libata-pmp: implement Port Multiplier support

Implement Port Multiplier support.  To support PMP, a LLDD has to
supply ops->pmp_read() and pmp_write().  If non-null, ->pmp_attach and
->pmp_detach are called on PMP attach and detach, respectively.

->pmp_read/write() can be called while the port is frozen, so they
must be implemented by polling.  This patch supplies several helpers
to ease ->pmp_read/write() implementation.

Also, irq_handler and error_handler must be PMP aware.  Most of PMP
aware EH can be done by calling ata_pmp_do_eh() with appropriate
methods.  PMP EH uses separate set of reset methods and this patch
implements standard prereset, hardreset and postreset methods.

This patch only implements PMP support.  The next patch will integrate
PMP into the reset of libata and thus enable PMP support.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 1182 insertions, 0 deletions

diff --git a/drivers/ata/libata-pmp.c b/drivers/ata/libata-pmp.c
new file mode 100644
index 000000000000..671d171055a3
--- /dev/null
+++ b/drivers/ata/libata-pmp.c
@@ -0,0 +1,1182 @@
+/*
+ * libata-pmp.c - libata port multiplier support
+ *
+ * Copyright (c) 2007  SUSE Linux Products GmbH
+ * Copyright (c) 2007  Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/libata.h>
+#include "libata.h"
+
+/**
+ *	sata_pmp_read - read PMP register
+ *	@link: link to read PMP register for
+ *	@reg: register to read
+ *	@r_val: resulting value
+ *
+ *	Wrapper around ap->ops->pmp_read to make it easier to call and
+ *	nomarlize error return value.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sata_pmp_read(struct ata_link *link, int reg, u32 *r_val)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_device *pmp_dev = ap->link.device;
+	int rc;
+
+	might_sleep();
+
+	rc = ap->ops->pmp_read(pmp_dev, link->pmp, reg, r_val);
+	if (rc)
+		rc = -EIO;
+	return rc;
+}
+
+/**
+ *	sata_pmp_write - write PMP register
+ *	@link: link to write PMP register for
+ *	@reg: register to write
+ *	@r_val: value to write
+ *
+ *	Wrapper around ap->ops->pmp_write to make it easier to call
+ *	and nomarlize error return value.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sata_pmp_write(struct ata_link *link, int reg, u32 val)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_device *pmp_dev = ap->link.device;
+	int rc;
+
+	might_sleep();
+
+	rc = ap->ops->pmp_write(pmp_dev, link->pmp, reg, val);
+	if (rc)
+		rc = -EIO;
+	return rc;
+}
+
+/**
+ *	sata_pmp_read_init_tf - initialize TF for PMP read
+ *	@tf: taskfile to initialize
+ *	@dev: PMP dev
+ *	@pmp: port multiplier port number
+ *	@reg: register to read
+ *
+ *	Initialize @tf for PMP read command.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void sata_pmp_read_init_tf(struct ata_taskfile *tf,
+			   struct ata_device *dev, int pmp, int reg)
+{
+	ata_tf_init(dev, tf);
+	tf->command = ATA_CMD_PMP_READ;
+	tf->protocol = ATA_PROT_NODATA;
+	tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf->feature = reg;
+	tf->device = pmp;
+}
+
+/**
+ *	sata_pmp_read_val - extract PMP read result from TF
+ *	@tf: target TF
+ *
+ *	Determine PMP read result from @tf.
+ *
+ *	LOCKING:
+ *	None.
+ */
+u32 sata_pmp_read_val(const struct ata_taskfile *tf)
+{
+	return tf->nsect | tf->lbal << 8 | tf->lbam << 16 | tf->lbah << 24;
+}
+
+/**
+ *	sata_pmp_read_init_tf - initialize TF for PMP write
+ *	@tf: taskfile to initialize
+ *	@dev: PMP dev
+ *	@pmp: port multiplier port number
+ *	@reg: register to read
+ *	@val: value to write
+ *
+ *	Initialize @tf for PMP write command.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void sata_pmp_write_init_tf(struct ata_taskfile *tf,
+			    struct ata_device *dev, int pmp, int reg, u32 val)
+{
+	ata_tf_init(dev, tf);
+	tf->command = ATA_CMD_PMP_WRITE;
+	tf->protocol = ATA_PROT_NODATA;
+	tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf->feature = reg;
+	tf->device = pmp;
+	tf->nsect = val & 0xff;
+	tf->lbal = (val >> 8) & 0xff;
+	tf->lbam = (val >> 16) & 0xff;
+	tf->lbah = (val >> 24) & 0xff;
+}
+
+/**
+ *	sata_pmp_scr_read - read PSCR
+ *	@link: ATA link to read PSCR for
+ *	@reg: PSCR to read
+ *	@r_val: resulting value
+ *
+ *	Read PSCR @reg into @r_val for @link, to be called from
+ *	ata_scr_read().
