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Message-Id: <20211126125244.126300-3-abailon@baylibre.com>
Date: Fri, 26 Nov 2021 13:52:44 +0100
From: Alexandre Bailon <abailon@...libre.com>
To: rafael@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org,
amitk@...nel.org
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
ben.tseng@...iatek.com, khilman@...libre.com, mka@...omium.org,
Alexandre Bailon <abailon@...libre.com>
Subject: [PATCH v4 2/2] thermal: add a virtual sensor to aggregate temperatures
This adds a virtual thermal sensor driver that reads temperature from
multiple hardware sensors and returns an aggregated temperature.
Currently, this supports three aggregations:
the minimum, maximum and average temperature.
Signed-off-by: Alexandre Bailon <abailon@...libre.com>
---
drivers/thermal/Kconfig | 8 +
drivers/thermal/Makefile | 1 +
drivers/thermal/virtual_thermal_sensor.c | 218 +++++++++++++++++++++++
3 files changed, 227 insertions(+)
create mode 100644 drivers/thermal/virtual_thermal_sensor.c
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index d7f44deab5b1..b326fae5ad1d 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -228,6 +228,14 @@ config THERMAL_MMIO
register or shared memory, is a potential candidate to work with this
driver.
+config VIRTUAL_THERMAL
+ tristate "DT-based virtual thermal sensor driver"
+ depends on THERMAL_OF || COMPILE_TEST
+ help
+ This option enables the generic DT-based thermal sensor aggregator.
+ This driver creates a thermal sensor that reads multiple hardware
+ sensors and aggregates their output.
+
config HISI_THERMAL
tristate "Hisilicon thermal driver"
depends on ARCH_HISI || COMPILE_TEST
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 82fc3e616e54..8bf55973059c 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -60,3 +60,4 @@ obj-$(CONFIG_UNIPHIER_THERMAL) += uniphier_thermal.o
obj-$(CONFIG_AMLOGIC_THERMAL) += amlogic_thermal.o
obj-$(CONFIG_SPRD_THERMAL) += sprd_thermal.o
obj-$(CONFIG_KHADAS_MCU_FAN_THERMAL) += khadas_mcu_fan.o
+obj-$(CONFIG_VIRTUAL_THERMAL) += virtual_thermal_sensor.o
diff --git a/drivers/thermal/virtual_thermal_sensor.c b/drivers/thermal/virtual_thermal_sensor.c
new file mode 100644
index 000000000000..9f38af925fd1
--- /dev/null
+++ b/drivers/thermal/virtual_thermal_sensor.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * virtual_thermal_sensor.c - DT-based virtual thermal sensor driver.
+ *
+ * Copyright (c) 2021 BayLibre
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/types.h>
+#include <linux/string.h>
+
+#include <dt-bindings/thermal/virtual-sensor.h>
+
+struct virtual_thermal_zone_device {
+ struct thermal_zone_device *zone;
+ struct module *owner;
+};
+
+struct virtual_thermal_sensor {
+ int count;
+ struct virtual_thermal_zone_device *zones;
+ struct thermal_zone_device *tzd;
+ int (*aggr_temp)(int temp1, int temp2);
+
+ struct list_head node;
+};
+
+static int max_temp(int temp1, int temp2)
+{
+ return max(temp1, temp2);
+}
+
+static int min_temp(int temp1, int temp2)
+{
+ return min(temp1, temp2);
+}
+
+static int avg_temp(int temp1, int temp2)
+{
+ return (temp1 + temp2) / 2;
+}
+
+static int virtual_thermal_sensor_get_temp(void *data, int *temperature)
+{
+ struct virtual_thermal_sensor *sensor = data;
+ int max_temp = INT_MIN;
+ int temp;
+ int i;
+
+ for (i = 0; i < sensor->count; i++) {
+ struct thermal_zone_device *zone;
+
+ zone = sensor->zones[i].zone;
+ zone->ops->get_temp(zone, &temp);
+ max_temp = sensor->aggr_temp(max_temp, temp);
+ }
+
+ *temperature = max_temp;
+
+ return 0;
+}
+
