[PATCH v2 2/3] eal/riscv: add RISC-V specific I/O device memory operations

[dangshiwei]

The current rte_io.h for RISC-V only includes generic/rte_io.h,
which uses volatile pointer casts for MMIO read/write. While this
prevents compiler optimizations, it does not prevent CPU-level
reordering on RISC-V, which is a weak-ordered architecture.

This patch adds a RISC-V specific implementation using explicit
load/store instructions:
- lbu/lhu/lwu/ld for reads (zero-extending to avoid sign-bit pollution)
- sb/sh/sw/sd for writes

Signed-off-by: Dang Shiwei <1138222970gg at gmail.com>
---
 lib/eal/riscv/include/rte_io.h | 152 ++++++++++++++++++++++++++++++++-
 1 file changed, 149 insertions(+), 3 deletions(-)

diff --git a/lib/eal/riscv/include/rte_io.h b/lib/eal/riscv/include/rte_io.h
index 4ae1f087ba..e67b5c1c9c 100644
--- a/lib/eal/riscv/include/rte_io.h
+++ b/lib/eal/riscv/include/rte_io.h
@@ -5,9 +5,155 @@
  * Copyright(c) 2022 Semihalf
  */
 
-#ifndef RTE_IO_RISCV_H
-#define RTE_IO_RISCV_H
+#ifndef _RTE_IO_RISCV_H_
+#define _RTE_IO_RISCV_H_
+
+#include <stdint.h>
+
+#define RTE_OVERRIDE_IO_H
 
 #include "generic/rte_io.h"
+#include <rte_compat.h>
+#include "rte_atomic.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static __rte_always_inline uint8_t
+rte_read8_relaxed(const volatile void *addr)
+{
+	uint8_t val;
+	asm volatile("lbu %0, 0(%1)" : "=r"(val) : "r"(addr));
+	return val;
+}
+
+static __rte_always_inline uint16_t
+rte_read16_relaxed(const volatile void *addr)
+{
+	uint16_t val;
+	asm volatile("lhu %0, 0(%1)" : "=r"(val) : "r"(addr));
+	return val;
+}
+
+static __rte_always_inline uint32_t
+rte_read32_relaxed(const volatile void *addr)
+{
+	uint32_t val;
+	asm volatile("lwu %0, 0(%1)" : "=r"(val) : "r"(addr));
+	return val;
+}
+
+static __rte_always_inline uint64_t
+rte_read64_relaxed(const volatile void *addr)
+{
+	uint64_t val;
+	asm volatile("ld %0, 0(%1)" : "=r"(val) : "r"(addr));
+	return val;
+}
+
+static __rte_always_inline void
+rte_write8_relaxed(uint8_t val, volatile void *addr)
+{
+	asm volatile("sb %1, 0(%0)" : : "r"(addr), "r"(val));
+}
+
+static __rte_always_inline void
+rte_write16_relaxed(uint16_t val, volatile void *addr)
+{
+	asm volatile("sh %1, 0(%0)" : : "r"(addr), "r"(val));
+}
+
+static __rte_always_inline void
+rte_write32_relaxed(uint32_t val, volatile void *addr)
+{
+	asm volatile("sw %1, 0(%0)" : : "r"(addr), "r"(val));
+}
+
+static __rte_always_inline void
+rte_write64_relaxed(uint64_t val, volatile void *addr)
+{
+	asm volatile("sd %1, 0(%0)" : : "r"(addr), "r"(val));
+}
+
+
+static __rte_always_inline uint8_t
+rte_read8(const volatile void *addr)
+{
+	uint8_t val = rte_read8_relaxed(addr);
+	rte_io_rmb();
+	return val;
+}
+
+static __rte_always_inline uint16_t
+rte_read16(const volatile void *addr)
+{
+	uint16_t val = rte_read16_relaxed(addr);
+	rte_io_rmb();
+	return val;
+}
+
+static __rte_always_inline uint32_t
+rte_read32(const volatile void *addr)
+{
+	uint32_t val = rte_read32_relaxed(addr);
+	rte_io_rmb();
+	return val;
+}
+
+static __rte_always_inline uint64_t
+rte_read64(const volatile void *addr)
+{
+	uint64_t val = rte_read64_relaxed(addr);
+	rte_io_rmb();
+	return val;
+}
+
+
+static __rte_always_inline void
+rte_write8(uint8_t val, volatile void *addr)
+{
+	rte_io_wmb();
+	rte_write8_relaxed(val, addr);
+}
+
+static __rte_always_inline void
+rte_write16(uint16_t val, volatile void *addr)
+{
+	rte_io_wmb();
+	rte_write16_relaxed(val, addr);
+}
+
+static __rte_always_inline void
+rte_write32(uint32_t val, volatile void *addr)
+{
+	rte_io_wmb();
+	rte_write32_relaxed(val, addr);
+}
+
+static __rte_always_inline void
+rte_write64(uint64_t val, volatile void *addr)
+{
+	rte_io_wmb();
+	rte_write64_relaxed(val, addr);
+}
+
+__rte_experimental
+static __rte_always_inline void
+rte_write32_wc(uint32_t val, volatile void *addr)
+{
+	rte_write32(val, addr);
+}
+
+__rte_experimental
+static __rte_always_inline void
+rte_write32_wc_relaxed(uint32_t val, volatile void *addr)
+{
+	rte_write32_relaxed(val, addr);
+}
+
+#ifdef __cplusplus
+}
+#endif
 
-#endif /* RTE_IO_RISCV_H */
+#endif /* _RTE_IO_RISCV_H_ */
-- 
2.43.0