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *r_val)
+{
+	if (reg > SATA_PMP_PSCR_CONTROL)
+		return -EINVAL;
+
+	return sata_pmp_read(link, reg, r_val);
+}
+
+/**
+ *	sata_pmp_scr_write - write PSCR
+ *	@link: ATA link to write PSCR for
+ *	@reg: PSCR to write
+ *	@val: value to be written
+ *
+ *	Write @val to PSCR @reg for @link, to be called from
+ *	ata_scr_write() and ata_scr_write_flush().
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val)
+{
+	if (reg > SATA_PMP_PSCR_CONTROL)
+		return -EINVAL;
+
+	return sata_pmp_write(link, reg, val);
+}
+
+/**
+ *	sata_pmp_std_prereset - prepare PMP link for reset
+ *	@link: link to be reset
+ *	@deadline: deadline jiffies for the operation
+ *
+ *	@link is about to be reset.  Initialize it.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+int sata_pmp_std_prereset(struct ata_link *link, unsigned long deadline)
+{
+	struct ata_eh_context *ehc = &link->eh_context;
+	const unsigned long *timing = sata_ehc_deb_timing(ehc);
+	int rc;
+
+	/* force HRST? */
+	if (link->flags & ATA_LFLAG_NO_SRST)
+		ehc->i.action |= ATA_EH_HARDRESET;
+
+	/* handle link resume */
+	if ((ehc->i.flags & ATA_EHI_RESUME_LINK) &&
+	    (link->flags & ATA_LFLAG_HRST_TO_RESUME))
+		ehc->i.action |= ATA_EH_HARDRESET;
+
+	/* if we're about to do hardreset, nothing more to do */
+	if (ehc->i.action & ATA_EH_HARDRESET)
+		return 0;
+
+	/* resume link */
+	rc = sata_link_resume(link, timing, deadline);
+	if (rc) {
+		/* phy resume failed */
+		ata_link_printk(link, KERN_WARNING, "failed to resume link "
+				"for reset (errno=%d)\n", rc);
+		return rc;
+	}
+
+	/* clear SError bits including .X which blocks the port when set */
+	rc = sata_scr_write(link, SCR_ERROR, 0xffffffff);
+	if (rc) {
+		ata_link_printk(link, KERN_ERR,
+				"failed to clear SError (errno=%d)\n", rc);
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ *	sata_pmp_std_hardreset - standard hardreset method for PMP link
+ *	@link: link to be reset
+ *	@class: resulting class of attached device
+ *	@deadline: deadline jiffies for the operation
+ *
+ *	Hardreset PMP port @link.  Note that this function doesn't
+ *	wait for BSY clearance.  There simply isn't a generic way to
+ *	wait the event.  Instead, this function return -EAGAIN thus
+ *	telling libata-EH to followup with softreset.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+int sata_pmp_std_hardreset(struct ata_link *link, unsigned int *class,
+			   unsigned long deadline)
+{
+	const unsigned long *timing = sata_ehc_deb_timing(&link->eh_context);
+	u32 tmp;
+	int rc;
+
+	DPRINTK("ENTER\n");
+
+	/* do hardreset */
+	rc = sata_link_hardreset(link, timing, deadline);
+	if (rc) {
+		ata_link_printk(link, KERN_ERR,
+				"COMRESET failed (errno=%d)\n", rc);
+		goto out;
+	}
+
+	/* clear SError bits including .X which blocks the port when set */
+	rc = sata_scr_write(link, SCR_ERROR, 0xffffffff);
+	if (rc) {
+		ata_link_printk(link, KERN_ERR, "failed to clear SError "
+				"during hardreset (errno=%d)\n", rc);
+		goto out;
+	}
+
+	/* if device is present, follow up with srst to wait for !BSY */
+	if (ata_link_online(link))
+		rc = -EAGAIN;
+ out:
+	/* if SCR isn't accessible, we need to reset the PMP */
+	if (rc && rc != -EAGAIN && sata_scr_read(link, SCR_STATUS, &tmp))
+		rc = -ERESTART;
+
+	DPRINTK("EXIT, rc=%d\n", rc);
+	return rc;
+}
+
+/**
+ *	ata_std_postreset - standard postreset method for PMP link
+ *	@link: the target ata_link
+ *	@classes: classes of attached devices
+ *
+ *	This function is invoked after a successful reset.  Note that
+ *	the device might have been reset more than once using
+ *	different reset methods before postreset is invoked.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ */
+void sata_pmp_std_postreset(struct ata_link *link, unsigned int *class)
+{
+	u32 serror;
+
+	DPRINTK("ENTER\n");
