hd.c

LINUX1.0源代码,代码条理清晰

/*
 *  linux/kernel/hd.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * This is the low-level hd interrupt support. It traverses the
 * request-list, using interrupts to jump between functions. As
 * all the functions are called within interrupts, we may not
 * sleep. Special care is recommended.
 * 
 *  modified by Drew Eckhardt to check nr of hd's from the CMOS.
 *
 *  Thanks to Branko Lankester, [e-mail], who found a bug
 *  in the early extended-partition checks and added DM partitions
 */


#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/hdreg.h>
#include <linux/genhd.h>
#include <linux/config.h>

#define REALLY_SLOW_IO
#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>

#define MAJOR_NR HD_MAJOR
#include "blk.h"

#define HD_IRQ 14

static int revalidate_hddisk(int, int);

static inline unsigned char CMOS_READ(unsigned char addr)
{
	outb_p(addr,0x70);
	return inb_p(0x71);
}

#define	HD_DELAY	0

#define MAX_ERRORS     16	/* Max read/write errors/sector */
#define RESET_FREQ      8	/* Reset controller every 8th retry */
#define RECAL_FREQ      4	/* Recalibrate every 4th retry */
#define MAX_HD		2

static void recal_intr(void);
static void bad_rw_intr(void);

static char recalibrate[ MAX_HD ] = { 0, };
static int access_count[MAX_HD] = {0, };
static char busy[MAX_HD] = {0, };
static struct wait_queue * busy_wait = NULL;

static int reset = 0;
static int hd_error = 0;

#if (HD_DELAY > 0)
unsigned long last_req, read_timer();
#endif

/*
 *  This struct defines the HD's and their types.
 */
struct hd_i_struct {
	unsigned int head,sect,cyl,wpcom,lzone,ctl;
	};
#ifdef HD_TYPE
struct hd_i_struct hd_info[] = { HD_TYPE };
static int NR_HD = ((sizeof (hd_info))/(sizeof (struct hd_i_struct)));
#else
struct hd_i_struct hd_info[] = { {0,0,0,0,0,0},{0,0,0,0,0,0} };
static int NR_HD = 0;
#endif

static struct hd_struct hd[MAX_HD<<6]={{0,0},};
static int hd_sizes[MAX_HD<<6] = {0, };
static int hd_blocksizes[MAX_HD<<6] = {0, };

#if (HD_DELAY > 0)
unsigned long read_timer(void)
{
	unsigned long t;
	int i;

	cli();
	t = jiffies * 11932;
    	outb_p(0, 0x43);
	i = inb_p(0x40);
	i |= inb(0x40) << 8;
	sti();
	return(t - i);
}
#endif

void hd_setup(char *str, int *ints)
{
	int hdind = 0;

	if (ints[0] != 3)
		return;
	if (hd_info[0].head != 0)
		hdind=1;
	hd_info[hdind].head = ints[2];
	hd_info[hdind].sect = ints[3];
	hd_info[hdind].cyl = ints[1];
	hd_info[hdind].wpcom = 0;
	hd_info[hdind].lzone = ints[1];
	hd_info[hdind].ctl = (ints[2] > 8 ? 8 : 0);
	NR_HD = hdind+1;
}

static int win_result(void)
{
	int i=inb_p(HD_STATUS);

	if ((i & (BUSY_STAT | READY_STAT | WRERR_STAT | SEEK_STAT | ERR_STAT))
		== (READY_STAT | SEEK_STAT)) {
	        hd_error = 0;
		return 0; /* ok */
	}
	printk("HD: win_result: status = 0x%02x\n",i);
	if (i&1) {
		hd_error = inb(HD_ERROR);
		printk("HD: win_result: error = 0x%02x\n",hd_error);
	}	
	return 1;
}

static int controller_busy(void);
static int status_ok(void);

static int controller_ready(unsigned int drive, unsigned int head)
{
	int retry = 100;

	do {
		if (controller_busy() & BUSY_STAT)
			return 0;
		outb_p(0xA0 | (drive<<4) | head, HD_CURRENT);
		if (status_ok())
			return 1;
	} while (--retry);
	return 0;
}

static int status_ok(void)
{
	unsigned char status = inb_p(HD_STATUS);

	if (status & BUSY_STAT)
		return 1;
	if (status & WRERR_STAT)
		return 0;
	if (!(status & READY_STAT))
		return 0;
	if (!(status & SEEK_STAT))
		return 0;
	return 1;
}

static int controller_busy(void)
{
	int retries = 100000;
	unsigned char status;

	do {
		status = inb_p(HD_STATUS);
	} while ((status & BUSY_STAT) && --retries);
	return status;
}

static void hd_out(unsigned int drive,unsigned int nsect,unsigned int sect,
		unsigned int head,unsigned int cyl,unsigned int cmd,
		void (*intr_addr)(void))
{
	unsigned short port;

	if (drive>1 || head>15)
		panic("Trying to write bad sector");
#if (HD_DELAY > 0)
	while (read_timer() - last_req < HD_DELAY)
		/* nothing */;
#endif
	if (reset)
		return;
	if (!controller_ready(drive, head)) {
		reset = 1;
		return;
	}
	SET_INTR(intr_addr);
	outb_p(hd_info[drive].ctl,HD_CMD);
	port=HD_DATA;
	outb_p(hd_info[drive].wpcom>>2,++port);
	outb_p(nsect,++port);
	outb_p(sect,++port);
	outb_p(cyl,++port);
	outb_p(cyl>>8,++port);
	outb_p(0xA0|(drive<<4)|head,++port);
	outb_p(cmd,++port);
}

