int ata_dev_read_id()

in libata-core.c [1753:1937]

• 119 lines of code
• 33 McCabe index (conditional complexity)

int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
		    unsigned int flags, u16 *id)
{
	struct ata_port *ap = dev->link->ap;
	unsigned int class = *p_class;
	struct ata_taskfile tf;
	unsigned int err_mask = 0;
	const char *reason;
	bool is_semb = class == ATA_DEV_SEMB;
	int may_fallback = 1, tried_spinup = 0;
	int rc;

retry:
	ata_tf_init(dev, &tf);

	switch (class) {
	case ATA_DEV_SEMB:
		class = ATA_DEV_ATA;	/* some hard drives report SEMB sig */
		fallthrough;
	case ATA_DEV_ATA:
	case ATA_DEV_ZAC:
		tf.command = ATA_CMD_ID_ATA;
		break;
	case ATA_DEV_ATAPI:
		tf.command = ATA_CMD_ID_ATAPI;
		break;
	default:
		rc = -ENODEV;
		reason = "unsupported class";
		goto err_out;
	}

	tf.protocol = ATA_PROT_PIO;

	/* Some devices choke if TF registers contain garbage.  Make
	 * sure those are properly initialized.
	 */
	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;

	/* Device presence detection is unreliable on some
	 * controllers.  Always poll IDENTIFY if available.
	 */
	tf.flags |= ATA_TFLAG_POLLING;

	if (ap->ops->read_id)
		err_mask = ap->ops->read_id(dev, &tf, (__le16 *)id);
	else
		err_mask = ata_do_dev_read_id(dev, &tf, (__le16 *)id);

	if (err_mask) {
		if (err_mask & AC_ERR_NODEV_HINT) {
			ata_dev_dbg(dev, "NODEV after polling detection\n");
			return -ENOENT;
		}

		if (is_semb) {
			ata_dev_info(dev,
		     "IDENTIFY failed on device w/ SEMB sig, disabled\n");
			/* SEMB is not supported yet */
			*p_class = ATA_DEV_SEMB_UNSUP;
			return 0;
		}

		if ((err_mask == AC_ERR_DEV) && (tf.feature & ATA_ABORTED)) {
			/* Device or controller might have reported
			 * the wrong device class.  Give a shot at the
			 * other IDENTIFY if the current one is
			 * aborted by the device.
			 */
			if (may_fallback) {
				may_fallback = 0;

				if (class == ATA_DEV_ATA)
					class = ATA_DEV_ATAPI;
				else
					class = ATA_DEV_ATA;
				goto retry;
			}

			/* Control reaches here iff the device aborted
			 * both flavors of IDENTIFYs which happens
			 * sometimes with phantom devices.
			 */
			ata_dev_dbg(dev,
				    "both IDENTIFYs aborted, assuming NODEV\n");
			return -ENOENT;
		}

		rc = -EIO;
		reason = "I/O error";
		goto err_out;
	}

	if (dev->horkage & ATA_HORKAGE_DUMP_ID) {
		ata_dev_info(dev, "dumping IDENTIFY data, "
			    "class=%d may_fallback=%d tried_spinup=%d\n",
			    class, may_fallback, tried_spinup);
		print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET,
			       16, 2, id, ATA_ID_WORDS * sizeof(*id), true);
	}

	/* Falling back doesn't make sense if ID data was read
	 * successfully at least once.
	 */
	may_fallback = 0;

	swap_buf_le16(id, ATA_ID_WORDS);

	/* sanity check */
	rc = -EINVAL;
	reason = "device reports invalid type";

	if (class == ATA_DEV_ATA || class == ATA_DEV_ZAC) {
		if (!ata_id_is_ata(id) && !ata_id_is_cfa(id))
			goto err_out;
		if (ap->host->flags & ATA_HOST_IGNORE_ATA &&
							ata_id_is_ata(id)) {
			ata_dev_dbg(dev,
				"host indicates ignore ATA devices, ignored\n");
			return -ENOENT;
		}
	} else {
		if (ata_id_is_ata(id))
			goto err_out;
	}

	if (!tried_spinup && (id[2] == 0x37c8 || id[2] == 0x738c)) {
		tried_spinup = 1;
		/*
		 * Drive powered-up in standby mode, and requires a specific
		 * SET_FEATURES spin-up subcommand before it will accept
		 * anything other than the original IDENTIFY command.
		 */
		err_mask = ata_dev_set_feature(dev, SETFEATURES_SPINUP, 0);
		if (err_mask && id[2] != 0x738c) {
			rc = -EIO;
			reason = "SPINUP failed";
			goto err_out;
		}
		/*
		 * If the drive initially returned incomplete IDENTIFY info,
		 * we now must reissue the IDENTIFY command.
		 */
		if (id[2] == 0x37c8)
			goto retry;
	}

	if ((flags & ATA_READID_POSTRESET) &&
	    (class == ATA_DEV_ATA || class == ATA_DEV_ZAC)) {
		/*
		 * The exact sequence expected by certain pre-ATA4 drives is:
		 * SRST RESET
		 * IDENTIFY (optional in early ATA)
		 * INITIALIZE DEVICE PARAMETERS (later IDE and ATA)
		 * anything else..
		 * Some drives were very specific about that exact sequence.
		 *
		 * Note that ATA4 says lba is mandatory so the second check
		 * should never trigger.
		 */
		if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
			err_mask = ata_dev_init_params(dev, id[3], id[6]);
			if (err_mask) {
				rc = -EIO;
				reason = "INIT_DEV_PARAMS failed";
				goto err_out;
			}

			/* current CHS translation info (id[53-58]) might be
			 * changed. reread the identify device info.
			 */
			flags &= ~ATA_READID_POSTRESET;
			goto retry;
		}
	}

	*p_class = class;

	return 0;

 err_out:
	ata_dev_warn(dev, "failed to IDENTIFY (%s, err_mask=0x%x)\n",
		     reason, err_mask);
	return rc;
}