[libata] Add ATA transport class

This is a scheleton for libata transport class.
All information is read only, exporting information from libata:
- ata_port class: one per ATA port
- ata_link class: one per ATA port or 15 for SATA Port Multiplier
- ata_device class: up to 2 for PATA link, usually one for SATA.

Signed-off-by: Gwendal Grignou <gwendal@google.com>
Reviewed-by: Grant Grundler <grundler@google.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Documentation/ABI/testing/sysfs-ata

@@ -0,0 +1,99 @@
+What:		/sys/class/ata_...
+Date:		August 2008
+Contact:	Gwendal Grignou<gwendal@google.com>
+Description:
+
+Provide a place in sysfs for storing the ATA topology of the system.  This allows
+retrieving various information about ATA objects.
+
+Files under /sys/class/ata_port
+-------------------------------
+
+	For each port, a directory ataX is created where X is the ata_port_id of
+	the port. The device parent is the ata host device.
+
+idle_irq (read)
+
+	Number of IRQ received by the port while idle [some ata HBA only].
+
+nr_pmp_links (read)
+
+	If a SATA Port Multiplier (PM) is connected, number of link behind it.
+
+Files under /sys/class/ata_link
+-------------------------------
+
+	Behind each port, there is a ata_link. If there is a SATA PM in the
+	topology, 15 ata_link objects are created.
+
+	If a link is behind a port, the directory name is linkX, where X is
+	ata_port_id of the port.
+	If a link is behind a PM, its name is linkX.Y where X is ata_port_id
+	of the parent port and Y the PM port.
+
+hw_sata_spd_limit
+
+	Maximum speed supported by the connected SATA device.
+
+sata_spd_limit
+
+	Maximum speed imposed by libata.
+
+sata_spd
+
+	Current speed of the link [1.5, 3Gps,...].
+
+Files under /sys/class/ata_device
+---------------------------------
+
+	Behind each link, up to two ata device are created.
+	The name of the directory is devX[.Y].Z where:
+	- X is ata_port_id of the port where the device is connected,
+	- Y the port of the PM if any, and
+	- Z the device id: for PATA, there is usually 2 devices [0,1],
+	only 1 for SATA.
+
+class
+	Device class. Can be "ata" for disk, "atapi" for packet device,
+	"pmp" for PM, or "none" if no device was found behind the link.
+
+dma_mode
+
+	Transfer modes supported by the device when in DMA mode.
+	Mostly used by PATA device.
+
+pio_mode
+
+	Transfer modes supported by the device when in PIO mode.
+	Mostly used by PATA device.
+
+xfer_mode
+
+	Current transfer mode.
+
+id
+
+	Cached result of IDENTIFY command, as described in ATA8 7.16 and 7.17.
+	Only valid if the device is not a PM.
+
+gscr
+
+	Cached result of the dump of PM GSCR register.
+	Valid registers are:
+	0: 	SATA_PMP_GSCR_PROD_ID,
+	1: 	SATA_PMP_GSCR_REV,
+	2: 	SATA_PMP_GSCR_PORT_INFO,
+	32:	SATA_PMP_GSCR_ERROR,
+	33:	SATA_PMP_GSCR_ERROR_EN,
+	64:	SATA_PMP_GSCR_FEAT,
+	96:	SATA_PMP_GSCR_FEAT_EN,
+	130:	SATA_PMP_GSCR_SII_GPIO
+	Only valid if the device is a PM.
+
+spdn_cnt
+
+	Number of time libata decided to lower the speed of link due to errors.
+
+ering
+
+	Formatted output of the error ring of the device.

drivers/ata/Makefile

@@ -99,7 +99,7 @@ obj-$(CONFIG_ATA_GENERIC)	+= ata_generic.o
 # Should be last libata driver
 obj-$(CONFIG_PATA_LEGACY)	+= pata_legacy.o
 
-libata-objs	:= libata-core.o libata-scsi.o libata-eh.o
+libata-objs	:= libata-core.o libata-scsi.o libata-eh.o libata-transport.o
 libata-$(CONFIG_ATA_SFF)	+= libata-sff.o
 libata-$(CONFIG_SATA_PMP)	+= libata-pmp.o
 libata-$(CONFIG_ATA_ACPI)	+= libata-acpi.o

drivers/ata/libata-core.c

@@ -68,7 +68,7 @@
 #include <linux/ratelimit.h>
 
 #include "libata.h"
-
+#include "libata-transport.h"
 
