Re: [PATCH v2 08/10] qcom: cpuidle: Add cpuidle driver for QCOM cpus

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 08/12/2014 09:43 PM, Lina Iyer wrote:
> Add cpuidle driver interface to allow cpus to go into C-States.
>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

Hi Lina,

I think you should based this driver on top of Lorenzo's work.

Cc Lorenzo.

> ---
>   .../devicetree/bindings/arm/msm/qcom,cpuidle.txt   |  73 +++++++++++
>   drivers/cpuidle/Makefile                           |   1 +
>   drivers/cpuidle/cpuidle-qcom.c                     | 140 +++++++++++++++++++++
>   3 files changed, 214 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,cpuidle.txt
>   create mode 100644 drivers/cpuidle/cpuidle-qcom.c
>
> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,cpuidle.txt b/Documentation/devicetree/bindings/arm/msm/qcom,cpuidle.txt
> new file mode 100644
> index 0000000..b094baf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,cpuidle.txt
> @@ -0,0 +1,73 @@
> +Qualcomm CPUIdle driver
> +
> +The Qualcomm cpuidle driver enables the processor to enter low power modes
> +when idle. The processors support 4 low power modes.
> +	wfi - also known as clock gating
> +	retention - processor clock gated and processor power is reduced.
> +	standalone-pc - processor is powered down and when reset, the core
> +		boots into secure mode and trampolines back to the kernel.
> +		Every core can individually enter this low power mode without
> +		affecting the state of the other cores.
> +	pc - essentially standalone power collapse, but indicates that the
> +		latency to put SoC into a low power state is tolerable.
> +
> +The cpuidle node is comprised of nodes, each of which represent a C-State the
> +processor can achieve. Each node provides the latency and residency which
> +helps the cpuidle governor to choose the appropriate low power mode based on
> +the time available. Not all SoCs may support all the above low power modes.
> +
> +PROPERTIES
> +
> +- compatible:
> +	Usage: required
> +	Value type: <string>
> +	Definition: Should be "qcom,cpuidle"
> +
> +- qcom,cpu-level:
> +	Usage: required
> +	Value type: { Node }
> +	Definition: Describes a C-State of the processor
> +
> +	PROPERTIES of qcom,cpu-level
> +
> +	- reg:
> +		Usage: required
> +		Value type: <integer>
> +		Definition: Index of the C-State
> +
> +	- qcom,state-name:
> +		Usage: required
> +		Value type: <string>
> +		Definition: C-State moniker
> +
> +	- qcom,spm-cpu-mode:
> +		Usage: required
> +		Value type: <string>
> +		Definition: The description of the h/w mode that will be
> +			achieved in this C-State.
> +
> +	- qcom,latency-us:
> +		Usage: required
> +		Value type: <integer>
> +		Defintion: Time taken to exit from the C-State
> +
> +	- qcom,residency-us:
> +		Usage: required
> +		Value type: <integer>
> +		Defintion: Time to be spent in this C-State for the power
> +			saving to be beneficial.
> +
> +Example:
> +
> +	qcom,cpuidle {
> +		compatible = "qcom,cpuidle";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		qcom,cpu-level@0 {
> +			reg = <0x0>;
> +			qcom,state-name = "C1";
> +			qcom,spm-cpu-mode = "wfi";
> +			qcom,latency-us = <1>;
> +			qcom,residency-us = <1>;
> +		};
> +	};
> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> index 11edb31..4a2c446 100644
> --- a/drivers/cpuidle/Makefile
> +++ b/drivers/cpuidle/Makefile
> @@ -16,6 +16,7 @@ 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..8e70a88
