[PATCH v2] 85xxCDS: Make sure restart resets the PCI bus.

[Randy Vinson]

The current 85xxCDS restart code fails to reset the PCI bus which can
lead to odd behavior after the restart. This patch uses the VIA Super
Southbridge to perform a PCI reset which will reset the entire system.
NOTE: Since the VIA chip is behind a PCI-to-PCI bridge which can be
disabled with a switch setting, it may not be possible to perform the
PCI bus reset. In this case, the code defaults to the previous restart
mechanism.

Signed-off-by: Randy Vinson <rvinson at mvista.com>
---
Updated to incorporate feedback from M. Greer.

 arch/powerpc/platforms/85xx/mpc85xx_cds.c |   35 +++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/platforms/85xx/mpc85xx_cds.c b/arch/powerpc/platforms/85xx/mpc85xx_cds.c
index bc01364..a8720bf 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_cds.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_cds.c
@@ -63,6 +63,37 @@ static volatile u8 *cadmus;
 
 extern int mpc85xx_pci2_busno;
 
+static void mpc85xx_cds_restart(char *cmd)
+{
+	struct pci_dev *dev;
+	u_char tmp;
+
+	if ((dev = pci_get_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686,
+					NULL))) {
+
+		/* Use the VIA Super Southbridge to force a PCI reset */
+		pci_read_config_byte(dev, 0x47, &tmp);
+		pci_write_config_byte(dev, 0x47, tmp | 1);
+
+		/* Flush the outbound PCI write queues */
+		pci_read_config_byte(dev, 0x47, &tmp);
+
+		/*
+		 *  At this point, the harware reset should have triggered.
+		 *  However, if it doesn't work for some mysterious reason,
+		 *  just fall through to the default reset below.
+		 */
+
+		pci_dev_put(dev);
+	}
+
+	/*
+	 *  If we can't find the VIA chip (maybe the P2P bridge is disabled)
+	 *  or the VIA chip reset didn't work, just use the default reset.
+	 */
+	mpc85xx_restart(NULL);
+}
+
 static int mpc85xx_exclude_device(u_char bus, u_char devfn)
 {
 	if (bus == 0 && PCI_SLOT(devfn) == 0)
@@ -320,7 +351,11 @@ define_machine(mpc85xx_cds) {
 	.init_IRQ	= mpc85xx_cds_pic_init,
 	.show_cpuinfo	= mpc85xx_cds_show_cpuinfo,
 	.get_irq	= mpic_get_irq,
+#ifdef CONFIG_PCI
+	.restart	= mpc85xx_cds_restart,
+#else
 	.restart	= mpc85xx_restart,
+#endif
 	.calibrate_decr = generic_calibrate_decr,
 	.progress	= udbg_progress,
 };
-- 
1.5.0.GIT