hwmon: (coretemp) Let the user force TjMax
On old CPUs (and even some recent Atom CPUs) TjMax can't be read from
the CPU registers, so it is guessed by the driver using a complex
heuristic which isn't reliable. So let users who know their CPU's
TjMax pass it as a module parameter.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "R, Durgadoss" <durgadoss.r@intel.com>
Cc: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index 256f708..5a41e9d 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -36,11 +36,20 @@
#include <linux/cpu.h>
#include <linux/pci.h>
#include <linux/smp.h>
+#include <linux/moduleparam.h>
#include <asm/msr.h>
#include <asm/processor.h>
#define DRVNAME "coretemp"
+/*
+ * force_tjmax only matters when TjMax can't be read from the CPU itself.
+ * When set, it replaces the driver's suboptimal heuristic.
+ */
+static int force_tjmax;
+module_param_named(tjmax, force_tjmax, int, 0444);
+MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");
+
#define BASE_SYSFS_ATTR_NO 2 /* Sysfs Base attr no for coretemp */
#define NUM_REAL_CORES 16 /* Number of Real cores per cpu */
#define CORETEMP_NAME_LENGTH 17 /* String Length of attrs */
@@ -398,6 +407,12 @@
}
}
+ if (force_tjmax) {
+ dev_notice(dev, "TjMax forced to %d degrees C by user\n",
+ force_tjmax);
+ return force_tjmax * 1000;
+ }
+
/*
* An assumption is made for early CPUs and unreadable MSR.
* NOTE: the calculated value may not be correct.