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Date: Fri, 20 Aug 2021 14:52:33 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Alexandre Bailon <abailon@...libre.com>, rui.zhang@...el.com,
amitk@...nel.org
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
ben.tseng@...iatek.com, khilman@...libre.com
Subject: Re: [RFC PATCH 2/2] thermal: add a virtual sensor to aggregate
temperatures
On 19/08/2021 14:32, Alexandre Bailon wrote:
> This adds a virtual thermal sensor that reads temperature from
> hardware sensor and return an aggregated temperature.
> Currently, this only return the max temperature.
>
> Signed-off-by: Alexandre Bailon <abailon@...libre.com>
> ---
> drivers/thermal/Kconfig | 8 ++
> drivers/thermal/Makefile | 1 +
> drivers/thermal/thermal_aggregator.c | 134 +++++++++++++++++++++++++++
> 3 files changed, 143 insertions(+)
> create mode 100644 drivers/thermal/thermal_aggregator.c
>
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 7a4ba50ba97d0..f9c152cfb95bc 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 THERMAL_AGGREGATOR
We discussed the virtual sensor doing aggregation but may be we can give
it another purpose in the future like returning a constant temp or
low/high pass filter.
It may make sense to use a more generic name like virtual sensor for
example.
> + tristate "Generic thermal aggregator driver"
> + depends on TERMAL_OF || COMPILE_TEST
s/TERMAL_OF/THERMAL_OF/
> + help
> + This option enables the generic thermal sensor aggregator.
> + This driver creates a thermal sensor that reads the hardware sensors
> + and aggregate the temperature.
> +
> config HISI_THERMAL
> tristate "Hisilicon thermal driver"
> depends on ARCH_HISI || COMPILE_TEST
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 9729a2b089919..5b20ef15aebbe 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_THERMAL_AGGREGATOR) += thermal_aggregator.o
> diff --git a/drivers/thermal/thermal_aggregator.c b/drivers/thermal/thermal_aggregator.c
> new file mode 100644
> index 0000000000000..76f871dbfee9e
> --- /dev/null
> +++ b/drivers/thermal/thermal_aggregator.c
> @@ -0,0 +1,134 @@
> +#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>
> +
> +const char *aggr_types[] = {
> + "min",
> + "max",
> + "avg",
> +};
> +
> +struct thermal_aggr;
> +
> +typedef int (*aggregate_fn)(struct thermal_aggr *aggr);
> +
> +struct thermal_aggr_sensor {
> + struct thermal_sensor *sensor;
> +
> + struct list_head node;
> +};
> +
> +struct thermal_aggr {
> + struct list_head sensors;
> + aggregate_fn *aggregate;
> + //struct thermal_zone_device *tz;
> +};
> +
> +static int thermal_aggr_read_temp(void *data, int *temperature)
> +{
> + struct thermal_aggr *aggr = data;
> + struct thermal_aggr_sensor *sensor;
> + int max_temp = 0;
> + int temp;
> +
What happens if a hardware sensor module is unloaded ?
> + list_for_each_entry(sensor, &aggr->sensors, node) {
> + if (!sensor->sensor) {
> + return -ENODEV;
> + }
> + sensor->sensor->ops->get_temp(sensor->sensor->sensor_data, &temp);
> + max_temp = max(max_temp, temp);
> + }
> +
> + *temperature = max_temp;
> +
> + return 0;
> +}
> +
> +static const struct thermal_zone_of_device_ops thermal_aggr_max_ops = {
> + .get_temp = thermal_aggr_read_temp,
.get_temp = thermal_virtual_sensor_get_temp ?
> +};
> +
> +static int thermal_aggr_probe(struct platform_device *pdev)
> +{
> + struct thermal_aggr *aggr;
> + struct device *dev = &pdev->dev;
> + struct of_phandle_args args;
> + int count;
> + int ret;
> + int i;
> +
> + count = of_count_phandle_with_args(dev->of_node,
> + "thermal-sensors",
> + "#thermal-sensor-cells");
> + if (count <= 0)
> + return -EINVAL;
> +
> + aggr = kzalloc(sizeof(*aggr), GFP_KERNEL);
devm_kzalloc
> + INIT_LIST_HEAD(&aggr->sensors);
> +
> + for (i = 0; i < count; i++) {
> + struct thermal_sensor *sensor;
> + struct thermal_aggr_sensor *aggr_sensor;
> + int id;
> +
> + ret = of_parse_phandle_with_args(dev->of_node,
> + "thermal-sensors",
> + "#thermal-sensor-cells",
> + i,
> + &args);
> + if (ret) {
> + return ret;
> + }
> +
> + id = args.args_count ? args.args[0] : 0;
> + sensor = thermal_of_get_sensor(args.np, id);
> + if (sensor == NULL) {
> + return -EPROBE_DEFER;
> + }
> +
> + aggr_sensor = kzalloc(sizeof(*aggr_sensor), GFP_KERNEL);
devm_kzalloc
> + aggr_sensor->np = args.np;
Why the 'np' and id are stored, they won't be needed anymore, no ?
> + aggr_sensor->id = id;
> + aggr_sensor->sensor = sensor;
> + list_add(&aggr_sensor->node, &aggr->sensors);
> + }
> +
> + /*tzdev = */devm_thermal_zone_of_sensor_register(dev, 0, aggr, &thermal_aggr_max_ops);
> +
> + return 0;
> +}
> +
> +static int thermal_aggr_remove(struct platform_device *pdev)
> +{
> + return 0;
> +}
> +
> +static const struct of_device_id thermal_aggr_of_match[] = {
> + {
> + .compatible = "generic,thermal-aggregator", "^virtual,.*":
As stated in the documentation
Documentation/devicetree/bindings/vendor-prefixes.yaml
"^virtual,.*":
description: Used for virtual device without specific vendor.
I suggest something like:
.compatible = "virtual,thermal-sensor",
> + },
> + {
> + },
> +};
> +MODULE_DEVICE_TABLE(of, thermal_aggr_of_match);
> +
> +static struct platform_driver thermal_aggr = {
> + .probe = thermal_aggr_probe,
> + .remove = thermal_aggr_remove,
> + .driver = {
> + .name = "thermal-aggregator",
> + .of_match_table = thermal_aggr_of_match,
> + },
> +};
> +
> +module_platform_driver(thermal_aggr);
> +MODULE_AUTHOR("Alexandre Bailon <abailon@...libre.com>");
> +MODULE_DESCRIPTION("Thermal sensor aggregator");
> +MODULE_LICENSE("GPL v2");
>
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