+
+	/* clear SError */
+	if (sata_scr_read(link, SCR_ERROR, &serror) == 0)
+		sata_scr_write(link, SCR_ERROR, serror);
+
+	/* print link status */
+	sata_print_link_status(link);
+
+	DPRINTK("EXIT\n");
+}
+
+/**
+ *	sata_pmp_read_gscr - read GSCR block of SATA PMP
+ *	@dev: PMP device
+ *	@gscr: buffer to read GSCR block into
+ *
+ *	Read selected PMP GSCRs from the PMP at @dev.  This will serve
+ *	as configuration and identification info for the PMP.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sata_pmp_read_gscr(struct ata_device *dev, u32 *gscr)
+{
+	static const int gscr_to_read[] = { 0, 1, 2, 32, 33, 64, 96 };
+	int i, rc;
+
+	for (i = 0; i < ARRAY_SIZE(gscr_to_read); i++) {
+		int reg = gscr_to_read[i];
+
+		rc = sata_pmp_read(dev->link, reg, &gscr[reg]);
+		if (rc) {
+			ata_dev_printk(dev, KERN_ERR, "failed to read "
+				       "PMP GSCR[%d] (errno=%d)\n", reg, rc);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static const char *sata_pmp_spec_rev_str(const u32 *gscr)
+{
+	u32 rev = gscr[SATA_PMP_GSCR_REV];
+
+	if (rev & (1 << 2))
+		return "1.1";
+	if (rev & (1 << 1))
+		return "1.0";
+	return "<unknown>";
+}
+
+static int sata_pmp_configure(struct ata_device *dev, int print_info)
+{
+	struct ata_port *ap = dev->link->ap;
+	u32 *gscr = dev->gscr;
+	const char *reason;
+	int nr_ports, rc;
+
+	nr_ports = sata_pmp_gscr_ports(gscr);
+
+	if (nr_ports <= 0 || nr_ports > SATA_PMP_MAX_PORTS) {
+		rc = -EINVAL;
+		reason = "invalid nr_ports";
+		goto fail;
+	}
+
+	if ((ap->flags & ATA_FLAG_AN) &&
+	    (gscr[SATA_PMP_GSCR_FEAT] & SATA_PMP_FEAT_NOTIFY))
+		dev->flags |= ATA_DFLAG_AN;
+
+	/* monitor SERR_PHYRDY_CHG on fan-out ports */
+	rc = sata_pmp_write(dev->link, SATA_PMP_GSCR_ERROR_EN, SERR_PHYRDY_CHG);
+	if (rc) {
+		reason = "failed to write GSCR_ERROR_EN";
+		goto fail;
+	}
+
+	/* turn off notification till fan-out ports are reset and configured */
+	if (gscr[SATA_PMP_GSCR_FEAT_EN] & SATA_PMP_FEAT_NOTIFY) {
+		gscr[SATA_PMP_GSCR_FEAT_EN] &= ~SATA_PMP_FEAT_NOTIFY;
+
+		rc = sata_pmp_write(dev->link, SATA_PMP_GSCR_FEAT_EN,
+				    gscr[SATA_PMP_GSCR_FEAT_EN]);
+		if (rc) {
+			reason = "failed to write GSCR_FEAT_EN";
+			goto fail;
+		}
+	}
+
+	if (print_info) {
+		ata_dev_printk(dev, KERN_INFO, "Port Multiplier %s, "
+			       "0x%04x:0x%04x r%d, %d ports, feat 0x%x/0x%x\n",
+			       sata_pmp_spec_rev_str(gscr),
+			       sata_pmp_gscr_vendor(gscr),
+			       sata_pmp_gscr_devid(gscr),
+			       sata_pmp_gscr_rev(gscr),
+			       nr_ports, gscr[SATA_PMP_GSCR_FEAT_EN],
+			       gscr[SATA_PMP_GSCR_FEAT]);
+
+		if (!(dev->flags & ATA_DFLAG_AN))
+			ata_dev_printk(dev, KERN_INFO,
+				"Asynchronous notification not supported, "
+				"hotplug won't\n         work on fan-out "
+				"ports. Use warm-plug instead.\n");
+	}
+
+	return 0;
+
+ fail:
+	ata_dev_printk(dev, KERN_ERR,
+		       "failed to configure Port Multiplier (%s)\n", reason);
+	return rc;
+}
+
+static int sata_pmp_init_links(struct ata_port *ap, int nr_ports)
+{
+	struct ata_link *pmp_link = ap->pmp_link;
+	int i;
+
+	if (!pmp_link) {
+		pmp_link = kzalloc(sizeof(pmp_link[0]) * SATA_PMP_MAX_PORTS,
+				   GFP_NOIO);
+		if (!pmp_link)
+			return -ENOMEM;
+
+		for (i = 0; i < SATA_PMP_MAX_PORTS; i++)
+			ata_link_init(ap, &pmp_link[i], i);
+
+		ap->pmp_link = pmp_link;
+	}
+
+	for (i = 0; i < nr_ports; i++) {
+		struct ata_link *link = &pmp_link[i];
+		struct ata_eh_context *ehc = &link->eh_context;
+
+		link->flags = 0;
+		ehc->i.probe_mask |= 1;
+		ehc->i.action |= ATA_EH_SOFTRESET;
+		ehc->i.flags |= ATA_EHI_RESUME_LINK;
+	}
+
+	return 0;
+}
+
+static void sata_pmp_quirks(struct ata_port *ap)
+{
+	u32 *gscr = ap->link.device->gscr;
+	u16 vendor = sata_pmp_gscr_vendor(gscr);
+	u16 devid = sata_pmp_gscr_devid(gscr);
+	struct ata_link *link;
+
+	if (vendor == 0x1095 && devid == 0x3726) {