+static const struct thermal_zone_of_device_ops virtual_thermal_sensor_ops = {
+ .get_temp = virtual_thermal_sensor_get_temp,
+};
+
+static int virtual_thermal_sensor_get_module(struct virtual_thermal_zone_device *zone,
+ const char *name)
+{
+ struct platform_device *sensor_pdev;
+ struct device_node *node;
+
+ node = of_find_node_by_name(NULL, name);
+ if (!node)
+ return -ENODEV;
+
+ node = of_parse_phandle(node, "thermal-sensors", 0);
+ if (!node)
+ return -ENODEV;
+
+ sensor_pdev = of_find_device_by_node(node);
+ if (!sensor_pdev)
+ return -ENODEV;
+
+ if (!sensor_pdev->dev.driver)
+ return -EPROBE_DEFER;
+
+ if (!try_module_get(sensor_pdev->dev.driver->owner))
+ return -ENODEV;
+
+ zone->owner = sensor_pdev->dev.driver->owner;
+
+ return 0;
+}
+
+static void virtual_thermal_sensor_put_modules(struct virtual_thermal_sensor *sensor)
+{
+ int i;
+
+ for (i = 0; i < sensor->count; i++) {
+ if (sensor->zones[i].zone)
+ module_put(sensor->zones[i].owner);
+ }
+}
+
+static int virtual_thermal_sensor_probe(struct platform_device *pdev)
+{
+ struct virtual_thermal_sensor *sensor;
+ struct device *dev = &pdev->dev;
+ struct property *prop;
+ const char *name;
+ u32 type;
+ int ret;
+ int i = 0;
+
+ sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
+ if (!sensor)
+ return -ENOMEM;
+ sensor->count = of_property_count_strings(dev->of_node, "thermal-sensors");
+ if (sensor->count <= 0)
+ return -EINVAL;
+
+ sensor->zones = devm_kmalloc_array(dev, sensor->count,
+ sizeof(*sensor->zones),
+ GFP_KERNEL);
+ if (!sensor->zones)
+ return -ENOMEM;
+
+ of_property_for_each_string(dev->of_node, "thermal-sensors", prop, name) {
+ struct virtual_thermal_zone_device *virtual_zone;
+ struct thermal_zone_device *zone;
+
+ virtual_zone = &sensor->zones[i++];
+
+ zone = thermal_zone_get_zone_by_name(name);
+ if (IS_ERR(zone))
+ return PTR_ERR(zone);
+
+ ret = virtual_thermal_sensor_get_module(virtual_zone, name);
+ if (ret)
+ goto err;
+
+ virtual_zone->zone = zone;
+ }
+
+ ret = of_property_read_u32(dev->of_node, "aggregation-function", &type);
+ if (ret)
+ return ret;
+
+ switch (type) {
+ case VIRTUAL_THERMAL_SENSOR_MAX_VAL:
+ sensor->aggr_temp = max_temp;
+ break;
+ case VIRTUAL_THERMAL_SENSOR_MIN_VAL:
+ sensor->aggr_temp = min_temp;
+ break;
+ case VIRTUAL_THERMAL_SENSOR_AVG_VAL:
+ sensor->aggr_temp = avg_temp;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ sensor->tzd = devm_thermal_zone_of_sensor_register(dev, 0, sensor,
+ &virtual_thermal_sensor_ops);
+ if (IS_ERR(sensor->tzd))
+ return PTR_ERR(sensor->tzd);
+
+ platform_set_drvdata(pdev, sensor);
+
+ return 0;
+
+err:
+ virtual_thermal_sensor_put_modules(sensor);
+
+ return ret;
+}
+
+static int virtual_thermal_sensor_remove(struct platform_device *pdev)
+{
+ struct virtual_thermal_sensor *sensor;
+
+ sensor = platform_get_drvdata(pdev);
+ list_del(&sensor->node);
+
+ virtual_thermal_sensor_put_modules(sensor);
+
+ return 0;
+}
+
+static const struct of_device_id virtual_thermal_sensor_of_match[] = {
+ {
+ .compatible = "virtual,thermal-sensor",
+ },
+ {
+ },
+};
+MODULE_DEVICE_TABLE(of, virtual_thermal_sensor_of_match);
+
+static struct platform_driver virtual_thermal_sensor = {
+ .probe = virtual_thermal_sensor_probe,
+ .remove = virtual_thermal_sensor_remove,
+ .driver = {
+ .name = "virtual-thermal-sensor",
+ .of_match_table = virtual_thermal_sensor_of_match,
+ },
+};
+
+module_platform_driver(virtual_thermal_sensor);
+MODULE_AUTHOR("Alexandre Bailon <abailon@...libre.com>");
+MODULE_DESCRIPTION("Virtual thermal sensor");
+MODULE_LICENSE("GPL v2");
--
2.25.1
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