drivers: thermal: regulator: Add Regulator cooling device

Add a snapshot of regulator cooling device from kernel 4.9
as of 'commit <375365b94b6> ("drivers: thermal: regulator_cdev: Add a
voltage regulator cooling device")'.

Change-Id: I0c0aacf246c752ba51de6315fbde63277f3fd56c
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>

Documentation/devicetree/bindings/thermal/regulator-cdev.txt

@@ -0,0 +1,38 @@
+Regulator cooling device.
+
+The regulator cooling device, will be used to place a voltage floor
+restriction on a rail.
+
+Properties:
+
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: shall be "qcom,regulator-cooling-device"
+
+- cdev-supply:
+	Usage: required
+	Value type: <phandle>
+	Definition: phandle to the regulator to which the cooling device will
+			place a floor mitigation.
+
+- regulator-levels:
+	Usage: required
+	Value type: <U32 array>
+	Definition: Array of regulator voltages the cooling device should
+			use to place a floor restriction. The voltages should
+			be specified in descending order.
+
+- #cooling-cells: Must be 2. Please refer to
+			<devicetree/bindings/thermal/thermal.txt> for more
+			details.
+
+Example:
+
+	mv_cdev: mx-cdev-lvl {
+		compatible = "qcom,regulator-cooling-device";
+		cdev-supply = <&regulator-cdev-supply>;
+		regulator-levels = <RPMH_REGULATOR_LEVEL_NOM
+			RPMH_REGULATOR_LEVEL_OFF>;
+		#cooling-cells = <2>;
+	};

drivers/thermal/qcom/Kconfig

@@ -29,3 +29,14 @@ config QTI_AOP_REG_COOLING_DEVICE
 	  device will be used by QTI chipset to place a floor voltage
 	  restriction at low temperatures. The cooling device will message
 	  the AOP using mail box to establish the floor voltage.
+
+config REGULATOR_COOLING_DEVICE
+	bool "Regulator voltage floor cooling device"
+	depends on REGULATOR && THERMAL_OF
+	help
+	  This implements a mitigation device to place a minimum voltage floor
+	  on a particular regulator. This mitigation device will be used by low
+	  temperature reliability rules to mitigate a regulator at nominal
+	  voltage.
+
+	  If you want this support, you should say Y here.

drivers/thermal/qcom/Makefile

@@ -2,3 +2,4 @@ obj-$(CONFIG_QCOM_TSENS)	+= qcom_tsens.o
 qcom_tsens-y			+= tsens.o tsens-common.o tsens-8916.o tsens-8974.o tsens-8960.o tsens-8996.o
 obj-$(CONFIG_QTI_THERMAL_LIMITS_DCVS) += msm_lmh_dcvs.o lmh_dbg.o
 obj-$(CONFIG_QTI_AOP_REG_COOLING_DEVICE) += regulator_aop_cdev.o
+obj-$(CONFIG_REGULATOR_COOLING_DEVICE) += regulator_cdev.o

