soc/intel/broadwell_de: Implement smbios_cpu_get_maximum_freq_mhz()

Determine maximum speed by looking at either turbo flex limit or
uncore ratio limit.

Signed-off-by: Andrey Petrov <anpetrov@fb.com>
Change-Id: I0f3a64a40cb1d28d8eb9380c2071ec748e345b88
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36284
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>

src/soc/intel/fsp_broadwell_de/cpu.c

@@ -20,6 +20,7 @@
 #include <cpu/cpu.h>
 #include <cpu/intel/microcode.h>
 #include <cpu/intel/smm_reloc.h>
+#include <cpu/intel/turbo.h>
 #include <cpu/x86/cache.h>
 #include <cpu/x86/lapic.h>
 #include <cpu/x86/mp.h>
@@ -27,6 +28,8 @@
 #include <cpu/x86/mtrr.h>
 #include <device/device.h>
 #include <device/pci_ops.h>
+#include <smbios.h>
+#include <soc/broadwell_de.h>
 #include <soc/lpc.h>
 #include <soc/msr.h>
 #include <soc/pattrs.h>
@@ -98,6 +101,25 @@ static void set_max_ratio(void)
 	wrmsr(IA32_PERF_CTL, perf_ctl);
 }
 
+unsigned int smbios_cpu_get_max_speed_mhz(void)
+{
+	msr_t msr;
+	uint32_t uncore_max_ratio, turbo_max_ratio = 0;
+
+	/*
+	 * Use turbo's max ratio if it is enabled, otherwise use
+	 * uncore's max ratio.
+	 */
+	msr = rdmsr(MSR_UNCORE_RATIO_LIMIT);
+	uncore_max_ratio = msr.lo & 0x7f;
+	if (get_turbo_state() == TURBO_ENABLED) {
+		msr = rdmsr(MSR_TURBO_RATIO_LIMIT);
+		turbo_max_ratio = msr.lo & 0xff; /* 1 core */
+	}
+
+	return MAX(uncore_max_ratio, turbo_max_ratio) * CPU_BCLK;
+}
+
 static void alt_smm_lock(void)
 {
 	struct device *dev = pcidev_on_root(LPC_DEV, LPC_FUNC);

src/soc/intel/fsp_broadwell_de/include/soc/msr.h

@@ -23,6 +23,7 @@
 #define MSR_TURBO_RATIO_LIMIT	0x1ad
 #define MSR_PKG_POWER_SKU_UNIT	0x606
 #define MSR_PKG_POWER_LIMIT	0x610
+#define MSR_UNCORE_RATIO_LIMIT	0x620
 #define MSR_CONFIG_TDP_NOMINAL	0x648
 
 #define SMM_MCA_CAP_MSR		0x17d