From 3a8ee3a9f4f6caca192fd2fdc88c1ce56c521b38 Mon Sep 17 00:00:00 2001 From: Yunhui Cui Date: Tue, 22 Jul 2025 17:15:04 +0800 Subject: [PATCH] riscv: introduce ioremap_wc() Compared with IO attributes, NC attributes can improve performance, specifically in these aspects: Relaxed Order, Gathering, Supports Read Speculation, Supports Unaligned Access. Signed-off-by: Yunhui Cui Signed-off-by: Qingfang Deng Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20250722091504.45974-2-cuiyunhui@bytedance.com Signed-off-by: Paul Walmsley --- arch/riscv/include/asm/io.h | 4 ++++ arch/riscv/include/asm/pgtable.h | 1 + 2 files changed, 5 insertions(+) diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h index a0e51840b9db4..09bb5f57a9d34 100644 --- a/arch/riscv/include/asm/io.h +++ b/arch/riscv/include/asm/io.h @@ -28,6 +28,10 @@ #ifdef CONFIG_MMU #define IO_SPACE_LIMIT (PCI_IO_SIZE - 1) #define PCI_IOBASE ((void __iomem *)PCI_IO_START) + +#define ioremap_wc(addr, size) \ + ioremap_prot((addr), (size), __pgprot(_PAGE_KERNEL_NC)) + #endif /* CONFIG_MMU */ /* diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 91697fbf1f901..3d17399a06c77 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -203,6 +203,7 @@ extern struct pt_alloc_ops pt_ops __meminitdata; #define PAGE_TABLE __pgprot(_PAGE_TABLE) +#define _PAGE_KERNEL_NC ((_PAGE_KERNEL & ~_PAGE_MTMASK) | _PAGE_NOCACHE) #define _PAGE_IOREMAP ((_PAGE_KERNEL & ~_PAGE_MTMASK) | _PAGE_IO) #define PAGE_KERNEL_IO __pgprot(_PAGE_IOREMAP) -- 2.47.3