[CASSINI]: Program parent Intel31154 bridge when necessary.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 86 insertions, 0 deletions

diff --git a/drivers/net/cassini.c b/drivers/net/cassini.c
index 9c77eadb6767..33ac2ef67778 100644
--- a/drivers/net/cassini.c
+++ b/drivers/net/cassini.c
@@ -4846,6 +4846,90 @@ static int cas_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
         return rc;
 }
 
+/* When this chip sits underneath an Intel 31154 bridge, it is the
+ * only subordinate device and we can tweak the bridge settings to
+ * reflect that fact.
+ */
+static void __devinit cas_program_bridge(struct pci_dev *cas_pdev)
+{
+        struct pci_dev *pdev = cas_pdev->bus->self;
+        u32 val;
+
+        if (!pdev)
+                return;
+
+        if (pdev->vendor != 0x8086 || pdev->device != 0x537c)
+                return;
+
+        /* Clear bit 10 (Bus Parking Control) in the Secondary
+         * Arbiter Control/Status Register which lives at offset
+         * 0x41.  Using a 32-bit word read/modify/write at 0x40
+         * is much simpler so that's how we do this.
+         */
+        pci_read_config_dword(pdev, 0x40, &val);
+        val &= ~0x00040000;
+        pci_write_config_dword(pdev, 0x40, val);
+
+        /* Max out the Multi-Transaction Timer settings since
+         * Cassini is the only device present.
+         *
+         * The register is 16-bit and lives at 0x50.  When the
+         * settings are enabled, it extends the GRANT# signal
+         * for a requestor after a transaction is complete.  This
+         * allows the next request to run without first needing
+         * to negotiate the GRANT# signal back.
+         *
+         * Bits 12:10 define the grant duration:
+         *
+         *      1       --      16 clocks
+         *      2       --      32 clocks
+         *      3       --      64 clocks
+         *      4       --      128 clocks
+         *      5       --      256 clocks
+         *
+         * All other values are illegal.
+         *
+         * Bits 09:00 define which REQ/GNT signal pairs get the
+         * GRANT# signal treatment.  We set them all.
+         */
+        pci_write_config_word(pdev, 0x50, (5 << 10) | 0x3ff);
+
+        /* The Read Prefecth Policy register is 16-bit and sits at
+         * offset 0x52.  It enables a "smart" pre-fetch policy.  We
+         * enable it and max out all of the settings since only one
+         * device is sitting underneath and thus bandwidth sharing is
+         * not an issue.
+         *
+         * The register has several 3 bit fields, which indicates a
+         * multiplier applied to the base amount of prefetching the
+         * chip would do.  These fields are at:
+         *
+         *      15:13   ---     ReRead Primary Bus
+         *      12:10   ---     FirstRead Primary Bus
+         *      09:07   ---     ReRead Secondary Bus
+         *      06:04   ---     FirstRead Secondary Bus
+         *
+         * Bits 03:00 control which REQ/GNT pairs the prefetch settings
+         * get enabled on.  Bit 3 is a grouped enabler which controls
+         * all of the REQ/GNT pairs from [8:3].  Bits 2 to 0 control
+         * the individual REQ/GNT pairs [2:0].
+         */
+        pci_write_config_word(pdev, 0x52,
+                              (0x7 << 13) |
+                              (0x7 << 10) |
+                              (0x7 <<  7) |
+                              (0x7 <<  4) |
+                              (0xf <<  0));
+
+        /* Force cacheline size to 0x8 */
+        pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x08);
+
+        /* Force latency timer to maximum setting so Cassini can
+         * sit on the bus as long as it likes.
+         */
+        pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 0xff);
+}
+
 static int __devinit cas_init_one(struct pci_dev *pdev,
                                   const struct pci_device_id *ent)
 {
@@ -4901,6 +4985,8 @@ static int __devinit cas_init_one(struct pci_dev *pdev,
                 printk(KERN_WARNING PFX "Could not enable MWI for %s\n",
                        pci_name(pdev));
 
+        cas_program_bridge(pdev);
+
         /*
          * On some architectures, the default cache line size set
          * by pci_try_set_mwi reduces perforamnce.  We have to increase