power: introducing pwr_avg console command

pwr_avg provides an average voltage, current, and power over the last
1 minute. It's up to the battery drivers to implement this
functionality.
This change allows us to have better power tracking while minimizing
the power impact on the EC, because
- the pwr_avg command only needs to be called once every minute, and is
short, thus less expensive to parse on ECs without a UART buffer
- the work done to keep the avg is partially done by the batteries
already and it's just a question of retrieving it.

undefined on wheatley since no power debugging planned on that board.

usage:
> pwr_avg
mv = 7153
ma = -605
mw = -4327

BUG=chromium:752320
BRANCH=None
TEST=make buildall -j

Change-Id: Id1a3479d277aedf90dfa965afb4ee9136654b1cf
Signed-off-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/823884
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

board/wheatley/board.h

@@ -147,6 +147,7 @@
 #undef CONFIG_CONSOLE_CMDHELP
 #undef CONFIG_CMD_I2C_SCAN
 #undef CONFIG_CONSOLE_HISTORY
+#undef CONFIG_CMD_PWR_AVG
 
 /* Features of eSPI */
 #undef CONFIG_ESPI       /* Use eSPI protocol for host interface of x86 CPU */

common/charge_state_v2.c

@@ -1556,6 +1556,34 @@ DECLARE_HOST_COMMAND(EC_CMD_CHARGE_STATE, charge_command_charge_state,
 /*****************************************************************************/
 /* Console commands */
 
+#ifdef CONFIG_CMD_PWR_AVG
+
+static int command_pwr_avg(int argc, char **argv)
+{
+	int avg_mv;
+	int avg_ma;
+	int avg_mw;
+
+	if (argc != 1)
+		return EC_ERROR_PARAM_COUNT;
+
+	avg_mv = battery_get_avg_voltage();
+	if (avg_mv < 0)
+		return EC_ERROR_UNKNOWN;
+	avg_ma = battery_get_avg_current();
+	avg_mw = avg_mv * avg_ma / 1000;
+
+	ccprintf("mv = %d\nma = %d\nmw = %d\n",
+		avg_mv, avg_ma, avg_mw);
+	return EC_SUCCESS;
+}
+
+DECLARE_CONSOLE_COMMAND(pwr_avg, command_pwr_avg,
+			NULL,
+			"Get 1 min power average");
+
+#endif /* CONFIG_CMD_PWR_AVG */
+
 static int command_chgstate(int argc, char **argv)
 {
 	int rv;

driver/battery/max17055.c

@@ -263,6 +263,20 @@ void battery_get_params(struct batt_params *batt)
 		batt->flags |= BATT_FLAG_WANT_CHARGE;
 }
 
+#ifdef CONFIG_CMD_PWR_AVG
+int battery_get_avg_current(void)
+{
+	/* TODO(crbug.com/752320) implement this */
+	return EC_ERROR_UNIMPLEMENTED;
+}
+
+int battery_get_avg_voltage(void)
+{
+	/* TODO(crbug.com/752320) implement this */
+	return -EC_ERROR_UNIMPLEMENTED;
+}
+#endif /* CONFIG_CMD_PWR_AVG */
+
 /* Wait until battery is totally stable. */
 int battery_wait_for_stable(void)
 {

driver/battery/smart.c

@@ -283,6 +283,30 @@ test_mockable int battery_device_chemistry(char *dest, int size)
 	return sb_read_string(SB_DEVICE_CHEMISTRY, dest, size);
 }
 
+#ifdef CONFIG_CMD_PWR_AVG
+int battery_get_avg_current(void)
+{
+	int current;
+
+	/* This is a signed 16-bit value. */
+	sb_read(SB_AVERAGE_CURRENT, &current);
+	return (int16_t)current;
+}
+
+/*
+ * Technically returns only the instantaneous reading, but tests showed that
+ * for the majority of charge states above 3% this varies by less than 40mV
+ * every minute, so we accept the inaccuracy here.
+ */
+int battery_get_avg_voltage(void)
+{
+	int voltage = -EC_ERROR_UNKNOWN;
+
+	sb_read(SB_VOLTAGE, &voltage);
+	return voltage;
+}
+#endif /* CONFIG_CMD_PWR_AVG */
+
 void battery_get_params(struct batt_params *batt)
 {
 	struct batt_params batt_new = {0};

include/battery.h

@@ -74,6 +74,16 @@ struct batt_params {
 	int flags;            /* Flags */
 };
 
+/*
+ * Provide a 1 minute average of the current and voltage on the battery.
+ * Does not check for flags or whether those values are bad readings.
+ * See driver/battery/[your_driver].h/c for details on implementation and
+ * how the average is calculated.
+ */
+
+int battery_get_avg_current(void); /* in mA */
+int battery_get_avg_voltage(void); /* in mV */
+
 /* Flags for batt_params */
 
 /* Battery wants to be charged */

include/config.h

@@ -783,6 +783,7 @@
 #undef  CONFIG_CMD_PMU
 #define CONFIG_CMD_POWERINDEBUG
 #undef  CONFIG_CMD_POWERLED
+#define CONFIG_CMD_PWR_AVG
 #define CONFIG_CMD_POWER_AP
 #undef  CONFIG_CMD_PPC_DUMP
 #define CONFIG_CMD_REGULATOR
@@ -3281,6 +3282,13 @@
 #undef CONFIG_HOSTCMD_PD
 #endif
 
+/*
+ * Power Average task only works when there's a battery to talk to.
+ */
+#ifndef CONFIG_BATTERY
+#undef CONFIG_CMD_PWR_AVG
+#endif
+
 /*****************************************************************************/
 /*
  * Apply test config overrides last, since tests need to override some of the