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From 9cfa64ddaba49975b420ce5e5020efc3301061ac Mon Sep 17 00:00:00 2001
From: Gabor Juhos <juhosg@openwrt.org>
Date: Tue, 26 Jun 2012 10:19:46 +0200
Subject: [PATCH 01/34] MIPS: pci-ar724x: avoid data bus error due to a missing PCIe module
If the controller has no PCIe module attached,
accessing of the device configuration space
causes a data bus error. Avoid this by checking
the status of the PCIe link in advance, and
indicate an error if the link is down.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
---
arch/mips/pci/pci-ar724x.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
--- a/arch/mips/pci/pci-ar724x.c
+++ b/arch/mips/pci/pci-ar724x.c
@@ -23,9 +23,12 @@
#define AR724X_PCI_MEM_BASE 0x10000000
#define AR724X_PCI_MEM_SIZE 0x08000000
+#define AR724X_PCI_REG_RESET 0x18
#define AR724X_PCI_REG_INT_STATUS 0x4c
#define AR724X_PCI_REG_INT_MASK 0x50
+#define AR724X_PCI_RESET_LINK_UP BIT(0)
+
#define AR724X_PCI_INT_DEV0 BIT(14)
#define AR724X_PCI_IRQ_COUNT 1
@@ -38,6 +41,15 @@ static void __iomem *ar724x_pci_ctrl_bas
static u32 ar724x_pci_bar0_value;
static bool ar724x_pci_bar0_is_cached;
+static bool ar724x_pci_link_up;
+
+static inline bool ar724x_pci_check_link(void)
+{
+ u32 reset;
+
+ reset = __raw_readl(ar724x_pci_ctrl_base + AR724X_PCI_REG_RESET);
+ return reset & AR724X_PCI_RESET_LINK_UP;
+}
static int ar724x_pci_read(struct pci_bus *bus, unsigned int devfn, int where,
int size, uint32_t *value)
@@ -46,6 +58,9 @@ static int ar724x_pci_read(struct pci_bu
void __iomem *base;
u32 data;
+ if (!ar724x_pci_link_up)
+ return PCIBIOS_DEVICE_NOT_FOUND;
+
if (devfn)
return PCIBIOS_DEVICE_NOT_FOUND;
@@ -96,6 +111,9 @@ static int ar724x_pci_write(struct pci_b
u32 data;
int s;
+ if (!ar724x_pci_link_up)
+ return PCIBIOS_DEVICE_NOT_FOUND;
+
if (devfn)
return PCIBIOS_DEVICE_NOT_FOUND;
@@ -280,6 +298,10 @@ int __init ar724x_pcibios_init(int irq)
if (ar724x_pci_ctrl_base == NULL)
goto err_unmap_devcfg;
+ ar724x_pci_link_up = ar724x_pci_check_link();
+ if (!ar724x_pci_link_up)
+ pr_warn("ar724x: PCIe link is down\n");
+
ar724x_pci_irq_init(irq);
register_pci_controller(&ar724x_pci_controller);
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