 /* debounce timing parameters in msecs { interval, duration, timeout } */
 const unsigned long sata_deb_timing_normal[]		= {   5,  100, 2000 };
@@ -1017,7 +1017,7 @@ const char *ata_mode_string(unsigned long xfer_mask)
 	return "<n/a>";
 }
 
-static const char *sata_spd_string(unsigned int spd)
+const char *sata_spd_string(unsigned int spd)
 {
 	static const char * const spd_str[] = {
 		"1.5 Gbps",
@@ -5517,7 +5517,8 @@ void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp)
 	int i;
 
 	/* clear everything except for devices */
-	memset(link, 0, offsetof(struct ata_link, device[0]));
+	memset((void *)link + ATA_LINK_CLEAR_BEGIN, 0,
+	       ATA_LINK_CLEAR_END - ATA_LINK_CLEAR_BEGIN);
 
 	link->ap = ap;
 	link->pmp = pmp;
@@ -5591,7 +5592,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
 	ap = kzalloc(sizeof(*ap), GFP_KERNEL);
 	if (!ap)
 		return NULL;
-
+	
 	ap->pflags |= ATA_PFLAG_INITIALIZING;
 	ap->lock = &host->lock;
 	ap->print_id = -1;
@@ -6093,9 +6094,18 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
 	for (i = 0; i < host->n_ports; i++)
 		host->ports[i]->print_id = ata_print_id++;
 
+
+	/* Create associated sysfs transport objects  */
+	for (i = 0; i < host->n_ports; i++) {
+		rc = ata_tport_add(host->dev,host->ports[i]);
+		if (rc) {
+			goto err_tadd;
+		}
+	}
+
 	rc = ata_scsi_add_hosts(host, sht);
 	if (rc)
-		return rc;
+		goto err_tadd;
 
 	/* associate with ACPI nodes */
 	ata_acpi_associate(host);
@@ -6136,6 +6146,13 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
 	}
 
 	return 0;
+
+ err_tadd:
+	while (--i >= 0) {
+		ata_tport_delete(host->ports[i]);
+	}
+	return rc;
+
 }
 
 /**
@@ -6226,6 +6243,13 @@ static void ata_port_detach(struct ata_port *ap)
 	cancel_rearming_delayed_work(&ap->hotplug_task);
 
  skip_eh:
+	if (ap->pmp_link) {
+		int i;
+		for (i = 0; i < SATA_PMP_MAX_PORTS; i++)
+			ata_tlink_delete(&ap->pmp_link[i]);
+	}
+	ata_tport_delete(ap);
+
 	/* remove the associated SCSI host */
 	scsi_remove_host(ap->scsi_host);
 }
@@ -6542,7 +6566,7 @@ static void __init ata_parse_force_param(void)
 
 static int __init ata_init(void)
 {
-	int rc = -ENOMEM;
+	int rc;
 
 	ata_parse_force_param();
 
@@ -6552,12 +6576,25 @@ static int __init ata_init(void)
 		return rc;
 	}
 
+	libata_transport_init();
+	ata_scsi_transport_template = ata_attach_transport();
+	if (!ata_scsi_transport_template) {
+		ata_sff_exit();
+		rc = -ENOMEM;
+		goto err_out;
+	}		
+
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
+
+err_out:
+	return rc;
 }
 
 static void __exit ata_exit(void)
 {
+	ata_release_transport(ata_scsi_transport_template);
+	libata_transport_exit();
 	ata_sff_exit();
 	kfree(ata_force_tbl);
 }

drivers/ata/libata-eh.c

@@ -57,6 +57,7 @@ enum {
 	/* error flags */
 	ATA_EFLAG_IS_IO			= (1 << 0),
 	ATA_EFLAG_DUBIOUS_XFER		= (1 << 1),
+	ATA_EFLAG_OLD_ER                = (1 << 31),
 
 	/* error categories */
 	ATA_ECAT_NONE			= 0,
@@ -396,14 +397,9 @@ static struct ata_ering_entry *ata_ering_top(struct ata_ering *ering)
 	return NULL;
 }
 
