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Message-ID: <dfb5a14d-bd35-4271-9ded-888eb5c0cff3@baylibre.com>
Date: Thu, 23 May 2024 15:23:59 +0200
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Subject: Re: [PATCH v2 2/3] thermal: Add support of multi sensors to
 thermal_core
To: Pin-yen Lin <treapking@chromium.org>
Cc: rafael@kernel.org, daniel.lezcano@linaro.org, robh+dt@kernel.org,
 krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, rui.zhang@intel.com,
 lukasz.luba@arm.com, linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, Hsin-Te Yuan <yuanhsinte@chromium.org>
References: <20240119110842.772606-1-abailon@baylibre.com>
 <20240119110842.772606-3-abailon@baylibre.com>
 <CAEXTbpeJ=3kxeKy4rXUfNEO==XYQ2DQx+ex2nLNkur_X6p1VVQ@mail.gmail.com>
Content-Language: en-US
From: Alexandre Bailon <abailon@baylibre.com>
In-Reply-To: <CAEXTbpeJ=3kxeKy4rXUfNEO==XYQ2DQx+ex2nLNkur_X6p1VVQ@mail.gmail.com>
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Hi Pin-yen,

> Hi Alexandre,
> 
> On Thu, Apr 11, 2024 at 4:34 PM Alexandre Bailon <abailon@baylibre.com> wrote:
>>
>> This adds support of multi sensors to thermal.
>> Currently, this only support the get_temp operation.
>> This returns an average temperature of all the sensors.
>> If defined, a coefficient is applied to the value read from the sensor
>> before computing the average.
>>
>> Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
>> ---
>>   drivers/thermal/Makefile        |   1 +
>>   drivers/thermal/thermal_core.h  |   7 ++
>>   drivers/thermal/thermal_multi.c | 178 ++++++++++++++++++++++++++++++++
>>   3 files changed, 186 insertions(+)
>>   create mode 100644 drivers/thermal/thermal_multi.c
>>
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index c934cab309ae..757289a406f7 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -6,6 +6,7 @@ CFLAGS_thermal_core.o           := -I$(src)
>>   obj-$(CONFIG_THERMAL)          += thermal_sys.o
>>   thermal_sys-y                  += thermal_core.o thermal_sysfs.o
>>   thermal_sys-y                  += thermal_trip.o thermal_helpers.o
>> +thermal_sys-y                  += thermal_multi.o
>>
>>   # netlink interface to manage the thermal framework
>>   thermal_sys-$(CONFIG_THERMAL_NETLINK)          += thermal_netlink.o
>> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
>> index 0a3b3ec5120b..26e83a5c8298 100644
>> --- a/drivers/thermal/thermal_core.h
>> +++ b/drivers/thermal/thermal_core.h
>> @@ -138,6 +138,13 @@ ssize_t weight_show(struct device *, struct device_attribute *, char *);
>>   ssize_t weight_store(struct device *, struct device_attribute *, const char *,
>>                       size_t);
>>
>> +/* Multi sensors */
>> +int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offset);
>> +int thermal_multi_sensor_register(const char *name,
>> +       struct thermal_zone_device *sensor_tz, int coeff);
>> +void thermal_multi_sensor_unregister(struct thermal_zone_device *sensor_tz);
>> +
>> +
>>   #ifdef CONFIG_THERMAL_STATISTICS
>>   void thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,
>>                                           unsigned long new_state);
>> diff --git a/drivers/thermal/thermal_multi.c b/drivers/thermal/thermal_multi.c
>> new file mode 100644
>> index 000000000000..a5a4f1f2d594
>> --- /dev/null
>> +++ b/drivers/thermal/thermal_multi.c
>> @@ -0,0 +1,178 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include <linux/err.h>
>> +#include <linux/export.h>
>> +#include <linux/of.h>
>> +#include <linux/slab.h>
>> +#include <linux/thermal.h>
>> +#include <linux/types.h>
>> +#include <linux/string.h>
>> +
>> +#include "thermal_core.h"
>> +
>> +struct sensor_interface {
>> +       struct thermal_zone_device *tz;
>> +       int coeff;
>> +
>> +       struct list_head node;
>> +};
>> +
>> +struct multi_sensor_thermal_zone {
>> +       struct thermal_zone_device *tz;
>> +       struct mutex sensors_lock;
>> +       struct list_head sensors;
>> +
>> +       struct list_head node;
>> +};
>> +
>> +static DEFINE_MUTEX(multi_tz_mutex);
>> +static LIST_HEAD(multi_tz_list);
>> +
>> +#define TJ_MAX 120000
>> +
>> +static int multi_sensor_get_temp(struct thermal_zone_device *tz, int *temp)
>> +{
>> +       struct multi_sensor_thermal_zone *multi_tz = tz->devdata;
>> +       struct sensor_interface *sensor;
>> +       int accumulated_temp = 0;
>> +       u32 accumulated_coeff;
> 
> Should we initialize accumulated_coeff to 0 as well?
Yes, indeed, I will fix it.