drivers/thermal/qcom/regulator_cdev.c

@@ -0,0 +1,184 @@
+/* Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
+ *
+ * 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/thermal.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/regulator/consumer.h>
+
+#define REG_CDEV_DRIVER "reg-cooling-device"
+
+struct reg_cooling_device {
+	struct regulator		*reg;
+	struct thermal_cooling_device	*cool_dev;
+	unsigned int			min_reg_state;
+	unsigned int			*lvl;
+	unsigned int			lvl_ct;
+	char				reg_name[THERMAL_NAME_LENGTH];
+	bool				reg_enable;
+};
+
+static int reg_get_max_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct reg_cooling_device *reg_dev = cdev->devdata;
+
+	*state = reg_dev->lvl_ct;
+	return 0;
+}
+
+static int reg_get_min_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct reg_cooling_device *reg_dev = cdev->devdata;
+
+	*state = reg_dev->min_reg_state;
+	return 0;
+}
+
+static int reg_set_min_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	struct reg_cooling_device *reg_dev = cdev->devdata;
+	int ret = 0;
+
+	if (state > reg_dev->lvl_ct)
+		state = reg_dev->lvl_ct;
+
+	if (reg_dev->min_reg_state == state)
+		return ret;
+
+	ret = regulator_set_voltage(reg_dev->reg,
+			reg_dev->lvl[state], INT_MAX);
+	if (ret) {
+		dev_err(&cdev->device,
+			"switching to floor %lu err:%d\n",
+			state, ret);
+		return ret;
+	}
+	if (reg_dev->reg_enable && state == reg_dev->lvl_ct) {
+		ret = regulator_disable(reg_dev->reg);
+		if (ret) {
+			dev_err(&cdev->device,
+				"regulator disable err:%d\n", ret);
+			return ret;
+		}
+		reg_dev->reg_enable = false;
+	} else if (!reg_dev->reg_enable && state != reg_dev->lvl_ct) {
+		ret = regulator_enable(reg_dev->reg);
+		if (ret) {
+			dev_err(&cdev->device,
+				"regulator enable err:%d\n", ret);
+			return ret;
+		}
+		reg_dev->reg_enable = true;
+	}
+	reg_dev->min_reg_state = state;
+
+	return ret;
+}
+
+static int reg_get_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	*state = 0;
+	return 0;
+}
+
+static int reg_set_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	/* regulator cooling device doesn't support voltage ceil */
+	return 0;
+}
+
+static struct thermal_cooling_device_ops reg_device_ops = {
+	.get_max_state = reg_get_max_state,
+	.get_cur_state = reg_get_cur_state,
+	.set_cur_state = reg_set_cur_state,
+	.set_min_state = reg_set_min_state,
+	.get_min_state = reg_get_min_state,
+};
+
+static int reg_cdev_probe(struct platform_device *pdev)
+{
+	struct reg_cooling_device *reg_dev;
+	int ret = 0;
+	struct device_node *np;
+
+	np = dev_of_node(&pdev->dev);
+	if (!np) {
+		dev_err(&pdev->dev,
+			"of node not available for cooling device\n");
+		return -EINVAL;
+	}
+
+	reg_dev = devm_kzalloc(&pdev->dev, sizeof(*reg_dev), GFP_KERNEL);
+	if (!reg_dev)
+		return -ENOMEM;
+
+	reg_dev->reg = devm_regulator_get(&pdev->dev, "regulator-cdev");
+	if (IS_ERR_OR_NULL(reg_dev->reg)) {
+		ret = PTR_ERR(reg_dev->reg);
+		dev_err(&pdev->dev, "regulator register err:%d\n", ret);
+		return ret;
+	}
+	ret = of_property_count_u32_elems(np, "regulator-levels");
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "Invalid levels err:%d\n", ret);
+		return ret;
+	}
+	reg_dev->lvl_ct = ret;
+	reg_dev->lvl = devm_kcalloc(&pdev->dev, reg_dev->lvl_ct,
+			sizeof(*reg_dev->lvl), GFP_KERNEL);
+	if (!reg_dev->lvl)
+		return -ENOMEM;
+	ret = of_property_read_u32_array(np, "regulator-levels",
+				reg_dev->lvl, reg_dev->lvl_ct);
+	if (ret) {
+		dev_err(&pdev->dev, "cdev level fetch err:%d\n", ret);
+		return ret;
+	}
+	/* level count is an index and it depicts the max possible index */
+	reg_dev->lvl_ct--;
+	reg_dev->min_reg_state = reg_dev->lvl_ct;
+	reg_dev->reg_enable = false;
+	strlcpy(reg_dev->reg_name, np->name, THERMAL_NAME_LENGTH);
+
+	reg_dev->cool_dev = thermal_of_cooling_device_register(
+					np, reg_dev->reg_name, reg_dev,
+					&reg_device_ops);
+	if (IS_ERR(reg_dev->cool_dev)) {
+		ret = PTR_ERR(reg_dev->cool_dev);
+		dev_err(&pdev->dev, "regulator cdev register err:%d\n",
+				ret);
+		return ret;
+	}
+
+	return ret;
+}
+
+static const struct of_device_id reg_cdev_of_match[] = {
+	{.compatible = "qcom,regulator-cooling-device", },
+	{}
+};
+
+static struct platform_driver reg_cdev_driver = {
+	.driver = {
+		.name = REG_CDEV_DRIVER,
+		.of_match_table = reg_cdev_of_match,
+	},
+	.probe = reg_cdev_probe,
+};
+builtin_platform_driver(reg_cdev_driver);