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linux-hd.c_hdhdhd x

hdhdhd x
/*/*
*  linux/kernel/hd.c
*
*  (C) 1991  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.
*/
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/hdreg.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>
#define MAJOR_NR 3
#include "blk.h"
#define CMOS_READ(addr) ({ /                    //--读CMOS中硬盘信息
outb_p(0x80|addr,0x70); /
inb_p(0x71); /
})
/* Max read/write errors/sector */
#define MAX_ERRORS    7
#define MAX_HD        2
static void recal_intr(void);
static void bad_rw_intr(void);
static int recalibrate = 0;
static int reset = 0;
/*
*  This struct defines the HD's and their types.
*/
struct hd_i_struct {                            //--定义硬盘参数及类型
    int head,sect,cyl,wpcom,lzone,ctl;
    };
#ifdef HD_TYPE
struct hd_i_struct hd_info[] = { HD_TYPE };
#define 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 {
    long start_sect;
    long nr_sects;
} hd[5*MAX_HD]={{0,0},};
static int hd_sizes[5*MAX_HD] = {0, };
#define port_read(port,buf,nr) /                //--读端口嵌入汇编宏
__asm__("cld;rep;insw"::"d" (port),"D" (buf),"c" (nr):"cx","di")
#define port_write(port,buf,nr) /                //--写端口嵌入汇编宏
__asm__("cld;rep;outsw"::"d" (port),"S" (buf),"c" (nr):"cx","si")
extern void hd_interrupt(void);                    //--硬盘中断过程
extern void rd_load(void);                        //--虚拟盘创建加载函数
/* This may be used only once, enforced by 'static int callable' */
int sys_setup(void * BIOS)                        //--系统设置函数,只在初始化时被调用一次
{                //--BIOS为指向硬盘参数表结构的指针
    static int callable = 1;
    int i,drive;
    unsigned char cmos_disks;
    struct partition *p;
    struct buffer_head * bh;
    if (!callable)                                //--只调用一次
        return -1;
    callable = 0;
#ifndef HD_TYPE
    for (drive=0 ; drive<2 ; drive++) {
        hd_info[drive].cyl = *(unsigned short *) BIOS;            //--柱面数
        hd_info[drive].head = *(unsigned char *) (2+BIOS);        //--磁头数
        hd_info[drive].wpcom = *(unsigned short *) (5+BIOS);    //--写前预补偿柱面号
        hd_info[drive].ctl = *(unsigned char *) (8+BIOS);        //--控制字节
        hd_info[drive].lzone = *(unsigned short *) (12+BIOS);    //--磁头着陆区柱面号
        hd_info[drive].sect = *(unsigned char *) (14+BIOS);        //--每磁道扇区数
        BIOS += 16;                                //--每个硬盘参数表长16个字节,这里指向下一表
    }
    if (hd_info[1].cyl)                            //--如果没有第二个硬盘,则信息为空
        NR_HD=2;
    else
        NR_HD=1;
#endif
    for (i=0 ; i<NR_HD ; i++) {                    //--设置硬盘分区结构数组hd[]
        hd[i*5].start_sect = 0;
        hd[i*5].nr_sects = hd_info[i].head*
                hd_info[i].sect*hd_info[i].cyl;
    }
    /*
        We querry CMOS about hard disks : it could be that
        we have a SCSI/ESDI/etc controller that is BIOS
        compatable with ST-506, and thus showing up in our
        BIOS table, but not register compatable, and therefore
        not present in CMOS.
        Furthurmore, we will assume that our ST-506 drives
        <if any> are the primary drives in the system, and
        the ones reflected as drive 1 or 2.
        The first drive is stored in the high nibble of CMOS
        byte 0x12, the second in the low nibble.  This will be
        either a 4 bit drive type or 0xf indicating use byte 0x19
        for an 8 bit type, drive 1, 0x1a for drive 2 in CMOS.
        Needless to say, a non-zero value means we have
        an AT controller hard disk for that drive.
