From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lina Iyer Subject: [PATCH v9 6/9] qcom: cpuidle: Add cpuidle driver for QCOM cpus Date: Fri, 24 Oct 2014 17:40:21 -0600 Message-ID: <1414194024-55547-7-git-send-email-lina.iyer@linaro.org> References: <1414194024-55547-1-git-send-email-lina.iyer@linaro.org> Return-path: Received: from mail-pd0-f172.google.com ([209.85.192.172]:48722 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932850AbaJXXk5 (ORCPT ); Fri, 24 Oct 2014 19:40:57 -0400 Received: by mail-pd0-f172.google.com with SMTP id r10so2276211pdi.17 for ; Fri, 24 Oct 2014 16:40:57 -0700 (PDT) In-Reply-To: <1414194024-55547-1-git-send-email-lina.iyer@linaro.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org 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, devicetree@vger.kernel.org, Lina Iyer 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 Standby and Standalone Power Collapse. Signed-off-by: Lina Iyer --- .../bindings/arm/msm/qcom,idle-state.txt | 81 ++++++++++++++++++++++ drivers/cpuidle/Kconfig.arm | 7 ++ drivers/cpuidle/Makefile | 1 + drivers/cpuidle/cpuidle-qcom.c | 72 +++++++++++++++++++ 4 files changed, 161 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..ae1b07f --- /dev/null +++ b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt @@ -0,0 +1,81 @@ +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. + +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 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-stby", + "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/arm/idle-states.txt diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm index 8c16ab2..13c7c1f 100644 --- a/drivers/cpuidle/Kconfig.arm +++ b/drivers/cpuidle/Kconfig.arm @@ -63,3 +63,10 @@ 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..1c1dcbc --- /dev/null +++ b/drivers/cpuidle/cpuidle-qcom.c @@ -0,0 +1,72 @@ +/* + * 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 "dt_idle_states.h" + +static struct qcom_cpu_pm_ops *lpm_ops; + +static int qcom_cpu_stby(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int index) +{ + lpm_ops->standby(NULL); + + return index; +} + +static int qcom_cpu_spc(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int index) +{ + lpm_ops->spc(NULL); + + return index; +} + +static struct cpuidle_driver qcom_cpuidle_driver = { + .name = "qcom_cpuidle", +}; + +static const struct of_device_id qcom_idle_state_match[] = { + { .compatible = "qcom,idle-state-stby", .data = qcom_cpu_stby}, + { .compatible = "qcom,idle-state-spc", .data = qcom_cpu_spc }, + { }, +}; + +static int qcom_cpuidle_probe(struct platform_device *pdev) +{ + struct cpuidle_driver *drv = &qcom_cpuidle_driver; + int ret; + + lpm_ops = pdev->dev.platform_data; + + /* Probe for other states, including standby */ + ret = dt_init_idle_driver(drv, qcom_idle_state_match, 0); + if (ret < 0) + return ret; + + return cpuidle_register(drv, NULL); +} + +static struct platform_driver qcom_cpuidle_plat_driver = { + .probe = qcom_cpuidle_probe, + .driver = { + .name = "qcom_cpuidle", + }, +}; + +module_platform_driver(qcom_cpuidle_plat_driver); -- 2.1.0