Re: [PATCH 2/2] riscv,mmio: Use the generic implementation for the I/O accesses

[Conor Dooley]

On Tue, Jul 11, 2023 at 03:33:48PM +0200, Andrea Parri wrote:
> The current implementation of readX(), writeX() and their "relaxed"
> variants, readX_relaxed() and writeX_relaxed(), matches the generic
> implementation; remove the redundant code.
> 
> No functional change intended.
> 
> Signed-off-by: Andrea Parri <parri.andrea@xxxxxxxxx>

This fails to build for (64-bit, I didn't check 32-bit) nommu:
arch/riscv/include/asm/timex.h:20:16: error: implicit declaration of function 'readq_relaxed' [-Werror=implicit-function-declaration]
include/asm-generic/io.h:342:23: error: conflicting types for 'readq_relaxed'; have 'u64(const volatile void *)' {aka 'long long unsigned int(const volatile void *)'}

Cheers,
Conor.

> ---
>  arch/riscv/include/asm/mmio.h | 68 ++++-------------------------------
>  1 file changed, 6 insertions(+), 62 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/mmio.h b/arch/riscv/include/asm/mmio.h
> index 4c58ee7f95ecf..116b898fe969d 100644
> --- a/arch/riscv/include/asm/mmio.h
> +++ b/arch/riscv/include/asm/mmio.h
> @@ -80,72 +80,16 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
>  #endif
>  
>  /*
> - * Unordered I/O memory access primitives.  These are even more relaxed than
> - * the relaxed versions, as they don't even order accesses between successive
> - * operations to the I/O regions.
> - */
> -#define readb_cpu(c)		({ u8  __r = __raw_readb(c); __r; })
> -#define readw_cpu(c)		({ u16 __r = le16_to_cpu((__force __le16)__raw_readw(c)); __r; })
> -#define readl_cpu(c)		({ u32 __r = le32_to_cpu((__force __le32)__raw_readl(c)); __r; })
> -
> -#define writeb_cpu(v, c)	((void)__raw_writeb((v), (c)))
> -#define writew_cpu(v, c)	((void)__raw_writew((__force u16)cpu_to_le16(v), (c)))
> -#define writel_cpu(v, c)	((void)__raw_writel((__force u32)cpu_to_le32(v), (c)))
> -
> -#ifdef CONFIG_64BIT
> -#define readq_cpu(c)		({ u64 __r = le64_to_cpu((__force __le64)__raw_readq(c)); __r; })
> -#define writeq_cpu(v, c)	((void)__raw_writeq((__force u64)cpu_to_le64(v), (c)))
> -#endif
> -
> -/*
> - * Relaxed I/O memory access primitives. These follow the Device memory
> - * ordering rules but do not guarantee any ordering relative to Normal memory
> - * accesses.  These are defined to order the indicated access (either a read or
> - * write) with all other I/O memory accesses to the same peripheral. Since the
> - * platform specification defines that all I/O regions are strongly ordered on
> - * channel 0, no explicit fences are required to enforce this ordering.
> - */
> -/* FIXME: These are now the same as asm-generic */
> -#define __io_rbr()		do {} while (0)
> -#define __io_rar()		do {} while (0)
> -#define __io_rbw()		do {} while (0)
> -#define __io_raw()		do {} while (0)
> -
> -#define readb_relaxed(c)	({ u8  __v; __io_rbr(); __v = readb_cpu(c); __io_rar(); __v; })
> -#define readw_relaxed(c)	({ u16 __v; __io_rbr(); __v = readw_cpu(c); __io_rar(); __v; })
> -#define readl_relaxed(c)	({ u32 __v; __io_rbr(); __v = readl_cpu(c); __io_rar(); __v; })
> -
> -#define writeb_relaxed(v, c)	({ __io_rbw(); writeb_cpu((v), (c)); __io_raw(); })
> -#define writew_relaxed(v, c)	({ __io_rbw(); writew_cpu((v), (c)); __io_raw(); })
> -#define writel_relaxed(v, c)	({ __io_rbw(); writel_cpu((v), (c)); __io_raw(); })
> -
> -#ifdef CONFIG_64BIT
> -#define readq_relaxed(c)	({ u64 __v; __io_rbr(); __v = readq_cpu(c); __io_rar(); __v; })
> -#define writeq_relaxed(v, c)	({ __io_rbw(); writeq_cpu((v), (c)); __io_raw(); })
> -#endif
> -
> -/*
> - * I/O memory access primitives.  Reads are ordered relative to any following
> - * Normal memory read and delay() loop.  Writes are ordered relative to any
> - * prior Normal memory write.  The memory barriers here are necessary as RISC-V
> - * doesn't define any ordering between the memory space and the I/O space.
> + * I/O barriers
> + *
> + * See Documentation/memory-barriers.txt, "Kernel I/O barrier effects".
> + *
> + * Assume that each I/O region is strongly ordered on channel 0, following the
> + * RISC-V Platform Specification, "OS-A Common Requirements".
>   */
>  #define __io_br()	do {} while (0)
>  #define __io_ar(v)	({ __asm__ __volatile__ ("fence i,ir" : : : "memory"); })
>  #define __io_bw()	({ __asm__ __volatile__ ("fence w,o" : : : "memory"); })
>  #define __io_aw()	mmiowb_set_pending()
>  
> -#define readb(c)	({ u8  __v; __io_br(); __v = readb_cpu(c); __io_ar(__v); __v; })
> -#define readw(c)	({ u16 __v; __io_br(); __v = readw_cpu(c); __io_ar(__v); __v; })
> -#define readl(c)	({ u32 __v; __io_br(); __v = readl_cpu(c); __io_ar(__v); __v; })
> -
> -#define writeb(v, c)	({ __io_bw(); writeb_cpu((v), (c)); __io_aw(); })
> -#define writew(v, c)	({ __io_bw(); writew_cpu((v), (c)); __io_aw(); })
> -#define writel(v, c)	({ __io_bw(); writel_cpu((v), (c)); __io_aw(); })
> -
> -#ifdef CONFIG_64BIT
> -#define readq(c)	({ u64 __v; __io_br(); __v = readq_cpu(c); __io_ar(__v); __v; })
> -#define writeq(v, c)	({ __io_bw(); writeq_cpu((v), (c)); __io_aw(); })
> -#endif
> -
>  #endif /* _ASM_RISCV_MMIO_H */
> -- 
> 2.34.1
>

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