        
    */
    if ((cmos_disks = CMOS_READ(0x12)) & 0xf0)    //--检测硬盘是不是AT控制器兼容的。
        if (cmos_disks & 0x0f)
            NR_HD = 2;
        else
            NR_HD = 1;
    else
        NR_HD = 0;
    for (i = NR_HD ; i < 2 ; i++) {
        hd[i*5].start_sect = 0;
        hd[i*5].nr_sects = 0;
    }                                            //--到此最终确定硬盘数量
    for (drive=0 ; drive<NR_HD ; drive++) {        //--读取硬盘上第一个扇区的分区表信息,来设置分区结构数组hd[]
        if (!(bh = bread(0x300 + drive*5,0))) {    //--bread()读取硬盘第一个数据块
            printk("Unable to read partition table of drive %d/n/r",
                drive);
            panic("");
        }
        if (bh->b_data[510] != 0x55 || (unsigned char)
            bh->b_data[511] != 0xAA) {
            printk("Bad partition table on drive %d/n/r",drive);
            panic("");
        }
        p = 0x1BE + (void *)bh->b_data;
        for (i=1;i<5;i++,p++) {
            hd[i+5*drive].start_sect = p->start_sect;
            hd[i+5*drive].nr_sects = p->nr_sects;
        }
        brelse(bh);                                //--释放为存放硬盘数据块而申请的缓冲区
    }
    for (i=0 ; i<5*MAX_HD ; i++)                //--对每个分区中数据块进行统计并保存
        hd_sizes[i] = hd[i].nr_sects>>1 ;
    blk_size[MAJOR_NR] = hd_sizes;
    if (NR_HD)
        printk("Partition table%s ok./n/r",(NR_HD>1)?"s":"");
    rd_load();
    init_swapping();
    mount_root();
    return (0);
}
static int controller_ready(void)                //--判断并循环等待硬盘控制器就绪
{
    int retries = 100000;
    while (--retries && (inb_p(HD_STATUS)&0xc0)!=0x40);
    return (retries);
}
static int win_result(void)                        //--检测硬盘执行命令后的状态
{
    int i=inb_p(HD_STATUS);
    if ((i & (BUSY_STAT | READY_STAT | WRERR_STAT | SEEK_STAT | ERR_STAT))
        == (READY_STAT | SEEK_STAT))
        return(0); /* ok */
    if (i&1) i=inb(HD_ERROR);
    return (1);
}
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))                //--向硬盘控制器发送命令块
{            //--在硬盘控制器就绪之后,先设置全局函数指针变量do_hd指向硬盘中断处理程序中将会调用的C处理函数
    register int port asm("dx");    //--然后再发送硬盘控制字节和7字节的参数命令块。
    if (drive>1 || head>15)
        panic("Trying to write bad sector");
    if (!controller_ready())
        panic("HD controller not ready");
    SET_INTR(intr_addr);                    //--do_hd = 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(cmd,++port);
}
static int drive_busy(void)                    //--等待硬盘就绪
{
    unsigned int i;
    unsigned char c;
    for (i = 0; i < 50000; i++) {            //--循环50000次等待HD_STATUS
        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/n/r");
    return(1);
}
static void reset_controller(void)            //--重新校正硬盘控制器
{
    int    i;
    outb(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/r");
    if ((i = inb(HD_ERROR)) != 1)
        printk("HD-controller reset failed: %02x/n/r",i);
}
static void reset_hd(void)                    //--硬盘复位操作
{
    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);
    } else
        do_hd_request();
}
void unexpected_hd_interrupt(void)            //--意外硬盘中断处理函数
{
    printk("Unexpected HD interrupt/n/r");
    reset = 1;
    do_hd_request();
}
static void bad_rw_intr(void)                //--读写硬盘失败处理函数
{
    if (++CURRENT->errors >= MAX_ERRORS)
