[SCSI] hpsa: Increase the number of scatter gather elements supported.

This uses the scatter-gather chaining feature of Smart Array
controllers.  32 scatter-gather elements are embedded in the
"command list", and the last element in the list may be marked
as a "chain pointer", and point to an additional block of
scatter gather elements.  The precise number of scatter gather
elements supported is dependent on the particular kind of
Smart Array, and is determined at runtime by querying the
hardware.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/hpsa.c

@@ -187,7 +187,6 @@ static struct scsi_host_template hpsa_driver_template = {
 	.scan_finished		= hpsa_scan_finished,
 	.change_queue_depth	= hpsa_change_queue_depth,
 	.this_id		= -1,
-	.sg_tablesize		= MAXSGENTRIES,
 	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = hpsa_eh_device_reset_handler,
 	.ioctl			= hpsa_ioctl,
@@ -844,6 +843,76 @@ static void hpsa_scsi_setup(struct ctlr_info *h)
 	spin_lock_init(&h->devlock);
 }
 
+static void hpsa_free_sg_chain_blocks(struct ctlr_info *h)
+{
+	int i;
+
+	if (!h->cmd_sg_list)
+		return;
+	for (i = 0; i < h->nr_cmds; i++) {
+		kfree(h->cmd_sg_list[i]);
+		h->cmd_sg_list[i] = NULL;
+	}
+	kfree(h->cmd_sg_list);
+	h->cmd_sg_list = NULL;
+}
+
+static int hpsa_allocate_sg_chain_blocks(struct ctlr_info *h)
+{
+	int i;
+
+	if (h->chainsize <= 0)
+		return 0;
+
+	h->cmd_sg_list = kzalloc(sizeof(*h->cmd_sg_list) * h->nr_cmds,
+				GFP_KERNEL);
+	if (!h->cmd_sg_list)
+		return -ENOMEM;
+	for (i = 0; i < h->nr_cmds; i++) {
+		h->cmd_sg_list[i] = kmalloc(sizeof(*h->cmd_sg_list[i]) *
+						h->chainsize, GFP_KERNEL);
+		if (!h->cmd_sg_list[i])
+			goto clean;
+	}
+	return 0;
+
+clean:
+	hpsa_free_sg_chain_blocks(h);
+	return -ENOMEM;
+}
+
+static void hpsa_map_sg_chain_block(struct ctlr_info *h,
+	struct CommandList *c)
+{
+	struct SGDescriptor *chain_sg, *chain_block;
+	u64 temp64;
+
+	chain_sg = &c->SG[h->max_cmd_sg_entries - 1];
+	chain_block = h->cmd_sg_list[c->cmdindex];
+	chain_sg->Ext = HPSA_SG_CHAIN;
+	chain_sg->Len = sizeof(*chain_sg) *
+		(c->Header.SGTotal - h->max_cmd_sg_entries);
+	temp64 = pci_map_single(h->pdev, chain_block, chain_sg->Len,
+				PCI_DMA_TODEVICE);
+	chain_sg->Addr.lower = (u32) (temp64 & 0x0FFFFFFFFULL);
+	chain_sg->Addr.upper = (u32) ((temp64 >> 32) & 0x0FFFFFFFFULL);
+}
+
+static void hpsa_unmap_sg_chain_block(struct ctlr_info *h,
+	struct CommandList *c)
+{
+	struct SGDescriptor *chain_sg;
+	union u64bit temp64;
+
+	if (c->Header.SGTotal <= h->max_cmd_sg_entries)
+		return;
+
+	chain_sg = &c->SG[h->max_cmd_sg_entries - 1];
+	temp64.val32.lower = chain_sg->Addr.lower;
+	temp64.val32.upper = chain_sg->Addr.upper;
+	pci_unmap_single(h->pdev, temp64.val, chain_sg->Len, PCI_DMA_TODEVICE);
+}
+
 static void complete_scsi_command(struct CommandList *cp,
 	int timeout, u32 tag)
 {
@@ -860,6 +929,8 @@ static void complete_scsi_command(struct CommandList *cp,
 	h = cp->h;
 
