[PATCH 4/4] stex: add hard reset function

[Ed Lin]

For 'shasta' type controller there are at least one P2P bridge in it
and MU/ATU on the secondary bus under the bridge. When there is a
hardware/firmware hang, use the reset secondary bus function of P2P
bridge to actually reset and recover the hardware. As our MU/ATU is
the only device on this secondary bus, this reset action would not
affect other devices.

Signed-off-by: Ed Lin <ed.lin@xxxxxxxxxxx>
---
 stex.c |   37 +++++++++++++++++++++++++++++++++++++
 1 files changed, 37 insertions(+)
diff -urN a/drivers/scsi/stex.c b/drivers/scsi/stex.c
--- a/drivers/scsi/stex.c	2006-07-28 05:59:16.000000000 -0400
+++ b/drivers/scsi/stex.c	2006-07-28 06:02:04.000000000 -0400
@@ -882,6 +882,40 @@
 	return result;
 }
 
+static void stex_hard_reset(struct st_hba *hba)
+{
+	struct pci_bus *bus;
+	int i;
+	u16 pci_cmd;
+	u8 pci_bctl;
+
+	for (i = 0; i < 16; i++)
+		pci_read_config_dword(hba->pdev, i * 4,
+			&hba->pdev->saved_config_space[i]);
+
+	/* Reset secondary bus. Our controller(MU/ATU) is the only device on
+	   secondary bus. Consult Intel 80331/3 developer's manual for detail */
+	bus = hba->pdev->bus;
+	pci_read_config_byte(bus->self, PCI_BRIDGE_CONTROL, &pci_bctl);
+	pci_bctl |= PCI_BRIDGE_CTL_BUS_RESET;
+	pci_write_config_byte(bus->self, PCI_BRIDGE_CONTROL, pci_bctl);
+	msleep(1);
+	pci_bctl &= ~PCI_BRIDGE_CTL_BUS_RESET;
+	pci_write_config_byte(bus->self, PCI_BRIDGE_CONTROL, pci_bctl);
+
+	for (i = 0; i < MU_MAX_DELAY_TIME; i++) {
+		pci_read_config_word(hba->pdev, PCI_COMMAND, &pci_cmd);
+		if (pci_cmd & PCI_COMMAND_MASTER)
+			break;
+		msleep(1);
+	}
+
+	ssleep(5);
+	for (i = 0; i < 16; i++)
+		pci_write_config_dword(hba->pdev, i * 4,
+			hba->pdev->saved_config_space[i]);
+}
+
 static int stex_reset(struct scsi_cmnd *cmd)
 {
 	struct st_hba *hba;
@@ -916,6 +950,9 @@
 
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
+	if (hba->cardtype == st_shasta)
+		stex_hard_reset(hba);
+
 	if (stex_handshake(hba)) {
 		printk(KERN_WARNING DRV_NAME
 			"(%s): resetting: handshake failed\n",

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