mb/google/hatch/vr/puff: Add psys_pmax calculation

This patch adds psys_pmax calculation. There are two types of power
sources. One is barrel jack and the other is USB TYPE-C. The voltage
level is fixed for a barrel jack while TYPE-C may vary depending
on power ratings. We need to get voltage information from
EC and calculate correct psys_pmax value. The psys_pmax needs to be
set before FSP-S since FSP-S will handle the setting passing to pcode,
so move the routine ahead to variant_ramstage_init.

BUG=b:151972149
TEST=emerge-puff coreboot chromeos-bootimage
     check firmware log and ensure psys_pmax is passed to FSP
     check the data from dump_intel_rapl_consumption in the OS and
     ensure the power data is close to an external power meter.

Signed-off-by: Gaggery Tsai <gaggery.tsai@intel.com>
Change-Id: I8ea01f856411e05a533489280fc2b4a46a1440c5
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39850
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

1 files changed, 37 insertions, 18 deletions

diff --git a/src/mainboard/google/hatch/variants/puff/mainboard.c b/src/mainboard/google/hatch/variants/puff/mainboard.c
index 3f74c968b1..ceeb0c5aba 100644
--- a/src/mainboard/google/hatch/variants/puff/mainboard.c
+++ b/src/mainboard/google/hatch/variants/puff/mainboard.c
@@ -31,23 +31,6 @@ static void wait_for_hpd(gpio_t gpio, long timeout)
 	       stopwatch_duration_msecs(&sw));
 }
 
-void variant_ramstage_init(void)
-{
-	static const long display_timeout_ms = 3000;
-
-	/* This is reconfigured back to whatever FSP-S expects by
-	   gpio_configure_pads. */
-	gpio_input(GPIO_HDMI_HPD);
-	gpio_input(GPIO_DP_HPD);
-	if (display_init_required()
-		&& !gpio_get(GPIO_HDMI_HPD)
-		&& !gpio_get(GPIO_DP_HPD)) {
-		/* This has to be done before FSP-S runs. */
-		if (google_chromeec_wait_for_displayport(display_timeout_ms))
-			wait_for_hpd(GPIO_DP_HPD, display_timeout_ms);
-	}
-}
-
 /*
  * For type-C chargers, set PL2 to 90% of max power to account for
  * cable loss and FET Rdson loss in the path from the source.
@@ -86,6 +69,24 @@ void variant_ramstage_init(void)
  * | n  (U22)    |  29 |   .9n   |   .9n   | x(43) |
  * +-------------+-----+---------+---------+-------+
  */
+
+/*
+ * Psys_pmax considerations
+ *
+ * Given the hardware design in puff, the serial shunt resistor is 0.01ohm.
+ * The full scale of hardware PSYS signal 0.8v maps to system current 9.6A
+ * instead of real system power. The equation is shown below:
+ * PSYS = 0.8v = (0.01ohm x Iinput) x 50 (INA213, gain 50V/V) x 15k/(15k + 75k)
+ * Hence, Iinput (Amps) = 9.6A
+ * Since there is no voltage information from PSYS, different voltage input
+ * would map to different Psys_pmax settings:
+ * For Type-C 15V, the Psys_pmax sholud be 15v x 9.6A = 144W
+ * For Type-C 20V, the Psys_pmax should be 20v x 9.6A = 192W
+ * For a barral jack, the Psys_pmax should be 19v x 9.6A = 182.4W
+ */
+#define PSYS_IMAX	9600
+#define BJ_VOLTS_MV	19000
+
 static void mainboard_set_power_limits(config_t *conf)
 {
 	enum usb_chg_type type;
@@ -108,15 +109,33 @@ static void mainboard_set_power_limits(config_t *conf)
 		/* set minimum duty cycle */
 		conf->tdp_psyspl3_dutycycle = PUFF_MIN_DUTYCYCLE;
 		conf->tdp_pl4 = SET_PSYSPL2(psyspl2);
+	} else {
+		/* Input type is barrel jack */
+		volts_mv = BJ_VOLTS_MV;
 	}
+	/* voltage unit is milliVolts and current is in milliAmps */
+	conf->psys_pmax = (u16)(((u32)PSYS_IMAX * volts_mv) / 1000000);
 
 	conf->tdp_pl2_override = PUFF_PL2;
 	/* set psyspl2 to 90% of max adapter power */
 	conf->tdp_psyspl2 = SET_PSYSPL2(psyspl2);
 }
 
-void variant_mainboard_enable(struct device *dev)
+void variant_ramstage_init(void)
 {
+	static const long display_timeout_ms = 3000;
 	config_t *conf = config_of_soc();
+
+	/* This is reconfigured back to whatever FSP-S expects by gpio_configure_pads. */
+	gpio_input(GPIO_HDMI_HPD);
+	gpio_input(GPIO_DP_HPD);
+	if (display_init_required()
+		&& !gpio_get(GPIO_HDMI_HPD)
+		&& !gpio_get(GPIO_DP_HPD)) {
+		/* This has to be done before FSP-S runs. */
+		if (google_chromeec_wait_for_displayport(display_timeout_ms))
+			wait_for_hpd(GPIO_DP_HPD, display_timeout_ms);
+	}
+	/* Psys_pmax needs to be setup before FSP-S */
 	mainboard_set_power_limits(conf);
 }