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

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 <redacted>
---
 arch/powerpc/platforms/85xx/mpc85xx_cds.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/platforms/85xx/mpc85xx_cds.c b/arch/powerpc/platforms/85xx/mpc85xx_cds.c
index 431aaa2..f1eaf07 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_cds.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_cds.c

@@ -62,6 +62,28 @@ 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);
+
+		pci_dev_put(dev);
+	}
+
+	/*
+	 *  We should only get here if the P2P bridge is disabled. In that
+	 *  case, 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)

@@ -327,7 +349,11 @@ 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

On Thu, Jun 07, 2007 at 01:38:07PM -0700, Randy Vinson wrote:

+	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);

How about adding another "pci_read_config_byte(dev, 0x47, &tmp);" to
flush the write out of any fifo's and adding a comment that explains
that once that write hits the hardware, the reset is essentially
instantaneous.  IOW, there isn't a race between this reset and the reset
you'd call if/when it falls out of this 'if'.

+
+		pci_dev_put(dev);
+	}
+
+	/*
+	 *  We should only get here if the P2P bridge is disabled. In that
+	 *  case, just use the default reset.
+	 */
+	mpc85xx_restart(NULL);

Mark