1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/scsi/libata-bmdma.c b/drivers/scsi/libata-bmdma.c
index a89e44b21f4d..999725ca8d09 100644
--- a/drivers/scsi/libata-bmdma.c
+++ b/drivers/scsi/libata-bmdma.c
@@ -700,5 +700,41 @@ err_out:
         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 */