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-qcom.c
> @@ -0,0 +1,140 @@
> +/* Copyright (c) 2014, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2014 Linaro.
> + *
> + * 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 <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/cpuidle.h>
> +
> +#include <soc/qcom/pm.h>
> +
> +struct lookup {
> +	enum msm_pm_sleep_mode mode;
> +	char *name;
> +};
> +
> +static enum msm_pm_sleep_mode spm_sleep_modes[MSM_PM_SLEEP_MODE_NR];
> +
> +static int qcom_lpm_enter(struct cpuidle_device *dev,
> +				struct cpuidle_driver *drv,
> +				int index)
> +{
> +	return msm_cpu_pm_enter_sleep(spm_sleep_modes[index], true);
> +}
> +
> +static struct cpuidle_driver qcom_cpuidle_driver = {
> +	.name	= "qcom_cpuidle",
> +	.owner	= THIS_MODULE,
> +};
> +
> +static int qcom_cpuidle_probe(struct platform_device *pdev)
> +{
> +	int ret;
> +	struct device_node *top = pdev->dev.of_node;
> +	struct device_node *n;
> +	char *key;
> +	const char *val;
> +	int index = 0;
> +	int i;
> +	struct cpuidle_state *state;
> +	static const struct lookup pm_sm_lookup[] = {
> +		{MSM_PM_SLEEP_MODE_WAIT_FOR_INTERRUPT,
> +			"wfi"},
> +		{MSM_PM_SLEEP_MODE_POWER_COLLAPSE_STANDALONE,
> +			"standalone_pc"},
> +		{MSM_PM_SLEEP_MODE_POWER_COLLAPSE,
> +			"pc"},
> +		{MSM_PM_SLEEP_MODE_RETENTION,
> +			"retention"},
> +	};
> +
> +	if (!top)
> +		return -ENODEV;
> +
> +	for_each_child_of_node(top, n) {
> +		key = "qcom,cpu-level";
> +		if (of_node_cmp(n->name, key))
> +			continue;
> +
> +		state = &qcom_cpuidle_driver.states[index];
> +
> +		key = "qcom,spm-cpu-mode";
> +		ret = of_property_read_string(n, key, &val);
> +		if (ret)
> +			goto failed;
> +		for (i = 0; i < ARRAY_SIZE(pm_sm_lookup); i++) {
> +			if (!strcmp(val, pm_sm_lookup[i].name)) {
> +				spm_sleep_modes[index] = pm_sm_lookup[i].mode;
> +				break;
> +			}
> +		}
> +		if (i == ARRAY_SIZE(pm_sm_lookup)) {
> +			ret = -EFAULT;
> +			goto failed;
> +		}
> +
> +		strncpy(state->desc, val, CPUIDLE_DESC_LEN);
> +
> +		key = "qcom,state-name";
> +		ret = of_property_read_string(n, key, &val);
> +		if (ret)
> +			goto failed;
> +		strncpy(state->name, val, CPUIDLE_NAME_LEN);
> +
> +		key = "qcom,latency-us";
> +		ret = of_property_read_u32(n, key, &state->exit_latency);
> +		if (ret)
> +			goto failed;
> +
> +		key = "qcom,residency-us";
> +		ret = of_property_read_u32(n, key, &state->target_residency);
> +		if (ret)
> +			goto failed;
> +
> +		state->flags = CPUIDLE_FLAG_TIME_VALID;
> +		state->enter = qcom_lpm_enter;
> +		index++;
> +	}
> +
> +	qcom_cpuidle_driver.state_count = index;
> +	qcom_cpuidle_driver.safe_state_index = 0;
> +
> +	ret = cpuidle_register(&qcom_cpuidle_driver, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to register cpuidle driver\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +
> +failed:
> +	dev_err(&pdev->dev, "error parsing key: %s\n", key);
> +	return ret;
> +}
> +
> +static struct of_device_id qcom_cpuidle_match_tbl[] = {
> +	{.compatible = "qcom,cpuidle"},
> +	{},
> +};
> +
> +static struct platform_driver qcom_cpuidle_platform_driver = {
> +	.probe	= qcom_cpuidle_probe,
> +	.driver	= {
> +		.name = "qcom,cpuidle",
> +		.owner = THIS_MODULE,
> +		.of_match_table = qcom_cpuidle_match_tbl,
> +	},
> +};
> +
> +module_platform_driver(qcom_cpuidle_platform_driver);
>


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