prep for hotplug support

index 5f81136..4ce390a 100644
@@ -52,8 +52,9 @@
 #define SECTOR_SIZE	512
 
 typedef unsigned int (*ata_xlat_func_t)(struct ata_queued_cmd *qc, const u8 *scsicmd);
-static struct ata_device *
-ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev);
+
+static struct ata_device *__ata_scsi_find_dev(struct ata_port *ap,
+					      const struct scsi_device *scsidev);
 
 #define RW_RECOVERY_MPAGE 0x1
 #define RW_RECOVERY_MPAGE_LEN 12

@@ -2317,6 +2318,17 @@ static unsigned int atapi_xlat(struct at
 	return 0;
 }
 
+static struct ata_device *
+__ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev)
+{
+	/* skip commands not addressed to targets we simulate */
+	if (likely(scsidev->id < ATA_MAX_DEVICES &&
+		   scsidev->channel == 0 && scsidev->lun == 0))
+		return &ap->device[scsidev->id];
+
+	return NULL;
+}
+
 /**
  *	ata_scsi_find_dev - lookup ata_device from scsi_cmnd
  *	@ap: ATA port to which the device is attached

@@ -2333,23 +2345,12 @@ static unsigned int atapi_xlat(struct at
  *	RETURNS:
  *	Associated ATA device, or %NULL if not found.
  */
-
 static struct ata_device *
 ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev)
 {
-	struct ata_device *dev;
-
-	/* skip commands not addressed to targets we simulate */
-	if (likely(scsidev->id < ATA_MAX_DEVICES))
-		dev = &ap->device[scsidev->id];
-	else
-		return NULL;
-
-	if (unlikely((scsidev->channel != 0) ||
-		     (scsidev->lun != 0)))
-		return NULL;
+	struct ata_device *dev = __ata_scsi_find_dev(ap, scsidev);
 
-	if (unlikely(!ata_dev_enabled(dev)))
+	if (unlikely(!dev || !ata_dev_enabled(dev)))
 		return NULL;
 
 	if (!atapi_enabled || (ap->flags & ATA_FLAG_NO_ATAPI)) {

index 0509340..9c18526 100644
@@ -208,6 +208,8 @@ enum {
 	SERR_PERSISTENT		= (1 << 9), /* persistent data/comm error */
 	SERR_PROTOCOL		= (1 << 10), /* protocol violation */
 	SERR_INTERNAL		= (1 << 11), /* host internal error */
+	SERR_PHYRDY_CHG		= (1 << 16), /* PHY RDY changed */
+	SERR_DEV_XCHG		= (1 << 26), /* device exchanged */
 
 	/* struct ata_taskfile flags */
 	ATA_TFLAG_LBA48		= (1 << 0), /* enable 48-bit LBA and "HOB" */

index d49d4c7..1378b6f 100644
@@ -1433,6 +1433,27 @@ err_out_nosup:
 }
 
 /**
+ *	ata_dev_init - Initialize an ata_device structure
+ *	@ap: ATA port device to initialize is attached to
+ *	@dev: Device structure to initialize
+ *
+ *	Initialize @dev in preparation for probing.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+static void ata_dev_init(struct ata_port *ap, struct ata_device *dev)
+{
+	memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
+	       sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
+	dev->devno = dev - ap->device;
+	dev->pio_mask = UINT_MAX;
+	dev->mwdma_mask = UINT_MAX;
+	dev->udma_mask = UINT_MAX;
+	ata_ering_init(&dev->ering, ATA_DEV_ERING_SIZE);
+}
+
+/**
  *	ata_bus_probe - Reset and probe ATA bus
  *	@ap: Bus to probe
  *

@@ -4828,7 +4849,6 @@ static void ata_host_remove(struct ata_p
  *	LOCKING:
  *	Inherited from caller.
  */
-
 static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
 			  struct ata_host_set *host_set,
 			  const struct ata_probe_ent *ent, unsigned int port_no)

@@ -4865,11 +4885,7 @@ static void ata_host_init(struct ata_por
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
-		dev->devno = i;
-		dev->pio_mask = UINT_MAX;
-		dev->mwdma_mask = UINT_MAX;
-		dev->udma_mask = UINT_MAX;
-		ata_ering_init(&dev->ering, ATA_DEV_ERING_SIZE);
+		ata_dev_init(ap, dev);
 	}
 
 #ifdef ATA_IRQ_TRAP

index 1378b6f..3406f3d 100644
@@ -1446,7 +1446,6 @@ static void ata_dev_init(struct ata_port
 {
 	memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
 	       sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
-	dev->devno = dev - ap->device;
 	dev->pio_mask = UINT_MAX;
 	dev->mwdma_mask = UINT_MAX;
 	dev->udma_mask = UINT_MAX;

