hwmon: (coretemp) Add support for dynamic ttarget

Tjmax value retrieved from MSR_IA32_TEMPERATURE_TARGET can be changed at
runtime when the Intel SST-PP (Intel Speed Select Technology -
Performance Profile) level is changed. As a result, the ttarget value
also becomes dyamic.

Improve the code to always get updated ttarget value.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20221113153145.32696-4-rui.zhang@intel.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index 5e03cfb..ca7a9b3 100644 (file)
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -69,7 +69,6 @@ MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");
  */
 struct temp_data {
        int temp;
-       int ttarget;
        int tjmax;
        unsigned long last_updated;
        unsigned int cpu;
@@ -306,6 +305,30 @@ static int get_tjmax(struct temp_data *tdata, struct device *dev)
        return tdata->tjmax;
 }
 
+static int get_ttarget(struct temp_data *tdata, struct device *dev)
+{
+       u32 eax, edx;
+       int tjmax, ttarget_offset, ret;
+
+       /*
+        * ttarget is valid only if tjmax can be retrieved from
+        * MSR_IA32_TEMPERATURE_TARGET
+        */
+       if (tdata->tjmax)
+               return -ENODEV;
+
+       ret = rdmsr_safe_on_cpu(tdata->cpu, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
+       if (ret)
+               return ret;
+
+       tjmax = (eax >> 16) & 0xff;
+
+       /* Read the still undocumented bits 8:15 of IA32_TEMPERATURE_TARGET. */
+       ttarget_offset = (eax >> 8) & 0xff;
+
+       return (tjmax - ttarget_offset) * 1000;
+}
+
 /* Keep track of how many zone pointers we allocated in init() */
 static int max_zones __read_mostly;
 /* Array of zone pointers. Serialized by cpu hotplug lock */
@@ -359,8 +382,16 @@ static ssize_t show_ttarget(struct device *dev,
 {
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct platform_data *pdata = dev_get_drvdata(dev);
+       struct temp_data *tdata = pdata->core_data[attr->index];
+       int ttarget;
 
-       return sprintf(buf, "%d\n", pdata->core_data[attr->index]->ttarget);
+       mutex_lock(&tdata->update_lock);
+       ttarget = get_ttarget(tdata, dev);
+       mutex_unlock(&tdata->update_lock);
+
+       if (ttarget < 0)
+               return ttarget;
+       return sprintf(buf, "%d\n", ttarget);
 }
 
 static ssize_t show_temp(struct device *dev,
@@ -469,7 +500,7 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
        struct platform_data *pdata = platform_get_drvdata(pdev);
        struct cpuinfo_x86 *c = &cpu_data(cpu);
        u32 eax, edx;
-       int err, index, attr_no, tjmax;
+       int err, index, attr_no;
 
        /*
         * Find attr number for sysfs:
@@ -503,23 +534,17 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
        if (err)
                goto exit_free;
 
-       /* We can access status register. Get Critical Temperature */
-       tjmax = get_tjmax(tdata, &pdev->dev);
+       /* Make sure tdata->tjmax is a valid indicator for dynamic/static tjmax */
+       get_tjmax(tdata, &pdev->dev);
 
        /*
-        * Read the still undocumented bits 8:15 of IA32_TEMPERATURE_TARGET.
-        * The target temperature is available on older CPUs but not in this
-        * register. Atoms don't have the register at all.
+        * The target temperature is available on older CPUs but not in the
+        * MSR_IA32_TEMPERATURE_TARGET register. Atoms don't have the register
+        * at all.
         */
-       if (c->x86_model > 0xe && c->x86_model != 0x1c) {
-               err = rdmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET,
-                                       &eax, &edx);
-               if (!err) {
-                       tdata->ttarget
-                         = tjmax - ((eax >> 8) & 0xff) * 1000;
+       if (c->x86_model > 0xe && c->x86_model != 0x1c)
+               if (get_ttarget(tdata, &pdev->dev) >= 0)
                        tdata->attr_size++;
-               }
-       }
 
        pdata->core_data[attr_no] = tdata;