ACPI: thermal: Support for linking devices associated with the thermal zone

As ACPI spec said, '_TZD' evaluates to a package of device names.
Each name corresponds to a device in the ACPI namespace that is
associated with the thermal zone. The temperature reported by the
thermal zone is roughly correspondent to that of each of the devices.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
---
 drivers/acpi/thermal.c | 114 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 113 insertions(+), 1 deletion(-)

On Tue, Nov 12, 2024 at 3:14 AM Huisong Li <lihuisong@huawei.com> wrote:
>
> As ACPI spec said, '_TZD' evaluates to a package of device names.
> Each name corresponds to a device in the ACPI namespace that is
> associated with the thermal zone. The temperature reported by the
> thermal zone is roughly correspondent to that of each of the devices.
>
> Signed-off-by: Huisong Li <lihuisong@huawei.com>

You need to say in the changelog why exposing this information is
needed and how it is going to be used by its consumers.

Thanks!

> ---
>  drivers/acpi/thermal.c | 114 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 113 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
> index 78db38c7076e..398195a5d42f 100644
> --- a/drivers/acpi/thermal.c
> +++ b/drivers/acpi/thermal.c
> @@ -119,6 +119,9 @@ struct acpi_thermal {
>         struct work_struct thermal_check_work;
>         struct mutex thermal_check_lock;
>         refcount_t thermal_check_count;
> +       int num_domain_devices;
> +       struct acpi_device **domain_devices;
> +       struct kobject *holders_dir;
>  };
>
>  /* --------------------------------------------------------------------------
> @@ -589,6 +592,103 @@ static const struct thermal_zone_device_ops acpi_thermal_zone_ops = {
>         .critical = acpi_thermal_zone_device_critical,
>  };
>
> +static void acpi_thermal_remove_domain_devices(struct acpi_thermal *tz)
> +{
> +       int i;
> +
> +       if (!tz->num_domain_devices)
> +               return;
> +
> +       for (i = 0; i < tz->num_domain_devices; i++) {
> +               struct acpi_device *obj = tz->domain_devices[i];
> +
> +               if (!obj)
> +                       continue;
> +
> +               sysfs_remove_link(tz->holders_dir,
> +                                 kobject_name(&obj->dev.kobj));
> +               acpi_dev_put(obj);
> +       }
> +
> +       kfree(tz->domain_devices);
> +       kobject_put(tz->holders_dir);
> +       tz->num_domain_devices = 0;
> +}
> +
> +static int acpi_thermal_read_domain_devices(struct acpi_thermal *tz)
> +{
> +       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +       union acpi_object *pss;
> +       acpi_status status;
> +       int ret = 0;
> +       int i;
> +
> +       status = acpi_evaluate_object(tz->device->handle, "_TZD", NULL,
> +                                     &buffer);
> +       if (ACPI_FAILURE(status)) {
> +               acpi_evaluation_failure_warn(tz->device->handle, "_TZD",
> +                                            status);
> +               return -ENODEV;
> +       }
> +
> +       pss = buffer.pointer;
> +       if (!pss ||
> +           pss->type != ACPI_TYPE_PACKAGE) {
> +               dev_err(&tz->device->dev, "Thermal zone invalid _TZD data\n");
> +               ret = -EFAULT;
> +               goto end;
> +       }
> +
> +       if (!pss->package.count)
> +               goto end;
> +
> +       tz->domain_devices = kcalloc(pss->package.count,
> +                                    sizeof(struct acpi_device *), GFP_KERNEL);
> +       if (!tz->domain_devices) {
> +               ret = -ENOMEM;
> +               goto end;
> +       }
> +
> +       tz->holders_dir = kobject_create_and_add("measures",
> +                                                &tz->device->dev.kobj);
> +       if (!tz->holders_dir) {
> +               ret = -ENOMEM;
> +               goto exit_free;
> +       }
> +
> +       tz->num_domain_devices = pss->package.count;
> +       for (i = 0; i < pss->package.count; i++) {
> +               struct acpi_device *obj;
> +               union acpi_object *element = &pss->package.elements[i];
> +
> +               /* Refuse non-references */
> +               if (element->type != ACPI_TYPE_LOCAL_REFERENCE)
> +                       continue;
> +
> +               /* Create a symlink to domain objects */
> +               obj = acpi_get_acpi_dev(element->reference.handle);
> +               tz->domain_devices[i] = obj;
> +               if (!obj)
> +                       continue;
> +
> +               ret = sysfs_create_link(tz->holders_dir, &obj->dev.kobj,
> +                                       kobject_name(&obj->dev.kobj));
> +               if (ret) {
> +                       acpi_dev_put(obj);
> +                       tz->domain_devices[i] = NULL;
> +               }
> +       }
> +
> +       ret = 0;
> +       goto end;
> +
> +exit_free:
> +       kfree(tz->domain_devices);
> +end:
> +       kfree(buffer.pointer);
> +       return ret;
> +}
> +
>  static int acpi_thermal_zone_sysfs_add(struct acpi_thermal *tz)
>  {
>         struct device *tzdev = thermal_zone_device(tz->thermal_zone);
> @@ -602,8 +702,19 @@ static int acpi_thermal_zone_sysfs_add(struct acpi_thermal *tz)
>         ret = sysfs_create_link(&tzdev->kobj,
>                                    &tz->device->dev.kobj, "device");
>         if (ret)
> -               sysfs_remove_link(&tz->device->dev.kobj, "thermal_zone");
> +               goto remove_thermal_zone;
>
> +       /* _TZD method is optional. */
> +       ret = acpi_thermal_read_domain_devices(tz);
> +       if (ret != -ENODEV)
> +               goto remove_device;
> +
> +       return 0;
> +
> +remove_device:
> +       sysfs_remove_link(&tz->device->dev.kobj, "device");
> +remove_thermal_zone:
> +       sysfs_remove_link(&tz->device->dev.kobj, "thermal_zone");
>         return ret;
>  }
>
> @@ -611,6 +722,7 @@ static void acpi_thermal_zone_sysfs_remove(struct acpi_thermal *tz)
>  {
>         struct device *tzdev = thermal_zone_device(tz->thermal_zone);
>
> +       acpi_thermal_remove_domain_devices(tz);
>         sysfs_remove_link(&tz->device->dev.kobj, "thermal_zone");
>         sysfs_remove_link(&tzdev->kobj, "device");
>  }
> --
> 2.22.0
>