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Create ata.c

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Gregory Kenneth Bowne
2026-01-18 17:48:39 -08:00
committed by GitHub
parent 4079d18a45
commit 09b2b8cd11
1 changed files with 91 additions and 0 deletions
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kernel/ata.c Normal file
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#include "ata.h"
#include "io.h"
#include "print.h"
#define ATA_TIMEOUT 100000
static inline void ata_delay(void) {
/* 400ns delay by reading alternate status */
inb(ATA_PRIMARY_CTRL);
inb(ATA_PRIMARY_CTRL);
inb(ATA_PRIMARY_CTRL);
inb(ATA_PRIMARY_CTRL);
}
static bool ata_wait(uint8_t mask) {
for (int i = 0; i < ATA_TIMEOUT; i++) {
uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
if (!(status & ATA_SR_BSY) && (status & mask))
return true;
}
return false;
}
bool ata_init(void) {
outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xA0); // master
ata_delay();
outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_IDENTIFY);
ata_delay();
uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
if (status == 0)
return false; // no drive
if (!ata_wait(ATA_SR_DRQ))
return false;
uint16_t identify[256];
for (int i = 0; i < 256; i++)
identify[i] = inw(ATA_PRIMARY_IO);
print_string("[ATA] Primary master detected\n");
return true;
}
bool ata_read_sector(uint32_t lba, uint8_t* buffer) {
if (!buffer) return false;
outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
if (!ata_wait(ATA_SR_DRQ))
return false;
for (int i = 0; i < 256; i++) {
uint16_t data = inw(ATA_PRIMARY_IO);
buffer[i * 2] = data & 0xFF;
buffer[i * 2 + 1] = data >> 8;
}
ata_delay();
return true;
}
bool ata_write_sector(uint32_t lba, const uint8_t* buffer) {
if (!buffer) return false;
outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_WRITE_PIO);
if (!ata_wait(ATA_SR_DRQ))
return false;
for (int i = 0; i < 256; i++) {
uint16_t word =
buffer[i * 2] |
(buffer[i * 2 + 1] << 8);
outw(ATA_PRIMARY_IO, word);
}
ata_delay();
return true;
}