ARM: memremap: implement arch_memremap_wb()

The generic memremap() falls back to using ioremap_cache() to create
MEMREMAP_WB mappings if the requested region is not already covered
by the linear mapping, unless the architecture provides an implementation
of arch_memremap_wb().

Since ioremap_cache() is not appropriate on ARM to map memory with the
same attributes used for the linear mapping, implement arch_memremap_wb()
which does exactly that. Also, relax the WARN() check to allow MT_MEMORY_RW
mappings of pfn_valid() pages.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index fb94de2..781ef5f 100644 (file)
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -392,6 +392,9 @@ void __iomem *ioremap(resource_size_t res_cookie, size_t size);
 #define ioremap ioremap
 #define ioremap_nocache ioremap
 
+/*
+ * Do not use ioremap_cache for mapping memory. Use memremap instead.
+ */
 void __iomem *ioremap_cache(resource_size_t res_cookie, size_t size);
 #define ioremap_cache ioremap_cache
 
@@ -408,6 +411,9 @@ void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size);
 void iounmap(volatile void __iomem *iomem_cookie);
 #define iounmap iounmap
 
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size);
+#define arch_memremap_wb arch_memremap_wb
+
 /*
  * io{read,write}{16,32}be() macros
  */

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index d5350f6..ff0eed2 100644 (file)
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -297,9 +297,10 @@ static void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
        }
 
        /*
-        * Don't allow RAM to be mapped - this causes problems with ARMv6+
+        * Don't allow RAM to be mapped with mismatched attributes - this
+        * causes problems with ARMv6+
         */
-       if (WARN_ON(pfn_valid(pfn)))
+       if (WARN_ON(pfn_valid(pfn) && mtype != MT_MEMORY_RW))
                return NULL;
 
        area = get_vm_area_caller(size, VM_IOREMAP, caller);
@@ -418,6 +419,13 @@ __arm_ioremap_exec(phys_addr_t phys_addr, size_t size, bool cached)
                        __builtin_return_address(0));
 }
 
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
+{
+       return (__force void *)arch_ioremap_caller(phys_addr, size,
+                                                  MT_MEMORY_RW,
+                                                  __builtin_return_address(0));
+}
+
 void __iounmap(volatile void __iomem *io_addr)
 {
        void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);

diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index f24967e..ca6d8e8 100644 (file)
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -384,6 +384,11 @@ void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
 }
 EXPORT_SYMBOL(ioremap_wc);
 
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
+{
+       return (void *)phys_addr;
+}
+
 void __iounmap(volatile void __iomem *addr)
 {
 }