On Tue, Sep 23, 2025 at 09:15:49PM +0530, Manikanta Guntupalli wrote:
> Add MMIO accessors to support big-endian memory operations. These helpers
> include {read, write}{w, l, q}_be() and {read, write}s{w, l, q}_be(),
> which allows to access big-endian memory regions while returning
> the results in the CPU’s native endianness.
>
> This provides a consistent interface to interact with hardware using
> big-endian register layouts.
>
> Signed-off-by: Manikanta Guntupalli <[email protected]>
> ---Reviewed-by: Frank Li <[email protected]> > Changes since V7: > This patch introduced in V7. > --- > include/asm-generic/io.h | 202 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 202 insertions(+) > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h > index 11abad6c87e1..d18a8ca6c06c 100644 > --- a/include/asm-generic/io.h > +++ b/include/asm-generic/io.h > @@ -295,6 +295,96 @@ static inline void writeq(u64 value, volatile void > __iomem *addr) > #endif > #endif /* CONFIG_64BIT */ > > +/* > + * {read,write}{w,l,q}_be() access big endian memory and return result > + * in native endianness. > + */ > + > +#ifndef readw_be > +#define readw_be readw_be > +static inline u16 readw_be(const volatile void __iomem *addr) > +{ > + u16 val; > + > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_); > + __io_br(); > + val = __be16_to_cpu((__be16 __force)__raw_readw(addr)); > + __io_ar(val); > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_); > + return val; > +} > +#endif > + > +#ifndef readl_be > +#define readl_be readl_be > +static inline u32 readl_be(const volatile void __iomem *addr) > +{ > + u32 val; > + > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_); > + __io_br(); > + val = __be32_to_cpu((__be32 __force)__raw_readl(addr)); > + __io_ar(val); > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_); > + return val; > +} > +#endif > + > +#ifdef CONFIG_64BIT > +#ifndef readq_be > +#define readq_be readq_be > +static inline u64 readq_be(const volatile void __iomem *addr) > +{ > + u64 val; > + > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_); > + __io_br(); > + val = __be64_to_cpu((__be64 __force)__raw_readq(addr)); > + __io_ar(val); > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_); > + return val; > +} > +#endif > +#endif /* CONFIG_64BIT */ > + > +#ifndef writew_be > +#define writew_be writew_be > +static inline void writew_be(u16 value, volatile void __iomem *addr) > +{ > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_); > + __io_bw(); > + __raw_writew((u16 __force)__cpu_to_be16(value), addr); > + __io_aw(); > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_); > +} > +#endif > + > +#ifndef writel_be > +#define writel_be writel_be > +static inline void writel_be(u32 value, volatile void __iomem *addr) > +{ > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_); > + __io_bw(); > + __raw_writel((u32 __force)__cpu_to_be32(value), addr); > + __io_aw(); > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_); > +} > +#endif > + > +#ifdef CONFIG_64BIT > +#ifndef writeq_be > +#define writeq_be writeq_be > +static inline void writeq_be(u64 value, volatile void __iomem *addr) > +{ > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_); > + __io_bw(); > + __raw_writeq((u64 __force)__cpu_to_be64(value), addr); > + __io_aw(); > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_); > +} > +#endif > +#endif /* CONFIG_64BIT */ > + > /* > * {read,write}{b,w,l,q}_relaxed() are like the regular version, but > * are not guaranteed to provide ordering against spinlocks or memory > @@ -524,6 +614,118 @@ static inline void writesq(volatile void __iomem *addr, > const void *buffer, > #endif > #endif /* CONFIG_64BIT */ > > +/* > + * {read,write}s{w,l,q}_be() repeatedly access the same memory address > + * in big endianness in 16-, 32- or 64-bit chunks (@count times) and > + * return result in native endianness. > + */ > + > +#ifndef readsw_be > +#define readsw_be readsw_be > +static inline void readsw_be(const volatile void __iomem *addr, > + void *buffer, > + unsigned int count) > +{ > + if (count) { > + u16 *buf = buffer; > + > + do { > + u16 x = __be16_to_cpu((__be16 > __force)__raw_readw(addr)); > + *buf++ = x; > + } while (--count); > + } > +} > +#endif > + > +#ifndef readsl_be > +#define readsl_be readsl_be > +static inline void readsl_be(const volatile void __iomem *addr, > + void *buffer, > + unsigned int count) > +{ > + if (count) { > + u32 *buf = buffer; > + > + do { > + u32 x = __be32_to_cpu((__be32 > __force)__raw_readl(addr)); > + *buf++ = x; > + } while (--count); > + } > +} > +#endif > + > +#ifdef CONFIG_64BIT > +#ifndef readsq_be > +#define readsq_be readsq_be > +static inline void readsq_be(const volatile void __iomem *addr, > + void *buffer, > + unsigned int count) > +{ > + if (count) { > + u64 *buf = buffer; > + > + do { > + u64 x = __be64_to_cpu((__be64 > __force)__raw_readq(addr)); > + *buf++ = x; > + } while (--count); > + } > +} > +#endif > +#endif /* CONFIG_64BIT */ > + > +#ifndef writesw_be > +#define writesw_be writesw_be > +static inline void writesw_be(volatile void __iomem *addr, > + const void *buffer, > + unsigned int count) > +{ > + if (count) { > + const u16 *buf = buffer; > + > + do { > + __raw_writew((u16 __force)__cpu_to_be16(*buf), addr); > + buf++; > + } while (--count); > + } > +} > +#endif > + > +#ifndef writesl_be > +#define writesl_be writesl_be > +static inline void writesl_be(volatile void __iomem *addr, > + const void *buffer, > + unsigned int count) > +{ > + if (count) { > + const u32 *buf = buffer; > + > + do { > + __raw_writel((u32 __force)__cpu_to_be32(*buf), addr); > + buf++; > + } while (--count); > + } > +} > +#endif > + > +#ifdef CONFIG_64BIT > +#ifndef writesq_be > +#define writesq_be writesq_be > +static inline void writesq_be(volatile void __iomem *addr, > + const void *buffer, > + unsigned int count) > +{ > + if (count) { > + const u64 *buf = buffer; > + > + do { > + __raw_writeq((u64 __force)__cpu_to_be64(*buf), addr); > + buf++; > + } while (--count); > + } > +} > +#endif > +#endif /* CONFIG_64BIT */ > + > #ifndef PCI_IOBASE > #define PCI_IOBASE ((void __iomem *)0) > #endif > -- > 2.34.1 >
