[PATCH] libata: two new PCI helpers

The first performs the simplex clearing relevant to some chipsets that
report simplex by default but can in fact do more if poked. The second
is used to strip DMA modes from a PCI control with no BAR4 allocation.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/scsi/libata-bmdma.c

@@ -700,5 +700,41 @@ int ata_pci_init_one (struct pci_dev *pdev, struct ata_port_info **port_info,
 	return rc;
 }
 
+/**
+ *	ata_pci_clear_simplex	-	attempt to kick device out of simplex
+ *	@pdev: PCI device
+ *
+ *	Some PCI ATA devices report simplex mode but in fact can be told to
+ *	enter non simplex mode. This implements the neccessary logic to 
+ *	perform the task on such devices. Calling it on other devices will
+ *	have -undefined- behaviour.
+ */
+
+int ata_pci_clear_simplex(struct pci_dev *pdev)
+{
+	unsigned long bmdma = pci_resource_start(pdev, 4);
+	u8 simplex;
+
+	if (bmdma == 0)
+		return -ENOENT;
+
+	simplex = inb(bmdma + 0x02);
+	outb(simplex & 0x60, bmdma + 0x02);
+	simplex = inb(bmdma + 0x02);
+	if (simplex & 0x80)
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+unsigned long ata_pci_default_filter(const struct ata_port *ap, struct ata_device *adev, unsigned long xfer_mask)
+{
+	/* Filter out DMA modes if the device has been configured by
+	   the BIOS as PIO only */
+
+	if (ap->ioaddr.bmdma_addr == 0)
+		xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
+	return xfer_mask;
+}
+
 #endif /* CONFIG_PCI */