sh: Support explicit L1 cache disabling.

This reworks the cache mode configuration in Kconfig, and allows for
explicit selection of write-back/write-through/off configurations.
All of the cache flushing routines are optimized away for the off
case.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

6 files changed, 49 insertions, 26 deletions

diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index 9172e97dc26a..fdc245b7b043 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -143,12 +143,15 @@ static void __init cache_init(void)
                 flags &= ~CCR_CACHE_EMODE;
 #endif
 
-#ifdef CONFIG_SH_WRITETHROUGH
-        /* Turn on Write-through caching */
+#if defined(CONFIG_CACHE_WRITETHROUGH)
+        /* Write-through */
         flags |= CCR_CACHE_WT;
-#else
-        /* .. or default to Write-back */
+#elif defined(CONFIG_CACHE_WRITEBACK)
+        /* Write-back */
         flags |= CCR_CACHE_CB;
+#else
+        /* Off */
+        flags &= ~CCR_CACHE_ENABLE;
 #endif
 
         ctrl_outl(flags, CCR);
diff --git a/arch/sh/kernel/sh_ksyms.c b/arch/sh/kernel/sh_ksyms.c
index 37aef0a85197..de250705c35e 100644
--- a/arch/sh/kernel/sh_ksyms.c
+++ b/arch/sh/kernel/sh_ksyms.c
@@ -128,7 +128,8 @@ DECLARE_EXPORT(__movstrSI12_i4);
 #endif /* __GNUC__ == 4 */
 #endif
 
-#if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
+#if !defined(CONFIG_CACHE_OFF) && (defined(CONFIG_CPU_SH4) || \
+        defined(CONFIG_SH7705_CACHE_32KB))
 /* needed by some modules */
 EXPORT_SYMBOL(flush_cache_all);
 EXPORT_SYMBOL(flush_cache_range);
@@ -136,8 +137,8 @@ EXPORT_SYMBOL(flush_dcache_page);
 EXPORT_SYMBOL(__flush_purge_region);
 #endif
 
-#if defined(CONFIG_MMU) && (defined(CONFIG_CPU_SH4) || \
-        defined(CONFIG_SH7705_CACHE_32KB))
+#if !defined(CONFIG_CACHE_OFF) && defined(CONFIG_MMU) && \
+        (defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB))
 EXPORT_SYMBOL(clear_user_page);
 #endif
 
diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index 093d491424fd..c2777555003e 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -2,7 +2,6 @@
 # Processor families
 #
 config CPU_SH2
-        select SH_WRITETHROUGH if !CPU_SH2A
         bool
 
 config CPU_SH2A
@@ -414,8 +413,17 @@ config SH_DIRECT_MAPPED
           Turn this option off for platforms that do not have a direct-mapped
           cache, and you have no need to run the caches in such a configuration.
 
-config SH_WRITETHROUGH
-        bool "Use write-through caching"
+choice
+        prompt "Cache mode"
+        default CACHE_WRITEBACK if CPU_SH2A || CPU_SH3 || CPU_SH4
+        default CACHE_WRITETHROUGH if (CPU_SH2 && !CPU_SH2A)
+
+config CACHE_WRITEBACK
+        bool "Write-back"
+        depends on CPU_SH2A || CPU_SH3 || CPU_SH4
+
+config CACHE_WRITETHROUGH
+        bool "Write-through"
         help
           Selecting this option will configure the caches in write-through
           mode, as opposed to the default write-back configuration.
@@ -426,4 +434,9 @@ config SH_WRITETHROUGH
 
           If unsure, say N.
 
