pd.c

讲述linux的初始化过程

static void pd_doorlock( int unit, int func )

{       pi_connect(PI);
        if (pd_wait_for(unit,STAT_READY,"Lock") & STAT_ERR) {
                pi_disconnect(PI);
                return;
        }
        pd_send_command(unit,1,0,0,0,0,func);
        pd_wait_for(unit,STAT_READY,"Lock done");
        pi_disconnect(PI);
}

static void pd_eject( int unit )

{	pi_connect(PI);
        pd_wait_for(unit,0,DBMSG("before unlock on eject"));
        pd_send_command(unit,1,0,0,0,0,IDE_DOORUNLOCK);
        pd_wait_for(unit,0,DBMSG("after unlock on eject"));
        pd_wait_for(unit,0,DBMSG("before eject"));
        pd_send_command(unit,0,0,0,0,0,IDE_EJECT);
        pd_wait_for(unit,0,DBMSG("after eject"));
        pi_disconnect(PI);
}

static void pd_media_check( int unit )

{       int 	r;

        pi_connect(PI);
        r = pd_wait_for(unit,STAT_READY,DBMSG("before media_check"));
        if (!(r & STAT_ERR)) {
                pd_send_command(unit,1,1,0,0,0,IDE_READ_VRFY);  
                r = pd_wait_for(unit,STAT_READY,DBMSG("RDY after READ_VRFY"));
        } else PD.changed = 1;   /* say changed if other error */
        if (r & ERR_MC) {
                PD.changed = 1;
                pd_send_command(unit,1,0,0,0,0,IDE_ACKCHANGE);
                pd_wait_for(unit,STAT_READY,DBMSG("RDY after ACKCHANGE"));
		pd_send_command(unit,1,1,0,0,0,IDE_READ_VRFY);
                r = pd_wait_for(unit,STAT_READY,DBMSG("RDY after VRFY"));
        }
        pi_disconnect(PI);

}

static void pd_standby_off( int unit )

{       pi_connect(PI);
        pd_wait_for(unit,0,DBMSG("before STANDBY"));
        pd_send_command(unit,0,0,0,0,0,IDE_STANDBY);
        pd_wait_for(unit,0,DBMSG("after STANDBY"));
        pi_disconnect(PI);
}

#define  word_val(n) ((pd_scratch[2*n]&0xff)+256*(pd_scratch[2*n+1]&0xff))

static int pd_identify( int unit )

{       int	j;
	char id[PD_ID_LEN+1];

/* WARNING:  here there may be dragons.  reset() applies to both drives,
   but we call it only on probing the MASTER. This should allow most
   common configurations to work, but be warned that a reset can clear
   settings on the SLAVE drive.
*/ 

	if (PD.drive == 0) pd_reset(unit);

        pi_connect(PI);
	WR(0,6,DRIVE);
        pd_wait_for(unit,0,DBMSG("before IDENT"));  
        pd_send_command(unit,1,0,0,0,0,IDE_IDENTIFY);

        if (pd_wait_for(unit,STAT_DRQ,DBMSG("IDENT DRQ")) & STAT_ERR) {
                pi_disconnect(PI);
                return 0;
        }
        pi_read_block(PI,pd_scratch,512);
        pi_disconnect(PI);
        PD.sectors = word_val(6);
        PD.heads = word_val(3);
        PD.cylinders  = word_val(1);
        PD.capacity = PD.sectors*PD.heads*PD.cylinders;

        for(j=0;j<PD_ID_LEN;j++) id[j^1] = pd_scratch[j+PD_ID_OFF];
        j = PD_ID_LEN-1;
        while ((j >= 0) && (id[j] <= 0x20)) j--;
        j++; id[j] = 0;

        PD.removable = (word_val(0) & 0x80);
 
        printk("%s: %s, %s, %d blocks [%dM], (%d/%d/%d), %s media\n",
                    PD.name,id,
		    PD.drive?"slave":"master",
		    PD.capacity,PD.capacity/2048,
                    PD.cylinders,PD.heads,PD.sectors,
                    PD.removable?"removable":"fixed");

        if (PD.capacity) pd_init_dev_parms(unit);
        if (!PD.standby) pd_standby_off(unit);
	
        return 1;
}

static int pd_probe_drive( int unit )
{
	if (PD.drive == -1) {
		for (PD.drive=0;PD.drive<=1;PD.drive++)
			if (pd_identify(unit))
				return 1;
		return 0;
	}
	return pd_identify(unit);
}

static int pd_detect( void )

