ARM: imx: replicate the diagnostic register of boot cpu into secondary cores

The diagnostic register holds the errata bits.  Mostly bootloader
does not bring up secondary cores, so that when errata bits are set
in bootloader, they are set only for boot cpu.  But on a SMP
configuration, it should be equally done on every single core.
Set up the diagnostic register for secondary cores by replicating
the register from boot cpu.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Dirk Behme <dirk.behme@de.bosch.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/headsmp.S b/arch/arm/mach-imx/headsmp.S
index 67b9c48dcafe..627f16f0e9d1 100644
--- a/arch/arm/mach-imx/headsmp.S
+++ b/arch/arm/mach-imx/headsmp.S
@@ -18,8 +18,20 @@
         .section ".text.head", "ax"
 
 #ifdef CONFIG_SMP
+diag_reg_offset:
+        .word   g_diag_reg - .
+
+        .macro  set_diag_reg
+        adr     r0, diag_reg_offset
+        ldr     r1, [r0]
+        add     r1, r1, r0              @ r1 = physical &g_diag_reg
+        ldr     r0, [r1]
+        mcr     p15, 0, r0, c15, c0, 1  @ write diagnostic register
+        .endm
+
 ENTRY(v7_secondary_startup)
         bl      v7_invalidate_l1
+        set_diag_reg
         b       secondary_startup
 ENDPROC(v7_secondary_startup)
 #endif
diff --git a/arch/arm/mach-imx/platsmp.c b/arch/arm/mach-imx/platsmp.c
index 4a69305db65e..c6e1ab544882 100644
--- a/arch/arm/mach-imx/platsmp.c
+++ b/arch/arm/mach-imx/platsmp.c
@@ -12,6 +12,7 @@
 
 #include <linux/init.h>
 #include <linux/smp.h>
+#include <asm/cacheflush.h>
 #include <asm/page.h>
 #include <asm/smp_scu.h>
 #include <asm/mach/map.h>
@@ -21,6 +22,7 @@
 
 #define SCU_STANDBY_ENABLE      (1 << 5)
 
+u32 g_diag_reg;
 static void __iomem *scu_base;
 
 static struct map_desc scu_io_desc __initdata = {
@@ -80,6 +82,18 @@ void imx_smp_prepare(void)
 static void __init imx_smp_prepare_cpus(unsigned int max_cpus)
 {
         imx_smp_prepare();
+
+        /*
+         * The diagnostic register holds the errata bits.  Mostly bootloader
+         * does not bring up secondary cores, so that when errata bits are set
+         * in bootloader, they are set only for boot cpu.  But on a SMP
+         * configuration, it should be equally done on every single core.
+         * Read the register from boot cpu here, and will replicate it into
+         * secondary cores when booting them.
+         */
+        asm("mrc p15, 0, %0, c15, c0, 1" : "=r" (g_diag_reg) : : "cc");
+        __cpuc_flush_dcache_area(&g_diag_reg, sizeof(g_diag_reg));
+        outer_clean_range(__pa(&g_diag_reg), __pa(&g_diag_reg + 1));
 }
 
 struct smp_operations  imx_smp_ops __initdata = {