riscv: mm: dma-noncoherent: nonstandard cache operations support

Introduce support for nonstandard noncoherent systems in the RISC-V
architecture. It enables function pointer support to handle cache
management in such systems.

This patch adds a new configuration option called
"RISCV_NONSTANDARD_CACHE_OPS." This option is a boolean flag that
depends on "RISCV_DMA_NONCOHERENT" and enables the function pointer
support for cache management in nonstandard noncoherent systems.

Signed-off-by: Lad Prabhakar <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>
Tested-by: Conor Dooley <[email protected]> # tyre-kicking on a d1
Reviewed-by: Emil Renner Berthing <[email protected]>
Tested-by: Emil Renner Berthing <[email protected]> #
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

1 files changed, 43 insertions, 0 deletions

diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
index 06b8fea58e20..a4f3f37859ae 100644
--- a/arch/riscv/mm/dma-noncoherent.c
+++ b/arch/riscv/mm/dma-noncoherent.c
@@ -9,13 +9,26 @@
 #include <linux/dma-map-ops.h>
 #include <linux/mm.h>
 #include <asm/cacheflush.h>
+#include <asm/dma-noncoherent.h>
 
 static bool noncoherent_supported __ro_after_init;
 
+struct riscv_nonstd_cache_ops noncoherent_cache_ops __ro_after_init = {
+	.wback = NULL,
+	.inv = NULL,
+	.wback_inv = NULL,
+};
+
 static inline void arch_dma_cache_wback(phys_addr_t paddr, size_t size)
 {
 	void *vaddr = phys_to_virt(paddr);
 
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.wback)) {
+		noncoherent_cache_ops.wback(paddr, size);
+		return;
+	}
+#endif
 	ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
 }
 
@@ -23,6 +36,13 @@ static inline void arch_dma_cache_inv(phys_addr_t paddr, size_t size)
 {
 	void *vaddr = phys_to_virt(paddr);
 
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.inv)) {
+		noncoherent_cache_ops.inv(paddr, size);
+		return;
+	}
+#endif
+
 	ALT_CMO_OP(inval, vaddr, size, riscv_cbom_block_size);
 }
 
@@ -30,6 +50,13 @@ static inline void arch_dma_cache_wback_inv(phys_addr_t paddr, size_t size)
 {
 	void *vaddr = phys_to_virt(paddr);
 
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.wback_inv)) {
+		noncoherent_cache_ops.wback_inv(paddr, size);
+		return;
+	}
+#endif
+
 	ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
 }
 
@@ -95,6 +122,13 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	void *flush_addr = page_address(page);
 
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.wback_inv)) {
+		noncoherent_cache_ops.wback_inv(page_to_phys(page), size);
+		return;
+	}
+#endif
+
 	ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
 }
 
@@ -120,3 +154,12 @@ void riscv_noncoherent_supported(void)
 	     "Non-coherent DMA support enabled without a block size\n");
 	noncoherent_supported = true;
 }
+
+void riscv_noncoherent_register_cache_ops(const struct riscv_nonstd_cache_ops *ops)
+{
+	if (!ops)
+		return;
+
+	noncoherent_cache_ops = *ops;
+}
+EXPORT_SYMBOL_GPL(riscv_noncoherent_register_cache_ops);