libata: Handle drives that require a spin-up command before first access

(S)ATA drives can be configured for "power-up in standby",
a mode whereby a specific "spin up now!" command is required
before the first media access.

Currently, a drive with this feature enabled can not be used at all
with libata, and once in this mode, the drive becomes a doorstop.

The older drivers/ide subsystem at least enumerates the drive,
so that it can be woken up after the fact from a userspace HDIO_*
command, but not libata.

This patch adds support to libata for the "power-up in standby"
mode where a "spin up now!" command (SET_FEATURES) is needed.
With this, libata will recognize such drives, spin them up,
and then re-IDENTIFY them if necessary to get a full/complete
set of drive features data.

Drives in this state are determined by looking for
special values in id[2], as documented in the current ATA specs.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-core.c

@@ -1649,13 +1649,13 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
 	struct ata_taskfile tf;
 	unsigned int err_mask = 0;
 	const char *reason;
+	int tried_spinup = 0;
 	int rc;
 
 	if (ata_msg_ctl(ap))
 		ata_dev_printk(dev, KERN_DEBUG, "%s: ENTER\n", __FUNCTION__);
 
 	ata_dev_select(ap, dev->devno, 1, 1); /* select device 0/1 */
-
  retry:
 	ata_tf_init(dev, &tf);
 
@@ -1712,6 +1712,32 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
 			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.
+		 */
+		ata_tf_init(dev, &tf);
+		tf.command = ATA_CMD_SET_FEATURES;
+		tf.feature = SETFEATURES_SPINUP;
+		tf.protocol = ATA_PROT_NODATA;
+		tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+		err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0);
+		if (err_mask) {
+			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) {
 		/*
 		 * The exact sequence expected by certain pre-ATA4 drives is:

include/linux/ata.h

@@ -202,6 +202,8 @@ enum {
 	SETFEATURES_WC_ON	= 0x02, /* Enable write cache */
 	SETFEATURES_WC_OFF	= 0x82, /* Disable write cache */
 
+	SETFEATURES_SPINUP	= 0x07, /* Spin-up drive */
+
 	/* ATAPI stuff */
 	ATAPI_PKT_DMA		= (1 << 0),
 	ATAPI_DMADIR		= (1 << 2),	/* ATAPI data dir: