1 files changed, 38 insertions, 3 deletions

diff --git a/arch/arm/kernel/io.c b/arch/arm/kernel/io.c
index dcd5b4d86143..60b621295d6c 100644
--- a/arch/arm/kernel/io.c
+++ b/arch/arm/kernel/io.c
@@ -1,6 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/export.h>
 #include <linux/types.h>
 #include <linux/io.h>
+#include <linux/spinlock.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.
@@ -16,6 +52,7 @@ void _memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
 		from++;
 	}
 }
+EXPORT_SYMBOL(_memcpy_fromio);
 
 /*
  * Copy data from "real" memory space to IO memory space.
@@ -31,6 +68,7 @@ void _memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
 		to++;
 	}
 }
+EXPORT_SYMBOL(_memcpy_toio);
 
 /*
  * "memset" on IO memory space.
@@ -44,7 +82,4 @@ void _memset_io(volatile void __iomem *dst, int c, size_t count)
 		dst++;
 	}
 }
-
-EXPORT_SYMBOL(_memcpy_fromio);
-EXPORT_SYMBOL(_memcpy_toio);
 EXPORT_SYMBOL(_memset_io);