> 
>> +       int ret;
>> +
>> +       mutex_lock(&multi_tz->sensors_lock);
>> +
>> +       if (list_empty(&multi_tz->sensors)) {
>> +               mutex_unlock(&multi_tz->sensors_lock);
>> +               return -ENODEV;
>> +       }
>> +
>> +       list_for_each_entry(sensor, &multi_tz->sensors, node) {
>> +               ret = thermal_zone_get_temp(sensor->tz, temp);
>> +               if (ret) {
>> +                       mutex_unlock(&multi_tz->sensors_lock);
>> +                       return ret;
>> +               }
>> +
>> +               accumulated_temp += *temp * sensor->coeff;
>> +               accumulated_coeff += sensor->coeff;
>> +       }
>> +
>> +       mutex_unlock(&multi_tz->sensors_lock);
>> +
>> +       *temp = accumulated_temp / accumulated_coeff;
>> +       return ret;
>> +}
>> +
>> +struct thermal_zone_device_ops multi_sensor_ops = {
>> +       .get_temp = multi_sensor_get_temp,
>> +};
>> +
>> +int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offset)
>> +{
>> +       int max_accumulated_temp = 0;
>> +       int i;
>> +
>> +       for (i = 0; i < count; i++) {
>> +               max_accumulated_temp += TJ_MAX * coeff[i];
>> +               if (max_accumulated_temp < 0)
>> +                       return -EOVERFLOW;
>> +       }
>> +
>> +       max_accumulated_temp += offset;
>> +       return max_accumulated_temp < 0 ? -EOVERFLOW : 0;
>> +}
>> +
>> +static struct thermal_zone_device *multi_sensor_tz_alloc(const char *name)
>> +{
>> +       struct thermal_zone_device *tz;
>> +       struct thermal_zone_params tzp = {};
>> +       struct multi_sensor_thermal_zone *multi_tz;
>> +
>> +       tz = thermal_zone_get_zone_by_name(name);
>> +       if (!IS_ERR(tz)) {
>> +               mutex_unlock(&multi_tz_mutex);
>> +               return tz;
>> +       }
>> +
>> +       multi_tz = kzalloc(sizeof(*multi_tz), GFP_KERNEL);
>> +       if (!multi_tz)
>> +               return ERR_PTR(-ENOMEM);
>> +       mutex_init(&multi_tz->sensors_lock);
>> +       INIT_LIST_HEAD(&multi_tz->sensors);
>> +
>> +       tzp.no_hwmon = true;
>> +       tzp.slope = 1;
>> +       tzp.offset = 0;
>> +
>> +       tz = thermal_tripless_zone_device_register(name, multi_tz,
>> +                                                  &multi_sensor_ops, &tzp);
>> +       if (IS_ERR(tz)) {
>> +               kfree(multi_tz);
>> +       } else {
>> +               multi_tz->tz = tz;
>> +               list_add(&multi_tz->node, &multi_tz_list);
>> +       }
>> +
>> +       return tz;
>> +}
>> +
>> +int thermal_multi_sensor_register(const char *name,
>> +       struct thermal_zone_device *sensor_tz, int coeff)
>> +{
>> +       struct thermal_zone_device *tz;
>> +       struct multi_sensor_thermal_zone *multi_tz;
>> +       struct sensor_interface *sensor;
>> +
>> +       mutex_lock(&multi_tz_mutex);
>> +
>> +       tz = multi_sensor_tz_alloc(name);
>> +       if (IS_ERR(tz)) {
>> +               mutex_unlock(&multi_tz_mutex);
>> +               return PTR_ERR(tz);
>> +       }
>> +       multi_tz =  tz->devdata;
>> +
>> +       sensor = kzalloc(sizeof(*sensor), GFP_KERNEL);
>> +       if (!sensor) {
>> +               mutex_unlock(&multi_tz_mutex);
>> +               return -ENOMEM;
>> +       }
>> +
>> +       sensor->tz = sensor_tz;
>> +       sensor->coeff = coeff;
>> +       mutex_lock(&multi_tz->sensors_lock);
>> +       list_add(&sensor->node, &multi_tz->sensors);
>> +       mutex_unlock(&multi_tz->sensors_lock);
>> +
>> +       thermal_zone_device_enable(tz);
>> +
>> +       mutex_unlock(&multi_tz_mutex);
>> +
>> +       return 0;
>> +}
>> +
>> +void thermal_multi_sensor_unregister(struct thermal_zone_device *sensor_tz)
>> +{
>> +       struct multi_sensor_thermal_zone *multi_tz;
>> +       struct sensor_interface *sensor, *tmp;
>> +
>> +       mutex_lock(&multi_tz_mutex);
>> +       list_for_each_entry(multi_tz, &multi_tz_list, node) {
>> +               mutex_lock(&multi_tz->sensors_lock);
>> +               list_for_each_entry_safe(sensor, tmp, &multi_tz->sensors, node) {
>> +                       if (sensor->tz == sensor_tz) {
>> +                               list_del(&sensor->node);
>> +                               kfree(sensor);
>> +                               break;
>> +                       }
>> +               }
>> +
>> +               if (list_empty(&multi_tz->sensors)) {
>> +                       thermal_zone_device_unregister(multi_tz->tz);
>> +                       mutex_unlock(&multi_tz->sensors_lock);
>> +                       kfree(multi_tz);
>> +               } else {
>> +                       mutex_unlock(&multi_tz->sensors_lock);
>> +               }
>> +       }
>> +       mutex_unlock(&multi_tz_mutex);
>> +}
>> --
>> 2.41.0
>>
> 
> By the way, may I know why min/max aggregation is dropped in this
> version? I thought that checking max temperature is the most direct
> approach to protect the hardware and the users from high temperature.
You are right. The main reason was device tree bindings.
I was expecting getting this accepted first before adding max and min.

Thanks,
Alexandre
> 
> Best regards,
> Pin-yen