static int drive_busy(void)
{
	unsigned int i;
	unsigned char c;

	for (i = 0; i < 500000 ; i++) {
		c = inb_p(HD_STATUS);
		c &= (BUSY_STAT | READY_STAT | SEEK_STAT);
		if (c == (READY_STAT | SEEK_STAT))
			return 0;
	}
	printk("HD controller times out, status = 0x%02x\n",c);
	return 1;
}

static void reset_controller(void)
{
	int	i;

	printk(KERN_DEBUG "HD-controller reset\n");
	outb_p(4,HD_CMD);
	for(i = 0; i < 1000; i++) nop();
	outb(hd_info[0].ctl & 0x0f ,HD_CMD);
	if (drive_busy())
		printk("HD-controller still busy\n");
	if ((hd_error = inb(HD_ERROR)) != 1)
		printk("HD-controller reset failed: %02x\n",hd_error);
}

static void reset_hd(void)
{
	static int i;

repeat:
	if (reset) {
		reset = 0;
		i = -1;
		reset_controller();
	} else if (win_result()) {
		bad_rw_intr();
		if (reset)
			goto repeat;
	}
	i++;
	if (i < NR_HD) {
		hd_out(i,hd_info[i].sect,hd_info[i].sect,hd_info[i].head-1,
			hd_info[i].cyl,WIN_SPECIFY,&reset_hd);
		if (reset)
			goto repeat;
	} else
		do_hd_request();
}

/*
 * Ok, don't know what to do with the unexpected interrupts: on some machines
 * doing a reset and a retry seems to result in an eternal loop. Right now I
 * ignore it, and just set the timeout.
 */
void unexpected_hd_interrupt(void)
{
	sti();
	printk(KERN_DEBUG "Unexpected HD interrupt\n");
	SET_TIMER;
}

/*
 * bad_rw_intr() now tries to be a bit smarter and does things
 * according to the error returned by the controller.
 * -Mika Liljeberg ([e-mail])
 */
static void bad_rw_intr(void)
{
	int dev;

	if (!CURRENT)
		return;
	dev = MINOR(CURRENT->dev) >> 6;
	if (++CURRENT->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {
		end_request(0);
		recalibrate[dev] = 1;
	} else if (CURRENT->errors % RESET_FREQ == 0)
		reset = 1;
	else if ((hd_error & TRK0_ERR) || CURRENT->errors % RECAL_FREQ == 0)
		recalibrate[dev] = 1;
	/* Otherwise just retry */
}

static inline int wait_DRQ(void)
{
	int retries = 100000;

	while (--retries > 0)
		if (inb_p(HD_STATUS) & DRQ_STAT)
			return 0;
	return -1;
}

#define STAT_MASK (BUSY_STAT | READY_STAT | WRERR_STAT | SEEK_STAT | ERR_STAT)
#define STAT_OK (READY_STAT | SEEK_STAT)

static void read_intr(void)
{
	int i;
	int retries = 100000;

	do {
		i = (unsigned) inb_p(HD_STATUS);
		if (i & BUSY_STAT)
			continue;
		if ((i & STAT_MASK) != STAT_OK)
			break;
		if (i & DRQ_STAT)
			goto ok_to_read;
	} while (--retries > 0);
	sti();
	printk("HD: read_intr: status = 0x%02x\n",i);
	if (i & ERR_STAT) {
		hd_error = (unsigned) inb(HD_ERROR);
		printk("HD: read_intr: error = 0x%02x\n",hd_error);
	}
	bad_rw_intr();
	cli();
	do_hd_request();
	return;
ok_to_read:
	insw(HD_DATA,CURRENT->buffer,256);
	CURRENT->errors = 0;
	CURRENT->buffer += 512;
	CURRENT->sector++;
	i = --CURRENT->nr_sectors;
	--CURRENT->current_nr_sectors;
#ifdef DEBUG
	printk("hd%d : sector = %d, %d remaining to buffer = %08x\n",
		MINOR(CURRENT->dev), CURRENT->sector, i, CURRENT-> 
		buffer);
#endif
	if (!i || (CURRENT->bh && !SUBSECTOR(i)))
		end_request(1);
	if (i > 0) {
		SET_INTR(&read_intr);
		sti();
		return;
	}
	(void) inb_p(HD_STATUS);
#if (HD_DELAY > 0)
	last_req = read_timer();
#endif
	do_hd_request();
	return;
}

static void write_intr(void)
{
	int i;
	int retries = 100000;

	do {
		i = (unsigned) inb_p(HD_STATUS);
		if (i & BUSY_STAT)
			continue;
		if ((i & STAT_MASK) != STAT_OK)
			break;
		if ((CURRENT->nr_sectors <= 1) || (i & DRQ_STAT))
			goto ok_to_write;
	} while (--retries > 0);
	sti();
	printk("HD: write_intr: status = 0x%02x\n",i);
	if (i & ERR_STAT) {
		hd_error = (unsigned) inb(HD_ERROR);
		printk("HD: write_intr: error = 0x%02x\n",hd_error);
	}
	bad_rw_intr();
	cli();
	do_hd_request();
	return;
ok_to_write:
	CURRENT->sector++;
	i = --CURRENT->nr_sectors;
	--CURRENT->current_nr_sectors;
	CURRENT->buffer += 512;
	if (!i || (CURRENT->bh && !SUBSECTOR(i)))
		end_request(1);
	if (i > 0) {
		SET_INTR(&write_intr);
		outsw(HD_DATA,CURRENT->buffer,256);
		sti();
	} else {
#if (HD_DELAY > 0)
		last_req = read_timer();