+		/* sil3726 quirks */
+		ata_port_for_each_link(link, ap) {
+			/* SError.N need a kick in the ass to get working */
+			link->flags |= ATA_LFLAG_HRST_TO_RESUME;
+
+			/* class code report is unreliable */
+			if (link->pmp < 5)
+				link->flags |= ATA_LFLAG_ASSUME_ATA;
+
+			/* port 5 is for SEMB device and it doesn't like SRST */
+			if (link->pmp == 5)
+				link->flags |= ATA_LFLAG_NO_SRST |
+					       ATA_LFLAG_ASSUME_SEMB;
+		}
+	} else if (vendor == 0x1095 && devid == 0x4723) {
+		/* sil4723 quirks */
+		ata_port_for_each_link(link, ap) {
+			/* SError.N need a kick in the ass to get working */
+			link->flags |= ATA_LFLAG_HRST_TO_RESUME;
+
+			/* class code report is unreliable */
+			if (link->pmp < 2)
+				link->flags |= ATA_LFLAG_ASSUME_ATA;
+
+			/* the config device at port 2 locks up on SRST */
+			if (link->pmp == 2)
+				link->flags |= ATA_LFLAG_NO_SRST |
+					       ATA_LFLAG_ASSUME_ATA;
+		}
+	} else if (vendor == 0x1095 && devid == 0x4726) {
+		/* sil4726 quirks */
+		ata_port_for_each_link(link, ap) {
+			/* SError.N need a kick in the ass to get working */
+			link->flags |= ATA_LFLAG_HRST_TO_RESUME;
+
+			/* class code report is unreliable */
+			if (link->pmp < 5)
+				link->flags |= ATA_LFLAG_ASSUME_ATA;
+
+			/* The config device, which can be either at
+			 * port 0 or 5, locks up on SRST.
+			 */
+			if (link->pmp == 0 || link->pmp == 5)
+				link->flags |= ATA_LFLAG_NO_SRST |
+					       ATA_LFLAG_ASSUME_ATA;
+
+			/* Port 6 is for SEMB device which doesn't
+			 * like SRST either.
+			 */
+			if (link->pmp == 6)
+				link->flags |= ATA_LFLAG_NO_SRST |
+					       ATA_LFLAG_ASSUME_SEMB;
+		}
+	} else if (vendor == 0x1095 && (devid == 0x5723 || devid == 0x5733 ||
+					devid == 0x5734 || devid == 0x5744)) {
+		/* sil5723/5744 quirks */
+
+		/* sil5723/5744 has either two or three downstream
+		 * ports depending on operation mode.  The last port
+		 * is empty if any actual IO device is available or
+		 * occupied by a pseudo configuration device
+		 * otherwise.  Don't try hard to recover it.
+		 */
+		ap->pmp_link[ap->nr_pmp_links - 1].flags |= ATA_LFLAG_NO_RETRY;
+	} else if (vendor == 0x11ab && devid == 0x4140) {
+		/* Marvell 88SM4140 quirks.  Fan-out ports require PHY
+		 * reset to work; other than that, it behaves very
+		 * nicely.
+		 */
+		ata_port_for_each_link(link, ap)
+			link->flags |= ATA_LFLAG_HRST_TO_RESUME;
+	}
+}
+
+/**
+ *	sata_pmp_attach - attach a SATA PMP device
+ *	@dev: SATA PMP device to attach
+ *
+ *	Configure and attach SATA PMP device @dev.  This function is
+ *	also responsible for allocating and initializing PMP links.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_pmp_attach(struct ata_device *dev)
+{
+	struct ata_link *link = dev->link;
+	struct ata_port *ap = link->ap;
+	unsigned long flags;
+	struct ata_link *tlink;
+	int rc;
+
+	/* is it hanging off the right place? */
+	if (!(ap->flags & ATA_FLAG_PMP)) {
+		ata_dev_printk(dev, KERN_ERR,
+			       "host does not support Port Multiplier\n");
+		return -EINVAL;
+	}
+
+	if (!ata_is_host_link(link)) {
+		ata_dev_printk(dev, KERN_ERR,
+			       "Port Multipliers cannot be nested\n");
+		return -EINVAL;
+	}
+
+	if (dev->devno) {
+		ata_dev_printk(dev, KERN_ERR,
+			       "Port Multiplier must be the first device\n");
+		return -EINVAL;
+	}
+
+	WARN_ON(link->pmp != 0);
+	link->pmp = SATA_PMP_CTRL_PORT;
+
+	/* read GSCR block */
+	rc = sata_pmp_read_gscr(dev, dev->gscr);
+	if (rc)
+		goto fail;
+
+	/* config PMP */
+	rc = sata_pmp_configure(dev, 1);
+	if (rc)
+		goto fail;
+
+	rc = sata_pmp_init_links(ap, sata_pmp_gscr_ports(dev->gscr));
+	if (rc) {
+		ata_dev_printk(dev, KERN_INFO,
+			       "failed to initialize PMP links\n");
+		goto fail;
+	}
+
+	/* attach it */
+	spin_lock_irqsave(ap->lock, flags);
+	WARN_ON(ap->nr_pmp_links);
