[PATCH v3] riscv: use generic relaxed MMIO accessors

[Qingfang Deng <qingfang.deng@linux.dev>]

The relaxed MMIO accessors duplicate the generic implementation, as noted
by their FIXME comment. Remove those definitions and their empty barrier
hooks so asm-generic/io.h supplies them through the existing asm/io.h
include path.

The M-mode timer uses the lightweight asm/mmio.h header before the
generic relaxed accessors are available. Use readl_cpu() and readq_cpu()
there, which perform the same accesses and endian conversion as the
existing relaxed accessors.

Assisted-by: Codex:gpt-6-astra
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
---
v3: don't touch asm-generic, and preserve custom __raw_* helpers.

v2: split asm-generic/io.h to fix M-mode build
    https://lore.kernel.org/linux-riscv/20260920014357.7069-2-qingfang.deng@linux.dev/

v1: https://lore.kernel.org/linux-riscv/20250530032252.3092502-1-dqfext@gmail.com/
---
 arch/riscv/include/asm/mmio.h  | 27 ---------------------------
 arch/riscv/include/asm/timex.h |  6 +++---
 2 files changed, 3 insertions(+), 30 deletions(-)

diff --git a/arch/riscv/include/asm/mmio.h b/arch/riscv/include/asm/mmio.h
index 06cadfd7a237..61299a093b75 100644
--- a/arch/riscv/include/asm/mmio.h
+++ b/arch/riscv/include/asm/mmio.h
@@ -98,33 +98,6 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
 #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
diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h
index f660afa30530..9c4550902935 100644
--- a/arch/riscv/include/asm/timex.h
+++ b/arch/riscv/include/asm/timex.h
@@ -17,18 +17,18 @@ typedef unsigned long cycles_t;
 #ifdef CONFIG_64BIT
 static inline cycles_t get_cycles(void)
 {
-	return readq_relaxed(clint_time_val);
+	return readq_cpu(clint_time_val);
 }
 #else /* !CONFIG_64BIT */
 static inline u32 get_cycles(void)
 {
-	return readl_relaxed(((u32 __iomem *)clint_time_val));
+	return readl_cpu(((u32 __iomem *)clint_time_val));
 }
 #define get_cycles get_cycles
 
 static inline u32 get_cycles_hi(void)
 {
-	return readl_relaxed(((u32 __iomem *)clint_time_val) + 1);
+	return readl_cpu(((u32 __iomem *)clint_time_val) + 1);
 }
 #define get_cycles_hi get_cycles_hi
 #endif /* CONFIG_64BIT */
-- 
2.43.0