From ddce00e38e06f10a12191df6830eb4975364ff99 Mon Sep 17 00:00:00 2001
From: Peter Robinson <pbrobinson@gmail.com>
Date: Wed, 30 Mar 2016 12:17:33 +0100
Subject: [PATCH] fix memremap on ARM

http://www.spinics.net/lists/arm-kernel/msg488703.html
---
 arch/arm/include/asm/io.h       | 12 ++++++++++++
 arch/arm/mm/ioremap.c           | 16 ++++++++++++++--
 drivers/mtd/maps/pxa2xx-flash.c |  6 +++---
 kernel/memremap.c               | 11 ++++++++---
 4 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 4859820..781ef5f 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -392,9 +392,18 @@ 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
 
+/*
+ * Do not use ioremap_cached in new code. Provided for the benefit of
+ * the pxa2xx-flash MTD driver only.
+ */
+void __iomem *ioremap_cached(resource_size_t res_cookie, size_t size);
+
 void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size);
 #define ioremap_wc ioremap_wc
 #define ioremap_wt ioremap_wc
@@ -402,6 +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 66a978d..ff0eed2 100644
--- 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);
@@ -380,11 +381,15 @@ void __iomem *ioremap(resource_size_t res_cookie, size_t size)
 EXPORT_SYMBOL(ioremap);
 
 void __iomem *ioremap_cache(resource_size_t res_cookie, size_t size)
+	__alias(ioremap_cached);
+
+void __iomem *ioremap_cached(resource_size_t res_cookie, size_t size)
 {
 	return arch_ioremap_caller(res_cookie, size, MT_DEVICE_CACHED,
 				   __builtin_return_address(0));
 }
 EXPORT_SYMBOL(ioremap_cache);
+EXPORT_SYMBOL(ioremap_cached);
 
 void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
 {
@@ -414,6 +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/drivers/mtd/maps/pxa2xx-flash.c b/drivers/mtd/maps/pxa2xx-flash.c
index 7497090..2cde28e 100644
--- a/drivers/mtd/maps/pxa2xx-flash.c
+++ b/drivers/mtd/maps/pxa2xx-flash.c
@@ -71,8 +71,8 @@ static int pxa2xx_flash_probe(struct platform_device *pdev)
 		       info->map.name);
 		return -ENOMEM;
 	}
-	info->map.cached = memremap(info->map.phys, info->map.size,
-			MEMREMAP_WB);
+	info->map.cached =
+		ioremap_cached(info->map.phys, info->map.size);
 	if (!info->map.cached)
 		printk(KERN_WARNING "Failed to ioremap cached %s\n",
 		       info->map.name);
@@ -111,7 +111,7 @@ static int pxa2xx_flash_remove(struct platform_device *dev)
 	map_destroy(info->mtd);
 	iounmap(info->map.virt);
 	if (info->map.cached)
-		memunmap(info->map.cached);
+		iounmap(info->map.cached);
 	kfree(info);
 	return 0;
 }
diff --git a/kernel/memremap.c b/kernel/memremap.c
index a6d3823..6723c77 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -27,6 +27,13 @@ __weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
 }
 #endif
 
+#ifndef arch_memremap_wb
+static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
+{
+	return (__force void *)ioremap_cache(offset, size);
+}
+#endif
+
 static void *try_ram_remap(resource_size_t offset, size_t size)
 {
 	unsigned long pfn = PHYS_PFN(offset);
@@ -34,7 +41,7 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
 	/* In the simple case just return the existing linear address */
 	if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)))
 		return __va(offset);
-	return NULL; /* fallback to ioremap_cache */
+	return arch_memremap_wb(offset, size);
 }
 
 /**
@@ -89,8 +96,6 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 		 */
 		if (is_ram == REGION_INTERSECTS)
 			addr = try_ram_remap(offset, size);
-		if (!addr)
-			addr = ioremap_cache(offset, size);
 	}
 
 	/*
-- 
2.7.3