+	ap->nr_pmp_links = sata_pmp_gscr_ports(dev->gscr);
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	sata_pmp_quirks(ap);
+
+	if (ap->ops->pmp_attach)
+		ap->ops->pmp_attach(ap);
+
+	ata_port_for_each_link(tlink, ap)
+		sata_link_init_spd(tlink);
+
+	return 0;
+
+ fail:
+	link->pmp = 0;
+	return rc;
+}
+
+/**
+ *	sata_pmp_detach - detach a SATA PMP device
+ *	@dev: SATA PMP device to detach
+ *
+ *	Detach SATA PMP device @dev.  This function is also
+ *	responsible for deconfiguring PMP links.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void sata_pmp_detach(struct ata_device *dev)
+{
+	struct ata_link *link = dev->link;
+	struct ata_port *ap = link->ap;
+	struct ata_link *tlink;
+	unsigned long flags;
+
+	ata_dev_printk(dev, KERN_INFO, "Port Multiplier detaching\n");
+
+	WARN_ON(!ata_is_host_link(link) || dev->devno ||
+		link->pmp != SATA_PMP_CTRL_PORT);
+
+	if (ap->ops->pmp_detach)
+		ap->ops->pmp_detach(ap);
+
+	ata_port_for_each_link(tlink, ap)
+		ata_eh_detach_dev(tlink->device);
+
+	spin_lock_irqsave(ap->lock, flags);
+	ap->nr_pmp_links = 0;
+	link->pmp = 0;
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	sata_pmp_same_pmp - does new GSCR matches the configured PMP?
+ *	@dev: PMP device to compare against
+ *	@new_gscr: GSCR block of the new device
+ *
+ *	Compare @new_gscr against @dev and determine whether @dev is
+ *	the PMP described by @new_gscr.
+ *
+ *	LOCKING:
+ *	None.
+ *
+ *	RETURNS:
+ *	1 if @dev matches @new_gscr, 0 otherwise.
+ */
+static int sata_pmp_same_pmp(struct ata_device *dev, const u32 *new_gscr)
+{
+	const u32 *old_gscr = dev->gscr;
+	u16 old_vendor, new_vendor, old_devid, new_devid;
+	int old_nr_ports, new_nr_ports;
+
+	old_vendor = sata_pmp_gscr_vendor(old_gscr);
+	new_vendor = sata_pmp_gscr_vendor(new_gscr);
+	old_devid = sata_pmp_gscr_devid(old_gscr);
+	new_devid = sata_pmp_gscr_devid(new_gscr);
+	old_nr_ports = sata_pmp_gscr_ports(old_gscr);
+	new_nr_ports = sata_pmp_gscr_ports(new_gscr);
+
+	if (old_vendor != new_vendor) {
+		ata_dev_printk(dev, KERN_INFO, "Port Multiplier "
+			       "vendor mismatch '0x%x' != '0x%x'\n",
+			       old_vendor, new_vendor);
+		return 0;
+	}
+
+	if (old_devid != new_devid) {
+		ata_dev_printk(dev, KERN_INFO, "Port Multiplier "
+			       "device ID mismatch '0x%x' != '0x%x'\n",
+			       old_devid, new_devid);
+		return 0;
+	}
+
+	if (old_nr_ports != new_nr_ports) {
+		ata_dev_printk(dev, KERN_INFO, "Port Multiplier "
+			       "nr_ports mismatch '0x%x' != '0x%x'\n",
+			       old_nr_ports, new_nr_ports);
+		return 0;
+	}
+
+	return 1;
+}
+
+/**
+ *	sata_pmp_revalidate - revalidate SATA PMP
+ *	@dev: PMP device to revalidate
+ *	@new_class: new class code
+ *
+ *	Re-read GSCR block and make sure @dev is still attached to the
+ *	port and properly configured.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+static int sata_pmp_revalidate(struct ata_device *dev, unsigned int new_class)
+{
+	struct ata_link *link = dev->link;
+	struct ata_port *ap = link->ap;
+	u32 *gscr = (void *)ap->sector_buf;
+	int rc;
+
+	DPRINTK("ENTER\n");
+
+	ata_eh_about_to_do(link, NULL, ATA_EH_REVALIDATE);
+
+	if (!ata_dev_enabled(dev)) {
+		rc = -ENODEV;
+		goto fail;
+	}
+
+	/* wrong class? */
+	if (ata_class_enabled(new_class) && new_class != ATA_DEV_PMP) {
+		rc = -ENODEV;
+		goto fail;
+	}
+
+	/* read GSCR */
+	rc = sata_pmp_read_gscr(dev, gscr);
+	if (rc)
+		goto fail;
+
+	/* is the pmp still there? */
+	if (!sata_pmp_same_pmp(dev, gscr)) {
+		rc = -ENODEV;
+		goto fail;
+	}
+
+	memcpy(dev->gscr, gscr, sizeof(gscr[0]) * SATA_PMP_GSCR_DWORDS);
+
+	rc = sata_pmp_configure(dev, 0);
+	if (rc)
+		goto fail;
+
+	ata_eh_done(link, NULL, ATA_EH_REVALIDATE);
+
+	DPRINTK("EXIT, rc=0\n");
+	return 0;
+
+ fail:
+	ata_dev_printk(dev, KERN_ERR,
+		       "PMP revalidation failed (errno=%d)\n", rc);
+	DPRINTK("EXIT, rc=%d\n", rc);
+	return rc;
