3a5fa7ed90
Remove I_BUSY, B_BUSY, and intrans defs and usages One spinlock per buf to avoid ugly loop in bget fix race in filewrite (don't update f->off after releasing lock)
156 lines
3.2 KiB
C
156 lines
3.2 KiB
C
// Simple PIO-based (non-DMA) IDE driver code.
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#include "types.h"
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#include "defs.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "proc.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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// idequeue points to the buf now being read/written to the disk.
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// idequeue->qnext points to the next buf to be processed.
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// You must hold idelock while manipulating queue.
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static struct spinlock idelock;
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static struct buf *idequeue;
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static int havedisk1;
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static void idestart(struct buf*);
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// Wait for IDE disk to become ready.
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static int
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idewait(int checkerr)
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{
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int r;
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while(((r = inb(0x1f7)) & (IDE_BSY|IDE_DRDY)) != IDE_DRDY)
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;
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if(checkerr && (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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ideinit(void)
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{
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int i;
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initlock(&idelock, "ide");
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picenable(IRQ_IDE);
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ioapicenable(IRQ_IDE, ncpu - 1);
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idewait(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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havedisk1 = 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 idelock.
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static void
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idestart(struct buf *b)
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{
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if(b == 0)
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panic("idestart");
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idewait(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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ideintr(void)
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{
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struct buf *b;
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// Take first buffer off queue.
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acquire(&idelock);
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if((b = idequeue) == 0){
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release(&idelock);
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// cprintf("spurious IDE interrupt\n");
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return;
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}
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idequeue = b->qnext;
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// Read data if needed.
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if(!(b->flags & B_DIRTY) && idewait(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(idequeue != 0)
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idestart(idequeue);
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release(&idelock);
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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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iderw(struct buf *b)
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{
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struct buf **pp;
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if(!acquired_sleeplock(&b->sleeplock))
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panic("iderw: buf not busy");
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if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
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panic("iderw: nothing to do");
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if(b->dev != 0 && !havedisk1)
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panic("iderw: ide disk 1 not present");
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acquire(&idelock); // DOC:acquire-lock
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// Append b to idequeue.
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b->qnext = 0;
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for(pp=&idequeue; *pp; pp=&(*pp)->qnext) // DOC:insert-queue
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;
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*pp = b;
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// Start disk if necessary.
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if(idequeue == b)
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idestart(b);
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// Wait for request to finish.
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// Assuming will not sleep too long: ignore proc->killed.
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while((b->flags & (B_VALID|B_DIRTY)) != B_VALID){
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sleep(b, &idelock);
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}
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release(&idelock);
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}
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