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Message-ID: <CAJZ5v0jTMg=Wipt2VPU1DDnnO7Rh5pu0VYvUjHRW5Nada--O8A@mail.gmail.com>
Date: Wed, 13 Nov 2024 10:26:48 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Huisong Li <lihuisong@...wei.com>
Cc: linux-pm@...r.kernel.org, linux-acpi@...r.kernel.org, rafael@...nel.org,
linux-kernel@...r.kernel.org, rui.zhang@...el.com, liuyonglong@...wei.com,
zhanjie9@...ilicon.com, zhenglifeng1@...wei.com
Subject: Re: [PATCH v2] ACPI: thermal: Support for linking devices associated
with the thermal zone
On Wed, Nov 13, 2024 at 10:07 AM Huisong Li <lihuisong@...wei.com> wrote:
>
> There are many 'cdevX' files which link cooling devices under
> '/sys/class/thermal/thermal_zoneX/'. These devices contain active cooling
> devices and passive cooling devices. And user cann't directly know which
> devices temperature is represented by the thermal zone.
>
> However, ACPI spec provides a '_TZD' object which 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.
>
> User can get all devices a thermal zone measured by the 'measures'
> directory under the thermal zone device.
Well, that's kind of clear, but what exactly is the use case? Why
does the user need to know that?
> Signed-off-by: Huisong Li <lihuisong@...wei.com>
> ---
> v2: fix commitlog based on Rafael's comment.
> ---
> 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
>
>
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