
	return retval;
}


/*
 * si470x_stop - switch off radio
 */
static int si470x_stop(struct si470x_device *radio)
{
	int retval;

	/* sysconfig 1 */
	radio->registers[SYSCONFIG1] &= ~SYSCONFIG1_RDS;
	retval = si470x_set_register(radio, SYSCONFIG1);
	if (retval < 0)
		goto done;

	/* powercfg */
	radio->registers[POWERCFG] &= ~POWERCFG_DMUTE;
	/* POWERCFG_ENABLE has to automatically go low */
	radio->registers[POWERCFG] |= POWERCFG_ENABLE |	POWERCFG_DISABLE;
	retval = si470x_set_register(radio, POWERCFG);

done:
	return retval;
}


/*
 * si470x_rds_on - switch on rds reception
 */
static int si470x_rds_on(struct si470x_device *radio)
{
	int retval;

	/* sysconfig 1 */
	mutex_lock(&radio->lock);
	radio->registers[SYSCONFIG1] |= SYSCONFIG1_RDS;
	retval = si470x_set_register(radio, SYSCONFIG1);
	if (retval < 0)
		radio->registers[SYSCONFIG1] &= ~SYSCONFIG1_RDS;
	mutex_unlock(&radio->lock);

	return retval;
}



/**************************************************************************
 * General Driver Functions - ENTIRE_REPORT
 **************************************************************************/

/*
 * si470x_get_all_registers - read entire registers
 */
static int si470x_get_all_registers(struct si470x_device *radio)
{
	unsigned char buf[ENTIRE_REPORT_SIZE];
	int retval;
	unsigned char regnr;

	buf[0] = ENTIRE_REPORT;

	retval = si470x_get_report(radio, (void *) &buf, sizeof(buf));

	if (retval >= 0)
		for (regnr = 0; regnr < RADIO_REGISTER_NUM; regnr++)
			radio->registers[regnr] = get_unaligned_be16(
				&buf[regnr * RADIO_REGISTER_SIZE + 1]);

	return (retval < 0) ? -EINVAL : 0;
}



/**************************************************************************
 * General Driver Functions - LED_REPORT
 **************************************************************************/

/*
 * si470x_set_led_state - sets the led state
 */
static int si470x_set_led_state(struct si470x_device *radio,
		unsigned char led_state)
{
	unsigned char buf[LED_REPORT_SIZE];
	int retval;

	buf[0] = LED_REPORT;
	buf[1] = LED_COMMAND;
	buf[2] = led_state;

	retval = si470x_set_report(radio, (void *) &buf, sizeof(buf));

	return (retval < 0) ? -EINVAL : 0;
}



/**************************************************************************
 * General Driver Functions - SCRATCH_REPORT
 **************************************************************************/

/*
 * si470x_get_scratch_versions - gets the scratch page and version infos
 */
static int si470x_get_scratch_page_versions(struct si470x_device *radio)
{
	unsigned char buf[SCRATCH_REPORT_SIZE];
	int retval;

	buf[0] = SCRATCH_REPORT;

	retval = si470x_get_report(radio, (void *) &buf, sizeof(buf));

	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME ": si470x_get_scratch: "
			"si470x_get_report returned %d\n", retval);
	else {
		radio->software_version = buf[1];
		radio->hardware_version = buf[2];
	}

	return (retval < 0) ? -EINVAL : 0;
}



/**************************************************************************
 * RDS Driver Functions
 **************************************************************************/

/*
 * si470x_int_in_callback - rds callback and processing function
 *
 * TODO: do we need to use mutex locks in some sections?
 */
static void si470x_int_in_callback(struct urb *urb)
{
	struct si470x_device *radio = urb->context;
	unsigned char buf[RDS_REPORT_SIZE];
	int retval;
	unsigned char regnr;
	unsigned char blocknum;
	unsigned short bler; /* rds block errors */
	unsigned short rds;
	unsigned char tmpbuf[3];

	if (urb->status) {
		if (urb->status == -ENOENT ||
				urb->status == -ECONNRESET ||
				urb->status == -ESHUTDOWN) {
			return;
		} else {
			printk(KERN_WARNING DRIVER_NAME
			 ": non-zero urb status (%d)\n", urb->status);
			goto resubmit; /* Maybe we can recover. */
		}
	}

