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// Simple PIO-based (non-DMA) IDE driver code.
#include "types.h"
#include "defs.h"
#include "param.h"
#include "memlayout.h"
#include "mmu.h"
#include "proc.h"
#include "x86.h"
#include "traps.h"
#include "spinlock.h"
#include "buf.h"
#define IDE_BSY 0x80
#define IDE_DRDY 0x40
#define IDE_DF 0x20
#define IDE_ERR 0x01
#define IDE_CMD_READ 0x20
#define IDE_CMD_WRITE 0x30
// idequeue points to the buf now being read/written to the disk.
// idequeue->qnext points to the next buf to be processed.
// You must hold idelock while manipulating queue.
static struct spinlock idelock;
static struct buf *idequeue;
static int havedisk1;
static void idestart(struct buf*);
// Wait for IDE disk to become ready.
static int
idewait(int checkerr)
{
int r;
while(((r = inb(0x1f7)) & (IDE_BSY|IDE_DRDY)) != IDE_DRDY)
;
if(checkerr && (r & (IDE_DF|IDE_ERR)) != 0)
return -1;
return 0;
}
void
ideinit(void)
{
int i;
initlock(&idelock, "ide");
picenable(IRQ_IDE);
ioapicenable(IRQ_IDE, ncpu - 1);
idewait(0);
// Check if disk 1 is present
outb(0x1f6, 0xe0 | (1<<4));
for(i=0; i<1000; i++){
if(inb(0x1f7) != 0){
havedisk1 = 1;
break;
}
}
// Switch back to disk 0.
outb(0x1f6, 0xe0 | (0<<4));
}
// Start the request for b. Caller must hold idelock.
static void
idestart(struct buf *b)
{
if(b == 0)
panic("idestart");
idewait(0);
outb(0x3f6, 0); // generate interrupt
outb(0x1f2, 1); // number of sectors
outb(0x1f3, b->sector & 0xff);
outb(0x1f4, (b->sector >> 8) & 0xff);
outb(0x1f5, (b->sector >> 16) & 0xff);
outb(0x1f6, 0xe0 | ((b->dev&1)<<4) | ((b->sector>>24)&0x0f));
if(b->flags & B_DIRTY){
outb(0x1f7, IDE_CMD_WRITE);
outsl(0x1f0, b->data, 512/4);
} else {
outb(0x1f7, IDE_CMD_READ);
}
}
// Interrupt handler.
void
ideintr(void)
{
struct buf *b;
// First queued buffer is the active request.
acquire(&idelock);
if((b = idequeue) == 0){
release(&idelock);
// cprintf("spurious IDE interrupt\n");
return;
}
idequeue = b->qnext;
// Read data if needed.
if(!(b->flags & B_DIRTY) && idewait(1) >= 0)
insl(0x1f0, b->data, 512/4);
// Wake process waiting for this buf.
b->flags |= B_VALID;
b->flags &= ~B_DIRTY;
wakeup(b);
// Start disk on next buf in queue.
if(idequeue != 0)
idestart(idequeue);
release(&idelock);
}
//PAGEBREAK!
// Sync buf with disk.
// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
// Else if B_VALID is not set, read buf from disk, set B_VALID.
void
iderw(struct buf *b)
{
struct buf **pp;
if(!(b->flags & B_BUSY))
panic("iderw: buf not busy");
if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
panic("iderw: nothing to do");
if(b->dev != 0 && !havedisk1)
panic("iderw: ide disk 1 not present");
acquire(&idelock); //DOC: acquire-lock
// Append b to idequeue.
b->qnext = 0;
for(pp=&idequeue; *pp; pp=&(*pp)->qnext) //DOC: insert-queue
;
*pp = b;
// Start disk if necessary.
if(idequeue == b)
idestart(b);
// Wait for request to finish.
while((b->flags & (B_VALID|B_DIRTY)) != B_VALID){
sleep(b, &idelock);
}
release(&idelock);
}
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