diff mbox series

[v9,3/6] riscv: mm: dma-noncoherent: nonstandard cache operations support

Message ID 20230614104759.228372-4-prabhakar.mahadev-lad.rj@bp.renesas.com
State New
Headers show
Series [v9,1/6] riscv: asm: vendorid_list: Add Andes Technology to the vendors list | expand

Commit Message

Prabhakar June 14, 2023, 10:47 a.m. UTC 
From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

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 <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
v8 -> v9
* New patch
---
 arch/riscv/Kconfig                       |  7 ++++
 arch/riscv/include/asm/dma-noncoherent.h | 28 +++++++++++++++
 arch/riscv/mm/dma-noncoherent.c          | 43 ++++++++++++++++++++++++
 arch/riscv/mm/pmem.c                     | 13 +++++++
 4 files changed, 91 insertions(+)
 create mode 100644 arch/riscv/include/asm/dma-noncoherent.h

Comments

Prabhakar June 16, 2023, 12:13 p.m. UTC | #1 
Hi Arnd,

Thank you for the review.

On Wed, Jun 14, 2023 at 1:36 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Wed, Jun 14, 2023, at 12:47, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > 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 <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> I understand that Christoph will still not like this, but I think this
> is as good as it gets, making the standard variant the fast path,
> and using the function pointers only for the nonstandard cases.
>
>
> >  #include <asm/cacheflush.h>
> > +#include <asm/dma-noncoherent.h>
> >
> >  static bool noncoherent_supported;
> >
> > +struct riscv_cache_ops noncoherent_cache_ops = {
> > +     .clean = NULL,
> > +     .inval = NULL,
> > +     .flush = NULL,
> > +};
>
> This could be marked __read_mostly or __ro_after_init as
> a micro-optimization, if anyone cares.
>
Ok, I will do that in the next version.

Cheers,
Prabhakar
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 628aad4fb6e2..325ab2124f0a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -261,6 +261,13 @@  config RISCV_DMA_NONCOHERENT
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select DMA_DIRECT_REMAP
 
+config RISCV_NONSTANDARD_CACHE_OPS
+	bool
+	depends on RISCV_DMA_NONCOHERENT
+	help
+	  This enables function pointer support for non-standard noncoherent
+	  systems to handle cache management.
+
 config AS_HAS_INSN
 	def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
 
diff --git a/arch/riscv/include/asm/dma-noncoherent.h b/arch/riscv/include/asm/dma-noncoherent.h
new file mode 100644
index 000000000000..f4e9bb2d3800
--- /dev/null
+++ b/arch/riscv/include/asm/dma-noncoherent.h
@@ -0,0 +1,28 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023 Renesas Electronics Corp.
+ */
+
+#ifndef __ASM_DMA_NONCOHERENT_H
+#define __ASM_DMA_NONCOHERENT_H
+
+#include <linux/dma-direct.h>
+
+/*
+ * struct riscv_cache_ops - Structure for CMO function pointers
+ *
+ * @clean: Function pointer for clean cache
+ * @inval: Function pointer for invalidate cache
+ * @flush: Function pointer for flushing the cache
+ */
+struct riscv_cache_ops {
+	void (*clean)(phys_addr_t paddr, unsigned long size);
+	void (*inval)(phys_addr_t paddr, unsigned long size);
+	void (*flush)(phys_addr_t paddr, unsigned long size);
+};
+
+extern struct riscv_cache_ops noncoherent_cache_ops;
+
+void riscv_noncoherent_register_cache_ops(const struct riscv_cache_ops *ops);
+
+#endif	/* __ASM_DMA_NONCOHERENT_H */
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
index b9a9f57e02be..4cdaa879839a 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;
 
+struct riscv_cache_ops noncoherent_cache_ops = {
+	.clean = NULL,
+	.inval = NULL,
+	.flush = 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.clean)) {
+		noncoherent_cache_ops.clean(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.inval)) {
+		noncoherent_cache_ops.inval(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.flush)) {
+		noncoherent_cache_ops.flush(paddr, size);
+		return;
+	}
+#endif
+
 	ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size);
 }
 
@@ -50,6 +77,13 @@  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.flush)) {
+		noncoherent_cache_ops.flush(page_to_phys(page), size);
+		return;
+	}
+#endif
+
 	ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
 }
 
@@ -75,3 +109,12 @@  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_cache_ops *ops)
+{
+	if (!ops)
+		return;
+
+	noncoherent_cache_ops = *ops;
+}
+EXPORT_SYMBOL_GPL(riscv_noncoherent_register_cache_ops);
diff --git a/arch/riscv/mm/pmem.c b/arch/riscv/mm/pmem.c
index 089df92ae876..fb481f5b930a 100644
--- a/arch/riscv/mm/pmem.c
+++ b/arch/riscv/mm/pmem.c
@@ -7,15 +7,28 @@ 
 #include <linux/libnvdimm.h>
 
 #include <asm/cacheflush.h>
+#include <asm/dma-noncoherent.h>
 
 void arch_wb_cache_pmem(void *addr, size_t size)
 {
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.clean)) {
+		noncoherent_cache_ops.clean(virt_to_phys(addr), size);
+		return;
+	}
+#endif
 	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)
 {
+#ifdef CONFIG_RISCV_NONSTANDARD_CACHE_OPS
+	if (unlikely(noncoherent_cache_ops.inval)) {
+		noncoherent_cache_ops.inval(virt_to_phys(addr), size);
+		return;
+	}
+#endif
 	ALT_CMO_OP(inval, addr, size, riscv_cbom_block_size);
 }
 EXPORT_SYMBOL_GPL(arch_invalidate_pmem);