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[199.106.103.253]) by mx.google.com with ESMTPSA id rg1sm6030307pdb.14.2014.09.26.17.58.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 26 Sep 2014 17:58:38 -0700 (PDT) From: Lina Iyer To: daniel.lezcano@linaro.org, khilman@linaro.org, sboyd@codeaurora.org, galak@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: lorenzo.pieralisi@arm.com, msivasub@codeaurora.org, Lina Iyer Subject: [PATCH v7 5/7] qcom: cpuidle: Add cpuidle driver for QCOM cpus Date: Fri, 26 Sep 2014 18:58:13 -0600 Message-Id: <1411779495-39724-6-git-send-email-lina.iyer@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1411779495-39724-1-git-send-email-lina.iyer@linaro.org> References: <1411779495-39724-1-git-send-email-lina.iyer@linaro.org> Sender: linux-arm-msm-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: lina.iyer@linaro.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of patch+caf_=patchwork-forward=linaro.org@linaro.org designates 209.85.215.50 as permitted sender) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , Add cpuidle driver interface to allow cpus to go into C-States. Use the cpuidle DT interface common across ARM architectures to provide the C-State information to the cpuidle framework. Supported modes at this time are clock gating (wfi) and cpu power down (Standalone PC or spc). Signed-off-by: Lina Iyer --- .../bindings/arm/msm/qcom,idle-state.txt | 72 +++++++++++++++++ drivers/cpuidle/Kconfig.arm | 7 ++ drivers/cpuidle/Makefile | 1 + drivers/cpuidle/cpuidle-qcom.c | 89 ++++++++++++++++++++++ 4 files changed, 169 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt create mode 100644 drivers/cpuidle/cpuidle-qcom.c diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt new file mode 100644 index 0000000..47095b9 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt @@ -0,0 +1,72 @@ +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 - + + * WFI + * Retention + * Standalone Power Collapse (Standalone PC or SPC) + * Power Collapse (PC) + +WFI: WFI does a little more in addition to architectural clock gating. ARM +processors when execute the wfi instruction will gate their internal clocks. +QCOM cpus use this instruction as a trigger for the SPM state machine. Usually +with a cpu entering WFI, the SPM is configured to do clock-gating as well. The +SPM state machine waits for the interrrupt to trigger the core back in to +active. When all CPUs in the SoC, clock gate using the ARM wfi instruction, the +second level cache usually can also clock gate sensing no cpu activity. When a +cpu is ready to run, it needs the cache to be active before starting execution. +Allowing the SPM to execute the clock gating statemachine and waiting for +interrupt on behalf of the processor has a benefit of guaranteeing that the +system state is conducive for the core to resume execution. + +Retention: Retention is a low power state where the core is clockgated 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. Retention is triggered when the core executes wfi instruction. 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 WFI. + +Standalone PC: A cpu can power down and warmboot if there is a sufficient time +between now and the next know 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. Like WFI and Retention, the +core executes wfi and the SPM programmed to do SPC would use the cpu control +logic to power down the core's supply and restore it back when woken up by an +interrupt. Applying power and reseting the core causes the core to warmboot +back into secure mode which trampolines the control back to the kernel. To +enter a power down state the kernel needs to call into the secure layer which +would then execute the ARM wfi instruction. Failing to do so, would result in a +crash enforced by the warm boot code in the secure layer. On a SoC with +write-back L1 cache, the cache would need to be flushed. + +Power Collapse: This state is similiar to the SPC mode, but distinguishes +itself in the fact 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 turned off +and voltages reduced, provided all cpus enter this state. In other words, it is +a coupled idle 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 +processor in the SoC to indicate a complete subsystem shut down. + +The idle-state for QCOM SoCs are distinguished by the compatible property of +the node. They indicate to the cpuidle driver the entry point to use for +cpuidle. The devicetree representation of the idle state should be - + +Required properties: + +- compatible: Must be "arm,idle-state" + and one of - + "qcom,idle-state-wfi", + "qcom,idle-state-ret", + "qcom,idle-state-spc", + "qcom,idle-state-pc", + +Other required and optional properties are specified in [1]. + +[1]. Documentation/devicetree/bindings/arm/idle-states.txt diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm index 38cff69..6a9ee12 100644 --- a/drivers/cpuidle/Kconfig.arm +++ b/drivers/cpuidle/Kconfig.arm @@ -62,3 +62,10 @@ config ARM_MVEBU_V7_CPUIDLE depends on ARCH_MVEBU help Select this to enable cpuidle on Armada 370, 38x and XP processors. + +config ARM_QCOM_CPUIDLE + bool "CPU Idle drivers for Qualcomm processors" + depends on QCOM_PM + select DT_IDLE_STATES + help + Select this to enable cpuidle for QCOM processors diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile index 4d177b9..6c222d5 100644 --- a/drivers/cpuidle/Makefile +++ b/drivers/cpuidle/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_ARM_ZYNQ_CPUIDLE) += cpuidle-zynq.o obj-$(CONFIG_ARM_U8500_CPUIDLE) += cpuidle-ux500.o obj-$(CONFIG_ARM_AT91_CPUIDLE) += cpuidle-at91.o obj-$(CONFIG_ARM_EXYNOS_CPUIDLE) += cpuidle-exynos.o +obj-$(CONFIG_ARM_QCOM_CPUIDLE) += cpuidle-qcom.o ############################################################################### # MIPS drivers diff --git a/drivers/cpuidle/cpuidle-qcom.c b/drivers/cpuidle/cpuidle-qcom.c new file mode 100644 index 0000000..2fcf79a --- /dev/null +++ b/drivers/cpuidle/cpuidle-qcom.c @@ -0,0 +1,89 @@ +/* + * Copyright (c) 2014, Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include +#include +#include +#include +#include +#include + +#include +#include "dt_idle_states.h" + +static void (*qcom_idle_enter)(enum pm_sleep_mode); + +static int qcom_lpm_enter_wfi(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int index) +{ + qcom_idle_enter(PM_SLEEP_MODE_WFI); + + return index; +} + +static int qcom_lpm_enter_spc(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int index) +{ + cpu_pm_enter(); + qcom_idle_enter(PM_SLEEP_MODE_SPC); + cpu_pm_exit(); + + return index; +} + +static struct cpuidle_driver qcom_cpuidle_driver = { + .name = "qcom_cpuidle", + .owner = THIS_MODULE, +}; + +static const struct of_device_id qcom_idle_state_match[] __initconst = { + { .compatible = "qcom,idle-state-wfi", .data = qcom_lpm_enter_wfi }, + { .compatible = "qcom,idle-state-spc", .data = qcom_lpm_enter_spc }, + { }, +}; + +static int qcom_cpuidle_probe(struct platform_device *pdev) +{ + struct cpuidle_driver *drv = &qcom_cpuidle_driver; + int ret; + + qcom_idle_enter = (void *)(pdev->dev.platform_data); + if (!qcom_idle_enter) + return -EFAULT; + + /* Probe for other states including platform WFI */ + ret = dt_init_idle_driver(drv, qcom_idle_state_match, 0); + if (ret <= 0) { + pr_err("%s: No cpuidle state found.\n", __func__); + return ret; + } + + ret = cpuidle_register(drv, NULL); + if (ret) { + pr_err("%s: failed to register cpuidle driver\n", __func__); + return ret; + } + + return 0; +} + +static struct platform_driver qcom_cpuidle_plat_driver = { + .probe = qcom_cpuidle_probe, + .driver = { + .name = "qcom_cpuidle", + .owner = THIS_MODULE, + }, +}; + +module_platform_driver(qcom_cpuidle_plat_driver);