[coreboot-gerrit] Change in coreboot[master]: soc/intel/cannonlake: Add chip config to override CPU flex ratio

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/36864 )

Change subject: soc/intel/cannonlake: Add chip config to override CPU flex ratio
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soc/intel/cannonlake: Add chip config to override CPU flex ratio

This patch provides options to override descriptor default CPU flex
ratio from coreboot code. cpu_ratio_override to provide the required CPU
ratio.

Note: Don't override the flex ratio if cpu_ratio is 0.

BUG=b:142264107
TEST=Without override flex_ratio is 0 and verified booting to
OS after overriding with flex_ratio value 5.

Change-Id: Ib01650f52f3d402f669e7e7f5b28a648b86f08ec
Signed-off-by: Subrata Banik 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36864
Tested-by: build bot (Jenkins) 
Reviewed-by: Tim Wawrzynczak 
---
M src/soc/intel/cannonlake/chip.h
M src/soc/intel/cannonlake/romstage/fsp_params.c
2 files changed, 21 insertions(+), 4 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Tim Wawrzynczak: Looks good to me, approved

diff --git a/src/soc/intel/cannonlake/chip.h b/src/soc/intel/cannonlake/chip.h
index 17afdd1..507290f 100644
--- a/src/soc/intel/cannonlake/chip.h
+++ b/src/soc/intel/cannonlake/chip.h
@@ -424,6 +424,19 @@
     * Bit 0: MISCCFG_GPDLCGEN
     */
    uint8_t gpio_pm[TOTAL_GPIO_COMM];
+
+	/*
+	 * Override CPU flex ratio value:
+	 * CPU ratio value controls the maximum processor non-turbo ratio.
+	 * Valid Range 0 to 63.
+	 *
+	 * In general descriptor provides option to set default cpu flex ratio.
+	 * Default cpu flex ratio is 0 ensures booting with non-turbo max frequency.
+	 * Thats the reason FSP skips cpu_ratio override if cpu_ratio is 0.
+	 *
+	 * Only override CPU flex ratio if don't want to boot with non-turbo max.
+	 */
+	uint8_t cpu_ratio_override;
 };

typedef struct soc_intel_cannonlake_config config_t;
diff --git a/src/soc/intel/cannonlake/romstage/fsp_params.c b/src/soc/intel/cannonlake/romstage/fsp_params.c
index 996c135..5c74d4a 100644
--- a/src/soc/intel/cannonlake/romstage/fsp_params.c
+++ b/src/soc/intel/cannonlake/romstage/fsp_params.c
@@ -74,10 +74,14 @@
    m_cfg->SkipMpInit = !CONFIG_USE_INTEL_FSP_MP_INIT;
 #endif

-	/* Set CpuRatio to match existing MSR value */
-	msr_t flex_ratio;
-	flex_ratio = rdmsr(MSR_FLEX_RATIO);
-	m_cfg->CpuRatio = (flex_ratio.lo >> 8) & 0xff;
+	if (config->cpu_ratio_override) {
+		m_cfg->CpuRatio = config->cpu_ratio_override;
+	} else {
+		/* Set CpuRatio to match existing MSR value */
+		msr_t flex_ratio;
+		flex_ratio = rdmsr(MSR_FLEX_RATIO);
+		m_cfg->CpuRatio = (flex_ratio.lo >> 8) & 0xff;
+	}

/* If ISH is enabled, enable ISH elements */
    if (!dev)