+config CACHE_OFF
+        bool "Off"
+
+endchoice
+
 endmenu
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index 4061e89d84d0..e73d7f970ce0 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -4,9 +4,10 @@
 
 obj-y                   := init.o extable.o consistent.o
 
-obj-$(CONFIG_CPU_SH2)   += cache-sh2.o
-obj-$(CONFIG_CPU_SH3)   += cache-sh3.o
-obj-$(CONFIG_CPU_SH4)   += cache-sh4.o
+cache-$(CONFIG_CPU_SH2)         := cache-sh2.o
+cache-$(CONFIG_CPU_SH3)         := cache-sh3.o
+cache-$(CONFIG_CPU_SH4)         := cache-sh4.o pg-sh4.o
+cache-$(CONFIG_CACHE_OFF)       :=
 
 mmu-y                   := tlb-nommu.o pg-nommu.o
 mmu-$(CONFIG_CPU_SH3)   += fault-nommu.o
@@ -14,7 +15,7 @@ mmu-$(CONFIG_CPU_SH4)	+= fault-nommu.o
 mmu-$(CONFIG_MMU)       := fault.o clear_page.o copy_page.o tlb-flush.o \
                            ioremap.o
 
-obj-y                   += $(mmu-y)
+obj-y                   += $(cache-y) $(mmu-y)
 
 ifdef CONFIG_DEBUG_FS
 obj-$(CONFIG_CPU_SH4)           += cache-debugfs.o
@@ -22,7 +23,7 @@ endif
 
 ifdef CONFIG_MMU
 obj-$(CONFIG_CPU_SH3)           += tlb-sh3.o
-obj-$(CONFIG_CPU_SH4)           += tlb-sh4.o pg-sh4.o
+obj-$(CONFIG_CPU_SH4)           += tlb-sh4.o
 obj-$(CONFIG_SH7705_CACHE_32KB) += pg-sh7705.o
 endif
 
diff --git a/arch/sh/mm/pmb.c b/arch/sh/mm/pmb.c
index a08a4a958add..7d43758dc244 100644
--- a/arch/sh/mm/pmb.c
+++ b/arch/sh/mm/pmb.c
@@ -145,7 +145,7 @@ repeat:
 
         ctrl_outl(vpn | PMB_V, mk_pmb_addr(pos));
 
-#ifdef CONFIG_SH_WRITETHROUGH
+#ifdef CONFIG_CACHE_WRITETHROUGH
         /*
          * When we are in 32-bit address extended mode, CCR.CB becomes
          * invalid, so care must be taken to manually adjust cacheable
diff --git a/arch/sh/mm/tlb-sh4.c b/arch/sh/mm/tlb-sh4.c
index f74cf667c8fa..13fde8cc7179 100644
--- a/arch/sh/mm/tlb-sh4.c
+++ b/arch/sh/mm/tlb-sh4.c
@@ -34,22 +34,27 @@ void update_mmu_cache(struct vm_area_struct * vma,
         unsigned long flags;
         unsigned long pteval;
         unsigned long vpn;
-        struct page *page;
-        unsigned long pfn;
 
         /* Ptrace may call this routine. */
         if (vma && current->active_mm != vma->vm_mm)
                 return;
 
-        pfn = pte_pfn(pte);
-        if (pfn_valid(pfn)) {
-                page = pfn_to_page(pfn);
-                if (!test_bit(PG_mapped, &page->flags)) {
-                        unsigned long phys = pte_val(pte) & PTE_PHYS_MASK;
-                        __flush_wback_region((void *)P1SEGADDR(phys), PAGE_SIZE);
-                        __set_bit(PG_mapped, &page->flags);
+#ifndef CONFIG_CACHE_OFF
+        {
+                unsigned long pfn = pte_pfn(pte);
+
+                if (pfn_valid(pfn)) {
+                        struct page *page = pfn_to_page(pfn);
+
+                        if (!test_bit(PG_mapped, &page->flags)) {
+                                unsigned long phys = pte_val(pte) & PTE_PHYS_MASK;
+                                __flush_wback_region((void *)P1SEGADDR(phys),
+                                                     PAGE_SIZE);
+                                __set_bit(PG_mapped, &page->flags);
+                        }
                 }
         }
+#endif
 
         local_irq_save(flags);
 
@@ -66,7 +71,7 @@ void update_mmu_cache(struct vm_area_struct * vma,
 
         /* Set PTEL register */
         pteval &= _PAGE_FLAGS_HARDWARE_MASK; /* drop software flags */
-#ifdef CONFIG_SH_WRITETHROUGH
+#ifdef CONFIG_CACHE_WRITETHROUGH
         pteval |= _PAGE_WT;
 #endif
         /* conveniently, we want all the software flags to be 0 anyway */