cciss: Adds simple mode functionality

Signed-off-by: Joseph Handzik <[e-mail]>
Acked-by: Stephen M. Cameron <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

Documentation/blockdev/cciss.txt

···
 /dev/cciss/c1d1p2		Controller 1, disk 1, partition 2
 /dev/cciss/c1d1p3		Controller 1, disk 1, partition 3
 
+CCISS simple mode support
+-------------------------
+
+The "cciss_simple_mode=1" boot parameter may be used to prevent the driver
+from putting the controller into "performant" mode. The difference is that
+with simple mode, each command completion requires an interrupt, while with
+"performant mode" (the default, and ordinarily better performing) it is
+possible to have multiple command completions indicated by a single
+interrupt.
+
 SCSI tape drive and medium changer support
 ------------------------------------------
 

drivers/block/cciss.c

···
 module_param(cciss_tape_cmds, int, 0644);
 MODULE_PARM_DESC(cciss_tape_cmds,
 	"number of commands to allocate for tape devices (default: 6)");
+static int cciss_simple_mode;
+module_param(cciss_simple_mode, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(cciss_simple_mode,
+	"Use 'simple mode' rather than 'performant mode'");
 
 static DEFINE_MUTEX(cciss_mutex);
 static struct proc_dir_entry *proc_cciss;
···
 			unsigned int block_size, InquiryData_struct *inq_buff,
 				   drive_info_struct *drv);
 static void __devinit cciss_interrupt_mode(ctlr_info_t *);
+static int __devinit cciss_enter_simple_mode(struct ctlr_info *h);
 static void start_io(ctlr_info_t *h);
 static int sendcmd_withirq(ctlr_info_t *h, __u8 cmd, void *buff, size_t size,
 			__u8 page_code, unsigned char scsi3addr[],
···
 		h->product_name,
 		(unsigned long)h->board_id,
 		h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
-		h->firm_ver[3], (unsigned int)h->intr[PERF_MODE_INT],
+		h->firm_ver[3], (unsigned int)h->intr[h->intr_mode],
 		h->num_luns,
 		h->Qdepth, h->commands_outstanding,
 		h->maxQsinceinit, h->max_outstanding, h->maxSG);
···
 {
 	__u32 trans_support;
 
+	if (cciss_simple_mode)
+		return;
+
 	dev_dbg(&h->pdev->dev, "Trying to put board into Performant mode\n");
 	/* Attempt to put controller into performant mode if supported */
 	/* Does board support performant mode? */
···
 default_int_mode:
 #endif				/* CONFIG_PCI_MSI */
 	/* if we get here we're going to use the default interrupt mode */
-	h->intr[PERF_MODE_INT] = h->pdev->irq;
+	h->intr[h->intr_mode] = h->pdev->irq;
 	return;
 }
 
···
 	}
 	cciss_enable_scsi_prefetch(h);
 	cciss_p600_dma_prefetch_quirk(h);
+	err = cciss_enter_simple_mode(h);
+	if (err)
+		goto err_out_free_res;
 	cciss_put_controller_into_performant_mode(h);
 	return 0;
 
···
 	irqreturn_t (*intxhandler)(int, void *))
 {
 	if (h->msix_vector || h->msi_vector) {
-		if (!request_irq(h->intr[PERF_MODE_INT], msixhandler,
+		if (!request_irq(h->intr[h->intr_mode], msixhandler,
 				IRQF_DISABLED, h->devname, h))
 			return 0;
 		dev_err(&h->pdev->dev, "Unable to get msi irq %d"
-			" for %s\n", h->intr[PERF_MODE_INT],
+			" for %s\n", h->intr[h->intr_mode],
 			h->devname);
 		return -1;
 	}
 
