libata: implement libata.force module parameter

This patch implements libata.force module parameter which can
selectively override ATA port, link and device configurations
including cable type, SATA PHY SPD limit, transfer mode and NCQ.

For example, you can say "use 1.5Gbps for all fan-out ports attached
to the second port but allow 3.0Gbps for the PMP device itself, oh,
the device attached to the third fan-out port chokes on NCQ and
shouldn't go over UDMA4" by the following.

 libata.force=2:1.5g,2.15:3.0g,2.03:noncq,udma4

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

4 files changed, 420 insertions, 4 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7278295f94d2..9a5b6658c65e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -950,6 +950,41 @@ and is between 256 and 4096 characters. It is defined in the file
 			when set.
 			Format: <int>
 
+	libata.force=	[LIBATA] Force configurations.  The format is comma
+			separated list of "[ID:]VAL" where ID is
+			PORT[:DEVICE].  PORT and DEVICE are decimal numbers
+			matching port, link or device.  Basically, it matches
+			the ATA ID string printed on console by libata.  If
+			the whole ID part is omitted, the last PORT and DEVICE
+			values are used.  If ID hasn't been specified yet, the
+			configuration applies to all ports, links and devices.
+
+			If only DEVICE is omitted, the parameter applies to
+			the port and all links and devices behind it.  DEVICE
+			number of 0 either selects the first device or the
+			first fan-out link behind PMP device.  It does not
+			select the host link.  DEVICE number of 15 selects the
+			host link and device attached to it.
+
+			The VAL specifies the configuration to force.  As long
+			as there's no ambiguity shortcut notation is allowed.
+			For example, both 1.5 and 1.5G would work for 1.5Gbps.
+			The following configurations can be forced.
+
+			* Cable type: 40c, 80c, short40c, unk, ign or sata.
+			  Any ID with matching PORT is used.
+
+			* SATA link speed limit: 1.5Gbps or 3.0Gbps.
+
+			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
+			  udma[/][16,25,33,44,66,100,133] notation is also
+			  allowed.
+
+			* [no]ncq: Turn on or off NCQ.
+
+			If there are multiple matching configurations changing
+			the same attribute, the last one is used.
+
 	load_ramdisk=	[RAM] List of ramdisks to load from floppy
 			See Documentation/ramdisk.txt.
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index def3682f416a..60d1bb556973 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -87,6 +87,28 @@ static struct workqueue_struct *ata_wq;
 
 struct workqueue_struct *ata_aux_wq;
 
+struct ata_force_param {
+	const char	*name;
+	unsigned int	cbl;
+	int		spd_limit;
+	unsigned long	xfer_mask;
+	unsigned int	horkage_on;
+	unsigned int	horkage_off;
+};
+
+struct ata_force_ent {
+	int			port;
+	int			device;
+	struct ata_force_param	param;
+};
+
+static struct ata_force_ent *ata_force_tbl;
+static int ata_force_tbl_size;
+
+static char ata_force_param_buf[PAGE_SIZE] __initdata;
+module_param_string(force, ata_force_param_buf, sizeof(ata_force_param_buf), 0444);
+MODULE_PARM_DESC(force, "Force ATA configurations including cable type, link speed and transfer mode (see Documentation/kernel-parameters.txt for details)");
+
 int atapi_enabled = 1;
 module_param(atapi_enabled, int, 0444);
 MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");
@@ -130,6 +152,179 @@ MODULE_VERSION(DRV_VERSION);
 
