linux-kernel - [PATCH v3 22/22] riscv: dts: eswin: eic7700: Use physical memory ranges for DMA

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Message-ID: <20251113014656.2605447-23-samuel.holland@sifive.com>
Date: Wed, 12 Nov 2025 17:45:35 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <pjw@...nel.org>,
	linux-riscv@...ts.infradead.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	linux-mm@...ck.org
Cc: devicetree@...r.kernel.org,
	Suren Baghdasaryan <surenb@...gle.com>,
	linux-kernel@...r.kernel.org,
	Mike Rapoport <rppt@...nel.org>,
	Michal Hocko <mhocko@...e.com>,
	Conor Dooley <conor@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Alexandre Ghiti <alex@...ti.fr>,
	Emil Renner Berthing <kernel@...il.dk>,
	Rob Herring <robh+dt@...nel.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v3 22/22] riscv: dts: eswin: eic7700: Use physical memory ranges for DMA

EIC7700 provides a physical memory region which is a noncached alias of
normal cacheable DRAM. Declare this alias in the devicetree so Linux can
allocate noncached pages for noncoherent DMA, and M-mode firmware can
protect the noncached alias with PMPs.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

Changes in v3:
 - Fix the entry number of the paired region in the DT

Changes in v2:
 - New patch for v2

 arch/riscv/Kconfig.socs                | 2 ++
 arch/riscv/boot/dts/eswin/eic7700.dtsi | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
index a8950206fb75..df3ed1d322fe 100644
--- a/arch/riscv/Kconfig.socs
+++ b/arch/riscv/Kconfig.socs
@@ -9,6 +9,8 @@ config ARCH_ANDES
 
 config ARCH_ESWIN
 	bool "ESWIN SoCs"
+	select RISCV_DMA_NONCOHERENT
+	select RISCV_NONSTANDARD_CACHE_OPS
 	help
 	  This enables support for ESWIN SoC platform hardware,
 	  including the ESWIN EIC7700 SoC.
diff --git a/arch/riscv/boot/dts/eswin/eic7700.dtsi b/arch/riscv/boot/dts/eswin/eic7700.dtsi
index c3ed93008bca..d566bca4e09e 100644
--- a/arch/riscv/boot/dts/eswin/eic7700.dtsi
+++ b/arch/riscv/boot/dts/eswin/eic7700.dtsi
@@ -5,9 +5,14 @@
 
 /dts-v1/;
 
+#include <dt-bindings/riscv/physical-memory.h>
+
 / {
 	#address-cells = <2>;
 	#size-cells = <2>;
+	riscv,physical-memory-regions =
+		<0x000 0x80000000 0x00f 0x80000000 (PMA_RWXA | PMA_NONCOHERENT_MEMORY) 0x0>,
+		<0x0c0 0x00000000 0x010 0x00000000 (PMA_RWX | PMA_NONCACHEABLE_MEMORY | PMR_ALIAS(0)) 0x0>;
 
 	cpus {
 		#address-cells = <1>;
-- 
2.47.2