2 files changed, 43 insertions, 12 deletions

diff --git a/Documentation/hwmon/k10temp b/Documentation/hwmon/k10temp
index a7a18d453a51..6526eee525a6 100644
--- a/Documentation/hwmon/k10temp
+++ b/Documentation/hwmon/k10temp
@@ -3,8 +3,8 @@ Kernel driver k10temp
 
 Supported chips:
 * AMD Family 10h processors:
-  Socket F: Quad-Core/Six-Core/Embedded Opteron
-  Socket AM2+: Opteron, Phenom (II) X3/X4
+  Socket F: Quad-Core/Six-Core/Embedded Opteron (but see below)
+  Socket AM2+: Quad-Core Opteron, Phenom (II) X3/X4, Athlon X2 (but see below)
   Socket AM3: Quad-Core Opteron, Athlon/Phenom II X2/X3/X4, Sempron II
   Socket S1G3: Athlon II, Sempron, Turion II
 * AMD Family 11h processors:
@@ -36,10 +36,15 @@ Description
 This driver permits reading of the internal temperature sensor of AMD
 Family 10h and 11h processors.
 
-All these processors have a sensor, but on older revisions of Family 10h
-processors, the sensor may return inconsistent values (erratum 319). The
-driver will refuse to load on these revisions unless you specify the
-"force=1" module parameter.
+All these processors have a sensor, but on those for Socket F or AM2+,
+the sensor may return inconsistent values (erratum 319).  The driver
+will refuse to load on these revisions unless you specify the "force=1"
+module parameter.
+
+Due to technical reasons, the driver can detect only the mainboard's
+socket type, not the processor's actual capabilities.  Therefore, if you
+are using an AM3 processor on an AM2+ mainboard, you can safely use the
+"force=1" parameter.
 
 There is one temperature measurement value, available as temp1_input in
 sysfs. It is measured in degrees Celsius with a resolution of 1/8th degree.
diff --git a/drivers/hwmon/k10temp.c b/drivers/hwmon/k10temp.c
index d8a26d16d948..4c9d349b3ad9 100644
--- a/drivers/hwmon/k10temp.c
+++ b/drivers/hwmon/k10temp.c
@@ -33,6 +33,16 @@ static bool force;
 module_param(force, bool, 0444);
 MODULE_PARM_DESC(force, "force loading on processors with erratum 319");
 
+/* CPUID function 0x80000001, ebx */
+#define CPUID_PKGTYPE_MASK      0xf0000000
+#define CPUID_PKGTYPE_F         0x00000000
+#define CPUID_PKGTYPE_AM2R2_AM3 0x10000000
+
+/* DRAM controller (PCI function 2) */
+#define REG_DCT0_CONFIG_HIGH            0x094
+#define  DDR3_MODE                      0x00000100
+
+/* miscellaneous (PCI function 3) */
 #define REG_HARDWARE_THERMAL_CONTROL    0x64
 #define  HTC_ENABLE                     0x00000001
 
@@ -85,13 +95,28 @@ static SENSOR_DEVICE_ATTR(temp1_crit, S_IRUGO, show_temp_crit, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IRUGO, show_temp_crit, NULL, 1);
 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 
-static bool __devinit has_erratum_319(void)
+static bool __devinit has_erratum_319(struct pci_dev *pdev)
 {
+        u32 pkg_type, reg_dram_cfg;
+
+        if (boot_cpu_data.x86 != 0x10)
+                return false;
+
         /*
-         * Erratum 319: The thermal sensor of older Family 10h processors
-         *              (B steppings) may be unreliable.
+         * Erratum 319: The thermal sensor of Socket F/AM2+ processors
+         *              may be unreliable.
          */
-        return boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model <= 2;
+        pkg_type = cpuid_ebx(0x80000001) & CPUID_PKGTYPE_MASK;
+        if (pkg_type == CPUID_PKGTYPE_F)
+                return true;
+        if (pkg_type != CPUID_PKGTYPE_AM2R2_AM3)
+                return false;
+
+        /* Differentiate between AM2+ (bad) and AM3 (good) */
+        pci_bus_read_config_dword(pdev->bus,
+                                  PCI_DEVFN(PCI_SLOT(pdev->devfn), 2),
+                                  REG_DCT0_CONFIG_HIGH, &reg_dram_cfg);
+        return !(reg_dram_cfg & DDR3_MODE);
 }
 
 static int __devinit k10temp_probe(struct pci_dev *pdev,
@@ -99,9 +124,10 @@ static int __devinit k10temp_probe(struct pci_dev *pdev,
 {
         struct device *hwmon_dev;
         u32 reg_caps, reg_htc;
+        int unreliable = has_erratum_319(pdev);
         int err;
 
-        if (has_erratum_319() && !force) {
+        if (unreliable && !force) {
                 dev_err(&pdev->dev,
                         "unreliable CPU thermal sensor; monitoring disabled\n");
                 err = -ENODEV;
@@ -139,7 +165,7 @@ static int __devinit k10temp_probe(struct pci_dev *pdev,
         }
         dev_set_drvdata(&pdev->dev, hwmon_dev);
 
-        if (has_erratum_319() && force)
+        if (unreliable && force)
                 dev_warn(&pdev->dev,
                          "unreliable CPU thermal sensor; check erratum 319\n");
         return 0;