	/* safety checks */
	if (radio->disconnected)
		return;
	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
		goto resubmit;

	if (urb->actual_length > 0) {
		/* Update RDS registers with URB data */
		buf[0] = RDS_REPORT;
		for (regnr = 0; regnr < RDS_REGISTER_NUM; regnr++)
			radio->registers[STATUSRSSI + regnr] =
			    get_unaligned_be16(&radio->int_in_buffer[
				regnr * RADIO_REGISTER_SIZE + 1]);
		/* get rds blocks */
		if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSR) == 0) {
			/* No RDS group ready, better luck next time */
			goto resubmit;
		}
		if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSS) == 0) {
			/* RDS decoder not synchronized */
			goto resubmit;
		}
		for (blocknum = 0; blocknum < 4; blocknum++) {
			switch (blocknum) {
			default:
				bler = (radio->registers[STATUSRSSI] &
						STATUSRSSI_BLERA) >> 9;
				rds = radio->registers[RDSA];
				break;
			case 1:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERB) >> 14;
				rds = radio->registers[RDSB];
				break;
			case 2:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERC) >> 12;
				rds = radio->registers[RDSC];
				break;
			case 3:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERD) >> 10;
				rds = radio->registers[RDSD];
				break;
			};

			/* Fill the V4L2 RDS buffer */
			put_unaligned_le16(rds, &tmpbuf);
			tmpbuf[2] = blocknum;		/* offset name */
			tmpbuf[2] |= blocknum << 3;	/* received offset */
			if (bler > max_rds_errors)
				tmpbuf[2] |= 0x80; /* uncorrectable errors */
			else if (bler > 0)
				tmpbuf[2] |= 0x40; /* corrected error(s) */

			/* copy RDS block to internal buffer */
			memcpy(&radio->buffer[radio->wr_index], &tmpbuf, 3);
			radio->wr_index += 3;

			/* wrap write pointer */
			if (radio->wr_index >= radio->buf_size)
				radio->wr_index = 0;

			/* check for overflow */
			if (radio->wr_index == radio->rd_index) {
				/* increment and wrap read pointer */
				radio->rd_index += 3;
				if (radio->rd_index >= radio->buf_size)
					radio->rd_index = 0;
			}
		}
		if (radio->wr_index != radio->rd_index)
			wake_up_interruptible(&radio->read_queue);
	}

resubmit:
	/* Resubmit if we're still running. */
	if (radio->int_in_running && radio->usbdev) {
		retval = usb_submit_urb(radio->int_in_urb, GFP_ATOMIC);
		if (retval) {
			printk(KERN_WARNING DRIVER_NAME
			       ": resubmitting urb failed (%d)", retval);
			radio->int_in_running = 0;
		}
	}
}



/**************************************************************************
 * File Operations Interface
 **************************************************************************/

/*
 * si470x_fops_read - read RDS data
 */
static ssize_t si470x_fops_read(struct file *file, char __user *buf,
		size_t count, loff_t *ppos)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;
	unsigned int block_count = 0;

	/* switch on rds reception */
	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0) {
		si470x_rds_on(radio);
	}

	/* block if no new data available */
	while (radio->wr_index == radio->rd_index) {
		if (file->f_flags & O_NONBLOCK) {
			retval = -EWOULDBLOCK;
			goto done;
		}
		if (wait_event_interruptible(radio->read_queue,
			radio->wr_index != radio->rd_index) < 0) {
			retval = -EINTR;
			goto done;
		}
	}

	/* calculate block count from byte count */
	count /= 3;

	/* copy RDS block out of internal buffer and to user buffer */
	mutex_lock(&radio->lock);
	while (block_count < count) {
		if (radio->rd_index == radio->wr_index)
			break;

		/* always transfer rds complete blocks */
		if (copy_to_user(buf, &radio->buffer[radio->rd_index], 3))
			/* retval = -EFAULT; */
			break;

