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

[Lina Iyer <lina.iyer@linaro.org>]

On Wed, Aug 13, 2014 at 01:22:09PM +0200, Daniel Lezcano wrote:
>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.

OK, I wasnt aware of Lorenzo's patches. Stephen B pointed that to me
yesterday. Looking at it. Its quite similar to what I have here. I
yanked this driver out of the original patch that does both cpuidle and
SoCIdle, which does the cluster part of Lorenzo's drivers.


-Lina.

>
>>---
>>  .../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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