作者：opera Linux内核在缺省配置下最多支持10个IDE接口,IDE接口用ide_hwif_t结构来描述,每个IDE接口具有一对主-从驱动器接口,它们用ide_drive_t结构来描述,每个驱动器接口可接不同种类的IDE设备,如IDE硬盘,光驱等,它们用ide_driver_t结构来描述. 每个驱动器接口包含一个命令请求队列,用request_queue_t结构来描述,具体的请求用request结构来描述. 多个IDE驱动器可以共享一个中断,共享同一中断的驱动器形成一个组,用ide_hwgroup_t结构来描述.ide_intr()是所有的ide驱动器所共用的硬件中断入口,对之对应的ide_hwgroup_t指针将作为dev_id传递给ide_intr. 每次在读写某个驱动器之前,需要用ide_set_handler()来设置ide_intr将要调用的中断函数指针.中断产生以后,该函数指针被自动清除. do_rw_disk(drive,rq,block) 从逻辑扇区号block开始向IDE硬盘驱动器drive写入rq所描述的内容. 以下是硬盘PIO传输模式的有关代码. ; drivers/ide/ide-disk.c static ide_startstop_t do_rw_disk (ide_drive_t *drive, strUCt request *rq, unsigned long block) { if (IDE_CONTROL_REG) OUT_BYTE(drive->ctl,IDE_CONTROL_REG); OUT_BYTE(rq->nr_sectors,IDE_NSECTOR_REG); if (drive->select.b.lba) { 如果是逻辑块寻址模式 OUT_BYTE(block,IDE_SECTOR_REG); OUT_BYTE(block>>=8,IDE_LCYL_REG); OUT_BYTE(block>>=8,IDE_HCYL_REG); OUT_BYTE(((block>>&0x0f)drive->select.all,IDE_SELECT_REG); } else { unsigned int sect,head,cyl,track; track = block / drive->sect; sect = block % drive->sect + 1; OUT_BYTE(sect,IDE_SECTOR_REG); head = track % drive->head; cyl = track / drive->head; OUT_BYTE(cyl,IDE_LCYL_REG); OUT_BYTE(cyl>>8,IDE_HCYL_REG); OUT_BYTE(headdrive->select.all,IDE_SELECT_REG); } if (rq->cmd == READ) {{ ide_set_handler(drive, &read_intr, WAIT_CMD, NULL); WAIT_CMD为10秒超时 OUT_BYTE(drive->mult_count ? WIN_MULTREAD : WIN_READ, IDE_COMMAND_REG); return ide_started; } if (rq->cmd == WRITE) { ide_startstop_t startstop; OUT_BYTE(drive->mult_count ? WIN_MULTWRITE : WIN_WRITE, IDE_COMMAND_REG); if (ide_wait_stat(&startstop, drive, DATA_READY, drive->bad_wstat, WAIT_DRQ)) { printk(KERN_ERR "%s: no DRQ after issuing %s\n", drive->name, drive->mult_count ? "MULTWRITE" : "WRITE"); return startstop; } if (!drive->unmask) __cli(); /* local CPU only */ if (drive->mult_count) { 如果允许多扇区传送 ide_hwgroup_t *hwgroup = HWGROUP(drive); /* * Ugh.. this part looks ugly because we MUST set up * the interrupt handler before outputting the first block * of data to be written. If we hit an error (corrupted buffer list) * in ide_multwrite(), then we need to remove the handler/timer * before returning. Fortunately, this NEVER happens (right?). * * Except when you get an error it seems... */ hwgroup->wrq = *rq; /* scratchpad */ ide_set_handler (drive, &multwrite_intr, WAIT_CMD, NULL); if (ide_multwrite(drive, drive->mult_count)) { unsigned long flags; spin_lock_irqsave(&io_request_lock, flags); hwgroup->handler = NULL; del_timer(&hwgroup->timer); spin_unlock_irqrestore(&io_request_lock, flags); return ide_stopped; } } else { ide_set_handler (drive, &write_intr, WAIT_CMD, NULL); idedisk_output_data(drive, rq->buffer, SECTOR_WordS); 写入一扇区SECTOR_WORDS=512/4 } return ide_started; } printk(KERN_ERR "%s: bad command: %d\n", drive->name, rq->cmd); ide_end_request(0, HWGROUP(drive)); return ide_stopped; } void ide_set_handler (ide_drive_t *drive, ide_handler_t *handler, unsigned int timeout, ide_eXPiry_t *expiry) { unsigned long flags; ide_hwgroup_t *hwgroup = HWGROUP(drive); spin_lock_irqsave(&io_request_lock, flags); if (hwgroup->handler != NULL) { printk("%s: ide_set_handler: handler not null; old=%p, new=%p\n", drive->name, hwgroup->handler, handler); } hwgroup->handler = handler; hwgroup->expiry = expiry; hwgroup->timer.expires = jiffies + timeout; add_timer(&hwgroup->timer); spin_unlock_irqrestore(&io_request_lock, flags); } static inline void idedisk_output_data (ide_drive_t *drive, void *buffer, unsigned int wcount) { if (drive->bswap) { idedisk_bswap_data(buffer, wcount); ide_output_data(drive, buffer, wcount); idedisk_bswap_data(buffer, wcount); } else ide_output_data(drive, buffer, wcount); } void ide_output_data (ide_drive_t *drive, void *buffer, unsigned int wcount) { byte io_32bit = drive->io_32bit; if (io_32bit) { #if SUPPORT_VLB_SYNC if (io_32bit & 2) { unsigned long flags; __save_flags(flags); /* local CPU only */ __cli(); /* local CPU only */ do_vlb_sync(IDE_NSECTOR_REG); outsl(IDE_DATA_REG, buffer, wcount); __restore_flags(flags); /* local CPU only */ } else #endif /* SUPPORT_VLB_SYNC */ outsl(IDE_DATA_REG, buffer, wcount); } else { #if SUPPORT_SLOW_DATA_PORTS if (drive->slow) { unsigned short *ptr = (unsigned short *) buffer; while (wcount--) { outw_p(*ptr++, IDE_DATA_REG); outw_p(*ptr++, IDE_DATA_REG); } } else #endif /* SUPPORT_SLOW_DATA_PORTS */ outsw(IDE_DATA_REG, buffer, wcountcurrent_nr_sectors; if (nsect > mcount) nsect = mcount; mcount -= nsect; ; 这时mcount为剩余的必需传送的扇区数 idedisk_output_data(drive, rq->buffer, nsectnr_sectors -= nsect)) current_nr_sectors -= nsect) == 0) { if ((rq->bh = rq->bh->b_reqnext) != NULL) {{ rq->current_nr_sectors = rq->bh->b_size>>9; rq->buffer = rq->bh->b_data; } else { spin_unlock_irqrestore(&io_request_lock, flags); printk("%s: buffer list corrupted (%ld, %ld, %d)\n", drive->name, rq->current_nr_sectors, rq->nr_sectors, nsect); ide_end_request(0, hwgroup); return 1; } } else { /* Fix the pointer.. we ate data */ rq->buffer += nsect hwif; if (!ide_ack_intr(hwif)) { spin_unlock_irqrestore(&i
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