-static void ata_ering_clear(struct ata_ering *ering)
-{
-	memset(ering, 0, sizeof(*ering));
-}
-
-static int ata_ering_map(struct ata_ering *ering,
-			 int (*map_fn)(struct ata_ering_entry *, void *),
-			 void *arg)
+int ata_ering_map(struct ata_ering *ering,
+		  int (*map_fn)(struct ata_ering_entry *, void *),
+		  void *arg)
 {
 	int idx, rc = 0;
 	struct ata_ering_entry *ent;
@@ -422,6 +418,17 @@ static int ata_ering_map(struct ata_ering *ering,
 	return rc;
 }
 
+int ata_ering_clear_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+	ent->eflags |= ATA_EFLAG_OLD_ER;
+	return 0;
+}
+
+static void ata_ering_clear(struct ata_ering *ering)
+{
+	ata_ering_map(ering, ata_ering_clear_cb, NULL);
+}
+
 static unsigned int ata_eh_dev_action(struct ata_device *dev)
 {
 	struct ata_eh_context *ehc = &dev->link->eh_context;
@@ -572,19 +579,19 @@ void ata_scsi_error(struct Scsi_Host *host)
 		int nr_timedout = 0;
 
 		spin_lock_irqsave(ap->lock, flags);
-		
+
 		/* This must occur under the ap->lock as we don't want
 		   a polled recovery to race the real interrupt handler
-		   
+
 		   The lost_interrupt handler checks for any completed but
 		   non-notified command and completes much like an IRQ handler.
-		   
+
 		   We then fall into the error recovery code which will treat
 		   this as if normal completion won the race */
 
 		if (ap->ops->lost_interrupt)
 			ap->ops->lost_interrupt(ap);
-			
+
 		list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
 			struct ata_queued_cmd *qc;
 
@@ -628,7 +635,7 @@ void ata_scsi_error(struct Scsi_Host *host)
 		ap->eh_tries = ATA_EH_MAX_TRIES;
 	} else
 		spin_unlock_wait(ap->lock);
-		
+
 	/* If we timed raced normal completion and there is nothing to
 	   recover nr_timedout == 0 why exactly are we doing error recovery ? */
 
@@ -1755,7 +1762,7 @@ static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
 	struct speed_down_verdict_arg *arg = void_arg;
 	int cat;
 
-	if (ent->timestamp < arg->since)
+	if ((ent->eflags & ATA_EFLAG_OLD_ER) || (ent->timestamp < arg->since))
 		return -1;
 
 	cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,

drivers/ata/libata-pmp.c

@@ -11,6 +11,7 @@
 #include <linux/libata.h>
 #include <linux/slab.h>
 #include "libata.h"
+#include "libata-transport.h"
 
 const struct ata_port_operations sata_pmp_port_ops = {
 	.inherits		= &sata_port_ops,
@@ -312,10 +313,10 @@ static int sata_pmp_configure(struct ata_device *dev, int print_info)
 	return rc;
 }
 
-static int sata_pmp_init_links(struct ata_port *ap, int nr_ports)
+static int sata_pmp_init_links (struct ata_port *ap, int nr_ports)
 {
 	struct ata_link *pmp_link = ap->pmp_link;
-	int i;
+	int i, err;
 
 	if (!pmp_link) {
 		pmp_link = kzalloc(sizeof(pmp_link[0]) * SATA_PMP_MAX_PORTS,
@@ -327,6 +328,13 @@ static int sata_pmp_init_links(struct ata_port *ap, int nr_ports)
 			ata_link_init(ap, &pmp_link[i], i);
 
 		ap->pmp_link = pmp_link;
+
+		for (i = 0; i < SATA_PMP_MAX_PORTS; i++) {
+			err = ata_tlink_add(&pmp_link[i]);
+			if (err) {
+				goto err_tlink;
+			}
+		}
 	}
 
 	for (i = 0; i < nr_ports; i++) {
@@ -339,6 +347,12 @@ static int sata_pmp_init_links(struct ata_port *ap, int nr_ports)
 	}
 
 	return 0;
+  err_tlink:
+	while (--i >= 0)
+		ata_tlink_delete(&pmp_link[i]);
+	kfree(pmp_link);
+	ap->pmp_link = NULL;
+	return err;
 }
 
 static void sata_pmp_quirks(struct ata_port *ap)