+}
+
+/**
+ *	sata_pmp_revalidate_quick - revalidate SATA PMP quickly
+ *	@dev: PMP device to revalidate
+ *
+ *	Make sure the attached PMP is accessible.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+static int sata_pmp_revalidate_quick(struct ata_device *dev)
+{
+	u32 prod_id;
+	int rc;
+
+	rc = sata_pmp_read(dev->link, SATA_PMP_GSCR_PROD_ID, &prod_id);
+	if (rc) {
+		ata_dev_printk(dev, KERN_ERR, "failed to read PMP product ID\n");
+		return rc;
+	}
+
+	if (prod_id != dev->gscr[SATA_PMP_GSCR_PROD_ID]) {
+		ata_dev_printk(dev, KERN_ERR, "PMP product ID mismatch\n");
+		/* something weird is going on, request full PMP recovery */
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ *	sata_pmp_eh_recover_pmp - recover PMP
+ *	@ap: ATA port PMP is attached to
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method
+ *	@hardreset: hardreset method
+ *	@postreset: postreset method (can be NULL)
+ *
+ *	Recover PMP attached to @ap.  Recovery procedure is somewhat
+ *	similar to that of ata_eh_recover() except that reset should
+ *	always be performed in hard->soft sequence and recovery
+ *	failure results in PMP detachment.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sata_pmp_eh_recover_pmp(struct ata_port *ap,
+		ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+		ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+{
+	struct ata_link *link = &ap->link;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev = link->device;
+	int tries = ATA_EH_PMP_TRIES;
+	int detach = 0, rc = 0;
+	int reval_failed = 0;
+
+	DPRINTK("ENTER\n");
+
+	if (dev->flags & ATA_DFLAG_DETACH) {
+		detach = 1;
+		goto fail;
+	}
+
+ retry:
+	ehc->classes[0] = ATA_DEV_UNKNOWN;
+
+	if (ehc->i.action & ATA_EH_RESET_MASK) {
+		struct ata_link *tlink;
+
+		ata_eh_freeze_port(ap);
+
+		/* reset */
+		ehc->i.action = ATA_EH_HARDRESET;
+		rc = ata_eh_reset(link, 0, prereset, softreset, hardreset,
+				  postreset);
+		if (rc) {
+			ata_link_printk(link, KERN_ERR,
+					"failed to reset PMP, giving up\n");
+			goto fail;
+		}
+
+		ata_eh_thaw_port(ap);
+
+		/* PMP is reset, SErrors cannot be trusted, scan all */
+		ata_port_for_each_link(tlink, ap)
+			ata_ehi_schedule_probe(&tlink->eh_context.i);
+	}
+
+	/* If revalidation is requested, revalidate and reconfigure;
+	 * otherwise, do quick revalidation.
+	 */
+	if (ehc->i.action & ATA_EH_REVALIDATE)
+		rc = sata_pmp_revalidate(dev, ehc->classes[0]);
+	else
+		rc = sata_pmp_revalidate_quick(dev);
+
+	if (rc) {
+		tries--;
+
+		if (rc == -ENODEV) {
+			ehc->i.probe_mask |= 1;
+			detach = 1;
+			/* give it just two more chances */
+			tries = min(tries, 2);
+		}
+
+		if (tries) {
+			int sleep = ehc->i.flags & ATA_EHI_DID_RESET;
+
+			/* consecutive revalidation failures? speed down */
+			if (reval_failed)
+				sata_down_spd_limit(link);
+			else
+				reval_failed = 1;
+
+			ata_dev_printk(dev, KERN_WARNING,
+				       "retrying hardreset%s\n",
+				       sleep ? " in 5 secs" : "");
+			if (sleep)
+				ssleep(5);
+			ehc->i.action |= ATA_EH_HARDRESET;
+			goto retry;
+		} else {
+			ata_dev_printk(dev, KERN_ERR, "failed to recover PMP "
+				       "after %d tries, giving up\n",
+				       ATA_EH_PMP_TRIES);
+			goto fail;
+		}
+	}
+
+	/* okay, PMP resurrected */
+	ehc->i.flags = 0;
+
+	DPRINTK("EXIT, rc=0\n");
+	return 0;
+
+ fail:
+	sata_pmp_detach(dev);
+	if (detach)
+		ata_eh_detach_dev(dev);
+	else
+		ata_dev_disable(dev);
+
+	DPRINTK("EXIT, rc=%d\n", rc);
+	return rc;
+}
+
+static int sata_pmp_eh_handle_disabled_links(struct ata_port *ap)
+{
+	struct ata_link *link;
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	ata_port_for_each_link(link, ap) {
+		if (!(link->flags & ATA_LFLAG_DISABLED))
+			continue;
+
+		spin_unlock_irqrestore(ap->lock, flags);
+
+		/* Some PMPs require hardreset sequence to get
+		 * SError.N working.