@@ -4885,6 +4884,7 @@ static void ata_host_init(struct ata_por
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
+		dev->devno = i;
 		ata_dev_init(ap, dev);
 	}
 

index e86d63c..809f3b9 100644
@@ -395,10 +395,11 @@ struct ata_ering {
 	struct ata_ering_entry	name_entries[size];
 
 struct ata_device {
+	unsigned int		devno;		/* 0 or 1 */
+	/* fields above n_sectors are not cleared across device init */
 	u64			n_sectors;	/* size of device, if ATA */
 	unsigned long		flags;		/* ATA_DFLAG_xxx */
 	unsigned int		class;		/* ATA_DEV_xxx */
-	unsigned int		devno;		/* 0 or 1 */
 	u16			*id;		/* IDENTIFY xxx DEVICE data */
 	u8			pio_mode;
 	u8			dma_mode;

@@ -423,6 +424,8 @@ struct ata_device {
 	DEFINE_ATA_ERING	(ering, ATA_DEV_ERING_SIZE);
 };
 
+#define ATA_DEVICE_CLEAR_OFFSET		offsetof(struct ata_device, n_sectors)
+
 struct ata_port {
 	struct Scsi_Host	*host;	/* our co-allocated scsi host */
 	const struct ata_port_operations *ops;

index 09e82f9..930f387 100644
@@ -1444,6 +1444,8 @@ err_out_nosup:
  */
 static void ata_dev_init(struct ata_port *ap, struct ata_device *dev)
 {
+	dev->flags &= ~ATA_DFLAG_INIT_MASK;
+
 	memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
 	       sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
 	dev->pio_mask = UINT_MAX;

index 809f3b9..33ce8a4 100644
@@ -128,6 +128,7 @@ enum {
 
 	ATA_DFLAG_PIO		= (1 << 8), /* device currently in PIO mode */
 	ATA_DFLAG_FAILED	= (1 << 9), /* device has failed */
+	ATA_DFLAG_INIT_MASK	= (1 << 16) - 1,
 
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */

@@ -396,9 +397,9 @@ struct ata_ering {
 
 struct ata_device {
 	unsigned int		devno;		/* 0 or 1 */
+	unsigned long		flags;		/* ATA_DFLAG_xxx */
 	/* fields above n_sectors are not cleared across device init */
 	u64			n_sectors;	/* size of device, if ATA */
-	unsigned long		flags;		/* ATA_DFLAG_xxx */
 	unsigned int		class;		/* ATA_DEV_xxx */
 	u16			*id;		/* IDENTIFY xxx DEVICE data */
 	u8			pio_mode;

index a6c984f..0206791 100644
@@ -1473,7 +1473,7 @@ static void ata_dev_init(struct ata_port
  *	the port has no enabled device after probing, or any negative
  *	errno from ->probe_reset.
  */
-static int ata_bus_probe(struct ata_port *ap)
+int ata_bus_probe(struct ata_port *ap)
 {
 	int existing_dev_failed = 0;
 	unsigned int classes[ATA_MAX_DEVICES];

index 7faa9a4..659badb 100644
@@ -43,6 +43,7 @@ struct ata_scsi_args {
 extern int atapi_enabled;
 extern int atapi_dmadir;
 extern int libata_fua;
+extern int ata_bus_probe(struct ata_port *ap);
 extern struct ata_queued_cmd *ata_qc_new_init(struct ata_port *ap,
 				      struct ata_device *dev);
 extern int ata_rwcmd_protocol(struct ata_queued_cmd *qc);

index 3406f3d..09e82f9 100644
@@ -1466,7 +1466,6 @@ static void ata_dev_init(struct ata_port
  *	RETURNS:
  *	Zero on success, negative errno otherwise.
  */
-
 static int ata_bus_probe(struct ata_port *ap)
 {
 	unsigned int classes[ATA_MAX_DEVICES];

@@ -1476,8 +1475,10 @@ static int ata_bus_probe(struct ata_port
 
 	ata_port_probe(ap);
 
-	for (i = 0; i < ATA_MAX_DEVICES; i++)
+	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		tries[i] = ATA_PROBE_MAX_TRIES;
+		ata_dev_init(ap, &ap->device[i]);
+	}
 
  retry:
 	down_xfermask = 0;

@@ -4882,11 +4883,8 @@ static void ata_host_init(struct ata_por
 	INIT_WORK(&ap->port_task, NULL, NULL);
 	INIT_LIST_HEAD(&ap->eh_done_q);
 