		/* increment and wrap read pointer */
		radio->rd_index += 3;
		if (radio->rd_index >= radio->buf_size)
			radio->rd_index = 0;

		/* increment counters */
		block_count++;
		buf += 3;
		retval += 3;
	}
	mutex_unlock(&radio->lock);

done:
	return retval;
}


/*
 * si470x_fops_poll - poll RDS data
 */
static unsigned int si470x_fops_poll(struct file *file,
		struct poll_table_struct *pts)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* switch on rds reception */
	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0) {
		si470x_rds_on(radio);
	}

	poll_wait(file, &radio->read_queue, pts);

	if (radio->rd_index != radio->wr_index)
		retval = POLLIN | POLLRDNORM;

	return retval;
}


/*
 * si470x_fops_open - file open
 */
static int si470x_fops_open(struct file *file)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval;

	lock_kernel();
	radio->users++;

	retval = usb_autopm_get_interface(radio->intf);
	if (retval < 0) {
		radio->users--;
		retval = -EIO;
		goto done;
	}

	printk(KERN_INFO DRIVER_NAME
		 ": Opened radio (users now: %i)\n", radio->users);

	if (radio->users == 1) {
		/* start radio */
		retval = si470x_start(radio);
		if (retval < 0) {
			usb_autopm_put_interface(radio->intf);
			goto done;
		}
		/* Initialize interrupt URB. */
		usb_fill_int_urb(radio->int_in_urb, radio->usbdev,
			usb_rcvintpipe(radio->usbdev,
			radio->int_in_endpoint->bEndpointAddress),
			radio->int_in_buffer,
			le16_to_cpu(radio->int_in_endpoint->wMaxPacketSize),
			si470x_int_in_callback,
			radio,
			radio->int_in_endpoint->bInterval);

		radio->int_in_running = 1;
		mb();

		retval = usb_submit_urb(radio->int_in_urb, GFP_KERNEL);
		if (retval) {
			printk(KERN_INFO DRIVER_NAME
				 ": submitting int urb failed (%d)\n", retval);
			radio->int_in_running = 0;
			usb_autopm_put_interface(radio->intf);
		}

	}

done:
	unlock_kernel();
	return retval;
}


/*
 * si470x_fops_release - file release
 */
static int si470x_fops_release(struct file *file)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety check */
	if (!radio) {
		retval = -ENODEV;
		goto done;
	}

	mutex_lock(&radio->disconnect_lock);
	radio->users--;
	printk(KERN_INFO DRIVER_NAME
		 ": Closed radio (remaining users:%i)\n", radio->users);
	if (radio->users == 0) {

		/* Shutdown Interrupt handler */
		if (radio->int_in_running) {
			radio->int_in_running = 0;
		if (radio->int_in_urb)
			usb_kill_urb(radio->int_in_urb);
		}

		if (radio->disconnected) {
			video_unregister_device(radio->videodev);
			kfree(radio->int_in_buffer);
			kfree(radio->buffer);
			kfree(radio);
			goto unlock;
		}

		/* cancel read processes */
		wake_up_interruptible(&radio->read_queue);

		/* stop radio */
		retval = si470x_stop(radio);
		usb_autopm_put_interface(radio->intf);
	}
unlock:
	mutex_unlock(&radio->disconnect_lock);
done:
	return retval;
}


/*
 * si470x_fops - file operations interface
 */
static const struct v4l2_file_operations si470x_fops = {
	.owner		= THIS_MODULE,
	.read		= si470x_fops_read,
	.poll		= si470x_fops_poll,
	.ioctl		= video_ioctl2,
	.open		= si470x_fops_open,
	.release	= si470x_fops_release,
};



/**************************************************************************
 * Video4Linux Interface
 **************************************************************************/

/*
 * si470x_v4l2_queryctrl - query control
 */
static struct v4l2_queryctrl si470x_v4l2_queryctrl[] = {
	{
		.id		= V4L2_CID_AUDIO_VOLUME,
		.type		= V4L2_CTRL_TYPE_INTEGER,
		.name		= "Volume",
		.minimum	= 0,
		.maximum	= 15,
		.step		= 1,
		.default_value	= 15,
	},
	{
		.id		= V4L2_CID_AUDIO_MUTE,
		.type		= V4L2_CTRL_TYPE_BOOLEAN,
		.name		= "Mute",
		.minimum	= 0,
		.maximum	= 1,
		.step		= 1,
		.default_value	= 1,
	},
};


