From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH v12 07/10] qcom: cpuidle: Add cpuidle driver for QCOM cpus Date: Thu, 27 Nov 2014 09:55:12 +0100 Message-ID: <5476E6F0.1080408@linaro.org> References: <1417047195-18978-1-git-send-email-lina.iyer@linaro.org> <1417047195-18978-8-git-send-email-lina.iyer@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1417047195-18978-8-git-send-email-lina.iyer@linaro.org> Sender: linux-arm-msm-owner@vger.kernel.org To: Lina Iyer , 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 List-Id: linux-pm@vger.kernel.org On 11/27/2014 01:13 AM, Lina Iyer wrote: > Add cpuidle driver interface to allow cpus to go into idle states. Us= e > the cpuidle DT interface, common across ARM architectures, to provide > the idle state information to the cpuidle framework. > > Supported modes at this time are Standby and Standalone Power Collaps= e. > > Signed-off-by: Lina Iyer > Acked-by: Daniel Lezcano > Acked-by: Lorenzo Pieralisi > --- > .../bindings/arm/msm/qcom,idle-state.txt | 81 +++++++++++= +++++++++++ > drivers/cpuidle/Kconfig.arm | 7 ++ > drivers/cpuidle/Makefile | 1 + > drivers/cpuidle/cpuidle-qcom.c | 78 +++++++++++= ++++++++++ > 4 files changed, 167 insertions(+) > create mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,i= dle-state.txt > create mode 100644 drivers/cpuidle/cpuidle-qcom.c > > diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-stat= e.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 define= d 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 clo= ck gating. > +When the WFI instruction is executed the ARM core would gate its int= ernal > +clocks. In addition to gating the clocks, QCOM cpus use this instruc= tion as a > +trigger to execute the SPM state machine. The SPM state machine wait= s for the > +interrupt to trigger the core back in to active. This triggers the c= ache > +hierarchy to enter standby states, when all cpus are idle. An interr= upt brings > +the SPM state machine out of its wait, the next step is to ensure th= at 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 ga= ted 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 proce= ssor > +registers active. The SPM should be configured to execute the retent= ion > +sequence and would wait for interrupt, before restoring the cpu to e= xecution > +state. Retention may have a slightly higher latency than Standby. > + > +Standalone PC: A cpu can power down and warmboot if there is a suffi= cient 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 an= y other > +cpu or the system resources. This helps save power only on that core= =2E 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 war= mboot > +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 ca= che has to > +be flushed in s/w, before powering down the core. > + > +Power Collapse: This state is similar to the SPC mode, but distingui= shes > +itself in that the cpu acknowledges and permits the SoC to enter dee= per sleep > +modes. In a hierarchical power domain SoC, this means L2 and other c= aches can > +be flushed, system bus, clocks - lowered, and SoC main XO clock gate= d and > +voltages reduced, provided all cpus enter this state. Since the spa= n 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 h= andshake > +with the Resource power manager processor in the SoC to indicate a c= omplete > +application processor subsystem shut down. > + > +The idle-state for QCOM SoCs are distinguished by the compatible pro= perty 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 =3D "qcom,idle-state-spc", "arm,idle-state"; > + entry-latency-us =3D <150>; > + exit-latency-us =3D <200>; > + min-residency-us =3D <2000>; > + }; > + }; > + > +[1]. Documentation/devicetree/bindings/arm/idle-states.txt > diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.ar= m > index 8c16ab2..e98993c 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 processo= rs. > + > +config ARM_QCOM_CPUIDLE > + bool "CPU Idle drivers for Qualcomm processors" > + depends on ARCH_QCOM > + 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-$(CONFIG_ARM_ZYNQ_CPUIDLE) +=3D cpuidle-zynq.o > obj-$(CONFIG_ARM_U8500_CPUIDLE) +=3D cpuidle-ux500.o > obj-$(CONFIG_ARM_AT91_CPUIDLE) +=3D cpuidle-at91.o > obj-$(CONFIG_ARM_EXYNOS_CPUIDLE) +=3D cpuidle-exynos.o > +obj-$(CONFIG_ARM_QCOM_CPUIDLE) +=3D 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..5e54d9d > --- /dev/null > +++ b/drivers/cpuidle/cpuidle-qcom.c > @@ -0,0 +1,78 @@ > +/* > + * Copyright (c) 2014, Linaro Limited. > + * > + * This program is free software; you can redistribute it and/or mod= ify > + * it under the terms of the GNU General Public License version 2 an= d > + * 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) > +{ > + if (!lpm_ops->standby(NULL)) > + return -1; > + > + return index; > +} > + > +static int qcom_cpu_spc(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, int index) > +{ > + if (!lpm_ops->spc(NULL)) > + return -1; > + > + return index; > +} Really ? the lpm_ops return NULL on error ? ret =3D lpm_ops->spc(NULL); if (ret) return ret; --=20 Linaro.org =E2=94=82 Open source software fo= r ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog