drivers/hwmon/coretemp.c: get TjMax value from MSR

The MSR IA32_TEMPERATURE_TARGET contains the TjMax value in the newer
Intel processors.

Signed-off-by: Huaxu Wan <huaxu.wan@linux.intel.com>
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Yong Wang <yong.y.wang@linux.intel.com>
Cc: Rudolf Marek <r.marek@assembler.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/msr-index.h

@@ -236,6 +236,8 @@
 
 #define MSR_IA32_MISC_ENABLE		0x000001a0
 
+#define MSR_IA32_TEMPERATURE_TARGET	0x000001a2
+
 /* MISC_ENABLE bits: architectural */
 #define MSR_IA32_MISC_ENABLE_FAST_STRING	(1ULL << 0)
 #define MSR_IA32_MISC_ENABLE_TCC		(1ULL << 1)

drivers/hwmon/coretemp.c

@@ -241,6 +241,55 @@ static int __devinit adjust_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *
 	return tjmax;
 }
 
+static int __devinit get_tjmax(struct cpuinfo_x86 *c, u32 id,
+			       struct device *dev)
+{
+	/* The 100C is default for both mobile and non mobile CPUs */
+	int err;
+	u32 eax, edx;
+	u32 val;
+
+	/* 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);
+	if (err) {
+		dev_warn(dev, "Unable to read TjMax from CPU.\n");
+	} else {
+		val = (eax >> 16) & 0xff;
+		/*
+		 * If the TjMax is not plausible, an assumption
+		 * will be used
+		 */
+		if ((val > 80) && (val < 120)) {
+			dev_info(dev, "TjMax is %d C.\n", val);
+			return val * 1000;
+		}
+	}
+
+	/*
+	 * An assumption is made for early CPUs and unreadable MSR.
+	 * NOTE: the given value may not be correct.
+	 */
+
+	switch (c->x86_model) {
+	case 0xe:
+	case 0xf:
+	case 0x16:
+	case 0x1a:
+		dev_warn(dev, "TjMax is assumed as 100 C!\n");
+		return 100000;
+		break;
+	case 0x17:
+	case 0x1c:		/* Atom CPUs */
+		return adjust_tjmax(c, id, dev);
+		break;
+	default:
+		dev_warn(dev, "CPU (model=0x%x) is not supported yet,"
+			" using default TjMax of 100C.\n", c->x86_model);
+		return 100000;
+	}
+}
+
 static int __devinit coretemp_probe(struct platform_device *pdev)
 {
 	struct coretemp_data *data;
@@ -283,14 +332,18 @@ static int __devinit coretemp_probe(struct platform_device *pdev)
 		}
 	}
 
-	data->tjmax = adjust_tjmax(c, data->id, &pdev->dev);
+	data->tjmax = get_tjmax(c, data->id, &pdev->dev);
 	platform_set_drvdata(pdev, data);
 
-	/* read the still undocumented IA32_TEMPERATURE_TARGET it exists
-	   on older CPUs but not in this register, Atoms don't have it either */
+	/*
+	 * read the still undocumented IA32_TEMPERATURE_TARGET. It exists
+	 * on older CPUs but not in this register,
+	 * Atoms don't have it either.
+	 */
 
 	if ((c->x86_model > 0xe) && (c->x86_model != 0x1c)) {
-		err = rdmsr_safe_on_cpu(data->id, 0x1a2, &eax, &edx);
+		err = rdmsr_safe_on_cpu(data->id, MSR_IA32_TEMPERATURE_TARGET,
+		    &eax, &edx);
 		if (err) {
 			dev_warn(&pdev->dev, "Unable to read"
 					" IA32_TEMPERATURE_TARGET MSR\n");