radio-sf16fmi.c

讲述linux的初始化过程

/* SF16FMI radio driver for Linux radio support
 * heavily based on rtrack driver...
 * (c) 1997 M. Kirkwood
 * (c) 1998 Petr Vandrovec, [e-mail]
 *
 * Fitted to new interface by Alan Cox <[e-mail]>
 * Made working and cleaned up functions <[e-mail]>
 *
 * Notes on the hardware
 *
 *  Frequency control is done digitally -- ie out(port,encodefreq(95.8));
 *  No volume control - only mute/unmute - you have to use line volume
 *  control on SB-part of SF16FMI
 *  
 */

#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_SF16MI_PORT 	*/
#include <asm/semaphore.h>

struct fmi_device
{
	int port;
        int curvol; /* 1 or 0 */
        unsigned long curfreq; /* freq in kHz */
        __u32 flags;
};

#ifndef CONFIG_RADIO_SF16FMI_PORT
#define CONFIG_RADIO_SF16FMI_PORT -1
#endif

static int io = CONFIG_RADIO_SF16FMI_PORT; 
static int users = 0;
static struct semaphore lock;

/* freq is in 1/16 kHz to internal number, hw precision is 50 kHz */
/* It is only usefull to give freq in intervall of 800 (=0.05Mhz),
 * other bits will be truncated, e.g 92.7400016 -> 92.7, but 
 * 92.7400017 -> 92.75
 */
#define RSF16_ENCODE(x)	((x)/800+214)
#define RSF16_MINFREQ 87*16000
#define RSF16_MAXFREQ 108*16000

static void outbits(int bits, unsigned int data, int port)
{
	while(bits--) {
 		if(data & 1) {
			outb(5, port);
			udelay(6);
			outb(7, port);
			udelay(6);
		} else {
			outb(1, port);
			udelay(6);
			outb(3, port);
			udelay(6);
		}
		data>>=1;
	}
}

static inline void fmi_mute(int port)
{
	down(&lock);
	outb(0x00, port);
	up(&lock);
}

static inline void fmi_unmute(int port)
{
	down(&lock);
	outb(0x08, port);
	up(&lock);
}

static inline int fmi_setfreq(struct fmi_device *dev)
{
        int myport = dev->port;
	unsigned long freq = dev->curfreq;
	int i;
	
	down(&lock);
	
	outbits(16, RSF16_ENCODE(freq), myport);
	outbits(8, 0xC0, myport);
	for(i=0; i< 100; i++)
	{
		udelay(1400);
		if(current->need_resched)
			schedule();
	}
/* If this becomes allowed use it ... 	
	current->state = TASK_UNINTERRUPTIBLE;
	schedule_timeout(HZ/7);
*/	

	up(&lock);
	if (dev->curvol) fmi_unmute(myport);
	return 0;
}

static inline int fmi_getsigstr(struct fmi_device *dev)
{
	int val;
	int res;
	int myport = dev->port;
	int i;
	
	down(&lock);
	val = dev->curvol ? 0x08 : 0x00;	/* unmute/mute */
	outb(val, myport);
	outb(val | 0x10, myport);
	for(i=0; i< 100; i++)
	{
		udelay(1400);
		if(current->need_resched)
			schedule();
	}
/* If this becomes allowed use it ... 	
	current->state = TASK_UNINTERRUPTIBLE;
	schedule_timeout(HZ/7);
*/	
	res = (int)inb(myport+1);
	outb(val, myport);
	
	up(&lock);
	return (res & 2) ? 0 : 0xFFFF;
}

static int fmi_ioctl(struct video_device *dev, unsigned int cmd, void *arg)
{
	struct fmi_device *fmi=dev->priv;
	
	switch(cmd)
	{
		case VIDIOCGCAP:
		{
			struct video_capability v;
			strcpy(v.name, "SF16-FMx radio");
			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;
			if(copy_to_user(arg,&v,sizeof(v)))
				return -EFAULT;
			return 0;
		}
		case VIDIOCGTUNER:
		{
			struct video_tuner v;
			int mult;