/*
 * si470x_vidioc_querycap - query device capabilities
 */
static int si470x_vidioc_querycap(struct file *file, void *priv,
		struct v4l2_capability *capability)
{
	struct si470x_device *radio = video_drvdata(file);

	strlcpy(capability->driver, DRIVER_NAME, sizeof(capability->driver));
	strlcpy(capability->card, DRIVER_CARD, sizeof(capability->card));
	usb_make_path(radio->usbdev, capability->bus_info, sizeof(capability->bus_info));
	capability->version = DRIVER_KERNEL_VERSION;
	capability->capabilities = V4L2_CAP_HW_FREQ_SEEK |
		V4L2_CAP_TUNER | V4L2_CAP_RADIO;

	return 0;
}


/*
 * si470x_vidioc_queryctrl - enumerate control items
 */
static int si470x_vidioc_queryctrl(struct file *file, void *priv,
		struct v4l2_queryctrl *qc)
{
	unsigned char i = 0;
	int retval = -EINVAL;

	/* abort if qc->id is below V4L2_CID_BASE */
	if (qc->id < V4L2_CID_BASE)
		goto done;

	/* search video control */
	for (i = 0; i < ARRAY_SIZE(si470x_v4l2_queryctrl); i++) {
		if (qc->id == si470x_v4l2_queryctrl[i].id) {
			memcpy(qc, &(si470x_v4l2_queryctrl[i]), sizeof(*qc));
			retval = 0; /* found */
			break;
		}
	}

	/* disable unsupported base controls */
	/* to satisfy kradio and such apps */
	if ((retval == -EINVAL) && (qc->id < V4L2_CID_LASTP1)) {
		qc->flags = V4L2_CTRL_FLAG_DISABLED;
		retval = 0;
	}

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": query controls failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_g_ctrl - get the value of a control
 */
static int si470x_vidioc_g_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}

	switch (ctrl->id) {
	case V4L2_CID_AUDIO_VOLUME:
		ctrl->value = radio->registers[SYSCONFIG2] &
				SYSCONFIG2_VOLUME;
		break;
	case V4L2_CID_AUDIO_MUTE:
		ctrl->value = ((radio->registers[POWERCFG] &
				POWERCFG_DMUTE) == 0) ? 1 : 0;
		break;
	default:
		retval = -EINVAL;
	}

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": get control failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_s_ctrl - set the value of a control
 */
static int si470x_vidioc_s_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}

	switch (ctrl->id) {
	case V4L2_CID_AUDIO_VOLUME:
		radio->registers[SYSCONFIG2] &= ~SYSCONFIG2_VOLUME;
		radio->registers[SYSCONFIG2] |= ctrl->value;
		retval = si470x_set_register(radio, SYSCONFIG2);
		break;
	case V4L2_CID_AUDIO_MUTE:
		if (ctrl->value == 1)
			radio->registers[POWERCFG] &= ~POWERCFG_DMUTE;
		else
			radio->registers[POWERCFG] |= POWERCFG_DMUTE;
		retval = si470x_set_register(radio, POWERCFG);
		break;
	default:
		retval = -EINVAL;
	}

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": set control failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_g_audio - get audio attributes
 */
static int si470x_vidioc_g_audio(struct file *file, void *priv,
		struct v4l2_audio *audio)
{
	/* driver constants */
	audio->index = 0;
	strcpy(audio->name, "Radio");
	audio->capability = V4L2_AUDCAP_STEREO;
	audio->mode = 0;

	return 0;
}


/*
 * si470x_vidioc_g_tuner - get tuner attributes
 */
static int si470x_vidioc_g_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}
	if (tuner->index != 0) {
		retval = -EINVAL;
		goto done;
	}

	retval = si470x_get_register(radio, STATUSRSSI);
	if (retval < 0)
		goto done;

