arm64: Implement pmem API support

Add a clean-to-point-of-persistence cache maintenance helper, and wire
up the basic architectural support for the pmem driver based on it.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[catalin.marinas@arm.com: move arch_*_pmem() functions to arch/arm64/mm/flush.c]
[catalin.marinas@arm.com: change dmb(sy) to dmb(osh)]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2 files changed, 30 insertions, 0 deletions

diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index ed47fbbb4b05..7f1dbe962cf5 100644
--- a/arch/arm64/mm/cache.S
+++ b/arch/arm64/mm/cache.S
@@ -172,6 +172,20 @@ ENDPIPROC(__clean_dcache_area_poc)
 ENDPROC(__dma_clean_area)
 
 /*
+ *	__clean_dcache_area_pop(kaddr, size)
+ *
+ * 	Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
+ * 	are cleaned to the PoP.
+ *
+ *	- kaddr   - kernel address
+ *	- size    - size in question
+ */
+ENTRY(__clean_dcache_area_pop)
+	dcache_by_line_op cvap, sy, x0, x1, x2, x3
+	ret
+ENDPIPROC(__clean_dcache_area_pop)
+
+/*
  *	__dma_flush_area(start, size)
  *
  *	clean & invalidate D / U line
diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index 21a8d828cbf4..280f90ff33a2 100644
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -83,3 +83,19 @@ EXPORT_SYMBOL(flush_dcache_page);
  * Additional functions defined in assembly.
  */
 EXPORT_SYMBOL(flush_icache_range);
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+static inline void arch_wb_cache_pmem(void *addr, size_t size)
+{
+	/* Ensure order against any prior non-cacheable writes */
+	dmb(osh);
+	__clean_dcache_area_pop(addr, size);
+}
+EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
+
+static inline void arch_invalidate_pmem(void *addr, size_t size)
+{
+	__inval_dcache_area(addr, size);
+}
+EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
+#endif