-	for (i = 0; i < ATA_MAX_DEVICES; i++) {
-		struct ata_device *dev = &ap->device[i];
-		dev->devno = i;
-		ata_dev_init(ap, dev);
-	}
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		ap->device[i].devno = i;
 
 #ifdef ATA_IRQ_TRAP
 	ap->stats.unhandled_irq = 1;

index 930f387..45ef1e2 100644
@@ -1444,6 +1444,9 @@ err_out_nosup:
  */
 static void ata_dev_init(struct ata_port *ap, struct ata_device *dev)
 {
+	/* for now, SATA spd limit is bound to the first device */
+	ap->sata_spd_limit = ap->orig_sata_spd_limit;
+
 	dev->flags &= ~ATA_DFLAG_INIT_MASK;
 
 	memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,

@@ -2503,17 +2506,10 @@ static int sata_phy_resume(struct ata_po
 void ata_std_probeinit(struct ata_port *ap)
 {
 	if ((ap->flags & ATA_FLAG_SATA) && ap->ops->scr_read) {
-		u32 spd;
-
 		/* set cable type and resume link */
 		ap->cbl = ATA_CBL_SATA;
 		sata_phy_resume(ap);
 
-		/* init sata_spd_limit to the current value */
-		spd = (scr_read(ap, SCR_CONTROL) & 0xf0) >> 4;
-		if (spd)
-			ap->sata_spd_limit &= (1 << spd) - 1;
-
 		/* wait for device */
 		if (sata_dev_present(ap))
 			ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

@@ -4878,7 +4874,7 @@ static void ata_host_init(struct ata_por
 	ap->flags |= ent->host_flags;
 	ap->ops = ent->port_ops;
 	ap->cbl = ATA_CBL_NONE;
-	ap->sata_spd_limit = UINT_MAX;
+	ap->orig_sata_spd_limit = UINT_MAX;
 	ap->active_tag = ATA_TAG_POISON;
 	ap->last_ctl = 0xFF;
 

@@ -5037,6 +5033,14 @@ int ata_device_add(const struct ata_prob
 
 		ap = host_set->ports[i];
 
+		/* init ap->orig_sata_spd_limit to boot value */
+		if ((ap->flags & ATA_FLAG_SATA) && ap->ops->scr_read) {
+			u32 spd;
+			spd = (scr_read(ap, SCR_CONTROL) & 0xf0) >> 4;
+			if (spd)
+				ap->orig_sata_spd_limit &= (1 << spd) - 1;
+		}
+
 		DPRINTK("ata%u: bus probe begin\n", ap->id);
 		rc = ata_bus_probe(ap);
 		DPRINTK("ata%u: bus probe end\n", ap->id);

index 33ce8a4..94f1e9a 100644
@@ -449,6 +449,7 @@ struct ata_port {
 	unsigned int		mwdma_mask;
 	unsigned int		udma_mask;
 	unsigned int		cbl;	/* cable type; ATA_CBL_xxx */
+	unsigned int		orig_sata_spd_limit; /* boot value */
 	unsigned int		sata_spd_limit;	/* SATA PHY speed limit */
 
 	struct ata_device	device[ATA_MAX_DEVICES];

index e68a64d..a6c984f 100644
@@ -1469,18 +1469,24 @@ static void ata_dev_init(struct ata_port
  *	PCI/etc. bus probe sem.
  *
  *	RETURNS:
- *	Zero on success, negative errno otherwise.
+ *	Zero on success, one if any existing device failed, -ENODEV if
+ *	the port has no enabled device after probing, or any negative
+ *	errno from ->probe_reset.
  */
 static int ata_bus_probe(struct ata_port *ap)
 {
+	int existing_dev_failed = 0;
 	unsigned int classes[ATA_MAX_DEVICES];
 	int tries[ATA_MAX_DEVICES];
 	int i, rc, down_xfermask;
 	struct ata_device *dev;
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
-		tries[i] = ATA_PROBE_MAX_TRIES;
-		ata_dev_init(ap, &ap->device[i]);
+		if (ap->device[i].class == ATA_DEV_UNKNOWN) {
+			tries[i] = ATA_PROBE_MAX_TRIES;
+			ata_dev_init(ap, &ap->device[i]);
+		} else
+			tries[i] = -1;
 	}
 
  retry:

@@ -1514,6 +1520,16 @@ static int ata_bus_probe(struct ata_port
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		dev = &ap->device[i];
 
