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static int detect_disk(int channel, int master) {
static struct SAtaDisk *last_disk = NULL;
int i;
byte select, status, b1, b2;
uint16 bfr[256], w;
struct SAtaDisk *disk;

	select = (master ? 0xa0 : 0xb0);			// Set master / slave
	kprintf("%x\r\n", select);
	// Try to select the drive
	outb(select, channel + ATA_SELECT);
	// 400ns delay to allow channel time to select the drive
	for (i=0; i < 15; i++) {
		status = inb(channel + ATA_STATUS);
	}
	// The ATA specification says that we need to clear these ports to zero
	outw(0, channel + ATA_SECTOR_COUNT);
	outw(0, channel + ATA_LBA_LOW);
	outw(0, channel + ATA_LBA_MID);
	outw(0, channel + ATA_LBA_HIGH);
	// Send the IDENTIFY command
	outb(ATA_IDENTIFY, channel + ATA_COMMAND);
	// Check status. If zero, drive doesn't exist. Otherwise,
	// wait until BUSY clears;
	status = inb(channel + ATA_STATUS);
	if (status == 0) {
		return FALSE;
	}
	while (status & STATUS_BSY) {
		status = inb(channel + ATA_STATUS);
	}
	if (status & STATUS_ERR) {
		return FALSE;
	}
	// Check these ports for zero. If they are not zero the
	// drive is not an ATA drive.
	b1 = inb(channel + ATA_LBA_MID);
	b2 = inb(channel + ATA_LBA_HIGH);
	if ((b1 != 0) || (b2 != 0)) {
		return FALSE;
	}
	// Wait until DRQ or ERR is set
	status = inb(channel + ATA_STATUS);
	while (! (status & (STATUS_DRQ | STATUS_ERR))) {
		status = inb(channel + ATA_STATUS);
	}
	if (status & STATUS_ERR) {
		return FALSE;
	}

	// Read the IDENTIFY data
	for (i = 0; i < 256; i++) {
		bfr[i] = inw(channel + ATA_DATA);
	}
//	snap(&bfr[0], 256);

	// Create a disk control block from the IDENTIFY Data
	disk = kalloc(sizeof(struct SAtaDisk));
	if (! disk) {
		kputs("Out of memory in ata_init\r\n");
		panic();
	}
	if (! low_memory->first_ata) {
		low_memory->first_ata = disk;
	}
	if (last_disk) {
		last_disk->next = disk;
	}
	last_disk = disk;
	disk->channel = channel;
	disk->device = select;
	disk->dma = ATA_IDENT_DMA;
	disk->max_lba = bfr[ATA_IDENT_LBA28SECTORS] + (bfr[ATA_IDENT_LBA28SECTORS + 1] << 16);
	if (bfr[ATA_IDENT_SUPPORTLBA48] & 0x400) {
		disk->flags |= HD_LBA48;
	}
	if (disk->flags & HD_LBA48) {
		disk->max_lba = (uint64)bfr[ATA_IDENT_LBA28SECTORS] +
				        ((uint64)bfr[ATA_IDENT_LBA28SECTORS + 1] << 16) +
				        ((uint64)bfr[ATA_IDENT_LBA28SECTORS + 2] << 32) +
				        ((uint64)bfr[ATA_IDENT_LBA28SECTORS + 3] << 48);
	}
	for (i = 0; i < 40; i +=2) {
		w = bfr[ATA_IDENT_MODEL + (i / 2)];
		disk->model[i] = (w >> 8) & 0xff;
		disk->model[i+1] = w & 0xff;
	}
	bfr[40] = 0;

	return TRUE;
}

Code: Select all

int err = 0; // debugging
    int timeout = 0;
    while (1 && timeout < 10000) {
        // ATAPI devices are supposed to set ERR rather than BSY, and then DRQ
        // This is also needed to get CYL_LO and CYL_HI to be reads

        // NOTE: Some ATAPI devices do not set ERR (for some reason). Therefore we do the port check anyways to determine whether the device is ATAPI 
        uint8_t status = ide_read(device, ATA_REG_STATUS);
        if (status & ATA_SR_ERR) {
            // ERR was set
            err = 1;
            break; 
        } else if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRQ)) {
            // DRQ was set and BSY is cleared, likely an ATA device instead
            break;
        }

        timeout++; // Keep waiting...
    }

    // Did it timeout?
    if (timeout >= 10000) {
        LOG_DEVICE(INFO, device, "Timeout while waiting for ATA_CMD_IDENTIFY - assuming dead\n");
        return;
    }