        end_request(0);
    if (CURRENT->errors > MAX_ERRORS/2)
        reset = 1;
}
static void read_intr(void)                    //--读操作中断调用函数
{                                            //--硬盘读命令hd_out()结束时引发的硬盘中断过程中被调用
    if (win_result()) {
        bad_rw_intr();
        do_hd_request();
        return;
    }
    port_read(HD_DATA,CURRENT->buffer,256);    //--读数据到请求结构缓冲区
    CURRENT->errors = 0;
    CURRENT->buffer += 512;
    CURRENT->sector++;
    if (--CURRENT->nr_sectors) {
        SET_INTR(&read_intr);
        return;
    }
    end_request(1);
    do_hd_request();
}
static void write_intr(void)                //--写扇区中断调用函数
{
    if (win_result()) {
        bad_rw_intr();
        do_hd_request();
        return;
    }
    if (--CURRENT->nr_sectors) {
        CURRENT->sector++;
        CURRENT->buffer += 512;
        SET_INTR(&write_intr);
        port_write(HD_DATA,CURRENT->buffer,256);
        return;
    }
    end_request(1);
    do_hd_request();
}
static void recal_intr(void)                //--硬盘重新校正中断函数
{
    if (win_result())
        bad_rw_intr();
    do_hd_request();
}
void hd_times_out(void)                        //--硬盘操作超时处理
{                                            //--在kernel/sched.c line340中被调用
    if (!CURRENT)
        return;
    printk("HD timeout");
    if (++CURRENT->errors >= MAX_ERRORS)
        end_request(0);
    SET_INTR(NULL);
    reset = 1;
    do_hd_request();
}
void do_hd_request(void)                        //--执行硬盘读写请求操作
{
    int i,r;
    unsigned int block,dev;
    unsigned int sec,head,cyl;
    unsigned int nsect;
    INIT_REQUEST;
    dev = MINOR(CURRENT->dev);                    //--检测请求的合法性
    block = CURRENT->sector;
    if (dev >= 5*NR_HD || block+2 > hd[dev].nr_sects) {
        end_request(0);
        goto repeat;
    }
    block += hd[dev].start_sect;
    dev /= 5;                            //--根据求得的绝对扇区号block和硬盘号dev,计算磁道中的扇区号sec,柱面号syl,磁头号head.
    __asm__("divl %4":"=a" (block),"=d" (sec):"0" (block),"1" (0),
        "r" (hd_info[dev].sect));
    __asm__("divl %4":"=a" (cyl),"=d" (head):"0" (block),"1" (0),
        "r" (hd_info[dev].head));
    sec++;
    nsect = CURRENT->nr_sectors;
    if (reset) {                        //--向硬盘控制器发送i/o操作信息
        recalibrate = 1;
        reset_hd();
        return;
    }
    if (recalibrate) {
        recalibrate = 0;
        hd_out(dev,hd_info[CURRENT_DEV].sect,0,0,0,
            WIN_RESTORE,&recal_intr);
        return;
    }    
    if (CURRENT->cmd == WRITE) {
        hd_out(dev,nsect,sec,head,cyl,WIN_WRITE,&write_intr);
        for(i=0 ; i<10000 && !(r=inb_p(HD_STATUS)&DRQ_STAT) ; i++)
            /* nothing */ ;
        if (!r) {
            bad_rw_intr();
            goto repeat;
        }
        port_write(HD_DATA,CURRENT->buffer,256);
    } else if (CURRENT->cmd == READ) {
        hd_out(dev,nsect,sec,head,cyl,WIN_READ,&read_intr);
    } else
        panic("unknown hd-command");
}
void hd_init(void)                        //--硬盘系统初始化
{
    blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
    set_intr_gate(0x2E,&hd_interrupt);
    outb_p(inb_p(0x21)&0xfb,0x21);
    outb(inb_p(0xA1)&0xbf,0xA1);
}
|xGv00|fcc8d4de8197f69fde70263fb4d52380
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