cpu/intel/model_1067x: enable PECI

This is required for Super I/Os to be able to read the CPU temperature
through PECI.

On 45nm Core 2 CPUs (Wolfdale, Yorkfield) it is not enabled by default.
This is probably related to erratum AW67 "Enabling PECI via the PECI_CTL
MSR incorrectly writes CPUID_FEATURE_MASK1 MSR". The suggested
workaround is "Do not initialize PECI before processor update is
loaded". Since coreboot performs microcode updates before running this
code it should not cause any trouble. It was tested on a Core 2 Duo
E8400, stepping E0.

PECI is already enabled by default on older (65nm) CPUs. Tested: Pentium
Dual-Core E2160.

See commit edac28ce65 for the same change
on cpu/intel/model_6fx.

Signed-off-by: Michael Büchler <michael.buechler@posteo.net>
Change-Id: I5a3ec033bd816665af4ecc82f7b167857cd7c1b6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45184
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/cpu/intel/model_1067x/model_1067x_init.c

@@ -166,6 +166,8 @@ static void configure_emttm_tables(void)
 	wrmsr(MSR_EMTTM_CR_TABLE(5), msr);
 }
 
+#define IA32_PECI_CTL		0x5a0
+
 static void configure_misc(const int eist, const int tm2, const int emttm)
 {
 	msr_t msr;
@@ -208,6 +210,13 @@ static void configure_misc(const int eist, const int tm2, const int emttm)
 		msr.lo |= (1 << 20);	/* Lock Enhanced SpeedStep Enable */
 		wrmsr(IA32_MISC_ENABLE, msr);
 	}
+
+	/* Enable PECI
+	   WARNING: due to Erratum AW67 described in Intel document #318733
+	   the microcode must be updated before this MSR is written to. */
+	msr = rdmsr(IA32_PECI_CTL);
+	msr.lo |= 1;
+	wrmsr(IA32_PECI_CTL, msr);
 }
 
 #define PIC_SENS_CFG	0x1aa