152 lines
3.1 KiB
C
152 lines
3.1 KiB
C
// Simple PIO-based (non-DMA) IDE driver code.
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#include "types.h"
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#include "param.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "x86.h"
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#include "traps.h"
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#include "spinlock.h"
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#include "buf.h"
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#define IDE_BSY 0x80
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#define IDE_DRDY 0x40
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#define IDE_DF 0x20
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#define IDE_ERR 0x01
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#define IDE_CMD_READ 0x20
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#define IDE_CMD_WRITE 0x30
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// ide_queue points to the buf now being read/written to the disk.
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// ide_queue->qnext points to the next buf to be processed.
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// You must hold ide_lock while manipulating queue.
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static struct spinlock ide_lock;
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static struct buf *ide_queue;
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static int disk_1_present;
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static void ide_start_request();
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// Wait for IDE disk to become ready.
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static int
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ide_wait_ready(int check_error)
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{
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int r;
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while(((r = inb(0x1f7)) & IDE_BSY) || !(r & IDE_DRDY))
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;
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if(check_error && (r & (IDE_DF|IDE_ERR)) != 0)
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return -1;
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return 0;
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}
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void
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ide_init(void)
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{
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int i;
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initlock(&ide_lock, "ide");
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irq_enable(IRQ_IDE);
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ioapic_enable(IRQ_IDE, ncpu - 1);
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ide_wait_ready(0);
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// Check if disk 1 is present
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outb(0x1f6, 0xE0 | (1<<4));
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for(i=0; i<1000; i++){
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if(inb(0x1f7) != 0){
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disk_1_present = 1;
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break;
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}
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}
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// Switch back to disk 0.
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outb(0x1f6, 0xE0 | (0<<4));
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}
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// Start the request for b. Caller must hold ide_lock.
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static void
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ide_start_request(struct buf *b)
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{
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if(b == 0)
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panic("ide_start_request");
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ide_wait_ready(0);
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outb(0x3f6, 0); // generate interrupt
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outb(0x1f2, 1); // number of sectors
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outb(0x1f3, b->sector & 0xff);
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outb(0x1f4, (b->sector >> 8) & 0xff);
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outb(0x1f5, (b->sector >> 16) & 0xff);
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outb(0x1f6, 0xE0 | ((b->dev&1)<<4) | ((b->sector>>24)&0x0f));
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if(b->flags & B_DIRTY){
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outb(0x1f7, IDE_CMD_WRITE);
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outsl(0x1f0, b->data, 512/4);
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}else{
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outb(0x1f7, IDE_CMD_READ);
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}
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}
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// Interrupt handler.
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void
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ide_intr(void)
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{
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struct buf *b;
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acquire(&ide_lock);
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if((b = ide_queue) == 0){
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cprintf("stray ide interrupt\n");
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release(&ide_lock);
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return;
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}
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// Read data if needed.
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if(!(b->flags & B_DIRTY) && ide_wait_ready(1) >= 0)
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insl(0x1f0, b->data, 512/4);
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// Wake process waiting for this buf.
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b->flags |= B_VALID;
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b->flags &= ~B_DIRTY;
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wakeup(b);
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// Start disk on next buf in queue.
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if((ide_queue = b->qnext) != 0)
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ide_start_request(ide_queue);
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release(&ide_lock);
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}
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//PAGEBREAK!
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// Sync buf with disk.
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// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
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// Else if B_VALID is not set, read buf from disk, set B_VALID.
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void
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ide_rw(struct buf *b)
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{
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struct buf **pp;
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if(!(b->flags & B_BUSY))
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panic("ide_rw: buf not busy");
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if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
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panic("ide_rw: nothing to do");
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if(b->dev != 0 && !disk_1_present)
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panic("ide disk 1 not present");
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acquire(&ide_lock);
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// Append b to ide_queue.
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b->qnext = 0;
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for(pp=&ide_queue; *pp; pp=&(*pp)->qnext)
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;
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*pp = b;
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// Start disk if necessary.
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if(ide_queue == b)
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ide_start_request(b);
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// Wait for request to finish.
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while((b->flags & (B_VALID|B_DIRTY)) != B_VALID)
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sleep(b, &ide_lock);
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release(&ide_lock);
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}
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