mb/google/volteer: Override power limits with SKU-specific limits

Using guidance from Intel, a new set of power limits (PL1, PL2 & PL4)
are available for TGL-U. They are dependent upon the SKU of the CPU
that the mainboard is running on. Volteer is updated here to use these
new limits.

To accomplish this, the SoC chip config's power_limits_config member
was expanded to an array, which can be indexed by POWER_LIMITS_*_CORE
macros. Just before power limits are applied, the correct set of them
is chosen from the array based on System Agent PCI ID. Therefore, a
TGL board should have two sets of power limits available in the
devicetree.

BUG=b:152639350
TEST=On a Volteer SKU4 (4-core), verified the following console output:
CPU PL1 = 15 Watts
CPU PL2 = 60 Watts
CPU PL4 = 105 Watts

Change-Id: I18a66fc3aacbb3ab594b2e3d6e2a4ad84c10d8f0
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42436
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Caveh Jalali <caveh@chromium.org>

3 files changed, 40 insertions, 3 deletions

diff --git a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
index 8cd926cd88..f2e427f0bb 100644
--- a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
@@ -198,9 +198,15 @@ chip soc/intel/tigerlake
 	# Enable DPTF
 	register "dptf_enable" = "1"
 
-	register "power_limits_config" = "{
+	register "power_limits_config[POWER_LIMITS_U_4_CORE]" = "{
 		.tdp_pl1_override = 15,
 		.tdp_pl2_override = 60,
+		.tdp_pl4 = 105,
+	}"
+	register "power_limits_config[POWER_LIMITS_U_2_CORE]" = "{
+		.tdp_pl1_override = 15,
+		.tdp_pl2_override = 38,
+		.tdp_pl4 = 71,
 	}"
 
 	register "Device4Enable" = "1"
diff --git a/src/soc/intel/tigerlake/chip.h b/src/soc/intel/tigerlake/chip.h
index 30377aaf79..8b1fe2d03f 100644
--- a/src/soc/intel/tigerlake/chip.h
+++ b/src/soc/intel/tigerlake/chip.h
@@ -22,6 +22,11 @@
 #define MAX_HD_AUDIO_SNDW_LINKS 4
 #define MAX_HD_AUDIO_SSP_LINKS  6
 
+/* The first two are for TGL-U */
+#define POWER_LIMITS_U_4_CORE	0
+#define POWER_LIMITS_U_2_CORE	1
+#define POWER_LIMITS_MAX	2
+
 /*
  * Enable External V1P05 Rail in: BIT0:S0i1/S0i2,
  * BIT1:S0i3, BIT2:S3, BIT3:S4, BIT4:S5
@@ -55,7 +60,7 @@ struct soc_intel_tigerlake_config {
 	struct soc_intel_common_config common_soc_config;
 
 	/* Common struct containing power limits configuration information */
-	struct soc_power_limits_config power_limits_config;
+	struct soc_power_limits_config power_limits_config[POWER_LIMITS_MAX];
 
 	/* Gpio group routed to each dword of the GPE0 block. Values are
 	 * of the form PMC_GPP_[A:U] or GPD. */
diff --git a/src/soc/intel/tigerlake/systemagent.c b/src/soc/intel/tigerlake/systemagent.c
index 08d1ef387c..e428365c4d 100644
--- a/src/soc/intel/tigerlake/systemagent.c
+++ b/src/soc/intel/tigerlake/systemagent.c
@@ -6,9 +6,11 @@
  * Chapter number: 3
  */
 
+#include <console/console.h>
 #include <device/device.h>
 #include <delay.h>
 #include <device/pci.h>
+#include <device/pci_ids.h>
 #include <device/pci_ops.h>
 #include <intelblocks/power_limit.h>
 #include <intelblocks/systemagent.h>
@@ -53,8 +55,14 @@ void soc_add_fixed_mmio_resources(struct device *dev, int *index)
 void soc_systemagent_init(struct device *dev)
 {
 	struct soc_power_limits_config *soc_config;
+	struct device *sa;
+	uint16_t sa_pci_id;
 	config_t *config;
 
+	/* Get System Agent PCI ID */
+	sa = pcidev_path_on_root(SA_DEVFN_ROOT);
+	sa_pci_id = sa ? pci_read_config16(sa, PCI_DEVICE_ID) : 0xFFFF;
+
 	/* Enable Power Aware Interrupt Routing */
 	enable_power_aware_intr();
 
@@ -64,7 +72,25 @@ void soc_systemagent_init(struct device *dev)
 	/* Configure turbo power limits 1ms after reset complete bit */
 	mdelay(1);
 	config = config_of_soc();
-	soc_config = &config->power_limits_config;
+
+	/*
+	 * Choose a power limits configuration based on the SoC SKU,
+	 * differentiated here based on SA PCI ID.
+	 */
+	switch (sa_pci_id) {
+	case PCI_DEVICE_ID_INTEL_TGL_ID_U:
+	case PCI_DEVICE_ID_INTEL_TGL_ID_U_1:
+		soc_config = &config->power_limits_config[POWER_LIMITS_U_4_CORE];
+		break;
+	case PCI_DEVICE_ID_INTEL_TGL_ID_U_2_2:
+		soc_config = &config->power_limits_config[POWER_LIMITS_U_2_CORE];
+		break;
+	default:
+		printk(BIOS_ERR, "TGL: unknown SA ID: 0x%4x, skipping power limits "
+		       "configuration\n", sa_pci_id);
+		return;
+	}
+
 	set_power_limits(MOBILE_SKU_PL1_TIME_SEC, soc_config);
 }