2023-07-11 13:48:59

by Andrea Parri

[permalink] [raw]
Subject: [PATCH 0/2] riscv,mmio: I/O barriers fixes and cleanups

Andrea Parri (2):
riscv,mmio: Fix readX()-to-delay() ordering
riscv,mmio: Use the generic implementation for the I/O accesses

arch/riscv/include/asm/mmio.h | 72 ++++-------------------------------
1 file changed, 8 insertions(+), 64 deletions(-)

--
2.34.1



2023-07-11 14:18:37

by Andrea Parri

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

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 <[email protected]>
---
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


2023-07-12 07:28:29

by Conor Dooley

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

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 <[email protected]>

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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2023-07-12 15:54:38

by Andrea Parri

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

On Wed, Jul 12, 2023 at 08:05:16AM +0100, Conor Dooley wrote:
> 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 <[email protected]>
>
> 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 *)'}

Thank you for the report, Conor. Looking at it.

Andrea

Subject: Re: [PATCH 0/2] riscv,mmio: I/O barriers fixes and cleanups

Hello:

This series was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <[email protected]>:

On Tue, 11 Jul 2023 15:33:46 +0200 you wrote:
> Andrea Parri (2):
> riscv,mmio: Fix readX()-to-delay() ordering
> riscv,mmio: Use the generic implementation for the I/O accesses
>
> arch/riscv/include/asm/mmio.h | 72 ++++-------------------------------
> 1 file changed, 8 insertions(+), 64 deletions(-)

Here is the summary with links:
- [1/2] riscv,mmio: Fix readX()-to-delay() ordering
https://git.kernel.org/riscv/c/4eb2eb1b4c0e
- [2/2] riscv,mmio: Use the generic implementation for the I/O accesses
(no matching commit)

You are awesome, thank you!
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