xv6-cs450/ide.c

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// Simple PIO-based (non-DMA) IDE driver code.
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#include "types.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "x86.h"
#include "traps.h"
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#include "spinlock.h"
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#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
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// IDE request queue.
// The next request will be stored in request[head],
// and the request currently being served by the disk
// is request[tail].
// Must hold ide_lock while manipulating queue.
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struct ide_request {
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int diskno;
uint secno;
void *addr;
uint nsecs;
uint read;
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};
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static struct ide_request request[NREQUEST];
static int head, tail;
static struct spinlock ide_lock;
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static int disk_1_present;
static int disk_queue;
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static int ide_probe_disk1(void);
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// Wait for IDE disk to become ready.
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static int
ide_wait_ready(int check_error)
{
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(check_error && (r & (IDE_DF|IDE_ERR)) != 0)
return -1;
return 0;
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}
void
ide_init(void)
{
initlock(&ide_lock, "ide");
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irq_enable(IRQ_IDE);
ioapic_enable(IRQ_IDE, ncpu - 1);
ide_wait_ready(0);
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disk_1_present = ide_probe_disk1();
}
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// Interrupt handler - wake up the request that just finished.
void
ide_intr(void)
{
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acquire(&ide_lock);
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wakeup(&request[tail]);
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release(&ide_lock);
}
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// Probe to see if disk 1 exists (we assume disk 0 exists).
static int
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ide_probe_disk1(void)
{
int r, x;
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// wait for Device 0 to be ready
ide_wait_ready(0);
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// switch to Device 1
outb(0x1F6, 0xE0 | (1<<4));
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// check for Device 1 to be ready for a while
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for(x = 0; x < 1000 && (r = inb(0x1F7)) == 0; x++)
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;
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// switch back to Device 0
outb(0x1F6, 0xE0 | (0<<4));
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return x < 1000;
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}
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// Start the next request in the queue.
static void
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ide_start_request (void)
{
struct ide_request *r;
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if(head != tail) {
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r = &request[tail];
ide_wait_ready(0);
outb(0x3f6, 0); // generate interrupt
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outb(0x1F2, r->nsecs);
outb(0x1F3, r->secno & 0xFF);
outb(0x1F4, (r->secno >> 8) & 0xFF);
outb(0x1F5, (r->secno >> 16) & 0xFF);
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outb(0x1F6, 0xE0 | ((r->diskno&1)<<4) | ((r->secno>>24)&0x0F));
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if(r->read)
outb(0x1F7, IDE_CMD_READ);
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else {
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outb(0x1F7, IDE_CMD_WRITE);
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outsl(0x1F0, r->addr, 512/4);
}
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}
}
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// Run an entire disk operation.
void
ide_rw(int diskno, uint secno, void *addr, uint nsecs, int read)
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{
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struct ide_request *r;
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if(diskno && !disk_1_present)
panic("ide disk 1 not present");
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acquire(&ide_lock);
// Add request to queue.
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while((head + 1) % NREQUEST == tail)
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sleep(&disk_queue, &ide_lock);
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r = &request[head];
r->secno = secno;
r->addr = addr;
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r->nsecs = nsecs;
r->diskno = diskno;
r->read = read;
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head = (head + 1) % NREQUEST;
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// Start request if necessary.
ide_start_request();
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// Wait for request to finish.
sleep(r, &ide_lock);
// Finish request.
if(read){
if(ide_wait_ready(1) >= 0)
insl(0x1F0, addr, 512/4);
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}
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// Remove request from queue.
if((head + 1) % NREQUEST == tail)
wakeup(&disk_queue);
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tail = (tail + 1) % NREQUEST;
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release(&ide_lock);
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}
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// Synchronous disk write.
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int
ide_write(int diskno, uint secno, const void *src, uint nsecs)
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{
int r;
if(nsecs > 256)
panic("ide_write");
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ide_wait_ready(0);
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outb(0x1F2, nsecs);
outb(0x1F3, secno & 0xFF);
outb(0x1F4, (secno >> 8) & 0xFF);
outb(0x1F5, (secno >> 16) & 0xFF);
outb(0x1F6, 0xE0 | ((diskno&1)<<4) | ((secno>>24)&0x0F));
outb(0x1F7, 0x30); // CMD 0x30 means write sector
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for(; nsecs > 0; nsecs--, src += 512) {
if((r = ide_wait_ready(1)) < 0)
return r;
outsl(0x1F0, src, 512/4);
}
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return 0;
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}