[PATCH] libata-ncq: implement NCQ device configuration

Now that all NCQ related stuff are in place, implement NCQ device
configuration and bump ATA_MAX_QUEUE to 32 thus activating NCQ
support.

Original implementation is from Jens Axboe.

Signed-off-by: Tejun Heo <htejun@gmail.com>

3 files changed, 78 insertions, 3 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 14ffb5264b65..9051b6821c1c 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1251,6 +1251,28 @@ static inline u8 ata_dev_knobble(struct ata_device *dev)
         return ((dev->ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
 }
 
+static void ata_dev_config_ncq(struct ata_device *dev,
+                               char *desc, size_t desc_sz)
+{
+        struct ata_port *ap = dev->ap;
+        int hdepth = 0, ddepth = ata_id_queue_depth(dev->id);
+
+        if (!ata_id_has_ncq(dev->id)) {
+                desc[0] = '\0';
+                return;
+        }
+
+        if (ap->flags & ATA_FLAG_NCQ) {
+                hdepth = min(ap->host->can_queue, ATA_MAX_QUEUE - 1);
+                dev->flags |= ATA_DFLAG_NCQ;
+        }
+
+        if (hdepth >= ddepth)
+                snprintf(desc, desc_sz, "NCQ (depth %d)", ddepth);
+        else
+                snprintf(desc, desc_sz, "NCQ (depth %d/%d)", hdepth, ddepth);
+}
+
 /**
  *      ata_dev_configure - Configure the specified ATA/ATAPI device
  *      @dev: Target device to configure
@@ -1311,6 +1333,7 @@ static int ata_dev_configure(struct ata_device *dev, int print_info)
 
                 if (ata_id_has_lba(id)) {
                         const char *lba_desc;
+                        char ncq_desc[20];
 
                         lba_desc = "LBA";
                         dev->flags |= ATA_DFLAG_LBA;
@@ -1319,14 +1342,17 @@ static int ata_dev_configure(struct ata_device *dev, int print_info)
                                 lba_desc = "LBA48";
                         }
 
+                        /* config NCQ */
+                        ata_dev_config_ncq(dev, ncq_desc, sizeof(ncq_desc));
+
                         /* print device info to dmesg */
                         if (print_info)
                                 ata_dev_printk(dev, KERN_INFO, "ATA-%d, "
-                                        "max %s, %Lu sectors: %s\n",
+                                        "max %s, %Lu sectors: %s %s\n",
                                         ata_id_major_version(id),
                                         ata_mode_string(xfer_mask),
                                         (unsigned long long)dev->n_sectors,
-                                        lba_desc);
+                                        lba_desc, ncq_desc);
                 } else {
                         /* CHS */
 
@@ -5675,6 +5701,7 @@ EXPORT_SYMBOL_GPL(ata_port_queue_task);
 EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
 EXPORT_SYMBOL_GPL(ata_scsi_queuecmd);
 EXPORT_SYMBOL_GPL(ata_scsi_slave_config);
+EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
 EXPORT_SYMBOL_GPL(ata_scsi_release);
 EXPORT_SYMBOL_GPL(ata_host_intr);
 EXPORT_SYMBOL_GPL(sata_scr_valid);
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 9bef68c7c1de..996058af1bcd 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -41,6 +41,7 @@
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_request.h>
+#include <scsi/scsi_tcq.h>
 #include <scsi/scsi_transport.h>
 #include <linux/libata.h>
 #include <linux/hdreg.h>
@@ -684,6 +685,14 @@ static void ata_scsi_dev_config(struct scsi_device *sdev,
                 request_queue_t *q = sdev->request_queue;
                 blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
         }
+
+        if (dev->flags & ATA_DFLAG_NCQ) {
+                int depth;
+
+                depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
+                depth = min(ATA_MAX_QUEUE - 1, depth);
+                scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
+        }
 }
 
 /**
@@ -718,6 +727,43 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
 }
 
 /**
+ *      ata_scsi_change_queue_depth - SCSI callback for queue depth config
+ *      @sdev: SCSI device to configure queue depth for
+ *      @queue_depth: new queue depth
+ *
+ *      This is libata standard hostt->change_queue_depth callback.
+ *      SCSI will call into this callback when user tries to set queue
+ *      depth via sysfs.
+ *
+ *      LOCKING:
+ *      SCSI layer (we don't care)
+ *
+ *      RETURNS:
+ *      Newly configured queue depth.
+ */
+int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
+{
+        struct ata_port *ap = ata_shost_to_port(sdev->host);
+        struct ata_device *dev;
+        int max_depth;
+
+        if (queue_depth < 1)
+                return sdev->queue_depth;
+
+        dev = ata_scsi_find_dev(ap, sdev);
+        if (!dev || !ata_dev_enabled(dev))
+                return sdev->queue_depth;
+
+        max_depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
+        max_depth = min(ATA_MAX_QUEUE - 1, max_depth);
+        if (queue_depth > max_depth)
+                queue_depth = max_depth;
+
+        scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
+        return queue_depth;
+}
+
+/**
  *      ata_scsi_start_stop_xlat - Translate SCSI START STOP UNIT command
  *      @qc: Storage for translated ATA taskfile
  *      @scsicmd: SCSI command to translate
diff --git a/include/linux/libata.h b/include/linux/libata.h
index dd0db2d21bc5..fcdd798bb086 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -109,7 +109,7 @@ enum {
         ATA_MAX_PORTS           = 8,
         ATA_DEF_QUEUE           = 1,
         /* tag ATA_MAX_QUEUE - 1 is reserved for internal commands */
-        ATA_MAX_QUEUE           = 2,
+        ATA_MAX_QUEUE           = 32,
         ATA_TAG_INTERNAL        = ATA_MAX_QUEUE - 1,
         ATA_MAX_SECTORS         = 200,  /* FIXME */
         ATA_MAX_BUS             = 2,
@@ -679,6 +679,8 @@ extern int ata_std_bios_param(struct scsi_device *sdev,
                               struct block_device *bdev,
                               sector_t capacity, int geom[]);
 extern int ata_scsi_slave_config(struct scsi_device *sdev);
+extern int ata_scsi_change_queue_depth(struct scsi_device *sdev,
+                                       int queue_depth);
 extern struct ata_device *ata_dev_pair(struct ata_device *adev);
 
 /*