From patchwork Sat Dec 2 23:47:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Heidelberg X-Patchwork-Id: 1870973 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; secure) header.d=ixit.cz header.i=@ixit.cz header.a=rsa-sha256 header.s=dkim header.b=1cIHJLXW; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2604:1380:40f1:3f00::1; helo=sy.mirrors.kernel.org; envelope-from=devicetree+bounces-21015-incoming-dt=patchwork.ozlabs.org@vger.kernel.org; receiver=patchwork.ozlabs.org) Received: from sy.mirrors.kernel.org (sy.mirrors.kernel.org [IPv6:2604:1380:40f1:3f00::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4SjRTc71xNz1ySh for ; Sun, 3 Dec 2023 10:48:52 +1100 (AEDT) Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sy.mirrors.kernel.org (Postfix) with ESMTPS id A0976B20AE5 for ; Sat, 2 Dec 2023 23:48:51 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E3260224D1; Sat, 2 Dec 2023 23:48:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ixit.cz header.i=@ixit.cz header.b="1cIHJLXW" X-Original-To: devicetree@vger.kernel.org Received: from ixit.cz (ip-89-177-23-149.bb.vodafone.cz [89.177.23.149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C138EC8; Sat, 2 Dec 2023 15:48:40 -0800 (PST) Received: from newone.lan (unknown [10.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ixit.cz (Postfix) with ESMTPSA id C058B160B88; Sun, 3 Dec 2023 00:48:37 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ixit.cz; s=dkim; t=1701560917; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=yYAAnwjCtRQ2OW4JMv75Ia+LQsmjhgU723C/WzifIwA=; b=1cIHJLXWe5i7TC70bl0eezTByuNq/TMduEL0fbkVbSR6IiG0zDHeKVoFiD/NKudSvdQkz6 MYmTE4YdUMj12dpS9rNDto7vdjRTCYgceqy3lgXmSklSxMv2s+R4E0PWC5DFKAGZh40318 rNDrTwE2eH6n241dx/HzY9UNN8httkg= From: David Heidelberg To: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Paul Walmsley , Palmer Dabbelt , Albert Ou , David Heidelberg , Jonathan Cameron , Jonathan Corbet , Stephen Boyd , Lorenzo Pieralisi , Anup Patel Cc: Luca Weiss , Rob Herring , Ulf Hansson , Catalin Marinas , Krzysztof Kozlowski , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: [PATCH v4 1/3] dt-bindings: arm: merge qcom,idle-state with idle-state Date: Sun, 3 Dec 2023 00:47:17 +0100 Message-ID: <20231202234832.155306-1-david@ixit.cz> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Merge Qualcomm-specific idle-state binding with generic one. Signed-off-by: David Heidelberg --- v4: - drop Linux-specific details - integrate compatible into existing block - added surrounding patches fixing node names v3: - integrate into idle-state.yml - original patch name was: "[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML" .../bindings/arm/msm/qcom,idle-state.txt | 84 ------------------- .../devicetree/bindings/cpu/idle-states.yaml | 80 +++++++++++++++++- 2 files changed, 76 insertions(+), 88 deletions(-) delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt deleted file mode 100644 index 606b4b1b709d..000000000000 --- a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt +++ /dev/null @@ -1,84 +0,0 @@ -QCOM Idle States for cpuidle driver - -ARM provides idle-state node to define the cpuidle states, as defined in [1]. -cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle -states. Idle states have different enter/exit latency and residency values. -The idle states supported by the QCOM SoC are defined as - - - * Standby - * Retention - * Standalone Power Collapse (Standalone PC or SPC) - * Power Collapse (PC) - -Standby: Standby does a little more in addition to architectural clock gating. -When the WFI instruction is executed the ARM core would gate its internal -clocks. In addition to gating the clocks, QCOM cpus use this instruction as a -trigger to execute the SPM state machine. The SPM state machine waits for the -interrupt to trigger the core back in to active. This triggers the cache -hierarchy to enter standby states, when all cpus are idle. An interrupt brings -the SPM state machine out of its wait, the next step is to ensure that the -cache hierarchy is also out of standby, and then the cpu is allowed to resume -execution. This state is defined as a generic ARM WFI state by the ARM cpuidle -driver and is not defined in the DT. The SPM state machine should be -configured to execute this state by default and after executing every other -state below. - -Retention: Retention is a low power state where the core is clock gated and -the memory and the registers associated with the core are retained. The -voltage may be reduced to the minimum value needed to keep the processor -registers active. The SPM should be configured to execute the retention -sequence and would wait for interrupt, before restoring the cpu to execution -state. Retention may have a slightly higher latency than Standby. - -Standalone PC: A cpu can power down and warmboot if there is a sufficient time -between the time it enters idle and the next known wake up. SPC mode is used -to indicate a core entering a power down state without consulting any other -cpu or the system resources. This helps save power only on that core. The SPM -sequence for this idle state is programmed to power down the supply to the -core, wait for the interrupt, restore power to the core, and ensure the -system state including cache hierarchy is ready before allowing core to -resume. Applying power and resetting the core causes the core to warmboot -back into Elevation Level (EL) which trampolines the control back to the -kernel. Entering a power down state for the cpu, needs to be done by trapping -into a EL. Failing to do so, would result in a crash enforced by the warm boot -code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to -be flushed in s/w, before powering down the core. - -Power Collapse: This state is similar to the SPC mode, but distinguishes -itself in that the cpu acknowledges and permits