 	scsi_dma_unmap(cmd); /* undo the DMA mappings */
+	if (cp->Header.SGTotal > h->max_cmd_sg_entries)
+		hpsa_unmap_sg_chain_block(h, cp);
 
 	cmd->result = (DID_OK << 16); 		/* host byte */
 	cmd->result |= (COMMAND_COMPLETE << 8);	/* msg byte */
@@ -1064,6 +1135,7 @@ static int hpsa_scsi_detect(struct ctlr_info *h)
 	sh->max_id = HPSA_MAX_LUN;
 	sh->can_queue = h->nr_cmds;
 	sh->cmd_per_lun = h->nr_cmds;
+	sh->sg_tablesize = h->maxsgentries;
 	h->scsi_host = sh;
 	sh->hostdata[0] = (unsigned long) h;
 	sh->irq = h->intr[PERF_MODE_INT];
@@ -1765,16 +1837,17 @@ static void hpsa_update_scsi_devices(struct ctlr_info *h, int hostno)
  * dma mapping  and fills in the scatter gather entries of the
  * hpsa command, cp.
  */
-static int hpsa_scatter_gather(struct pci_dev *pdev,
+static int hpsa_scatter_gather(struct ctlr_info *h,
 		struct CommandList *cp,
 		struct scsi_cmnd *cmd)
 {
 	unsigned int len;
 	struct scatterlist *sg;
 	u64 addr64;
-	int use_sg, i;
+	int use_sg, i, sg_index, chained;
+	struct SGDescriptor *curr_sg;
 
-	BUG_ON(scsi_sg_count(cmd) > MAXSGENTRIES);
+	BUG_ON(scsi_sg_count(cmd) > h->maxsgentries);
 
 	use_sg = scsi_dma_map(cmd);
 	if (use_sg < 0)
@@ -1783,15 +1856,33 @@ static int hpsa_scatter_gather(struct pci_dev *pdev,
 	if (!use_sg)
 		goto sglist_finished;
 
+	curr_sg = cp->SG;
+	chained = 0;
+	sg_index = 0;
 	scsi_for_each_sg(cmd, sg, use_sg, i) {
+		if (i == h->max_cmd_sg_entries - 1 &&
+			use_sg > h->max_cmd_sg_entries) {
+			chained = 1;
+			curr_sg = h->cmd_sg_list[cp->cmdindex];
+			sg_index = 0;
+		}
 		addr64 = (u64) sg_dma_address(sg);
 		len  = sg_dma_len(sg);
-		cp->SG[i].Addr.lower =
-			(u32) (addr64 & (u64) 0x00000000FFFFFFFF);
-		cp->SG[i].Addr.upper =
-			(u32) ((addr64 >> 32) & (u64) 0x00000000FFFFFFFF);
-		cp->SG[i].Len = len;
-		cp->SG[i].Ext = 0;  /* we are not chaining */
+		curr_sg->Addr.lower = (u32) (addr64 & 0x0FFFFFFFFULL);
+		curr_sg->Addr.upper = (u32) ((addr64 >> 32) & 0x0FFFFFFFFULL);
+		curr_sg->Len = len;
+		curr_sg->Ext = 0;  /* we are not chaining */
+		curr_sg++;
+	}
+
+	if (use_sg + chained > h->maxSG)
+		h->maxSG = use_sg + chained;
+
+	if (chained) {
+		cp->Header.SGList = h->max_cmd_sg_entries;
+		cp->Header.SGTotal = (u16) (use_sg + 1);
+		hpsa_map_sg_chain_block(h, cp);
+		return 0;
 	}
 
 sglist_finished:
@@ -1887,7 +1978,7 @@ static int hpsa_scsi_queue_command(struct scsi_cmnd *cmd,
 		break;
 	}
 