{       int	k, unit;

	k = 0;
	if (pd_drive_count == 0) {  /* nothing spec'd - so autoprobe for 1 */
	    unit = 0;
	    if (pi_init(PI,1,-1,-1,-1,-1,-1,pd_scratch,
	             PI_PD,verbose,PD.name)) {
		if (pd_probe_drive(unit)) {
			PD.present = 1;
			k = 1;
		} else pi_release(PI);
	    }

   	} else for (unit=0;unit<PD_UNITS;unit++) if (DU[D_PRT])
	    if (pi_init(PI,0,DU[D_PRT],DU[D_MOD],DU[D_UNI],
			DU[D_PRO],DU[D_DLY],pd_scratch,
			PI_PD,verbose,PD.name)) {
                if (pd_probe_drive(unit)) {
                        PD.present = 1;
                        k = unit+1;
                } else pi_release(PI);
            }
	for (unit=0;unit<PD_UNITS;unit++)
		register_disk(&pd_gendisk,MKDEV(MAJOR_NR,unit<<PD_BITS),
				PD_PARTNS,&pd_fops,
				PD.present?PD.capacity:0);

/* We lie about the number of drives found, as the generic partition
   scanner assumes that the drives are numbered sequentially from 0.
   This can result in some bogus error messages if non-sequential
   drive numbers are used.
*/
	if (k)
		return k; 
        printk("%s: no valid drive found\n",name);
        return 0;
}

/* The i/o request engine */

static int pd_ready( void )

{ 	int unit = pd_unit;

	return (!(RR(1,6) & STAT_BUSY)) ;
}

static void do_pd_request (request_queue_t * q)

{       struct buffer_head * bh;
	int	unit;

        if (pd_busy) return;
repeat:
        if (QUEUE_EMPTY || (CURRENT->rq_status == RQ_INACTIVE)) return;
        INIT_REQUEST;

        pd_dev = MINOR(CURRENT->rq_dev);
	pd_unit = unit = DEVICE_NR(CURRENT->rq_dev);
        pd_block = CURRENT->sector;
        pd_run = CURRENT->nr_sectors;
        pd_count = CURRENT->current_nr_sectors;

	bh = CURRENT->bh;

        if ((pd_dev >= PD_DEVS) || 
	    ((pd_block+pd_count) > pd_hd[pd_dev].nr_sects)) {
                end_request(0);
                goto repeat;
        }

	pd_cmd = CURRENT->cmd;
	pd_poffs = pd_hd[pd_dev].start_sect;
        pd_block += pd_poffs;
        pd_buf = CURRENT->buffer;
        pd_retries = 0;

	pd_busy = 1;
        if (pd_cmd == READ) pi_do_claimed(PI,do_pd_read);
        else if (pd_cmd == WRITE) pi_do_claimed(PI,do_pd_write);
        else {  pd_busy = 0;
		end_request(0);
                goto repeat;
        }
}

static void pd_next_buf( int unit )

{	long	saved_flags;

	spin_lock_irqsave(&io_request_lock,saved_flags);
	end_request(1);
	if (!pd_run) {  spin_unlock_irqrestore(&io_request_lock,saved_flags);
			return; 
	}
	
/* paranoia */

	if (QUEUE_EMPTY ||
	    (CURRENT->cmd != pd_cmd) ||
	    (MINOR(CURRENT->rq_dev) != pd_dev) ||
	    (CURRENT->rq_status == RQ_INACTIVE) ||
	    (CURRENT->sector+pd_poffs != pd_block)) 
		printk("%s: OUCH: request list changed unexpectedly\n",
			PD.name);

	pd_count = CURRENT->current_nr_sectors;
	pd_buf = CURRENT->buffer;
	spin_unlock_irqrestore(&io_request_lock,saved_flags);
}

static void do_pd_read( void )

{	ps_set_intr(do_pd_read_start,0,0,nice);
}

static void do_pd_read_start( void )
 
