libata: add a host flag to ignore detected ATA devices

commit db63a4c8 upstream.

Where devices are visible via more than one host we sometimes wish to
indicate that cirtain devices should be ignored on a specific host.  Add a
host flag indicating that this host wishes to ignore ATA specific devices.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Cc: Victor Miasnikov <vvm@tut.by>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ata/libata-core.c

@@ -1973,6 +1973,12 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
 	if (class == ATA_DEV_ATA) {
 		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;

include/linux/libata.h

@@ -247,6 +247,7 @@ enum {
 	ATA_HOST_SIMPLEX	= (1 << 0),	/* Host is simplex, one DMA channel per host only */
 	ATA_HOST_STARTED	= (1 << 1),	/* Host started */
 	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
+	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
 
 	/* bits 24:31 of host->flags are reserved for LLD specific flags */