173 lines
3.3 KiB
C
173 lines
3.3 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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#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 request queue.
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// The next request will be stored in request[head],
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// and the request currently being served by the disk
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// is request[tail].
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// Must hold ide_lock while manipulating queue.
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struct ide_request {
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int diskno;
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uint secno;
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void *addr;
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uint nsecs;
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uint read;
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int done;
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};
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static struct ide_request request[NREQUEST];
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static int head, tail;
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static struct spinlock ide_lock;
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static int disk_1_present;
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static int disk_queue;
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static int ide_probe_disk1(void);
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//PAGEBREAK: 10
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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|IDE_DRDY)) != 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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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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disk_1_present = ide_probe_disk1();
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}
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// Probe to see if disk 1 exists (we assume disk 0 exists).
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static int
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ide_probe_disk1(void)
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{
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int r, x;
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// wait for Device 0 to be ready
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ide_wait_ready(0);
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// switch to Device 1
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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
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outb(0x1F6, 0xE0 | (0<<4));
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return x < 1000;
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}
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// Interrupt handler - wake up the request that just finished.
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void
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ide_intr(void)
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{
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acquire(&ide_lock);
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request[tail].done = 1;
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wakeup(&request[tail]);
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release(&ide_lock);
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}
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// Start the next request in the queue.
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static void
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ide_start_request (void)
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{
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struct ide_request *r;
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if(head != tail) {
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r = &request[tail];
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ide_wait_ready(0);
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outb(0x3f6, 0); // generate interrupt
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outb(0x1F2, r->nsecs);
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outb(0x1F3, r->secno & 0xFF);
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outb(0x1F4, (r->secno >> 8) & 0xFF);
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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)
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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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}
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}
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//PAGEBREAK: 30
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// Run an entire disk operation.
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void
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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)
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panic("ide disk 1 not present");
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acquire(&ide_lock);
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// 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];
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r->secno = secno;
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r->addr = addr;
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r->nsecs = nsecs;
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r->diskno = diskno;
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r->read = read;
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r->done = 0;
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head = (head + 1) % NREQUEST;
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// Start request if necessary.
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ide_start_request();
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// Wait for request to finish.
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while(!r->done)
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sleep(r, &ide_lock);
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// Finish request.
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if(read){
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if(ide_wait_ready(1) >= 0)
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insl(0x1F0, addr, 512/4);
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}
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// Remove request from queue.
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if((head + 1) % NREQUEST == tail)
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wakeup(&disk_queue);
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tail = (tail + 1) % NREQUEST;
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// Start next request in queue, if any.
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ide_start_request();
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release(&ide_lock);
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}
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