	/* driver constants */
	strcpy(tuner->name, "FM");
	tuner->type = V4L2_TUNER_RADIO;
	tuner->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;

	/* range limits */
	switch ((radio->registers[SYSCONFIG2] & SYSCONFIG2_BAND) >> 6) {
	/* 0: 87.5 - 108 MHz (USA, Europe, default) */
	default:
		tuner->rangelow  =  87.5 * FREQ_MUL;
		tuner->rangehigh = 108   * FREQ_MUL;
		break;
	/* 1: 76   - 108 MHz (Japan wide band) */
	case 1 :
		tuner->rangelow  =  76   * FREQ_MUL;
		tuner->rangehigh = 108   * FREQ_MUL;
		break;
	/* 2: 76   -  90 MHz (Japan) */
	case 2 :
		tuner->rangelow  =  76   * FREQ_MUL;
		tuner->rangehigh =  90   * FREQ_MUL;
		break;
	};

	/* stereo indicator == stereo (instead of mono) */
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_ST) == 0)
		tuner->rxsubchans = V4L2_TUNER_SUB_MONO;
	else
		tuner->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO;

	/* mono/stereo selector */
	if ((radio->registers[POWERCFG] & POWERCFG_MONO) == 0)
		tuner->audmode = V4L2_TUNER_MODE_STEREO;
	else
		tuner->audmode = V4L2_TUNER_MODE_MONO;

	/* min is worst, max is best; signal:0..0xffff; rssi: 0..0xff */
	/* measured in units of dbµV in 1 db increments (max at ~75 dbµV) */
	tuner->signal = (radio->registers[STATUSRSSI] & STATUSRSSI_RSSI);
	/* the ideal factor is 0xffff/75 = 873,8 */
	tuner->signal = (tuner->signal * 873) + (8 * tuner->signal / 10);

	/* automatic frequency control: -1: freq to low, 1 freq to high */
	/* AFCRL does only indicate that freq. differs, not if too low/high */
	tuner->afc = (radio->registers[STATUSRSSI] & STATUSRSSI_AFCRL) ? 1 : 0;

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": get tuner failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_s_tuner - set tuner attributes
 */
static int si470x_vidioc_s_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = -EINVAL;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}
	if (tuner->index != 0)
		goto done;

	/* mono/stereo selector */
	switch (tuner->audmode) {
	case V4L2_TUNER_MODE_MONO:
		radio->registers[POWERCFG] |= POWERCFG_MONO;  /* force mono */
		break;
	case V4L2_TUNER_MODE_STEREO:
		radio->registers[POWERCFG] &= ~POWERCFG_MONO; /* try stereo */
		break;
	default:
		goto done;
	}

	retval = si470x_set_register(radio, POWERCFG);

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": set tuner failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_g_frequency - get tuner or modulator radio frequency
 */
static int si470x_vidioc_g_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}
	if (freq->tuner != 0) {
		retval = -EINVAL;
		goto done;
	}

	freq->type = V4L2_TUNER_RADIO;
	retval = si470x_get_freq(radio, &freq->frequency);

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": get frequency failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_s_frequency - set tuner or modulator radio frequency
 */
static int si470x_vidioc_s_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}
	if (freq->tuner != 0) {
		retval = -EINVAL;
		goto done;
	}

	retval = si470x_set_freq(radio, freq->frequency);

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": set frequency failed with %d\n", retval);
	return retval;
}


/*
 * si470x_vidioc_s_hw_freq_seek - set hardware frequency seek
 */
static int si470x_vidioc_s_hw_freq_seek(struct file *file, void *priv,
		struct v4l2_hw_freq_seek *seek)
{
	struct si470x_device *radio = video_drvdata(file);
	int retval = 0;

	/* safety checks */
	if (radio->disconnected) {
		retval = -EIO;
		goto done;
	}
	if (seek->tuner != 0) {
		retval = -EINVAL;
		goto done;
	}

	retval = si470x_set_seek(radio, seek->wrap_around, seek->seek_upward);

done:
	if (retval < 0)
		printk(KERN_WARNING DRIVER_NAME
			": set hardware frequency seek failed with %d\n",
			retval);
	return retval;
}