+		/* Existing devices are EH's responsitbilities.  Just
+		 * revalidate them.
+		 */
+		if (tries[i] < 0) {
+			if (ata_dev_enabled(dev))
+				if (ata_dev_revalidate(ap, dev, 1))
+					existing_dev_failed = 1;
+			continue;
+		}
+
 		if (tries[i])
 			dev->class = classes[i];
 

@@ -1547,14 +1563,19 @@ static int ata_bus_probe(struct ata_port
 		rc = ata_set_mode(ap, &dev);
 
 	if (rc) {
-		down_xfermask = 1;
-		goto fail;
+		if (tries[dev->devno] < 0) {
+			existing_dev_failed = 1;
+		} else {
+			down_xfermask = 1;
+			goto fail;
+		}
 	}
 
+	rc = -ENODEV;
 	for (i = 0; i < ATA_MAX_DEVICES; i++)
 		if (ata_dev_enabled(&ap->device[i]))
-			return 0;
-	return -ENODEV;
+			rc = 0;
+	return existing_dev_failed ? 1 : rc;
 
  fail:
 	switch (rc) {

@@ -5041,7 +5062,7 @@ int ata_device_add(const struct ata_prob
 		rc = ata_bus_probe(ap);
 		DPRINTK("ata%u: bus probe end\n", ap->id);
 
-		if (rc && !ap->ops->error_handler) {
+		if (rc < 0 && !ap->ops->error_handler) {
 			/* no device attached and no hotplug support */
 			ata_port_disable(ap);
 			ap->ops->port_disable(ap);

index 94f1e9a..2a93c44 100644
@@ -130,6 +130,9 @@ enum {
 	ATA_DFLAG_FAILED	= (1 << 9), /* device has failed */
 	ATA_DFLAG_INIT_MASK	= (1 << 16) - 1,
 
+	ATA_DFLAG_DETACH_ATA	= (1 << 16), /* detach ATA device */
+	ATA_DFLAG_DETACH_SCSI	= (1 << 17), /* detach SCSI device */
+
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */
 	ATA_DEV_ATA_UNSUP	= 2,	/* ATA device (unsupported) */

@@ -161,9 +164,15 @@ enum {
 	ATA_FLAG_DISABLED	= (1 << 19), /* port is disabled, ignore it */
 	ATA_FLAG_FROZEN		= (1 << 20), /* port is frozen */
 	ATA_FLAG_SUSPENDED	= (1 << 21), /* port is suspended (power) */
-
 	/* bits 24:31 of ap->flags are reserved for LLDD specific flags */
 
+	/* struct ata_port hotplug_flags */
+	ATA_HOTPLUG_RUNNING	= (1 << 0), /* hotplugging online */
+	ATA_HOTPLUG_PROBE	= (1 << 1), /* probe requested */
+	ATA_HOTPLUG_DID_PROBE	= (1 << 2), /* already probed in this run */
+	ATA_HOTPLUG_SCSI_PLUG	= (1 << 3), /* SCSI hotplug scheduled */
+	ATA_HOTPLUG_SCSI_UNPLUG	= (1 << 4), /* SCSI hotunplug scheduled */
+
 	/* struct ata_queued_cmd flags */
 	ATA_QCFLAG_ACTIVE	= (1 << 0), /* cmd not yet ack'd to scsi lyer */
 	ATA_QCFLAG_SG		= (1 << 1), /* have s/g table? */

@@ -471,6 +480,8 @@ struct ata_port {
 	u32			msg_enable;
 	struct list_head	eh_done_q;
 
+	unsigned long		hotplug_flags;
+
 	void			*private_data;
 };
 

@@ -800,6 +811,30 @@ static inline unsigned int ata_dev_absen
 	return ata_class_absent(dev->class);
 }
 
+/* hotplug flag manipulation helpers */
+static inline void ata_set_hotplug_flags(struct ata_port *ap,
+					 unsigned int flags)
+{
+	unsigned long old;
+	do {
+		old = ap->hotplug_flags;
+	} while (cmpxchg(&ap->hotplug_flags, old, old | flags) != old);
+}
+
+static inline void ata_clr_hotplug_flags(struct ata_port *ap,
+					 unsigned int flags)
+{
+	unsigned long old;
+	do {
+		old = ap->hotplug_flags;
+	} while (cmpxchg(&ap->hotplug_flags, old, old & ~flags) != old);
+}
+
+static inline void ata_schedule_probe(struct ata_port *ap)
+{
+	ata_set_hotplug_flags(ap, ATA_HOTPLUG_PROBE);
+}
+
 static inline u8 ata_chk_status(struct ata_port *ap)
 {
 	return ap->ops->check_status(ap);

index 4ce390a..1793474 100644
@@ -2740,17 +2740,23 @@ void ata_scsi_simulate(struct ata_port *
 
 void ata_scsi_scan_host(struct ata_port *ap)
 {
-	struct ata_device *dev;
 	unsigned int i;
 
 	if (ap->flags & ATA_FLAG_DISABLED)
 		return;
 