 
 /**
+ *	ata_force_cbl - force cable type according to libata.force
+ *	@link: ATA link of interest
+ *
+ *	Force cable type according to libata.force and whine about it.
+ *	The last entry which has matching port number is used, so it
+ *	can be specified as part of device force parameters.  For
+ *	example, both "a:40c,1.00:udma4" and "1.00:40c,udma4" have the
+ *	same effect.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+void ata_force_cbl(struct ata_port *ap)
+{
+	int i;
+
+	for (i = ata_force_tbl_size - 1; i >= 0; i--) {
+		const struct ata_force_ent *fe = &ata_force_tbl[i];
+
+		if (fe->port != -1 && fe->port != ap->print_id)
+			continue;
+
+		if (fe->param.cbl == ATA_CBL_NONE)
+			continue;
+
+		ap->cbl = fe->param.cbl;
+		ata_port_printk(ap, KERN_NOTICE,
+				"FORCE: cable set to %s\n", fe->param.name);
+		return;
+	}
+}
+
+/**
+ *	ata_force_spd_limit - force SATA spd limit according to libata.force
+ *	@link: ATA link of interest
+ *
+ *	Force SATA spd limit according to libata.force and whine about
+ *	it.  When only the port part is specified (e.g. 1:), the limit
+ *	applies to all links connected to both the host link and all
+ *	fan-out ports connected via PMP.  If the device part is
+ *	specified as 0 (e.g. 1.00:), it specifies the first fan-out
+ *	link not the host link.  Device number 15 always points to the
+ *	host link whether PMP is attached or not.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+static void ata_force_spd_limit(struct ata_link *link)
+{
+	int linkno, i;
+
+	if (ata_is_host_link(link))
+		linkno = 15;
+	else
+		linkno = link->pmp;
+
+	for (i = ata_force_tbl_size - 1; i >= 0; i--) {
+		const struct ata_force_ent *fe = &ata_force_tbl[i];
+
+		if (fe->port != -1 && fe->port != link->ap->print_id)
+			continue;
+
+		if (fe->device != -1 && fe->device != linkno)
+			continue;
+
+		if (!fe->param.spd_limit)
+			continue;
+
+		link->hw_sata_spd_limit = (1 << fe->param.spd_limit) - 1;
+		ata_link_printk(link, KERN_NOTICE,
+			"FORCE: PHY spd limit set to %s\n", fe->param.name);
+		return;
+	}
+}
+
+/**
+ *	ata_force_xfermask - force xfermask according to libata.force
+ *	@dev: ATA device of interest
+ *
+ *	Force xfer_mask according to libata.force and whine about it.
+ *	For consistency with link selection, device number 15 selects
+ *	the first device connected to the host link.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+static void ata_force_xfermask(struct ata_device *dev)
+{
+	int devno = dev->link->pmp + dev->devno;
+	int alt_devno = devno;
+	int i;
+
+	/* allow n.15 for the first device attached to host port */
+	if (ata_is_host_link(dev->link) && devno == 0)
+		alt_devno = 15;
+
+	for (i = ata_force_tbl_size - 1; i >= 0; i--) {
+		const struct ata_force_ent *fe = &ata_force_tbl[i];
+		unsigned long pio_mask, mwdma_mask, udma_mask;
+
+		if (fe->port != -1 && fe->port != dev->link->ap->print_id)
+			continue;
+
+		if (fe->device != -1 && fe->device != devno &&
+		    fe->device != alt_devno)
+			continue;
+
+		if (!fe->param.xfer_mask)
+			continue;
+
+		ata_unpack_xfermask(fe->param.xfer_mask,
+				    &pio_mask, &mwdma_mask, &udma_mask);
+		if (udma_mask)
+			dev->udma_mask = udma_mask;
+		else if (mwdma_mask) {
+			dev->udma_mask = 0;
+			dev->mwdma_mask = mwdma_mask;
+		} else {
+			dev->udma_mask = 0;
+			dev->mwdma_mask = 0;
+			dev->pio_mask = pio_mask;
+		}
+
+		ata_dev_printk(dev, KERN_NOTICE,
+			"FORCE: xfer_mask set to %s\n", fe->param.name);
+		return;
+	}
+}
+
+/**
+ *	ata_force_horkage - force horkage according to libata.force
+ *	@dev: ATA device of interest
+ *
+ *	Force horkage according to libata.force and whine about it.
+ *	For consistency with link selection, device number 15 selects
+ *	the first device connected to the host link.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+static void ata_force_horkage(struct ata_device *dev)
+{
+	int devno = dev->link->pmp + dev->devno;
+	int alt_devno = devno;
+	int i;
+
+	/* allow n.15 for the first device attached to host port */
+	if (ata_is_host_link(dev->link) && devno == 0)
+		alt_devno = 15;
+
+	for (i = 0; i < ata_force_tbl_size; i++) {
+		const struct ata_force_ent *fe = &ata_force_tbl[i];
+
+		if (fe->port != -1 && fe->port != dev->link->ap->print_id)
+			continue;
+
+		if (fe->device != -1 && fe->device != devno &&
+		    fe->device != alt_devno)
+			continue;
+
+		if (!(~dev->horkage & fe->param.horkage_on) &&
+		    !(dev->horkage & fe->param.horkage_off))
+			continue;
+
+		dev->horkage |= fe->param.horkage_on;
+		dev->horkage &= ~fe->param.horkage_off;
+
+		ata_dev_printk(dev, KERN_NOTICE,
+			"FORCE: horkage modified (%s)\n", fe->param.name);
+	}
+}
+
+/**
  *	ata_tf_to_fis - Convert ATA taskfile to SATA FIS structure
  *	@tf: Taskfile to convert
  *	@pmp: Port multiplier port
@@ -2067,6 +2262,7 @@ int ata_dev_configure(struct ata_device *dev)
 
