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References: <20240119110842.772606-1-abailon@baylibre.com> <20240119110842.772606-3-abailon@baylibre.com>
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From: Pin-yen Lin <treapking@chromium.org>
Date: Thu, 11 Apr 2024 16:46:35 -0400
Message-ID: <CAEXTbpeJ=3kxeKy4rXUfNEO==XYQ2DQx+ex2nLNkur_X6p1VVQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/3] thermal: Add support of multi sensors to thermal_core
To: Alexandre Bailon <abailon@baylibre.com>
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>
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Hi Alexandre,

On Thu, Apr 11, 2024 at 4:34=E2=80=AFPM 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           :=3D -I$(src)
>  obj-$(CONFIG_THERMAL)          +=3D thermal_sys.o
>  thermal_sys-y                  +=3D thermal_core.o thermal_sysfs.o
>  thermal_sys-y                  +=3D thermal_trip.o thermal_helpers.o
> +thermal_sys-y                  +=3D thermal_multi.o
>
>  # netlink interface to manage the thermal framework
>  thermal_sys-$(CONFIG_THERMAL_NETLINK)          +=3D thermal_netlink.o
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_cor=
e.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_a=
ttribute *, char *);
>  ssize_t weight_store(struct device *, struct device_attribute *, const c=
har *,
>                      size_t);
>
> +/* Multi sensors */
> +int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offse=
t);
> +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_mu=
lti.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 *te=
mp)
> +{
> +       struct multi_sensor_thermal_zone *multi_tz =3D tz->devdata;
> +       struct sensor_interface *sensor;
> +       int accumulated_temp =3D 0;
> +       u32 accumulated_coeff;

Should we initialize accumulated_coeff to 0 as well?

> +       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 =3D thermal_zone_get_temp(sensor->tz, temp);
> +               if (ret) {
> +                       mutex_unlock(&multi_tz->sensors_lock);
> +                       return ret;
> +               }
> +
> +               accumulated_temp +=3D *temp * sensor->coeff;
> +               accumulated_coeff +=3D sensor->coeff;
> +       }
> +
> +       mutex_unlock(&multi_tz->sensors_lock);
> +
> +       *temp =3D accumulated_temp / accumulated_coeff;
> +       return ret;
> +}
> +
> +struct thermal_zone_device_ops multi_sensor_ops =3D {
> +       .get_temp =3D multi_sensor_get_temp,
> +};
> +
> +int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offse=
t)
> +{
> +       int max_accumulated_temp =3D 0;
> +       int i;
> +
> +       for (i =3D 0; i < count; i++) {
> +               max_accumulated_temp +=3D TJ_MAX * coeff[i];
> +               if (max_accumulated_temp < 0)
> +                       return -EOVERFLOW;
> +       }
> +
> +       max_accumulated_temp +=3D offset;
> +       return max_accumulated_temp < 0 ? -EOVERFLOW : 0;
> +}
> +
> +static struct thermal_zone_device *multi_sensor_tz_alloc(const char *nam=
e)
> +{
> +       struct thermal_zone_device *tz;
> +       struct thermal_zone_params tzp =3D {};
> +       struct multi_sensor_thermal_zone *multi_tz;
> +
> +       tz =3D thermal_zone_get_zone_by_name(name);
> +       if (!IS_ERR(tz)) {
> +               mutex_unlock(&multi_tz_mutex);
> +               return tz;
> +       }
> +
> +       multi_tz =3D 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 =3D true;
> +       tzp.slope =3D 1;
> +       tzp.offset =3D 0;
> +
> +       tz =3D thermal_tripless_zone_device_register(name, multi_tz,
> +                                                  &multi_sensor_ops, &tz=
p);
> +       if (IS_ERR(tz)) {
> +               kfree(multi_tz);
> +       } else {
> +               multi_tz->tz =3D 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 =3D multi_sensor_tz_alloc(name);
> +       if (IS_ERR(tz)) {
> +               mutex_unlock(&multi_tz_mutex);
> +               return PTR_ERR(tz);
> +       }
> +       multi_tz =3D  tz->devdata;
> +
> +       sensor =3D kzalloc(sizeof(*sensor), GFP_KERNEL);
> +       if (!sensor) {
> +               mutex_unlock(&multi_tz_mutex);
> +               return -ENOMEM;
> +       }
> +
> +       sensor->tz =3D sensor_tz;
> +       sensor->coeff =3D 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 =3D=3D 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.

Best regards,
Pin-yen