1 files changed, 39 insertions, 5 deletions

diff --git a/arch/arm/kernel/io.c b/arch/arm/kernel/io.c
index 6c20c1188b6..9203cf88333 100644
--- a/arch/arm/kernel/io.c
+++ b/arch/arm/kernel/io.c
@@ -1,13 +1,47 @@
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/types.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
 
-#include <asm/io.h>
+static DEFINE_RAW_SPINLOCK(__io_lock);
+
+/*
+ * Generic atomic MMIO modify.
+ *
+ * Allows thread-safe access to registers shared by unrelated subsystems.
+ * The access is protected by a single MMIO-wide lock.
+ */
+void atomic_io_modify_relaxed(void __iomem *reg, u32 mask, u32 set)
+{
+	unsigned long flags;
+	u32 value;
+
+	raw_spin_lock_irqsave(&__io_lock, flags);
+	value = readl_relaxed(reg) & ~mask;
+	value |= (set & mask);
+	writel_relaxed(value, reg);
+	raw_spin_unlock_irqrestore(&__io_lock, flags);
+}
+EXPORT_SYMBOL(atomic_io_modify_relaxed);
+
+void atomic_io_modify(void __iomem *reg, u32 mask, u32 set)
+{
+	unsigned long flags;
+	u32 value;
+
+	raw_spin_lock_irqsave(&__io_lock, flags);
+	value = readl_relaxed(reg) & ~mask;
+	value |= (set & mask);
+	writel(value, reg);
+	raw_spin_unlock_irqrestore(&__io_lock, flags);
+}
+EXPORT_SYMBOL(atomic_io_modify);
 
 /*
  * Copy data from IO memory space to "real" memory space.
  * This needs to be optimized.
  */
-void _memcpy_fromio(void *to, void __iomem *from, size_t count)
+void _memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
 {
 	unsigned char *t = to;
 	while (count) {
@@ -22,7 +56,7 @@ void _memcpy_fromio(void *to, void __iomem *from, size_t count)
  * Copy data from "real" memory space to IO memory space.
  * This needs to be optimized.
  */
-void _memcpy_toio(void __iomem *to, const void *from, size_t count)
+void _memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
 {
 	const unsigned char *f = from;
 	while (count) {
@@ -37,7 +71,7 @@ void _memcpy_toio(void __iomem *to, const void *from, size_t count)
  * "memset" on IO memory space.
  * This needs to be optimized.
  */
-void _memset_io(void __iomem *dst, int c, size_t count)
+void _memset_io(volatile void __iomem *dst, int c, size_t count)
 {
 	while (count) {
 		count--;