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//! ATA PIO block device driver
const ata_const = @import("../../common/constants/ata.zig");
const ata_limits = @import("../../common/limits/ata.zig");
const int = @import("../../utils/types/int.zig");
const io = @import("../../asm/io.zig");
const serial = @import("../serial/serial.zig");
pub const SECTOR_SIZE = ata_limits.SECTOR_SIZE;
fn wait_ready() void {
while ((io.in_byte(ata_const.PRIMARY_STATUS) & ata_const.STATUS_BSY) != 0) {}
}
fn wait_data_ready() bool {
var timeout: u32 = 0;
while (timeout < ata_limits.TIMEOUT_DATA_READY) : (timeout += 1) {
const status = io.in_byte(ata_const.PRIMARY_STATUS);
if ((status & ata_const.STATUS_ERR) != 0) return false;
if ((status & ata_const.STATUS_DRQ) != 0) return true;
}
return false;
}
pub const BlockDevice = struct {
disk_id: u8,
pub fn init() BlockDevice {
serial.printf("Initializing ATA PIO block device...\n", .{});
return BlockDevice{ .disk_id = 0 };
}
pub fn read_sector(self: *BlockDevice, lba: u64, buffer: []u8) bool {
if (buffer.len < SECTOR_SIZE) {
serial.printf("ERROR: Buffer too small for sector\n", .{});
return false;
}
wait_ready();
const drive_bits: u8 = 0xE0 | (self.disk_id << 4) | int.u8_of((lba >> 24) & 0x0F);
io.out_byte(ata_const.PRIMARY_DRIVE_SELECT, drive_bits);
io.out_byte(ata_const.PRIMARY_SECTOR_COUNT, 1);
io.out_byte(ata_const.PRIMARY_LBA_LOW, int.u8_of(lba));
io.out_byte(ata_const.PRIMARY_LBA_MID, int.u8_of(lba >> 8));
io.out_byte(ata_const.PRIMARY_LBA_HIGH, int.u8_of(lba >> 16));
io.out_byte(ata_const.PRIMARY_COMMAND, ata_const.CMD_READ_SECTORS);
if (!wait_data_ready()) {
serial.printf("ERROR: ATA read timeout\n", .{});
return false;
}
var i: usize = 0;
while (i < SECTOR_SIZE) : (i += 2) {
const word = io.in_word(ata_const.PRIMARY_DATA);
buffer[i] = int.u8_of(word);
buffer[i + 1] = int.u8_of(word >> 8);
}
return true;
}
};
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