[ARM] Kirkwood: add support for L2 cache WB/WT selection

Feroceon L2 cache can work in eighther write through or write back mode
on Kirkwood. Add the option to configure this mode according to Kconfig.
Signed-off-by: Ronen Shitrit <rshitrit@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>

arch/arm/mach-kirkwood/common.c

@@ -588,9 +588,15 @@ static char * __init kirkwood_id(void)
 	}
 }
 
-static int __init is_l2_writethrough(void)
+static void __init kirkwood_l2_init(void)
 {
-	return !!(readl(L2_CONFIG_REG) & L2_WRITETHROUGH);
+#ifdef CONFIG_CACHE_FEROCEON_L2_WRITETHROUGH
+	writel(readl(L2_CONFIG_REG) | L2_WRITETHROUGH, L2_CONFIG_REG);
+	feroceon_l2_init(1);
+#else
+	writel(readl(L2_CONFIG_REG) & ~L2_WRITETHROUGH, L2_CONFIG_REG);
+	feroceon_l2_init(0);
+#endif
 }
 
 void __init kirkwood_init(void)
@@ -605,6 +611,6 @@ void __init kirkwood_init(void)
 	kirkwood_setup_cpu_mbus();
 
 #ifdef CONFIG_CACHE_FEROCEON_L2
-	feroceon_l2_init(is_l2_writethrough());
+	kirkwood_l2_init();
 #endif
 }

arch/arm/mm/Kconfig

@@ -735,6 +735,14 @@ config CACHE_FEROCEON_L2
 	help
 	  This option enables the Feroceon L2 cache controller.
 
+config CACHE_FEROCEON_L2_WRITETHROUGH
+	bool "Force Feroceon L2 cache write through"
+	depends on CACHE_FEROCEON_L2
+	default n
+	help
+	  Say Y here to use the Feroceon L2 cache in writethrough mode.
+	  Unless you specifically require this, say N for writeback mode.
+
 config CACHE_L2X0
 	bool "Enable the L2x0 outer cache controller"
 	depends on REALVIEW_EB_ARM11MP || MACH_REALVIEW_PB11MP || MACH_REALVIEW_PB1176

arch/arm/mm/proc-feroceon.S

@@ -80,7 +80,8 @@ ENTRY(cpu_feroceon_proc_fin)
 	msr	cpsr_c, ip
 	bl	feroceon_flush_kern_cache_all
 
-#if defined(CONFIG_CACHE_FEROCEON_L2) && !defined(CONFIG_L2_CACHE_WRITETHROUGH)
+#if defined(CONFIG_CACHE_FEROCEON_L2) && \
+	!defined(CONFIG_CACHE_FEROCEON_L2_WRITETHROUGH)
 	mov	r0, #0
 	mcr	p15, 1, r0, c15, c9, 0		@ clean L2
 	mcr	p15, 0, r0, c7, c10, 4		@ drain WB
@@ -389,7 +390,8 @@ ENTRY(feroceon_range_cache_fns)
 
 	.align	5
 ENTRY(cpu_feroceon_dcache_clean_area)
-#if defined(CONFIG_CACHE_FEROCEON_L2) && !defined(CONFIG_L2_CACHE_WRITETHROUGH)
+#if defined(CONFIG_CACHE_FEROCEON_L2) && \
+	!defined(CONFIG_CACHE_FEROCEON_L2_WRITETHROUGH)
 	mov	r2, r0
 	mov	r3, r1
 #endif
@@ -397,7 +399,8 @@ ENTRY(cpu_feroceon_dcache_clean_area)
 	add	r0, r0, #CACHE_DLINESIZE
 	subs	r1, r1, #CACHE_DLINESIZE
 	bhi	1b
-#if defined(CONFIG_CACHE_FEROCEON_L2) && !defined(CONFIG_L2_CACHE_WRITETHROUGH)
+#if defined(CONFIG_CACHE_FEROCEON_L2) && \
+	!defined(CONFIG_CACHE_FEROCEON_L2_WRITETHROUGH)
 1:	mcr	p15, 1, r2, c15, c9, 1		@ clean L2 entry
 	add	r2, r2, #CACHE_DLINESIZE
 	subs	r3, r3, #CACHE_DLINESIZE
@@ -466,7 +469,8 @@ ENTRY(cpu_feroceon_set_pte_ext)
 	str	r2, [r0]			@ hardware version
 	mov	r0, r0
 	mcr	p15, 0, r0, c7, c10, 1		@ clean D entry
-#if defined(CONFIG_CACHE_FEROCEON_L2) && !defined(CONFIG_L2_CACHE_WRITETHROUGH)
+#if defined(CONFIG_CACHE_FEROCEON_L2) && \
+	!defined(CONFIG_CACHE_FEROCEON_L2_WRITETHROUGH)
 	mcr	p15, 1, r0, c15, c9, 1		@ clean L2 entry
 #endif
 	mcr	p15, 0, r0, c7, c10, 4		@ drain WB