-	if (hpsa_scatter_gather(h->pdev, c, cmd) < 0) { /* Fill SG list */
+	if (hpsa_scatter_gather(h, c, cmd) < 0) { /* Fill SG list */
 		cmd_free(h, c);
 		return SCSI_MLQUEUE_HOST_BUSY;
 	}
@@ -3283,6 +3374,23 @@ static int __devinit hpsa_pci_init(struct ctlr_info *h, struct pci_dev *pdev)
 
 	h->board_id = board_id;
 	h->max_commands = readl(&(h->cfgtable->MaxPerformantModeCommands));
+	h->maxsgentries = readl(&(h->cfgtable->MaxScatterGatherElements));
+
+	/*
+	 * Limit in-command s/g elements to 32 save dma'able memory.
+	 * Howvever spec says if 0, use 31
+	 */
+
+	h->max_cmd_sg_entries = 31;
+	if (h->maxsgentries > 512) {
+		h->max_cmd_sg_entries = 32;
+		h->chainsize = h->maxsgentries - h->max_cmd_sg_entries + 1;
+		h->maxsgentries--; /* save one for chain pointer */
+	} else {
+		h->maxsgentries = 31; /* default to traditional values */
+		h->chainsize = 0;
+	}
+
 	h->product_name = products[prod_index].product_name;
 	h->access = *(products[prod_index].access);
 	/* Allow room for some ioctls */
@@ -3463,6 +3571,8 @@ static int __devinit hpsa_init_one(struct pci_dev *pdev,
 		rc = -ENOMEM;
 		goto clean4;
 	}
+	if (hpsa_allocate_sg_chain_blocks(h))
+		goto clean4;
 	spin_lock_init(&h->lock);
 	spin_lock_init(&h->scan_lock);
 	init_waitqueue_head(&h->scan_wait_queue);
@@ -3485,6 +3595,7 @@ static int __devinit hpsa_init_one(struct pci_dev *pdev,
 	return 1;
 
 clean4:
+	hpsa_free_sg_chain_blocks(h);
 	kfree(h->cmd_pool_bits);
 	if (h->cmd_pool)
 		pci_free_consistent(h->pdev,
@@ -3560,6 +3671,7 @@ static void __devexit hpsa_remove_one(struct pci_dev *pdev)
 	hpsa_unregister_scsi(h);	/* unhook from SCSI subsystem */
 	hpsa_shutdown(pdev);
 	iounmap(h->vaddr);
+	hpsa_free_sg_chain_blocks(h);
 	pci_free_consistent(h->pdev,
 		h->nr_cmds * sizeof(struct CommandList),
 		h->cmd_pool, h->cmd_pool_dhandle);

drivers/scsi/hpsa.h

@@ -83,6 +83,10 @@ struct ctlr_info {
 	unsigned int maxQsinceinit;
 	unsigned int maxSG;
 	spinlock_t lock;
+	int maxsgentries;
+	u8 max_cmd_sg_entries;
+	int chainsize;
+	struct SGDescriptor **cmd_sg_list;
 
 	/* pointers to command and error info pool */
 	struct CommandList 	*cmd_pool;

drivers/scsi/hpsa_cmd.h

@@ -23,7 +23,8 @@
 
 /* general boundary defintions */
 #define SENSEINFOBYTES          32 /* may vary between hbas */
-#define MAXSGENTRIES            31
+#define MAXSGENTRIES            32
+#define HPSA_SG_CHAIN		0x80000000
 #define MAXREPLYQS              256
 
 /* Command Status value */
@@ -321,8 +322,8 @@ struct CommandList {
  */
 #define IS_32_BIT ((8 - sizeof(long))/4)
 #define IS_64_BIT (!IS_32_BIT)
-#define PAD_32 (8)
-#define PAD_64 (0)
+#define PAD_32 (24)
+#define PAD_64 (16)
 #define COMMANDLIST_PAD (IS_32_BIT * PAD_32 + IS_64_BIT * PAD_64)
 	u8 pad[COMMANDLIST_PAD];
 };