 	/* set horkage */
 	dev->horkage |= ata_dev_blacklisted(dev);
+	ata_force_horkage(dev);
 
 	/* let ACPI work its magic */
 	rc = ata_acpi_on_devcfg(dev);
@@ -3150,6 +3346,7 @@ int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
 			mode_mask = ATA_DMA_MASK_CFA;
 
 		ata_dev_xfermask(dev);
+		ata_force_xfermask(dev);
 
 		pio_mask = ata_pack_xfermask(dev->pio_mask, 0, 0);
 		dma_mask = ata_pack_xfermask(0, dev->mwdma_mask, dev->udma_mask);
@@ -6497,7 +6694,8 @@ void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp)
  */
 int sata_link_init_spd(struct ata_link *link)
 {
-	u32 scontrol, spd;
+	u32 scontrol;
+	u8 spd;
 	int rc;
 
 	rc = sata_scr_read(link, SCR_CONTROL, &scontrol);
@@ -6508,6 +6706,8 @@ int sata_link_init_spd(struct ata_link *link)
 	if (spd)
 		link->hw_sata_spd_limit &= (1 << spd) - 1;
 
+	ata_force_spd_limit(link);
+
 	link->sata_spd_limit = link->hw_sata_spd_limit;
 
 	return 0;
@@ -7218,10 +7418,187 @@ int ata_pci_device_resume(struct pci_dev *pdev)
 
 #endif /* CONFIG_PCI */
 
+static int __init ata_parse_force_one(char **cur,
+				      struct ata_force_ent *force_ent,
+				      const char **reason)
+{
+	/* FIXME: Currently, there's no way to tag init const data and
+	 * using __initdata causes build failure on some versions of
+	 * gcc.  Once __initdataconst is implemented, add const to the
+	 * following structure.
+	 */
+	static struct ata_force_param force_tbl[] __initdata = {
+		{ "40c",	.cbl		= ATA_CBL_PATA40 },
+		{ "80c",	.cbl		= ATA_CBL_PATA80 },
+		{ "short40c",	.cbl		= ATA_CBL_PATA40_SHORT },
+		{ "unk",	.cbl		= ATA_CBL_PATA_UNK },
+		{ "ign",	.cbl		= ATA_CBL_PATA_IGN },
+		{ "sata",	.cbl		= ATA_CBL_SATA },
+		{ "1.5Gbps",	.spd_limit	= 1 },
+		{ "3.0Gbps",	.spd_limit	= 2 },
+		{ "noncq",	.horkage_on	= ATA_HORKAGE_NONCQ },
+		{ "ncq",	.horkage_off	= ATA_HORKAGE_NONCQ },
+		{ "pio0",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 0) },
+		{ "pio1",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 1) },
+		{ "pio2",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 2) },
+		{ "pio3",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 3) },
+		{ "pio4",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 4) },
+		{ "pio5",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 5) },
+		{ "pio6",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 6) },
+		{ "mwdma0",	.xfer_mask	= 1 << (ATA_SHIFT_MWDMA + 0) },
+		{ "mwdma1",	.xfer_mask	= 1 << (ATA_SHIFT_MWDMA + 1) },
+		{ "mwdma2",	.xfer_mask	= 1 << (ATA_SHIFT_MWDMA + 2) },
+		{ "mwdma3",	.xfer_mask	= 1 << (ATA_SHIFT_MWDMA + 3) },
+		{ "mwdma4",	.xfer_mask	= 1 << (ATA_SHIFT_MWDMA + 4) },
+		{ "udma0",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 0) },
+		{ "udma16",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 0) },
+		{ "udma/16",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 0) },
+		{ "udma1",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 1) },
+		{ "udma25",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 1) },
+		{ "udma/25",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 1) },
+		{ "udma2",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 2) },
+		{ "udma33",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 2) },
+		{ "udma/33",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 2) },
+		{ "udma3",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 3) },
+		{ "udma44",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 3) },
+		{ "udma/44",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 3) },
+		{ "udma4",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 4) },
+		{ "udma66",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 4) },
+		{ "udma/66",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 4) },
+		{ "udma5",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 5) },
+		{ "udma100",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 5) },
+		{ "udma/100",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 5) },
+		{ "udma6",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 6) },
+		{ "udma133",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 6) },
+		{ "udma/133",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 6) },
+		{ "udma7",	.xfer_mask	= 1 << (ATA_SHIFT_UDMA + 7) },
+	};
+	char *start = *cur, *p = *cur;
+	char *id, *val, *endp;
+	const struct ata_force_param *match_fp = NULL;
+	int nr_matches = 0, i;
+
+	/* find where this param ends and update *cur */
+	while (*p != '\0' && *p != ',')
+		p++;
+
+	if (*p == '\0')
+		*cur = p;
+	else
+		*cur = p + 1;
+
+	*p = '\0';
+
+	/* parse */
+	p = strchr(start, ':');
+	if (!p) {
+		val = strstrip(start);
+		goto parse_val;
+	}
+	*p = '\0';
+
+	id = strstrip(start);
+	val = strstrip(p + 1);
+
+	/* parse id */
+	p = strchr(id, '.');
+	if (p) {
+		*p++ = '\0';
+		force_ent->device = simple_strtoul(p, &endp, 10);
+		if (p == endp || *endp != '\0') {
+			*reason = "invalid device";
+			return -EINVAL;
+		}
+	}
+
+	force_ent->port = simple_strtoul(id, &endp, 10);
+	if (p == endp || *endp != '\0') {
+		*reason = "invalid port/link";
+		return -EINVAL;
+	}
+
+ parse_val:
+	/* parse val, allow shortcuts so that both 1.5 and 1.5Gbps work */
+	for (i = 0; i < ARRAY_SIZE(force_tbl); i++) {
+		const struct ata_force_param *fp = &force_tbl[i];
+
+		if (strncasecmp(val, fp->name, strlen(val)))
+			continue;
+
+		nr_matches++;
+		match_fp = fp;
+
+		if (strcasecmp(val, fp->name) == 0) {
+			nr_matches = 1;
+			break;
+		}
+	}
+
+	if (!nr_matches) {
+		*reason = "unknown value";
+		return -EINVAL;
+	}
+	if (nr_matches > 1) {
+		*reason = "ambigious value";
+		return -EINVAL;
+	}
+
+	force_ent->param = *match_fp;
+
+	return 0;
+}
+
+static void __init ata_parse_force_param(void)
+{
+	int idx = 0, size = 1;
+	int last_port = -1, last_device = -1;
+	char *p, *cur, *next;
+
+	/* calculate maximum number of params and allocate force_tbl */
+	for (p = ata_force_param_buf; *p; p++)
+		if (*p == ',')
+			size++;
+
+	ata_force_tbl = kzalloc(sizeof(ata_force_tbl[0]) * size, GFP_KERNEL);
+	if (!ata_force_tbl) {
+		printk(KERN_WARNING "ata: failed to extend force table, "
+		       "libata.force ignored\n");
+		return;
+	}
+
+	/* parse and populate the table */
+	for (cur = ata_force_param_buf; *cur != '\0'; cur = next) {
+		const char *reason = "";
+		struct ata_force_ent te = { .port = -1, .device = -1 };
+
+		next = cur;
+		if (ata_parse_force_one(&next, &te, &reason)) {
+			printk(KERN_WARNING "ata: failed to parse force "
+			       "parameter \"%s\" (%s)\n",
+			       cur, reason);
+			continue;
+		}
+
+		if (te.port == -1) {
+			te.port = last_port;
+			te.device = last_device;
+		}
+
+		ata_force_tbl[idx++] = te;
+
+		last_port = te.port;
+		last_device = te.device;
+	}
+
+	ata_force_tbl_size = idx;
+}
 