-	if (!request_irq(h->intr[PERF_MODE_INT], intxhandler,
+	if (!request_irq(h->intr[h->intr_mode], intxhandler,
 			IRQF_DISABLED, h->devname, h))
 		return 0;
 	dev_err(&h->pdev->dev, "Unable to get irq %d for %s\n",
-		h->intr[PERF_MODE_INT], h->devname);
+		h->intr[h->intr_mode], h->devname);
 	return -1;
 }
 
···
 {
 	int ctlr = h->ctlr;
 
-	free_irq(h->intr[PERF_MODE_INT], h);
+	free_irq(h->intr[h->intr_mode], h);
 #ifdef CONFIG_PCI_MSI
 	if (h->msix_vector)
 		pci_disable_msix(h->pdev);
···
 	h = hba[i];
 	h->pdev = pdev;
 	h->busy_initializing = 1;
+	h->intr_mode = cciss_simple_mode ? SIMPLE_MODE_INT : PERF_MODE_INT;
 	INIT_LIST_HEAD(&h->cmpQ);
 	INIT_LIST_HEAD(&h->reqQ);
 	mutex_init(&h->busy_shutting_down);
···
 
 	dev_info(&h->pdev->dev, "%s: <0x%x> at PCI %s IRQ %d%s using DAC\n",
 	       h->devname, pdev->device, pci_name(pdev),
-	       h->intr[PERF_MODE_INT], dac ? "" : " not");
+	       h->intr[h->intr_mode], dac ? "" : " not");
 
 	if (cciss_allocate_cmd_pool(h))
 		goto clean4;
···
 		spin_lock_irqsave(&h->lock, flags);
 		h->access.set_intr_mask(h, CCISS_INTR_OFF);
 		spin_unlock_irqrestore(&h->lock, flags);
-		free_irq(h->intr[PERF_MODE_INT], h);
+		free_irq(h->intr[h->intr_mode], h);
 		rc = cciss_request_irq(h, cciss_msix_discard_completions,
 					cciss_intx_discard_completions);
 		if (rc) {
···
 	cciss_free_cmd_pool(h);
 	cciss_free_scatterlists(h);
 	cciss_free_sg_chain_blocks(h->cmd_sg_list, h->nr_cmds);
-	free_irq(h->intr[PERF_MODE_INT], h);
+	free_irq(h->intr[h->intr_mode], h);
 clean2:
 	unregister_blkdev(h->major, h->devname);
 clean1:
···
 	if (return_code != IO_OK)
 		dev_warn(&h->pdev->dev, "Error flushing cache\n");
 	h->access.set_intr_mask(h, CCISS_INTR_OFF);
-	free_irq(h->intr[PERF_MODE_INT], h);
+	free_irq(h->intr[h->intr_mode], h);
 }
+
+static int __devinit cciss_enter_simple_mode(struct ctlr_info *h)
+{
+	u32 trans_support;
+
+	trans_support = readl(&(h->cfgtable->TransportSupport));
+	if (!(trans_support & SIMPLE_MODE))
+		return -ENOTSUPP;
+
+	h->max_commands = readl(&(h->cfgtable->CmdsOutMax));
+	writel(CFGTBL_Trans_Simple, &(h->cfgtable->HostWrite.TransportRequest));
+	writel(CFGTBL_ChangeReq, h->vaddr + SA5_DOORBELL);
+	cciss_wait_for_mode_change_ack(h);
+	print_cfg_table(h);
+	if (!(readl(&(h->cfgtable->TransportActive)) & CFGTBL_Trans_Simple)) {
+		dev_warn(&h->pdev->dev, "unable to get board into simple mode\n");
+		return -ENODEV;
+	}
+	h->transMethod = CFGTBL_Trans_Simple;
+	return 0;
+}
+
 
 static void __devexit cciss_remove_one(struct pci_dev *pdev)
 {

drivers/block/cciss.h

···
 	unsigned int intr[4];
 	unsigned int msix_vector;
 	unsigned int msi_vector;
+	int	intr_mode;
 	int 	cciss_max_sectors;
 	BYTE	cciss_read;
 	BYTE	cciss_write;