Implement arch-specific atomic_io_modify and atomic_io_modify_relaxed,
which are based on writel/readl_relaxed and writel_relaxed/readl_relaxed,
respectively.
In both cases, by relaxing the readl, perfomance can be improved.
Signed-off-by: Ezequiel Garcia <ezequiel.gar...@free-electrons.com>
---
arch/arm/include/asm/io.h | 4 ++++
arch/arm/kernel/io.c | 29 +++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index d070741..53637b6 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -397,5 +397,9 @@ extern int devmem_is_allowed(unsigned long pfn);
extern void register_isa_ports(unsigned int mmio, unsigned int io,
unsigned int io_shift);
+#define __HAVE_ARCH_ATOMIC_IO_MODIFY
+extern void atomic_io_modify(void __iomem *reg, u32 mask, u32 set);
+extern void atomic_io_modify_relaxed(void __iomem *reg, u32 mask, u32 set);
+
#endif /* __KERNEL__ */
#endif /* __ASM_ARM_IO_H */
diff --git a/arch/arm/kernel/io.c b/arch/arm/kernel/io.c
index dcd5b4d..a8c9c9b 100644
--- a/arch/arm/kernel/io.c
+++ b/arch/arm/kernel/io.c
@@ -1,6 +1,35 @@
#include <linux/export.h>
#include <linux/types.h>
#include <linux/io.h>
+#include <linux/spinlock.h>
+
+static DEFINE_RAW_SPINLOCK(__io_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.
--
1.8.1.5
--
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