+		 */
+		if ((link->flags & ATA_LFLAG_HRST_TO_RESUME) &&
+		    (link->eh_context.i.flags & ATA_EHI_RESUME_LINK))
+			sata_link_hardreset(link, sata_deb_timing_normal,
+					    jiffies + ATA_TMOUT_INTERNAL_QUICK);
+
+		/* unconditionally clear SError.N */
+		rc = sata_scr_write(link, SCR_ERROR, SERR_PHYRDY_CHG);
+		if (rc) {
+			ata_link_printk(link, KERN_ERR, "failed to clear "
+					"SError.N (errno=%d)\n", rc);
+			return rc;
+		}
+
+		spin_lock_irqsave(ap->lock, flags);
+	}
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	return 0;
+}
+
+static int sata_pmp_handle_link_fail(struct ata_link *link, int *link_tries)
+{
+	struct ata_port *ap = link->ap;
+	unsigned long flags;
+
+	if (link_tries[link->pmp] && --link_tries[link->pmp])
+		return 1;
+
+	/* disable this link */
+	if (!(link->flags & ATA_LFLAG_DISABLED)) {
+		ata_link_printk(link, KERN_WARNING,
+			"failed to recover link after %d tries, disabling\n",
+			ATA_EH_PMP_LINK_TRIES);
+
+		spin_lock_irqsave(ap->lock, flags);
+		link->flags |= ATA_LFLAG_DISABLED;
+		spin_unlock_irqrestore(ap->lock, flags);
+	}
+
+	ata_dev_disable(link->device);
+	link->eh_context.i.action = 0;
+
+	return 0;
+}
+
+/**
+ *	sata_pmp_eh_recover - recover PMP-enabled port
+ *	@ap: ATA port to recover
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method
+ *	@hardreset: hardreset method
+ *	@postreset: postreset method (can be NULL)
+ *	@pmp_prereset: PMP prereset method (can be NULL)
+ *	@pmp_softreset: PMP softreset method (can be NULL)
+ *	@pmp_hardreset: PMP hardreset method (can be NULL)
+ *	@pmp_postreset: PMP postreset method (can be NULL)
+ *
+ *	Drive EH recovery operation for PMP enabled port @ap.  This
+ *	function recovers host and PMP ports with proper retrials and
+ *	fallbacks.  Actual recovery operations are performed using
+ *	ata_eh_recover() and sata_pmp_eh_recover_pmp().
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sata_pmp_eh_recover(struct ata_port *ap,
+		ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+		ata_reset_fn_t hardreset, ata_postreset_fn_t postreset,
+		ata_prereset_fn_t pmp_prereset, ata_reset_fn_t pmp_softreset,
+		ata_reset_fn_t pmp_hardreset, ata_postreset_fn_t pmp_postreset)
+{
+	int pmp_tries, link_tries[SATA_PMP_MAX_PORTS];
+	struct ata_link *pmp_link = &ap->link;
+	struct ata_device *pmp_dev = pmp_link->device;
+	struct ata_eh_context *pmp_ehc = &pmp_link->eh_context;
+	struct ata_link *link;
+	struct ata_device *dev;
+	u32 gscr_error, sntf;
+	int cnt, rc;
+
+	pmp_tries = ATA_EH_PMP_TRIES;
+	ata_port_for_each_link(link, ap)
+		link_tries[link->pmp] = ATA_EH_PMP_LINK_TRIES;
+
+ retry:
+	/* PMP attached? */
+	if (!ap->nr_pmp_links) {
+		rc = ata_eh_recover(ap, prereset, softreset, hardreset,
+				    postreset, NULL);
+		if (rc) {
+			ata_link_for_each_dev(dev, &ap->link)
+				ata_dev_disable(dev);
+			return rc;
+		}
+
+		if (pmp_dev->class != ATA_DEV_PMP)
+			return 0;
+
+		/* new PMP online */
+		ata_port_for_each_link(link, ap)
+			link_tries[link->pmp] = ATA_EH_PMP_LINK_TRIES;
+
+		/* fall through */
+	}
+
+	/* recover pmp */
+	rc = sata_pmp_eh_recover_pmp(ap, prereset, softreset, hardreset,
+				     postreset);
+	if (rc)
+		goto pmp_fail;
+
+	/* handle disabled links */
+	rc = sata_pmp_eh_handle_disabled_links(ap);
+	if (rc)
+		goto pmp_fail;
+
+	/* recover links */
+	rc = ata_eh_recover(ap, pmp_prereset, pmp_softreset, pmp_hardreset,
+			    pmp_postreset, &link);
+	if (rc)
+		goto link_fail;
+
+	/* Connection status might have changed while resetting other
+	 * links, check SATA_PMP_GSCR_ERROR before returning.
