Messages in this thread | | | Date | Wed, 28 Aug 2013 09:53:40 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v4 2/4] ARM: Add atomic_io_modify optimized routines |
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On Sat, Aug 24, 2013 at 04:35:30PM +0100, Ezequiel Garcia wrote: > 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.garcia@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);
Is this any different from the generic one introduced in patch 1/4? I would rather just use the generic definition. Similarly, a generic atomic_io_modify_relaxed() but guarded with something like __HAVE_ARCH_RELAXED_IO.
-- Catalin
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