arm: mvebu: Disable MMU before changing register base address

Only with disabled MMU its possible to switch the base register address on
Armada 38x. Without this the SDRAM located at >= 0x4000.0000 is also not
accessible, as its still locked to cache.

Signed-off-by: Stefan Roese <sr@denx.de>

diff --git a/arch/arm/mach-mvebu/cpu.c b/arch/arm/mach-mvebu/cpu.c
index 9bc9f00..9496d5f 100644 (file)
--- a/arch/arm/mach-mvebu/cpu.c
+++ b/arch/arm/mach-mvebu/cpu.c
@@ -163,6 +163,14 @@ static void update_sdram_window_sizes(void)
        }
 }
 
+void mmu_disable(void)
+{
+       asm volatile(
+               "mrc p15, 0, r0, c1, c0, 0\n"
+               "bic r0, #1\n"
+               "mcr p15, 0, r0, c1, c0, 0\n");
+}
+
 #ifdef CONFIG_ARCH_CPU_INIT
 static void set_cbar(u32 addr)
 {
@@ -172,6 +180,16 @@ static void set_cbar(u32 addr)
 
 int arch_cpu_init(void)
 {
+#ifndef CONFIG_SPL_BUILD
+       /*
+        * Only with disabled MMU its possible to switch the base
+        * register address on Armada 38x. Without this the SDRAM
+        * located at >= 0x4000.0000 is also not accessible, as its
+        * still locked to cache.
+        */
+       mmu_disable();
+#endif
+
        /* Linux expects the internal registers to be at 0xf1000000 */
        writel(SOC_REGS_PHY_BASE, INTREG_BASE_ADDR_REG);
        set_cbar(SOC_REGS_PHY_BASE + 0xC000);