[RFC,11/13] qcom: cpuidle: Add cpuidle driver for QCOM cpus

Message ID 1407470458-22900-12-git-send-email-lina.iyer@linaro.org
State New
Headers show

Commit Message

Lina Iyer Aug. 8, 2014, 4 a.m.
Add cpuidle driver interface to allow cpus to go into C-States.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 .../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

Patch

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);