[PATCH] ppc32: Fix MPC52xx configuration space access

This patch takes care of an errata of the MPC5200 by avoiding 32 bits access
in type 1 configuration accesses.  All others accesses are still 32 bits wide.
 It also adds some mb() since the simple out_be(...) are not sufficient in
this case.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 69 insertions, 14 deletions

diff --git a/arch/ppc/syslib/mpc52xx_pci.c b/arch/ppc/syslib/mpc52xx_pci.c
index e6cb3e26615a..2c5e6ddaf2c5 100644
--- a/arch/ppc/syslib/mpc52xx_pci.c
+++ b/arch/ppc/syslib/mpc52xx_pci.c
@@ -24,6 +24,12 @@
 #include <asm/machdep.h>
 
 
+/* This macro is defined to activate the workaround for the bug
+   435 of the MPC5200 (L25R). With it activated, we don't do any
+   32 bits configuration access during type-1 cycles */
+#define MPC5200_BUG_435_WORKAROUND
+
+
 static int
 mpc52xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
 				int offset, int len, u32 *val)
@@ -40,17 +46,39 @@ mpc52xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
 		((bus->number - hose->bus_offset) << 16) |
 		(devfn << 8) |
 		(offset & 0xfc));
+	mb();
+
+#ifdef MPC5200_BUG_435_WORKAROUND
+	if (bus->number != hose->bus_offset) {
+		switch (len) {
+			case 1:
+				value = in_8(((u8 __iomem *)hose->cfg_data) + (offset & 3));
+				break;
+			case 2:
+				value = in_le16(((u16 __iomem *)hose->cfg_data) + ((offset>>1) & 1));
+				break;
+
+			default:
+				value = in_le16((u16 __iomem *)hose->cfg_data) |
+					(in_le16(((u16 __iomem *)hose->cfg_data) + 1) << 16);
+				break;
+		}
+	}
+	else
+#endif
+	{
+		value = in_le32(hose->cfg_data);
 
-	value = in_le32(hose->cfg_data);
-
-	if (len != 4) {
-		value >>= ((offset & 0x3) << 3);
-		value &= 0xffffffff >> (32 - (len << 3));
+		if (len != 4) {
+			value >>= ((offset & 0x3) << 3);
+			value &= 0xffffffff >> (32 - (len << 3));
+		}
 	}
 
 	*val = value;
 
 	out_be32(hose->cfg_addr, 0);
+	mb();
 
 	return PCIBIOS_SUCCESSFUL;
 }
@@ -71,21 +99,48 @@ mpc52xx_pci_write_config(struct pci_bus *bus, unsigned int devfn,
 		((bus->number - hose->bus_offset) << 16) |
 		(devfn << 8) |
 		(offset & 0xfc));
+	mb();
+
+#ifdef MPC5200_BUG_435_WORKAROUND
+	if (bus->number != hose->bus_offset) {
+		switch (len) {
+			case 1:
+				out_8(((u8 __iomem *)hose->cfg_data) +
+					(offset & 3), val);
+				break;
+			case 2:
+				out_le16(((u16 __iomem *)hose->cfg_data) +
+					((offset>>1) & 1), val);
+				break;
+
+			default:
+				out_le16((u16 __iomem *)hose->cfg_data,
+					(u16)val);
+				out_le16(((u16 __iomem *)hose->cfg_data) + 1,
+					(u16)(val>>16));
+				break;
+		}
+	}
+	else
+#endif
+	{
+		if (len != 4) {
+			value = in_le32(hose->cfg_data);
 
-	if (len != 4) {
-		value = in_le32(hose->cfg_data);
+			offset = (offset & 0x3) << 3;
+			mask = (0xffffffff >> (32 - (len << 3)));
+			mask <<= offset;
 
-		offset = (offset & 0x3) << 3;
-		mask = (0xffffffff >> (32 - (len << 3)));
-		mask <<= offset;
+			value &= ~mask;
+			val = value | ((val << offset) & mask);
+		}
 
-		value &= ~mask;
-		val = value | ((val << offset) & mask);
+		out_le32(hose->cfg_data, val);
 	}
-
-	out_le32(hose->cfg_data, val);
+	mb();
 
 	out_be32(hose->cfg_addr, 0);
+	mb();
 
 	return PCIBIOS_SUCCESSFUL;
 }