[MMC] sdhci: more DMA capabilities tests

Properly test for controller interface to see if it's DMA capable.  As many
controllers are misconfigured in this regard, also add debug parameters to
force DMA support either way.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/mmc/sdhci.c

@@ -28,6 +28,9 @@
 #define DBG(f, x...) \
 	pr_debug(DRIVER_NAME " [%s()]: " f, __func__,## x)
 
+static unsigned int debug_nodma = 0;
+static unsigned int debug_forcedma = 0;
+
 static const struct pci_device_id pci_ids[] __devinitdata = {
 	/* handle any SD host controller */
 	{PCI_DEVICE_CLASS((PCI_CLASS_SYSTEM_SDHCI << 8), 0xFFFF00)},
@@ -1105,6 +1108,16 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
 		return -ENODEV;
 	}
 
+	if ((pdev->class & 0x0000FF) == PCI_SDHCI_IFVENDOR) {
+		printk(KERN_ERR DRIVER_NAME ": Vendor specific interface. Aborting.\n");
+		return -ENODEV;
+	}
+
+	if ((pdev->class & 0x0000FF) > PCI_SDHCI_IFVENDOR) {
+		printk(KERN_ERR DRIVER_NAME ": Unknown interface. Aborting.\n");
+		return -ENODEV;
+	}
+
 	mmc = mmc_alloc_host(sizeof(struct sdhci_host), &pdev->dev);
 	if (!mmc)
 		return -ENOMEM;
@@ -1146,7 +1159,16 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
 
 	caps = readl(host->ioaddr + SDHCI_CAPABILITIES);
 
-	if ((caps & SDHCI_CAN_DO_DMA) && ((pdev->class & 0x0000FF) == 0x01))
+	if (debug_nodma)
+		DBG("DMA forced off\n");
+	else if (debug_forcedma) {
+		DBG("DMA forced on\n");
+		host->flags |= SDHCI_USE_DMA;
+	} else if ((pdev->class & 0x0000FF) != PCI_SDHCI_IFDMA)
+		DBG("Controller doesn't have DMA interface\n");
+	else if (!(caps & SDHCI_CAN_DO_DMA))
+		DBG("Controller doesn't have DMA capability\n");
+	else
 		host->flags |= SDHCI_USE_DMA;
 
 	if (host->flags & SDHCI_USE_DMA) {
@@ -1429,7 +1451,13 @@ static void __exit sdhci_drv_exit(void)
 module_init(sdhci_drv_init);
 module_exit(sdhci_drv_exit);
 
+module_param(debug_nodma, uint, 0444);
+module_param(debug_forcedma, uint, 0444);
+
 MODULE_AUTHOR("Pierre Ossman <drzeus@drzeus.cx>");
 MODULE_DESCRIPTION("Secure Digital Host Controller Interface driver");
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL");
+
+MODULE_PARM_DESC(debug_nodma, "Forcefully disable DMA transfers. (default 0)");
+MODULE_PARM_DESC(debug_forcedma, "Forcefully enable DMA transfers. (default 0)");

drivers/mmc/sdhci.h

@@ -12,6 +12,10 @@
  * PCI registers
  */
 
+#define PCI_SDHCI_IFPIO			0x00
+#define PCI_SDHCI_IFDMA			0x01
+#define PCI_SDHCI_IFVENDOR		0x02
+
 #define PCI_SLOT_INFO			0x40	/* 8 bits */
 #define  PCI_SLOT_INFO_SLOTS(x)		((x >> 4) & 7)
 #define  PCI_SLOT_INFO_FIRST_BAR_MASK	0x07