 static int __init ata_init(void)
 {
 	ata_probe_timeout *= HZ;
+
+	ata_parse_force_param();
+
 	ata_wq = create_workqueue("ata");
 	if (!ata_wq)
 		return -ENOMEM;
@@ -7238,6 +7615,7 @@ static int __init ata_init(void)
 
 static void __exit ata_exit(void)
 {
+	kfree(ata_force_tbl);
 	destroy_workqueue(ata_wq);
 	destroy_workqueue(ata_aux_wq);
 }
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 4e31071acc02..698ce2cea52c 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2393,9 +2393,11 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
 	}
 
 	/* PDIAG- should have been released, ask cable type if post-reset */
-	if (ata_is_host_link(link) && ap->ops->cable_detect &&
-	    (ehc->i.flags & ATA_EHI_DID_RESET))
-		ap->cbl = ap->ops->cable_detect(ap);
+	if ((ehc->i.flags & ATA_EHI_DID_RESET) && ata_is_host_link(link)) {
+		if (ap->ops->cable_detect)
+			ap->cbl = ap->ops->cable_detect(ap);
+		ata_force_cbl(ap);
+	}
 
 	/* Configure new devices forward such that user doesn't see
 	 * device detection messages backwards.
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 409ffb9af163..6036dedfe377 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -61,6 +61,7 @@ extern int atapi_passthru16;
 extern int libata_fua;
 extern int libata_noacpi;
 extern int libata_allow_tpm;
+extern void ata_force_cbl(struct ata_port *ap);
 extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev);
 extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
 			   u64 block, u32 n_block, unsigned int tf_flags,