linux-kernel - [PATCH v4 2/4] RISC-V: Fix ioremap_cache() and ioremap

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Date:   Wed, 19 Oct 2022 18:41:26 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Cc:     Atish Patra <atishp@...shpatra.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <apatel@...tanamicro.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>
Subject: [PATCH v4 2/4] RISC-V: Fix ioremap_cache() and ioremap_wc() for systems with Svpbmt

Currently, all flavors of ioremap_xyz() function maps to the generic
ioremap() which means any ioremap_xyz() call will always map the
target memory as IO using _PAGE_IOREMAP page attributes. This breaks
ioremap_cache() and ioremap_wc() on systems with Svpbmt because memory
remapped using ioremap_cache() and ioremap_wc() will use _PAGE_IOREMAP
page attributes.

To address above (just like other architectures), we implement RISC-V
specific ioremap_cache() and ioremap_wc() which maps memory using page
attributes as defined by the Svpbmt specification.

Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support")
Co-developed-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/include/asm/io.h      | 10 ++++++++++
 arch/riscv/include/asm/pgtable.h |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 92080a227937..92a31e543388 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -133,6 +133,16 @@ __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 #define outsq(addr, buffer, count) __outsq(PCI_IOBASE + (addr), buffer, count)
 #endif
 
+#ifdef CONFIG_MMU
+#define ioremap_wc(addr, size)		\
+	ioremap_prot((addr), (size), _PAGE_IOREMAP_WC)
+#endif
+
 #include <asm-generic/io.h>
 
+#ifdef CONFIG_MMU
+#define ioremap_cache(addr, size)	\
+	ioremap_prot((addr), (size), _PAGE_KERNEL)
+#endif
+
 #endif /* _ASM_RISCV_IO_H */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7ec936910a96..346b7c1a3eeb 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -182,6 +182,8 @@ extern struct pt_alloc_ops pt_ops __initdata;
 #define PAGE_TABLE		__pgprot(_PAGE_TABLE)
 
 #define _PAGE_IOREMAP	((_PAGE_KERNEL & ~_PAGE_MTMASK) | _PAGE_IO)
+#define _PAGE_IOREMAP_WC	((_PAGE_KERNEL & ~_PAGE_MTMASK) | \
+				 _PAGE_NOCACHE)
 #define PAGE_KERNEL_IO		__pgprot(_PAGE_IOREMAP)
 
 extern pgd_t swapper_pg_dir[];
-- 
2.34.1