linux-kernel - [PATCH v2 17/18] riscv: dts: starfive: jh7100: Use physical memory ranges for DMA

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Message-ID: <20251009015839.3460231-18-samuel.holland@sifive.com>
Date: Wed,  8 Oct 2025 18:57:53 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <pjw@...nel.org>,
	linux-riscv@...ts.infradead.org
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Conor Dooley <conor@...nel.org>,
	Alexandre Ghiti <alex@...ti.fr>,
	Emil Renner Berthing <kernel@...il.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v2 17/18] riscv: dts: starfive: jh7100: Use physical memory ranges for DMA

JH7100 provides a physical memory region which is a noncached alias of
normal cacheable DRAM. Now that Linux can apply PMAs by selecting
between aliases of a physical memory region, any page of DRAM can be
marked as noncached for use with DMA, and the preallocated DMA pool is
no longer needed. This allows portable kernels to boot on JH7100 boards.

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

Changes in v2:
 - Move the JH7100 DT changes from jh7100-common.dtsi to jh7100.dtsi
 - Keep RISCV_DMA_NONCOHERENT and RISCV_NONSTANDARD_CACHE_OPS selected

 arch/riscv/Kconfig.errata                     | 19 ---------------
 arch/riscv/Kconfig.socs                       |  2 ++
 .../boot/dts/starfive/jh7100-common.dtsi      | 24 -------------------
 arch/riscv/boot/dts/starfive/jh7100.dtsi      |  4 ++++
 4 files changed, 6 insertions(+), 43 deletions(-)

diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
index e318119d570de..62700631a5c5d 100644
--- a/arch/riscv/Kconfig.errata
+++ b/arch/riscv/Kconfig.errata
@@ -53,25 +53,6 @@ config ERRATA_SIFIVE_CIP_1200
 
 	  If you don't know what to do here, say "Y".
 
-config ERRATA_STARFIVE_JH7100
-	bool "StarFive JH7100 support"
-	depends on ARCH_STARFIVE
-	depends on !DMA_DIRECT_REMAP
-	depends on NONPORTABLE
-	select DMA_GLOBAL_POOL
-	select RISCV_DMA_NONCOHERENT
-	select RISCV_NONSTANDARD_CACHE_OPS
-	select SIFIVE_CCACHE
-	default n
-	help
-	  The StarFive JH7100 was a test chip for the JH7110 and has
-	  caches that are non-coherent with respect to peripheral DMAs.
-	  It was designed before the Zicbom extension so needs non-standard
-	  cache operations through the SiFive cache controller.
-
-	  Say "Y" if you want to support the BeagleV Starlight and/or
-	  StarFive VisionFive V1 boards.
-
 config ERRATA_THEAD
 	bool "T-HEAD errata"
 	depends on RISCV_ALTERNATIVE
diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
index 848e7149e4435..a8950206fb750 100644
--- a/arch/riscv/Kconfig.socs
+++ b/arch/riscv/Kconfig.socs
@@ -50,6 +50,8 @@ config SOC_STARFIVE
 	bool "StarFive SoCs"
 	select PINCTRL
 	select RESET_CONTROLLER
+	select RISCV_DMA_NONCOHERENT
+	select RISCV_NONSTANDARD_CACHE_OPS
 	select ARM_AMBA
 	help
 	  This enables support for StarFive SoC platform hardware.
diff --git a/arch/riscv/boot/dts/starfive/jh7100-common.dtsi b/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
index ae1a6aeb0aeaa..47d0cf55bfc02 100644
--- a/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
+++ b/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
@@ -42,30 +42,6 @@ led-ack {
 		};
 	};
 
-	reserved-memory {
-		#address-cells = <2>;
-		#size-cells = <2>;
-		ranges;
-
-		dma-reserved@...00000 {
-			reg = <0x0 0xfa000000 0x0 0x1000000>;
-			no-map;
-		};
-
-		linux,dma@...a000000 {
-			compatible = "shared-dma-pool";
-			reg = <0x10 0x7a000000 0x0 0x1000000>;
-			no-map;
-			linux,dma-default;
-		};
-	};
-
-	soc {
-		dma-ranges = <0x00 0x80000000 0x00 0x80000000 0x00 0x7a000000>,
-			     <0x00 0xfa000000 0x10 0x7a000000 0x00 0x01000000>,
-			     <0x00 0xfb000000 0x00 0xfb000000 0x07 0x85000000>;
-	};
-
 	wifi_pwrseq: wifi-pwrseq {
 		compatible = "mmc-pwrseq-simple";
 		reset-gpios = <&gpio 37 GPIO_ACTIVE_LOW>;
diff --git a/arch/riscv/boot/dts/starfive/jh7100.dtsi b/arch/riscv/boot/dts/starfive/jh7100.dtsi
index 7de0732b8eabe..34ff65d65ac7e 100644
--- a/arch/riscv/boot/dts/starfive/jh7100.dtsi
+++ b/arch/riscv/boot/dts/starfive/jh7100.dtsi
@@ -7,11 +7,15 @@
 /dts-v1/;
 #include <dt-bindings/clock/starfive-jh7100.h>
 #include <dt-bindings/reset/starfive-jh7100.h>
+#include <dt-bindings/riscv/physical-memory.h>
 
 / {
 	compatible = "starfive,jh7100";
 	#address-cells = <2>;
 	#size-cells = <2>;
+	riscv,physical-memory-regions =
+		<0x00 0x80000000 0x08 0x00000000 (PMA_RWXA | PMA_NONCOHERENT_MEMORY) 0x0>,
+		<0x10 0x00000000 0x08 0x00000000 (PMA_RWX | PMA_NONCACHEABLE_MEMORY | PMR_ALIAS(1)) 0x0>;
 
 	cpus: cpus {
 		#address-cells = <1>;
-- 
2.47.2