hwmon: (coretemp) Add support for dynamic tjmax

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.

Improve the code to always use updated tjmax when it can be retrieved
from MSR_IA32_TEMPERATURE_TARGET.

When tjmax can not be retrieved from MSR_IA32_TEMPERATURE_TARGET, still
follow the previous logic and always use a static tjmax value.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20221113153145.32696-3-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 6b6ee56..5e03cfb 100644 (file)
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -55,6 +55,8 @@ MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");
 
 /*
  * Per-Core Temperature Data
+ * @tjmax: The static tjmax value when tjmax cannot be retrieved from
+ *             IA32_TEMPERATURE_TARGET MSR.
  * @last_updated: The time when the current temperature value was updated
  *             earlier (in jiffies).
  * @cpu_core_id: The CPU Core from which temperature values should be read
@@ -259,20 +261,25 @@ static bool cpu_has_tjmax(struct cpuinfo_x86 *c)
               model != 0x36;
 }
 
-static int get_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *dev)
+static int get_tjmax(struct temp_data *tdata, struct device *dev)
 {
+       struct cpuinfo_x86 *c = &cpu_data(tdata->cpu);
        int err;
        u32 eax, edx;
        u32 val;
 
+       /* use static tjmax once it is set */
+       if (tdata->tjmax)
+               return tdata->tjmax;
+
        /*
         * A new feature of current Intel(R) processors, the
         * IA32_TEMPERATURE_TARGET contains the TjMax value
         */
-       err = rdmsr_safe_on_cpu(id, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
+       err = rdmsr_safe_on_cpu(tdata->cpu, MSR_IA32_TEMPERATURE_TARGET, &eax, &edx);
        if (err) {
                if (cpu_has_tjmax(c))
-                       dev_warn(dev, "Unable to read TjMax from CPU %u\n", id);
+                       dev_warn(dev, "Unable to read TjMax from CPU %u\n", tdata->cpu);
        } else {
                val = (eax >> 16) & 0xff;
                /*
@@ -288,14 +295,15 @@ static int get_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *dev)
        if (force_tjmax) {
                dev_notice(dev, "TjMax forced to %d degrees C by user\n",
                           force_tjmax);
-               return force_tjmax * 1000;
+               tdata->tjmax = force_tjmax * 1000;
+       } else {
+               /*
+                * An assumption is made for early CPUs and unreadable MSR.
+                * NOTE: the calculated value may not be correct.
+                */
+               tdata->tjmax = adjust_tjmax(c, tdata->cpu, dev);
        }
-
-       /*
-        * An assumption is made for early CPUs and unreadable MSR.
-        * NOTE: the calculated value may not be correct.
-        */
-       return adjust_tjmax(c, id, dev);
+       return tdata->tjmax;
 }
 
 /* Keep track of how many zone pointers we allocated in init() */
@@ -336,8 +344,14 @@ static ssize_t show_tjmax(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 tjmax;
+
+       mutex_lock(&tdata->update_lock);
+       tjmax = get_tjmax(tdata, dev);
+       mutex_unlock(&tdata->update_lock);
 
-       return sprintf(buf, "%d\n", pdata->core_data[attr->index]->tjmax);
+       return sprintf(buf, "%d\n", tjmax);
 }
 
 static ssize_t show_ttarget(struct device *dev,
@@ -356,9 +370,11 @@ static ssize_t show_temp(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 tjmax;
 
        mutex_lock(&tdata->update_lock);
 
+       tjmax = get_tjmax(tdata, dev);
        /* Check whether the time interval has elapsed */
        if (time_after(jiffies, tdata->last_updated + HZ)) {
                rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);
@@ -368,7 +384,7 @@ static ssize_t show_temp(struct device *dev,
                 * Return it instead of reporting an error which doesn't
                 * really help at all.
                 */
-               tdata->temp = tdata->tjmax - ((eax >> 16) & 0x7f) * 1000;
+               tdata->temp = tjmax - ((eax >> 16) & 0x7f) * 1000;
                tdata->last_updated = jiffies;
        }
 
@@ -453,7 +469,7 @@ 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;
+       int err, index, attr_no, tjmax;
 
        /*
         * Find attr number for sysfs:
@@ -488,7 +504,7 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
                goto exit_free;
 
        /* We can access status register. Get Critical Temperature */
-       tdata->tjmax = get_tjmax(c, cpu, &pdev->dev);
+       tjmax = get_tjmax(tdata, &pdev->dev);
 
        /*
         * Read the still undocumented bits 8:15 of IA32_TEMPERATURE_TARGET.
@@ -500,7 +516,7 @@ static int create_core_data(struct platform_device *pdev, unsigned int cpu,
                                        &eax, &edx);
                if (!err) {
                        tdata->ttarget
-                         = tdata->tjmax - ((eax >> 8) & 0xff) * 1000;
+                         = tjmax - ((eax >> 8) & 0xff) * 1000;
                        tdata->attr_size++;
                }
        }