radio-aztech.c

讲述linux的初始化过程

/* radio-aztech.c - Aztech radio card driver for Linux 2.2 
 *
 * Adapted to support the Video for Linux API by 
 * Russell Kroll <[e-mail]>.  Based on original tuner code by:
 *
 * Quay Ly
 * Donald Song
 * Jason Lewis      ([e-mail]) 
 * Scott McGrath    ([e-mail])
 * William McGrath  ([e-mail])
 *
 * The basis for this code may be found at http://bigbang.vtc.vsc.edu/fmradio/
 * along with more information on the card itself.
 *
 * History:
 * 1999-02-24	Russell Kroll <[e-mail]>
 *		Fine tuning/VIDEO_TUNER_LOW
 * 		Range expanded to 87-108 MHz (from 87.9-107.8)
 *
 * Notable changes from the original source:
 * - includes stripped down to the essentials
 * - for loops used as delays replaced with udelay()
 * - #defines removed, changed to static values
 * - tuning structure changed - no more character arrays, other changes
*/

#include <linux/module.h>	/* Modules 			*/
#include <linux/init.h>		/* Initdata			*/
#include <linux/ioport.h>	/* check_region, request_region	*/
#include <linux/delay.h>	/* udelay			*/
#include <asm/io.h>		/* outb, outb_p			*/
#include <asm/uaccess.h>	/* copy to/from user		*/
#include <linux/videodev.h>	/* kernel radio structs		*/
#include <linux/config.h>	/* CONFIG_RADIO_AZTECH_PORT 	*/

/* acceptable ports: 0x350 (JP3 shorted), 0x358 (JP3 open) */

#ifndef CONFIG_RADIO_AZTECH_PORT
#define CONFIG_RADIO_AZTECH_PORT -1
#endif

static int io = CONFIG_RADIO_AZTECH_PORT; 
static int radio_wait_time = 1000;
static int users = 0;
static struct semaphore lock;

struct az_device
{
	int curvol;
	unsigned long curfreq;
	int stereo;
};

static int volconvert(int level)
{
	level>>=14;	 	/* Map 16bits down to 2 bit */
 	level&=3;
	
	/* convert to card-friendly values */
	switch (level) 
	{
		case 0: 
			return 0;
		case 1: 
			return 1;
		case 2:
			return 4;
		case 3:
			return 5;
	}
	return 0;	/* Quieten gcc */
}

static void send_0_byte (struct az_device *dev)
{
	udelay(radio_wait_time);
	outb_p(2+volconvert(dev->curvol), io);
	outb_p(64+2+volconvert(dev->curvol), io);
}

static void send_1_byte (struct az_device *dev)
{
	udelay (radio_wait_time);
	outb_p(128+2+volconvert(dev->curvol), io);
	outb_p(128+64+2+volconvert(dev->curvol), io);
}

static int az_setvol(struct az_device *dev, int vol)
{
	down(&lock);
	outb (volconvert(vol), io);
	up(&lock);
	return 0;
}

/* thanks to Michael Dwyer for giving me a dose of clues in
 * the signal strength department..
 *
 * This card has a stereo bit - bit 0 set = mono, not set = stereo
 * It also has a "signal" bit - bit 1 set = bad signal, not set = good
 *
 */

static int az_getsigstr(struct az_device *dev)
{
	if (inb(io) & 2)	/* bit set = no signal present */
		return 0;
	return 1;		/* signal present */
}

static int az_getstereo(struct az_device *dev)
{
	if (inb(io) & 1) 	/* bit set = mono */
		return 0;
	return 1;		/* stereo */
}

static int az_setfreq(struct az_device *dev, unsigned long frequency)
{
	int  i;

	frequency += 171200;		/* Add 10.7 MHz IF		*/
	frequency /= 800;		/* Convert to 50 kHz units	*/
					
	down(&lock);
	
	send_0_byte (dev);		/*  0: LSB of frequency       */

	for (i = 0; i < 13; i++)	/*   : frequency bits (1-13)  */
		if (frequency & (1 << i))
			send_1_byte (dev);
		else
			send_0_byte (dev);

	send_0_byte (dev);		/* 14: test bit - always 0    */
	send_0_byte (dev);		/* 15: test bit - always 0    */
	send_0_byte (dev);		/* 16: band data 0 - always 0 */
	if (dev->stereo)		/* 17: stereo (1 to enable)   */
		send_1_byte (dev);
	else
		send_0_byte (dev);

	send_1_byte (dev);		/* 18: band data 1 - unknown  */
	send_0_byte (dev);		/* 19: time base - always 0   */
	send_0_byte (dev);		/* 20: spacing (0 = 25 kHz)   */
	send_1_byte (dev);		/* 21: spacing (1 = 25 kHz)   */
	send_0_byte (dev);		/* 22: spacing (0 = 25 kHz)   */
	send_1_byte (dev);		/* 23: AM/FM (FM = 1, always) */

