linux-kernel - [PATCH v2 0/2] Resolve MPM register space situation

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Message-Id: <20230328-topic-msgram_mpm-v2-0-e24a48e57f0d@linaro.org>
Date:   Wed, 05 Apr 2023 12:48:33 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Shawn Guo <shawn.guo@...aro.org>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: [PATCH v2 0/2] Resolve MPM register space situation

v1 -> v2:
- deprecate 'reg', make qcom,rpm-msg-ram required [1/2]
- Use devm_ioremap() [2/2]

Link to v1: https://lore.kernel.org/r/20230328-topic-msgram_mpm-v1-0-1b788a5f5a33@linaro.org

Depends on resolution of https://github.com/devicetree-org/dt-schema/issues/104

The MPM (and some other things, irrelevant to this patchset) resides
(as far as the ARM cores are concerned, anyway) in a MMIO-mapped region
that's a portion of the RPM (low-power management core)'s RAM, known
as the RPM Message RAM. Representing this relation in the Device Tree
creates some challenges, as one would either have to treat a memory
region as a bus, map nodes in a way such that their reg-s would be
overlapping, or supply the nodes with a slice of that region.

This series implements the third option, by adding a qcom,rpm-msg-ram
property, which has been used for some drivers poking into this region
before. Bindings ABI compatibility is preserved through keeping the
"normal" (a.k.a read the reg property and map that region) way of
passing the register space.

Example representation with this patchset:

/ {
	[...]

	mpm: interrupt-controller {
		compatible = "qcom,mpm";
		qcom,rpm-msg-ram = <&apss_mpm>;
		[...]
	};

	[...]

	soc: soc@0 {
		[...]

		rpm_msg_ram: sram@...0000 {
			compatible = "qcom,rpm-msg-ram", "mmio-sram";
			reg = <0 0x045f0000 0 0x7000>;
			#address-cells = <1>;
			#size-cells = <1>;
			ranges = <0 0x0 0x045f0000 0x7000>;

			apss_mpm: sram@1b8 {
				reg = <0x1b8 0x48>;
			};
		};
	};
};

Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
Konrad Dybcio (2):
      dt-bindings: interrupt-controller: mpm: Pass MSG RAM slice through phandle
      irqchip: irq-qcom-mpm: Support passing a slice of SRAM as reg space

 .../bindings/interrupt-controller/qcom,mpm.yaml     | 12 +++++++++---
 drivers/irqchip/irq-qcom-mpm.c                      | 21 ++++++++++++++++++---
 2 files changed, 27 insertions(+), 6 deletions(-)
---
base-commit: 8417c8f5007bf4567ccffda850a3157c7d905f67
change-id: 20230328-topic-msgram_mpm-c688be3bc294

Best regards,
-- 
Konrad Dybcio <konrad.dybcio@...aro.org>