/*
 * si470x_ioctl_ops - video device ioctl operations
 */
static const struct v4l2_ioctl_ops si470x_ioctl_ops = {
	.vidioc_querycap	= si470x_vidioc_querycap,
	.vidioc_queryctrl	= si470x_vidioc_queryctrl,
	.vidioc_g_ctrl		= si470x_vidioc_g_ctrl,
	.vidioc_s_ctrl		= si470x_vidioc_s_ctrl,
	.vidioc_g_audio		= si470x_vidioc_g_audio,
	.vidioc_g_tuner		= si470x_vidioc_g_tuner,
	.vidioc_s_tuner		= si470x_vidioc_s_tuner,
	.vidioc_g_frequency	= si470x_vidioc_g_frequency,
	.vidioc_s_frequency	= si470x_vidioc_s_frequency,
	.vidioc_s_hw_freq_seek	= si470x_vidioc_s_hw_freq_seek,
};


/*
 * si470x_viddev_template - video device interface
 */
static struct video_device si470x_viddev_template = {
	.fops			= &si470x_fops,
	.name			= DRIVER_NAME,
	.release		= video_device_release,
	.ioctl_ops		= &si470x_ioctl_ops,
};



/**************************************************************************
 * USB Interface
 **************************************************************************/

/*
 * si470x_usb_driver_probe - probe for the device
 */
static int si470x_usb_driver_probe(struct usb_interface *intf,
		const struct usb_device_id *id)
{
	struct si470x_device *radio;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	int i, int_end_size, retval = 0;

	/* private data allocation and initialization */
	radio = kzalloc(sizeof(struct si470x_device), GFP_KERNEL);
	if (!radio) {
		retval = -ENOMEM;
		goto err_initial;
	}
	radio->users = 0;
	radio->disconnected = 0;
	radio->usbdev = interface_to_usbdev(intf);
	radio->intf = intf;
	mutex_init(&radio->disconnect_lock);
	mutex_init(&radio->lock);

	iface_desc = intf->cur_altsetting;

	/* Set up interrupt endpoint information. */
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;
		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) ==
		 USB_DIR_IN) && ((endpoint->bmAttributes &
		 USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT))
			radio->int_in_endpoint = endpoint;
	}
	if (!radio->int_in_endpoint) {
		printk(KERN_INFO DRIVER_NAME
			": could not find interrupt in endpoint\n");
		retval = -EIO;
		goto err_radio;
	}

	int_end_size = le16_to_cpu(radio->int_in_endpoint->wMaxPacketSize);

	radio->int_in_buffer = kmalloc(int_end_size, GFP_KERNEL);
	if (!radio->int_in_buffer) {
		printk(KERN_INFO DRIVER_NAME
			"could not allocate int_in_buffer");
		retval = -ENOMEM;
		goto err_radio;
	}

	radio->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!radio->int_in_urb) {
		printk(KERN_INFO DRIVER_NAME "could not allocate int_in_urb");
		retval = -ENOMEM;
		goto err_intbuffer;
	}

	/* video device allocation and initialization */
	radio->videodev = video_device_alloc();
	if (!radio->videodev) {
		retval = -ENOMEM;
		goto err_intbuffer;
	}
	memcpy(radio->videodev, &si470x_viddev_template,
			sizeof(si470x_viddev_template));
	video_set_drvdata(radio->videodev, radio);

	/* show some infos about the specific si470x device */
	if (si470x_get_all_registers(radio) < 0) {
		retval = -EIO;
		goto err_video;
	}
	printk(KERN_INFO DRIVER_NAME ": DeviceID=0x%4.4hx ChipID=0x%4.4hx\n",
			radio->registers[DEVICEID], radio->registers[CHIPID]);

	/* get software and hardware versions */
	if (si470x_get_scratch_page_versions(radio) < 0) {
		retval = -EIO;
		goto err_video;
	}
	printk(KERN_INFO DRIVER_NAME
			": software version %d, hardware version %d\n",
			radio->software_version, radio->hardware_version);