the SoC to enter deeper sleep -modes. In a hierarchical power domain SoC, this means L2 and other caches can -be flushed, system bus, clocks - lowered, and SoC main XO clock gated and -voltages reduced, provided all cpus enter this state. Since the span of low -power modes possible at this state is vast, the exit latency and the residency -of this low power mode would be considered high even though at a cpu level, -this essentially is cpu power down. The SPM in this state also may handshake -with the Resource power manager (RPM) processor in the SoC to indicate a -complete application processor subsystem shut down. - -The idle-state for QCOM SoCs are distinguished by the compatible property of -the idle-states device node. - -The devicetree representation of the idle state should be - - -Required properties: - -- compatible: Must be one of - - "qcom,idle-state-ret", - "qcom,idle-state-spc", - "qcom,idle-state-pc", - and "arm,idle-state". - -Other required and optional properties are specified in [1]. - -Example: - - idle-states { - CPU_SPC: spc { - compatible = "qcom,idle-state-spc", "arm,idle-state"; - entry-latency-us = <150>; - exit-latency-us = <200>; - min-residency-us = <2000>; - }; - }; - -[1]. Documentation/devicetree/bindings/cpu/idle-states.yaml diff --git a/Documentation/devicetree/bindings/cpu/idle-states.yaml b/Documentation/devicetree/bindings/cpu/idle-states.yaml index b3a5356f9916..15abc786a978 100644 --- a/Documentation/devicetree/bindings/cpu/idle-states.yaml +++ b/Documentation/devicetree/bindings/cpu/idle-states.yaml @@ -243,7 +243,64 @@ description: |+ just supports idle_standby, an idle-states node is not required. =========================================== - 6 - References + 6 - Qualcomm specific STATES + =========================================== + + Idle states have different enter/exit latency and residency values. + The idle states supported by the QCOM SoC are defined as - + + * Standby + * Retention + * Standalone Power Collapse (Standalone PC or SPC) + * Power Collapse (PC) + + Standby: Standby does a little more in addition to architectural clock gating. + When the WFI instruction is executed the ARM core would gate its internal + clocks. In addition to gating the clocks, QCOM cpus use this instruction as a + trigger to execute the SPM state machine. The SPM state machine waits for the + interrupt to trigger the core back in to active. This triggers the cache + hierarchy to enter standby states, when all cpus are idle. An interrupt brings + the SPM state machine out of its wait, the next step is to ensure that the + cache hierarchy is also out of standby, and then the cpu is allowed to resume + execution. This state is defined as a generic ARM WFI state by the ARM cpuidle + driver and is not defined in the DT. The SPM state machine should be + configured to execute this state by default and after executing every other + state below. + + Retention: Retention is a low power state where the core is clock gated and + the memory and the registers associated with the core are retained. The + voltage may be reduced to the minimum value needed to keep the processor + registers active. The SPM should be configured to execute the retention + sequence and would wait for interrupt, before restoring the cpu to execution + state. Retention may have a slightly higher latency than Standby. + + Standalone PC: A cpu can power down and warmboot if there is a sufficient time + between the time it enters idle and the next known wake up. SPC mode is used + to indicate a core entering a power down state without consulting any other + cpu or the system resources. This helps save power only on that core. The SPM + sequence for this idle state is programmed to power down the supply to the + core, wait for the interrupt, restore power to the core, and ensure the + system state including cache hierarchy is ready before allowing core to + resume. Applying power and resetting the core causes the core to warmboot + back into Elevation Level (EL) which trampolines the control back to the + kernel. Entering a power down state for the cpu, needs to be done by trapping + into a EL. Failing to do so, would result in a crash enforced by the warm boot + code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to + be flushed in s/w, before powering down the core. + + Power Collapse: This state is similar to the SPC mode, but distinguishes + itself in that the cpu acknowledges and permits the SoC to enter deeper sleep + modes. In a hierarchical power domain SoC, this means L2 and other caches can + be flushed, system bus, clocks - lowered, and SoC main XO clock gated and + voltages reduced, provided all cpus enter this state. Since the span of low + power modes possible at this state is vast, the exit latency and the residency + of this low power mode would be considered high even though at a cpu level, + this essentially is cpu power down. The SPM in this state also may handshake + with the Resource power manager (RPM) processor in the SoC to indicate a + complete application processor subsystem shut down. + + =========================================== + 7 - References =========================================== [1] ARM Linux Kernel documentation - CPUs bindings @@ -301,9 +358,15 @@ patternProperties: properties: compatible: - enum: - - arm,idle-state - - riscv,idle-state + oneOf: + - const: arm,idle-state + - items: + - enum: + - qcom,idle-state-ret + - qcom,idle-state-spc + - qcom,idle-state-pc + - const: arm,idle-state + - const: riscv,idle-state arm,psci-suspend-param: $ref: /schemas/types.yaml#/definitions/uint32 @@ -852,4 +915,13 @@ examples: }; }; + // Example 4 - Qualcomm SPC + idle-states { + cpu_spc: cpu-spc { + compatible = "qcom,idle-state-spc", "arm,idle-state"; + entry-latency-us = <150>; + exit-latency-us = <200>; + min-residency-us = <2000>; + }; + }; ...