			if(copy_from_user(&v, arg,sizeof(v))!=0)
				return -EFAULT;
			if(v.tuner)	/* Only 1 tuner */
				return -EINVAL;
			strcpy(v.name, "FM");
			mult = (fmi->flags & VIDEO_TUNER_LOW) ? 1 : 1000;
			v.rangelow = RSF16_MINFREQ/mult;
			v.rangehigh = RSF16_MAXFREQ/mult;
			v.flags=fmi->flags;
			v.mode=VIDEO_MODE_AUTO;
			v.signal = fmi_getsigstr(fmi);
			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;
			fmi->flags = v.flags & VIDEO_TUNER_LOW;
			/* Only 1 tuner so no setting needed ! */
			return 0;
		}
		case VIDIOCGFREQ:
		{
			unsigned long tmp = fmi->curfreq;
			if (!(fmi->flags & VIDEO_TUNER_LOW))
				tmp /= 1000;
			if(copy_to_user(arg, &tmp, sizeof(tmp)))
				return -EFAULT;
			return 0;
		}
		case VIDIOCSFREQ:
		{
			unsigned long tmp;
			if(copy_from_user(&tmp, arg, sizeof(tmp)))
				return -EFAULT;
			if (!(fmi->flags & VIDEO_TUNER_LOW))
				tmp *= 1000;
			if ( tmp<RSF16_MINFREQ || tmp>RSF16_MAXFREQ )
			  return -EINVAL;
			/*rounding in steps of 800 to match th freq
			  that will be used */
			fmi->curfreq = (tmp/800)*800; 
			fmi_setfreq(fmi);
			return 0;
		}
		case VIDIOCGAUDIO:
		{	
			struct video_audio v;
			v.audio=0;
			v.volume=0;
			v.bass=0;
			v.treble=0;
			v.flags=( (!fmi->curvol)*VIDEO_AUDIO_MUTE | VIDEO_AUDIO_MUTABLE);
			strcpy(v.name, "Radio");
			v.mode=VIDEO_SOUND_STEREO;
			v.balance=0;
			v.step=0; /* No volume, just (un)mute */
			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;
			fmi->curvol= v.flags&VIDEO_AUDIO_MUTE ? 0 : 1;
			fmi->curvol ? 
			  fmi_unmute(fmi->port) : fmi_mute(fmi->port);
			return 0;
		}
	        case VIDIOCGUNIT:
		{
               		struct video_unit v;
			v.video=VIDEO_NO_UNIT;
			v.vbi=VIDEO_NO_UNIT;
			v.radio=dev->minor;
			v.audio=0; /* How do we find out this??? */
			v.teletext=VIDEO_NO_UNIT;
			if(copy_to_user(arg, &v, sizeof(v)))
				return -EFAULT;
			return 0;			
		}
		default:
			return -ENOIOCTLCMD;
	}
}

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

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

static struct fmi_device fmi_unit;

static struct video_device fmi_radio=
{
	name:		"SF16FMx radio",
	type:		VID_TYPE_TUNER,
	hardware:	VID_HARDWARE_SF16MI,
	open:		fmi_open,
	close:		fmi_close,
	ioctl:		fmi_ioctl,
};

static int __init fmi_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, "fmi")) 
	{
		printk(KERN_ERR "fmi: port 0x%x already in use\n", io);
		return -EBUSY;
	}

	fmi_unit.port = io;
	fmi_unit.curvol = 0;
	fmi_unit.curfreq = 0;
	fmi_unit.flags = VIDEO_TUNER_LOW;
	fmi_radio.priv = &fmi_unit;
	
	init_MUTEX(&lock);
	
	if(video_register_device(&fmi_radio, VFL_TYPE_RADIO)==-1)
	{
		release_region(io, 2);
		return -EINVAL;
	}
		
	printk(KERN_INFO "SF16FMx radio card driver at 0x%x.\n", io);
	printk(KERN_INFO "(c) 1998 Petr Vandrovec, [e-mail].\n");
	/* mute card - prevents noisy bootups */
	fmi_mute(io);
	return 0;
}

MODULE_AUTHOR("Petr Vandrovec, [e-mail] and M. Kirkwood");
MODULE_DESCRIPTION("A driver for the SF16MI radio.");
MODULE_PARM(io, "i");
MODULE_PARM_DESC(io, "I/O address of the SF16MI card (0x284 or 0x384)");

EXPORT_NO_SYMBOLS;

static void __exit fmi_cleanup_module(void)
{
	video_unregister_device(&fmi_radio);
	release_region(io,2);
}

module_init(fmi_init);
module_exit(fmi_cleanup_module);