[PATCH v6 2/3] RISC-V: Implement arch specific PMEM APIs

[Anup Patel]

The NVDIMM PMEM driver expects arch specific APIs for cache maintenance
and if arch does not provide these APIs then NVDIMM PMEM driver will
always use MEMREMAP_WT to map persistent memory which in-turn maps as
UC memory type defined by the RISC-V Svpbmt specification.

Now that the Svpbmt and Zicbom support is available in RISC-V kernel,
we implement PMEM APIs using ALT_CMO_OP() macros so that the NVDIMM
PMEM driver can use MEMREMAP_WB to map persistent memory.

Co-developed-by: Mayuresh Chitale <mchitale at ventanamicro.com>
Signed-off-by: Mayuresh Chitale <mchitale at ventanamicro.com>
Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 arch/riscv/Kconfig     |  1 +
 arch/riscv/mm/Makefile |  1 +
 arch/riscv/mm/pmem.c   | 21 +++++++++++++++++++++
 3 files changed, 23 insertions(+)
 create mode 100644 arch/riscv/mm/pmem.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index fa78595a6089..c0e22648bd16 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -25,6 +25,7 @@ config RISCV
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_MMIOWB
+	select ARCH_HAS_PMEM_API
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_DIRECT_MAP if MMU
 	select ARCH_HAS_SET_MEMORY if MMU
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index d76aabf4b94d..b4f35da889bf 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -13,6 +13,7 @@ obj-y += extable.o
 obj-$(CONFIG_MMU) += fault.o pageattr.o
 obj-y += cacheflush.o
 obj-y += context.o
+obj-y += pmem.o
 
 ifeq ($(CONFIG_MMU),y)
 obj-$(CONFIG_SMP) += tlbflush.o
diff --git a/arch/riscv/mm/pmem.c b/arch/riscv/mm/pmem.c
new file mode 100644
index 000000000000..089df92ae876
--- /dev/null
+++ b/arch/riscv/mm/pmem.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+
+#include <linux/export.h>
+#include <linux/libnvdimm.h>
+
+#include <asm/cacheflush.h>
+
+void arch_wb_cache_pmem(void *addr, size_t size)
+{
+	ALT_CMO_OP(clean, addr, size, riscv_cbom_block_size);
+}
+EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
+
+void arch_invalidate_pmem(void *addr, size_t size)
+{
+	ALT_CMO_OP(inval, addr, size, riscv_cbom_block_size);
+}
+EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
-- 
2.34.1