	/* check if device and firmware is current */
	if ((radio->registers[CHIPID] & CHIPID_FIRMWARE)
			< RADIO_SW_VERSION_CURRENT) {
		printk(KERN_WARNING DRIVER_NAME
			": This driver is known to work with "
			"firmware version %hu,\n", RADIO_SW_VERSION_CURRENT);
		printk(KERN_WARNING DRIVER_NAME
			": but the device has firmware version %hu.\n",
			radio->registers[CHIPID] & CHIPID_FIRMWARE);
		printk(KERN_WARNING DRIVER_NAME
			": If you have some trouble using this driver,\n");
		printk(KERN_WARNING DRIVER_NAME
			": please report to V4L ML at "
			"linux-media@vger.kernel.org\n");
	}

	/* set initial frequency */
	si470x_set_freq(radio, 87.5 * FREQ_MUL); /* available in all regions */

	/* set led to connect state */
	si470x_set_led_state(radio, BLINK_GREEN_LED);

	/* rds buffer allocation */
	radio->buf_size = rds_buf * 3;
	radio->buffer = kmalloc(radio->buf_size, GFP_KERNEL);
	if (!radio->buffer) {
		retval = -EIO;
		goto err_video;
	}

	/* rds buffer configuration */
	radio->wr_index = 0;
	radio->rd_index = 0;
	init_waitqueue_head(&radio->read_queue);

	/* register video device */
	retval = video_register_device(radio->videodev, VFL_TYPE_RADIO, radio_nr);
	if (retval) {
		printk(KERN_WARNING DRIVER_NAME
				": Could not register video device\n");
		goto err_all;
	}
	usb_set_intfdata(intf, radio);

	return 0;
err_all:
	kfree(radio->buffer);
err_video:
	video_device_release(radio->videodev);
err_intbuffer:
	kfree(radio->int_in_buffer);
err_radio:
	kfree(radio);
err_initial:
	return retval;
}


/*
 * si470x_usb_driver_suspend - suspend the device
 */
static int si470x_usb_driver_suspend(struct usb_interface *intf,
		pm_message_t message)
{
	printk(KERN_INFO DRIVER_NAME ": suspending now...\n");

	return 0;
}


/*
 * si470x_usb_driver_resume - resume the device
 */
static int si470x_usb_driver_resume(struct usb_interface *intf)
{
	printk(KERN_INFO DRIVER_NAME ": resuming now...\n");

	return 0;
}


/*
 * si470x_usb_driver_disconnect - disconnect the device
 */
static void si470x_usb_driver_disconnect(struct usb_interface *intf)
{
	struct si470x_device *radio = usb_get_intfdata(intf);

	mutex_lock(&radio->disconnect_lock);
	radio->disconnected = 1;
	usb_set_intfdata(intf, NULL);
	if (radio->users == 0) {
		/* set led to disconnect state */
		si470x_set_led_state(radio, BLINK_ORANGE_LED);

		/* Free data structures. */
		usb_free_urb(radio->int_in_urb);

		kfree(radio->int_in_buffer);
		video_unregister_device(radio->videodev);
		kfree(radio->buffer);
		kfree(radio);
	}
	mutex_unlock(&radio->disconnect_lock);
}


/*
 * si470x_usb_driver - usb driver interface
 */
static struct usb_driver si470x_usb_driver = {
	.name			= DRIVER_NAME,
	.probe			= si470x_usb_driver_probe,
	.disconnect		= si470x_usb_driver_disconnect,
	.suspend		= si470x_usb_driver_suspend,
	.resume			= si470x_usb_driver_resume,
	.id_table		= si470x_usb_driver_id_table,
	.supports_autosuspend	= 1,
};



/**************************************************************************
 * Module Interface
 **************************************************************************/

/*
 * si470x_module_init - module init
 */
static int __init si470x_module_init(void)
{
	printk(KERN_INFO DRIVER_DESC ", Version " DRIVER_VERSION "\n");
	return usb_register(&si470x_usb_driver);
}


/*
 * si470x_module_exit - module exit
 */
static void __exit si470x_module_exit(void)
{
	usb_deregister(&si470x_usb_driver);
}


module_init(si470x_module_init);
module_exit(si470x_module_exit);

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