+	 */
+
+	/* clear SNotification */
+	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
+	if (rc == 0)
+		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
+
+	/* enable notification */
+	if (pmp_dev->flags & ATA_DFLAG_AN) {
+		pmp_dev->gscr[SATA_PMP_GSCR_FEAT_EN] |= SATA_PMP_FEAT_NOTIFY;
+
+		rc = sata_pmp_write(pmp_dev->link, SATA_PMP_GSCR_FEAT_EN,
+				    pmp_dev->gscr[SATA_PMP_GSCR_FEAT_EN]);
+		if (rc) {
+			ata_dev_printk(pmp_dev, KERN_ERR,
+				       "failed to write PMP_FEAT_EN\n");
+			goto pmp_fail;
+		}
+	}
+
+	/* check GSCR_ERROR */
+	rc = sata_pmp_read(pmp_link, SATA_PMP_GSCR_ERROR, &gscr_error);
+	if (rc) {
+		ata_dev_printk(pmp_dev, KERN_ERR,
+			       "failed to read PMP_GSCR_ERROR\n");
+		goto pmp_fail;
+	}
+
+	cnt = 0;
+	ata_port_for_each_link(link, ap) {
+		if (!(gscr_error & (1 << link->pmp)))
+			continue;
+
+		if (sata_pmp_handle_link_fail(link, link_tries)) {
+			ata_ehi_hotplugged(&link->eh_context.i);
+			cnt++;
+		} else {
+			ata_link_printk(link, KERN_WARNING,
+				"PHY status changed but maxed out on retries, "
+				"giving up\n");
+			ata_link_printk(link, KERN_WARNING,
+				"Manully issue scan to resume this link\n");
+		}
+	}
+
+	if (cnt) {
+		ata_port_printk(ap, KERN_INFO, "PMP SError.N set for some "
+				"ports, repeating recovery\n");
+		goto retry;
+	}
+
+	return 0;
+
+ link_fail:
+	if (sata_pmp_handle_link_fail(link, link_tries)) {
+		pmp_ehc->i.action |= ATA_EH_HARDRESET;
+		goto retry;
+	}
+
+	/* fall through */
+ pmp_fail:
+	/* Control always ends up here after detaching PMP.  Shut up
+	 * and return if we're unloading.
+	 */
+	if (ap->pflags & ATA_PFLAG_UNLOADING)
+		return rc;
+
+	if (!ap->nr_pmp_links)
+		goto retry;
+
+	if (--pmp_tries) {
+		ata_port_printk(ap, KERN_WARNING,
+				"failed to recover PMP, retrying in 5 secs\n");
+		pmp_ehc->i.action |= ATA_EH_HARDRESET;
+		ssleep(5);
+		goto retry;
+	}
+
+	ata_port_printk(ap, KERN_ERR,
+			"failed to recover PMP after %d tries, giving up\n",
+			ATA_EH_PMP_TRIES);
+	sata_pmp_detach(pmp_dev);
+	ata_dev_disable(pmp_dev);
+
+	return rc;
+}
+
+/**
+ *	sata_pmp_do_eh - do standard error handling for PMP-enabled host
+ *	@ap: host port to handle error for
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method
+ *	@hardreset: hardreset method
+ *	@postreset: postreset method (can be NULL)
+ *	@pmp_prereset: PMP prereset method (can be NULL)
+ *	@pmp_softreset: PMP softreset method (can be NULL)
+ *	@pmp_hardreset: PMP hardreset method (can be NULL)
+ *	@pmp_postreset: PMP postreset method (can be NULL)
+ *
+ *	Perform standard error handling sequence for PMP-enabled host
+ *	@ap.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void sata_pmp_do_eh(struct ata_port *ap,
+		ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+		ata_reset_fn_t hardreset, ata_postreset_fn_t postreset,
+		ata_prereset_fn_t pmp_prereset, ata_reset_fn_t pmp_softreset,
+		ata_reset_fn_t pmp_hardreset, ata_postreset_fn_t pmp_postreset)
+{
+	ata_eh_autopsy(ap);
+	ata_eh_report(ap);
+	sata_pmp_eh_recover(ap, prereset, softreset, hardreset, postreset,
+			    pmp_prereset, pmp_softreset, pmp_hardreset,
+			    pmp_postreset);
+	ata_eh_finish(ap);
+}