ARM: pxa: fix DFI bus lockups on startup

After the conversion of pxa architecture to common clock framework, the
NAND clock can be disabled on startup if no nand driver claims it.

In this case, it happens that if the bootloader used the NAND and set
the DFI arbitration bit, the next access to a static memory controller
area, such as an ethernet card, the system bus will stall, and the core
will be stalled forever.

Fix this by clearing the DFI arbritration bit in pxa3xx startup. The bit
will be enabled the pxa3xx-nand driver on need anyway. The only left
requirement is that upon pxa3xx-nand removal, the bit should be cleared
before the clock is disabled.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>

diff --git a/arch/arm/mach-pxa/include/mach/addr-map.h b/arch/arm/mach-pxa/include/mach/addr-map.h
index d28fe291233a55ddb0173bcd71e124fc900010e2..07b93fd244747312be8b2ab4fe1d7de68d617675 100644 (file)
--- a/arch/arm/mach-pxa/include/mach/addr-map.h
+++ b/arch/arm/mach-pxa/include/mach/addr-map.h
@@ -43,6 +43,13 @@
  * 0xf6200000..0xf6201000
  */
 
+/*
+ * DFI Bus for NAND, PXA3xx only
+ */
+#define NAND_PHYS              0x43100000
+#define NAND_VIRT              IOMEM(0xf6300000)
+#define NAND_SIZE              0x00100000
+
 /*
  * Internal Memory Controller (PXA27x and later)
  */

diff --git a/arch/arm/mach-pxa/pxa3xx.c b/arch/arm/mach-pxa/pxa3xx.c
index ce0f8d6242e2a047429a031f7ab9e6e53193d917..06005d3f2ba33523d1ee4f9e96499290a9908572 100644 (file)
--- a/arch/arm/mach-pxa/pxa3xx.c
+++ b/arch/arm/mach-pxa/pxa3xx.c
@@ -47,6 +47,13 @@ extern void __init pxa_dt_irq_init(int (*fn)(struct irq_data *, unsigned int));
 #define ISRAM_START    0x5c000000
 #define ISRAM_SIZE     SZ_256K
 
+/*
+ * NAND NFC: DFI bus arbitration subset
+ */
+#define NDCR                   (*(volatile u32 __iomem*)(NAND_VIRT + 0))
+#define NDCR_ND_ARB_EN         (1 << 12)
+#define NDCR_ND_ARB_CNTL       (1 << 19)
+
 static void __iomem *sram;
 static unsigned long wakeup_src;
 
@@ -362,7 +369,12 @@ static struct map_desc pxa3xx_io_desc[] __initdata = {
                .pfn            = __phys_to_pfn(PXA3XX_SMEMC_BASE),
                .length         = SMEMC_SIZE,
                .type           = MT_DEVICE
-       }
+       }, {
+               .virtual        = (unsigned long)NAND_VIRT,
+               .pfn            = __phys_to_pfn(NAND_PHYS),
+               .length         = NAND_SIZE,
+               .type           = MT_DEVICE
+       },
 };
 
 void __init pxa3xx_map_io(void)
@@ -419,6 +431,13 @@ static int __init pxa3xx_init(void)
                 */
                ASCR &= ~(ASCR_RDH | ASCR_D1S | ASCR_D2S | ASCR_D3S);
 
+               /*
+                * Disable DFI bus arbitration, to prevent a system bus lock if
+                * somebody disables the NAND clock (unused clock) while this
+                * bit remains set.
+                */
+               NDCR = (NDCR & ~NDCR_ND_ARB_EN) | NDCR_ND_ARB_CNTL;
+
                if ((ret = pxa_init_dma(IRQ_DMA, 32)))
                        return ret;