	/* latch frequency */

	udelay (radio_wait_time);
	outb_p(128+64+volconvert(dev->curvol), io);
	
	up(&lock);

	return 0;
}

static int az_ioctl(struct video_device *dev, unsigned int cmd, void *arg)
{
	struct az_device *az=dev->priv;
	
	switch(cmd)
	{
		case VIDIOCGCAP:
		{
			struct video_capability v;
			v.type=VID_TYPE_TUNER;
			v.channels=1;
			v.audios=1;
			/* No we don't do pictures */
			v.maxwidth=0;
			v.maxheight=0;
			v.minwidth=0;
			v.minheight=0;
			strcpy(v.name, "Aztech Radio");
			if(copy_to_user(arg,&v,sizeof(v)))
				return -EFAULT;
			return 0;
		}
		case VIDIOCGTUNER:
		{
			struct video_tuner v;
			if(copy_from_user(&v, arg,sizeof(v))!=0) 
				return -EFAULT;
			if(v.tuner)	/* Only 1 tuner */ 
				return -EINVAL;
			v.rangelow=(87*16000);
			v.rangehigh=(108*16000);
			v.flags=VIDEO_TUNER_LOW;
			v.mode=VIDEO_MODE_AUTO;
			v.signal=0xFFFF*az_getsigstr(az);
			if(az_getstereo(az))
				v.flags|=VIDEO_TUNER_STEREO_ON;
			strcpy(v.name, "FM");
			if(copy_to_user(arg,&v, sizeof(v)))
				return -EFAULT;
			return 0;
		}
		case VIDIOCSTUNER:
		{
			struct video_tuner v;
			if(copy_from_user(&v, arg, sizeof(v)))
				return -EFAULT;
			if(v.tuner!=0)
				return -EINVAL;
			/* Only 1 tuner so no setting needed ! */
			return 0;
		}
		case VIDIOCGFREQ:
			if(copy_to_user(arg, &az->curfreq, sizeof(az->curfreq)))
				return -EFAULT;
			return 0;
		case VIDIOCSFREQ:
			if(copy_from_user(&az->curfreq, arg,sizeof(az->curfreq)))
				return -EFAULT;
			az_setfreq(az, az->curfreq);
			return 0;
		case VIDIOCGAUDIO:
		{	
			struct video_audio v;
			memset(&v,0, sizeof(v));
			v.flags|=VIDEO_AUDIO_MUTABLE|VIDEO_AUDIO_VOLUME;
			if(az->stereo)
				v.mode=VIDEO_SOUND_STEREO;
			else
				v.mode=VIDEO_SOUND_MONO;
			v.volume=az->curvol;
			v.step=16384;
			strcpy(v.name, "Radio");
			if(copy_to_user(arg,&v, sizeof(v)))
				return -EFAULT;
			return 0;			
		}
		case VIDIOCSAUDIO:
		{
			struct video_audio v;
			if(copy_from_user(&v, arg, sizeof(v))) 
				return -EFAULT;	
			if(v.audio) 
				return -EINVAL;
			az->curvol=v.volume;

			az->stereo=(v.mode&VIDEO_SOUND_STEREO)?1:0;
			if(v.flags&VIDEO_AUDIO_MUTE) 
				az_setvol(az,0);
			else
				az_setvol(az,az->curvol);								
			return 0;
		}
		default:
			return -ENOIOCTLCMD;
	}
}

static int az_open(struct video_device *dev, int flags)
{
	if(users)
		return -EBUSY;
	users++;
	MOD_INC_USE_COUNT;
	return 0;
}

static void az_close(struct video_device *dev)
{
	users--;
	MOD_DEC_USE_COUNT;
}

static struct az_device aztech_unit;

static struct video_device aztech_radio=
{
	name:		"Aztech radio",
	type:		VID_TYPE_TUNER,
	hardware:	VID_HARDWARE_AZTECH,
	open:		az_open,
	close:		az_close,
	ioctl:		az_ioctl,
};

static int __init aztech_init(void)
{
	if(io==-1)
	{
		printk(KERN_ERR "You must set an I/O address with io=0x???\n");
		return -EINVAL;
	}

	if (!request_region(io, 2, "aztech")) 
	{
		printk(KERN_ERR "aztech: port 0x%x already in use\n", io);
		return -EBUSY;
	}

	init_MUTEX(&lock);
	aztech_radio.priv=&aztech_unit;
	
	if(video_register_device(&aztech_radio, VFL_TYPE_RADIO)==-1)
	{
		release_region(io,2);
		return -EINVAL;
	}
		
	printk(KERN_INFO "Aztech radio card driver v1.00/19990224 [e-mail]\n");
	/* mute card - prevents noisy bootups */
	outb (0, io);
	return 0;
}

MODULE_AUTHOR("Russell Kroll, Quay Lu, Donald Song, Jason Lewis, Scott McGrath, William McGrath");
MODULE_DESCRIPTION("A driver for the Aztech radio card.");
MODULE_PARM(io, "i");
MODULE_PARM_DESC(io, "I/O address of the Aztech card (0x350 or 0x358)");

EXPORT_NO_SYMBOLS;

static void __exit aztech_cleanup(void)
{
	video_unregister_device(&aztech_radio);
	release_region(io,2);
}

module_init(aztech_init);
module_exit(aztech_cleanup);