{       int	unit = pd_unit;
	long    saved_flags;

	pd_busy = 1;

        pi_connect(PI);
        if (pd_wait_for(unit,STAT_READY,"do_pd_read") & STAT_ERR) {
                pi_disconnect(PI);
                if (pd_retries < PD_MAX_RETRIES) {
                        pd_retries++;
                        pi_do_claimed(PI,do_pd_read_start);
			return;
                }
		spin_lock_irqsave(&io_request_lock,saved_flags);
                end_request(0);
                pd_busy = 0;
		do_pd_request(NULL);
		spin_unlock_irqrestore(&io_request_lock,saved_flags);
                return;
        }
        pd_ide_command(unit,IDE_READ,pd_block,pd_run);
        ps_set_intr(do_pd_read_drq,pd_ready,PD_TMO,nice);
}

static void do_pd_read_drq( void )

{       int	unit = pd_unit;
	long    saved_flags;

	while (1) {
            if (pd_wait_for(unit,STAT_DRQ,"do_pd_read_drq") & STAT_ERR) {
                pi_disconnect(PI);
                if (pd_retries < PD_MAX_RETRIES) {
                        pd_retries++;
                        pi_do_claimed(PI,do_pd_read_start);
                        return;
                }
		spin_lock_irqsave(&io_request_lock,saved_flags);
                end_request(0);
                pd_busy = 0;
		do_pd_request(NULL);
		spin_unlock_irqrestore(&io_request_lock,saved_flags);
                return;
            }
            pi_read_block(PI,pd_buf,512);
            pd_count--; pd_run--;
            pd_buf += 512;
	    pd_block++;
	    if (!pd_run) break;
	    if (!pd_count) pd_next_buf(unit);
        }
        pi_disconnect(PI);
	spin_lock_irqsave(&io_request_lock,saved_flags);
        end_request(1);
        pd_busy = 0;
	do_pd_request(NULL);
	spin_unlock_irqrestore(&io_request_lock,saved_flags);
}

static void do_pd_write( void )

{	 ps_set_intr(do_pd_write_start,0,0,nice);
}

static void do_pd_write_start( void )

{       int 	unit = pd_unit;
	long    saved_flags;

	pd_busy = 1;

        pi_connect(PI);
        if (pd_wait_for(unit,STAT_READY,"do_pd_write") & STAT_ERR) {
                pi_disconnect(PI);
                if (pd_retries < PD_MAX_RETRIES) {
                        pd_retries++;
			pi_do_claimed(PI,do_pd_write_start);
                        return;
                }
		spin_lock_irqsave(&io_request_lock,saved_flags);
                end_request(0);
                pd_busy = 0;
		do_pd_request(NULL);
		spin_unlock_irqrestore(&io_request_lock,saved_flags);
                return;
        }
        pd_ide_command(unit,IDE_WRITE,pd_block,pd_run);
	while (1) {
            if (pd_wait_for(unit,STAT_DRQ,"do_pd_write_drq") & STAT_ERR) {
                pi_disconnect(PI);
                if (pd_retries < PD_MAX_RETRIES) {
                        pd_retries++;
                        pi_do_claimed(PI,do_pd_write_start);
                        return;
                }
		spin_lock_irqsave(&io_request_lock,saved_flags);
                end_request(0);
                pd_busy = 0;
		do_pd_request(NULL);
                spin_unlock_irqrestore(&io_request_lock,saved_flags);
		return;
            }
            pi_write_block(PI,pd_buf,512);
	    pd_count--; pd_run--;
	    pd_buf += 512;
	    pd_block++;
	    if (!pd_run) break;
	    if (!pd_count) pd_next_buf(unit);
	}
        ps_set_intr(do_pd_write_done,pd_ready,PD_TMO,nice);
}

static void do_pd_write_done( void )

{       int	unit = pd_unit;
	long    saved_flags;

        if (pd_wait_for(unit,STAT_READY,"do_pd_write_done") & STAT_ERR) {
                pi_disconnect(PI);
                if (pd_retries < PD_MAX_RETRIES) {
                        pd_retries++;
                        pi_do_claimed(PI,do_pd_write_start);
                        return;
                }
		spin_lock_irqsave(&io_request_lock,saved_flags);
                end_request(0);
                pd_busy = 0;
		do_pd_request(NULL);
		spin_unlock_irqrestore(&io_request_lock,saved_flags);
                return;
        }
        pi_disconnect(PI);
	spin_lock_irqsave(&io_request_lock,saved_flags);
        end_request(1);
        pd_busy = 0;
	do_pd_request(NULL);
	spin_unlock_irqrestore(&io_request_lock,saved_flags);
}

/* end of pd.c */