linux-kernel - Re: [PATCH v2 2/2] thermal: intel: int340x: Allow temperature override

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Message-ID: <0c415d9c5331c505d81072359a8421a84fc5fa4d.camel@intel.com>
Date: Mon, 16 Jun 2025 01:03:56 +0000
From: "Zhang, Rui" <rui.zhang@...el.com>
To: "srinivas.pandruvada@...ux.intel.com"
	<srinivas.pandruvada@...ux.intel.com>, "lukasz.luba@....com"
	<lukasz.luba@....com>, "rafael@...nel.org" <rafael@...nel.org>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>
CC: "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] thermal: intel: int340x: Allow temperature
 override

On Fri, 2025-06-13 at 14:49 -0700, Srinivas Pandruvada wrote:
> Add debugfs interface to override hardware provide temperature. This
> interface can be used primarily for debug. Alternatively this can
> be also used to use hardware control loops to manage temperature for
> virtual sensors. Virtual sensors are soft sensors created by kernel/
> user space aggregating other sensors.
> 
> There are three attributes to override the maximum three instances of
> platform temperature control.
> /sys/kernel/debug/platform_temperature_control/
> ├── temperature_0
> ├── temperature_1
> └── temperature_2
> 
> These are write only attributes requires admin privilege. Any value
> greater than 0, will override the temperature. A value of 0 will
> stop overriding the temperature.
> 
> Signed-off-by: Srinivas Pandruvada
> <srinivas.pandruvada@...ux.intel.com>

LGTM.

Reviewed-by: Zhang Rui <rui.zhang@...el.com>

-rui
> ---
> v2:
> - correct platform spelling
> - Move the ptc_create_debugfs under PROC_THERMAL_FEATURE_PTC mask
> 
>  .../platform_temperature_control.c            | 64 +++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git
> a/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
> b/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
> index 7850e91a6e2c..0ccc72c93499 100644
> ---
> a/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
> +++
> b/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
> @@ -38,6 +38,7 @@
>  
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/debugfs.h>
>  #include <linux/pci.h>
>  #include "processor_thermal_device.h"
>  
> @@ -53,6 +54,7 @@ struct mmio_reg {
>  
>  struct ptc_data {
>  	u32 offset;
> +	struct pci_dev *pdev;
>  	struct attribute_group ptc_attr_group;
>  	struct attribute *ptc_attrs[PTC_MAX_ATTRS];
>  	struct device_attribute temperature_target_attr;
> @@ -215,6 +217,63 @@ static int ptc_create_groups(struct pci_dev *pdev,
> int instance, struct ptc_data
>  }
>  
>  static struct ptc_data ptc_instance[PTC_MAX_INSTANCES];
> +static struct dentry *ptc_debugfs;
> +
> +#define PTC_TEMP_OVERRIDE_ENABLE_INDEX	4
> +#define PTC_TEMP_OVERRIDE_INDEX		5
> +
> +static ssize_t ptc_temperature_write(struct file *file, const char
> __user *data,
> +				     size_t count, loff_t *ppos)
> +{
> +	struct ptc_data *ptc_instance = file->private_data;
> +	struct pci_dev *pdev = ptc_instance->pdev;
> +	char buf[32];
> +	ssize_t len;
> +	u32 value;
> +
> +	len = min(count, sizeof(buf) - 1);
> +	if (copy_from_user(buf, data, len))
> +		return -EFAULT;
> +
> +	buf[len] = '\0';
> +	if (kstrtouint(buf, 0, &value))
> +		return -EINVAL;
> +
> +	if (ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].units)
> +		value /= ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].units;
> +
> +	if (value > ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].mask)
> +		return -EINVAL;
> +
> +	if (!value) {
> +		ptc_mmio_write(pdev, ptc_instance->offset,
> PTC_TEMP_OVERRIDE_ENABLE_INDEX, 0);
> +	} else {
> +		ptc_mmio_write(pdev, ptc_instance->offset,
> PTC_TEMP_OVERRIDE_INDEX, value);
> +		ptc_mmio_write(pdev, ptc_instance->offset,
> PTC_TEMP_OVERRIDE_ENABLE_INDEX, 1);
> +	}
> +
> +	return count;
> +}
> +
> +static const struct file_operations ptc_fops = {
> +	.open = simple_open,
> +	.write = ptc_temperature_write,
> +	.llseek = generic_file_llseek,
> +};
> +
> +static void ptc_create_debugfs(void)
> +{
> +	ptc_debugfs =
> debugfs_create_dir("platform_temperature_control", NULL);
> +
> +	debugfs_create_file("temperature_0",  0200, ptc_debugfs, 
> &ptc_instance[0], &ptc_fops);
> +	debugfs_create_file("temperature_1",  0200, ptc_debugfs, 
> &ptc_instance[1], &ptc_fops);
> +	debugfs_create_file("temperature_2",  0200, ptc_debugfs, 
> &ptc_instance[2], &ptc_fops);
> +}
> +
> +static void ptc_delete_debugfs(void)
> +{
> +	debugfs_remove_recursive(ptc_debugfs);
> +}
>  
>  int proc_thermal_ptc_add(struct pci_dev *pdev, struct
> proc_thermal_device *proc_priv)
>  {
> @@ -223,8 +282,11 @@ int proc_thermal_ptc_add(struct pci_dev *pdev,
> struct proc_thermal_device *proc_
>  
>  		for (i = 0; i < PTC_MAX_INSTANCES; i++) {
>  			ptc_instance[i].offset = ptc_offsets[i];
> +			ptc_instance[i].pdev = pdev;
>  			ptc_create_groups(pdev, i, &ptc_instance[i]);
>  		}
> +
> +		ptc_create_debugfs();
>  	}
>  
>  	return 0;
> @@ -240,6 +302,8 @@ void proc_thermal_ptc_remove(struct pci_dev *pdev)
>  
>  		for (i = 0; i < PTC_MAX_INSTANCES; i++)
>  			sysfs_remove_group(&pdev->dev.kobj,
> &ptc_instance[i].ptc_attr_group);
> +
> +		ptc_delete_debugfs();
>  	}
>  }
>  EXPORT_SYMBOL_GPL(proc_thermal_ptc_remove);