[ARM] Kirkwood: enable PCIe before reading device ID register

PCIe may have been disabled (by kirkwood_clock_gate)
if this kernel was started by kexec.  Make sure PCIe
is enabled before attempting to access the device ID
register, otherwise the system will hang.

Signed-off-by: Eric Cooper <ecc@cmu.edu>
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>

2 files changed, 9 insertions, 0 deletions

diff --git a/arch/arm/mach-kirkwood/common.h b/arch/arm/mach-kirkwood/common.h
index 95bb0a73adfb..a35b86235772 100644
--- a/arch/arm/mach-kirkwood/common.h
+++ b/arch/arm/mach-kirkwood/common.h
@@ -32,6 +32,7 @@ void kirkwood_init_irq(void);
 extern struct mbus_dram_target_info kirkwood_mbus_dram_info;
 void kirkwood_setup_cpu_mbus(void);
 
+void kirkwood_enable_pcie(void);
 void kirkwood_pcie_id(u32 *dev, u32 *rev);
 
 void kirkwood_ehci_init(void);
diff --git a/arch/arm/mach-kirkwood/pcie.c b/arch/arm/mach-kirkwood/pcie.c
index 513ad3102d7c..ca294ff6d5be 100644
--- a/arch/arm/mach-kirkwood/pcie.c
+++ b/arch/arm/mach-kirkwood/pcie.c
@@ -18,8 +18,16 @@
 #include <mach/bridge-regs.h>
 #include "common.h"
 
+void kirkwood_enable_pcie(void)
+{
+        u32 curr = readl(CLOCK_GATING_CTRL);
+        if (!(curr & CGC_PEX0))
+                writel(curr | CGC_PEX0, CLOCK_GATING_CTRL);
+}
+
 void __init kirkwood_pcie_id(u32 *dev, u32 *rev)
 {
+        kirkwood_enable_pcie();
         *dev = orion_pcie_dev_id((void __iomem *)PCIE_VIRT_BASE);
         *rev = orion_pcie_rev((void __iomem *)PCIE_VIRT_BASE);
 }