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#include <kernel/arch/amd64/ata.h>
#include <kernel/arch/amd64/port_io.h>
#include <kernel/panic.h>
#include <kernel/util.h>
#include <stdbool.h>
static struct {
enum {
DEV_UNKNOWN,
DEV_PATA,
DEV_PATAPI,
} type;
uint32_t sectors;
} ata_drives[4];
enum {
DATA = 0,
FEAT = 1,
SCNT = 2,
LBAlo = 3,
LBAmid = 4,
LBAhi = 5,
DRV = 6,
CMD = 7,
STATUS = 7,
CTRL = 0x206,
}; /* offsets */
static uint16_t ata_iobase(int drive) {
bool secondary = drive&2;
return secondary ? 0x170 : 0x1F0;
}
static void ata_400ns(void) {
uint16_t base = ata_iobase(0); /* the drive doesn't matter. */
for (int i = 0; i < 4; i++)
port_in8(base + STATUS);
}
static void ata_driveselect(int drive, int lba) {
uint8_t v = 0xE0;
if (drive&1) v |= 0x10; /* slave? */
v |= (lba >> 24) & 0xf;
port_out8(ata_iobase(drive) + DRV, v);
}
static int ata_poll(int drive, int timeout) {
uint16_t iobase = ata_iobase(drive);
/* if timeout < 0, cycle forever */
while (timeout < 0 || timeout--) {
uint8_t v = port_in8(iobase + STATUS);
if (v & 0x80) continue; /* BSY */
if (v & 0x40) return 0; /* RDY */
// TODO check for ERR
}
return -1;
}
static void ata_softreset(int drive) {
uint16_t iobase = ata_iobase(drive);
port_out8(iobase + CTRL, 4);
port_out8(iobase + CTRL, 0);
ata_400ns();
ata_poll(drive, 10000);
}
static void ata_detecttype(int drive) {
ata_softreset(drive);
ata_driveselect(drive, 0);
ata_400ns();
switch (port_in8(ata_iobase(drive) + LBAmid)) {
case 0:
ata_drives[drive].type = DEV_PATA;
break;
case 0x14:
ata_drives[drive].type = DEV_PATAPI;
break;
default:
ata_drives[drive].type = DEV_UNKNOWN;
break;
}
}
static bool ata_identify(int drive) {
uint16_t iobase = ata_iobase(drive);
uint16_t data[256];
uint8_t v;
ata_driveselect(drive, 0);
for (int i = 2; i < 6; i++)
port_out8(iobase + i, 0);
switch (ata_drives[drive].type) {
case DEV_PATA:
port_out8(iobase + CMD, 0xEC); // IDENTIFY
break;
case DEV_PATAPI:
port_out8(iobase + CMD, 0xA1); // IDENTIFY PACKET DEVICE
break;
default: panic_invalid_state();
}
v = port_in8(iobase + STATUS);
if (v == 0) return false; // nonexistent drive
while (port_in8(iobase + STATUS) & 0x80);
/* pool until bit 3 (DRQ) or 0 (ERR) is set */
while (!((v = port_in8(iobase + STATUS) & 0x9)));
if (v & 1) return false; /* ERR was set, bail */
for (int i = 0; i < 256; i++)
data[i] = port_in16(iobase);
ata_drives[drive].sectors = data[60] | (data[61] << 16);
return true;
}
void ata_init(void) {
for (int i = 0; i < 4; i++) {
ata_detecttype(i);
if (ata_drives[i].type == DEV_PATA) {
ata_identify(i);
}
}
}
bool ata_available(int drive) {
return ata_drives[drive].type != DEV_UNKNOWN;
}
size_t ata_size(int drive) {
return ata_drives[drive].sectors * 512;
}
int ata_read(int drive, void *buf, size_t len, size_t off) {
uint32_t lba, skip, cnt;
if (ata_drives[drive].type != DEV_PATA) {
panic_unimplemented();
}
lba = off / 512;
skip = off % 512;
cnt = (len - skip + 511) / 512;
if (skip) cnt += 1;
int iobase = ata_iobase(drive);
ata_driveselect(drive, lba);
port_out8(iobase + FEAT, 0); /* supposedly pointless */
port_out8(iobase + SCNT, cnt);
port_out8(iobase + LBAlo, lba);
port_out8(iobase + LBAmid, lba >> 8);
port_out8(iobase + LBAhi, lba >> 16);
port_out8(iobase + CMD, 0x20); /* READ SECTORS */
for (uint32_t i = 0; i < cnt; i++) {
union {
uint16_t s;
char b[2];
} d;
ata_poll(drive, -1);
for (int j = 0; j < 256; j++) {
d.s = port_in16(iobase);
for (int k = 0; k < 2; k++) {
size_t byte = i * 512 + j * 2 + k;
if (byte < skip) continue;
byte -= skip;
if (byte < len) {
((char*)buf)[byte] = d.b[k];
}
}
}
}
return len;
}
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