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
-		dev = &ap->device[i];
+		struct ata_device *dev = &ap->device[i];
 
-		if (ata_dev_enabled(dev))
-			scsi_scan_target(&ap->host->shost_gendev, 0, i, 0, 0);
+		if (ata_dev_enabled(dev) && dev->sdev == NULL) {
+			struct scsi_device *sdev;
+
+			sdev = __scsi_add_device(ap->host, 0, i, 0, NULL);
+			if (!IS_ERR(sdev)) {
+				dev->sdev = sdev;
+				scsi_device_put(sdev);
+			}
+		}
 	}
 }
 

index 2a93c44..5f8faca 100644
@@ -407,6 +407,7 @@ struct ata_ering {
 struct ata_device {
 	unsigned int		devno;		/* 0 or 1 */
 	unsigned long		flags;		/* ATA_DFLAG_xxx */
+	struct scsi_device	*sdev;		/* attached SCSI device */
 	/* fields above n_sectors are not cleared across device init */
 	u64			n_sectors;	/* size of device, if ATA */
 	unsigned int		class;		/* ATA_DEV_xxx */

index 45ef1e2..e68a64d 100644
@@ -1478,8 +1478,6 @@ static int ata_bus_probe(struct ata_port
 	int i, rc, down_xfermask;
 	struct ata_device *dev;
 
-	ata_port_probe(ap);
-
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		tries[i] = ATA_PROBE_MAX_TRIES;
 		ata_dev_init(ap, &ap->device[i]);

@@ -1556,10 +1554,6 @@ static int ata_bus_probe(struct ata_port
 	for (i = 0; i < ATA_MAX_DEVICES; i++)
 		if (ata_dev_enabled(&ap->device[i]))
 			return 0;
-
-	/* no device present, disable port */
-	ata_port_disable(ap);
-	ap->ops->port_disable(ap);
 	return -ENODEV;
 
  fail:

@@ -5033,6 +5027,8 @@ int ata_device_add(const struct ata_prob
 
 		ap = host_set->ports[i];
 
+		ata_port_probe(ap);
+
 		/* init ap->orig_sata_spd_limit to boot value */
 		if ((ap->flags & ATA_FLAG_SATA) && ap->ops->scr_read) {
 			u32 spd;

@@ -5045,13 +5041,10 @@ int ata_device_add(const struct ata_prob
 		rc = ata_bus_probe(ap);
 		DPRINTK("ata%u: bus probe end\n", ap->id);
 
-		if (rc) {
-			/* FIXME: do something useful here?
-			 * Current libata behavior will
-			 * tear down everything when
-			 * the module is removed
-			 * or the h/w is unplugged.
-			 */
+		if (rc && !ap->ops->error_handler) {
+			/* no device attached and no hotplug support */
+			ata_port_disable(ap);
+			ap->ops->port_disable(ap);
 		}
 
 		rc = scsi_add_host(ap->host, dev);

index 0206791..610f963 100644
@@ -72,6 +72,8 @@ static void ata_dev_xfermask(struct ata_
 static unsigned int ata_unique_id = 1;
 static struct workqueue_struct *ata_wq;
 
+struct workqueue_struct *ata_hotplug_wq;
+
 int atapi_enabled = 1;
 module_param(atapi_enabled, int, 0444);
 MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");

@@ -5300,6 +5302,12 @@ static int __init ata_init(void)
 	if (!ata_wq)
 		return -ENOMEM;
 
+	ata_hotplug_wq = create_workqueue("ata_hotplug");
+	if (!ata_hotplug_wq) {
+		destroy_workqueue(ata_wq);
+		return -ENOMEM;
+	}
+
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
 }

@@ -5307,6 +5315,7 @@ static int __init ata_init(void)
 static void __exit ata_exit(void)
 {
 	destroy_workqueue(ata_wq);
+	destroy_workqueue(ata_hotplug_wq);
 }
 
 module_init(ata_init);

index 659badb..09fddf6 100644
@@ -40,6 +40,7 @@ struct ata_scsi_args {
 };
 
 /* libata-core.c */
+extern struct workqueue_struct *ata_hotplug_wq;
 extern int atapi_enabled;
 extern int atapi_dmadir;
 extern int libata_fua;