Support DPTF charger current limiting

This enables the AP to limit charging current via ACPI.

BUG=chrome-os-partner:23971
BRANCH=rambi
TEST=manual
    drain battery down to <90%, then plug into AC
    (charger commands at EC console, iotools at root shell)

    iotools io_write8 0x66 0x81
    iotools io_write8 0x62 0x08
    iotools io_write8 0x62 3

    charger -> dptf limit 192, I_batt=192

    charger dptf 320
    charger -> dptf limit 320, I_batt=320

    iotools io_write8 0x66 0x80
    iotools io_write8 0x62 0x08
    iotools io_read8 0x62 -> 0x05

    iotools io_write8 0x66 0x81
    iotools io_write8 0x62 0x08
    iotools io_write8 0x62 0xff

    charger -> dptf disabled, I_batt=(something > 192)

    iotools io_write8 0x66 0x80
    iotools io_write8 0x62 0x08
    iotools io_read8 0x62 -> 0xff

Change-Id: Iace2ebbbc018143c0154310d7acd02d16a6b7339
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/185411
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

4 files changed, 82 insertions, 6 deletions

diff --git a/common/acpi.c b/common/acpi.c
index 69cf3bc837..eed20fdbe0 100644
--- a/common/acpi.c
+++ b/common/acpi.c
@@ -76,6 +76,15 @@ int acpi_ap_to_ec(int is_cmd, uint8_t value, uint8_t *resultptr)
 			result = dptf_query_next_sensor_event();
 			break;
 #endif
+#ifdef CONFIG_CHARGER
+		case EC_ACPI_MEM_CHARGING_LIMIT:
+			result = dptf_get_charging_current_limit();
+			if (result >= 0)
+				result /= EC_ACPI_MEM_CHARGING_LIMIT_STEP_MA;
+			else
+				result = EC_ACPI_MEM_CHARGING_LIMIT_DISABLED;
+			break;
+#endif
 		default:
 			CPRINTF("[%T ACPI read 0x%02x (ignored)]\n", acpi_addr);
 			break;
@@ -124,6 +133,16 @@ int acpi_ap_to_ec(int is_cmd, uint8_t value, uint8_t *resultptr)
 			break;
 		}
 #endif
+#ifdef CONFIG_CHARGER
+		case EC_ACPI_MEM_CHARGING_LIMIT:
+			if (data == EC_ACPI_MEM_CHARGING_LIMIT_DISABLED) {
+				dptf_set_charging_current_limit(-1);
+			} else {
+				data *= EC_ACPI_MEM_CHARGING_LIMIT_STEP_MA;
+				dptf_set_charging_current_limit(data);
+			}
+			break;
+#endif
 		default:
 			CPRINTF("[%T ACPI write 0x%02x = 0x%02x (ignored)]\n",
 				acpi_addr, data);
diff --git a/common/charger.c b/common/charger.c
index ebac3896c1..3780b2b5a1 100644
--- a/common/charger.c
+++ b/common/charger.c
@@ -8,6 +8,7 @@
 #include "charger.h"
 #include "common.h"
 #include "console.h"
+#include "dptf.h"
 #include "host_command.h"
 #include "printf.h"
 #include "util.h"
@@ -16,6 +17,19 @@
 #define CPUTS(outstr) cputs(CC_CHARGER, outstr)
 #define CPRINTF(format, args...) cprintf(CC_CHARGER, format, ## args)
 
+/* DPTF current limit, -1 = none */
+static int dptf_limit_ma = -1;
+
+void dptf_set_charging_current_limit(int ma)
+{
+	dptf_limit_ma = ma >= 0 ? ma : -1;
+}
+
+int dptf_get_charging_current_limit(void)
+{
+	return dptf_limit_ma;
+}
+
 int charger_closest_voltage(int voltage)
 {
 	const struct charger_info *info = charger_get_info();
@@ -39,6 +53,10 @@ int charger_closest_current(int current)
 {
 	const struct charger_info * const info = charger_get_info();
 
+	/* Apply DPTF limit if necessary */
+	if (dptf_limit_ma >= 0 && current > dptf_limit_ma)
+		current = dptf_limit_ma;
+
 	/*
 	 * If the requested current is non-zero but below our minimum,
 	 * return the minimum.  See crosbug.com/p/8662.
@@ -112,6 +130,13 @@ static int print_info(void)
 			 info->input_current_min, info->input_current_max,
 			 info->input_current_step);
 
+	/* dptf current limit */
+	print_item_name("I_dptf:");
+	if (dptf_limit_ma >= 0)
+		ccprintf("%5d\n", dptf_limit_ma);
+	else
+		ccputs("disabled\n");
+
 	return EC_SUCCESS;
 }
 
@@ -138,11 +163,17 @@ static int command_charger(int argc, char **argv)
 		if (*e)
 			return EC_ERROR_PARAM2;
 		return charger_set_voltage(d);
+	} else if (strcasecmp(argv[1], "dptf") == 0) {
+		d = strtoi(argv[2], &e, 0);
+		if (*e)
+			return EC_ERROR_PARAM2;
+		dptf_limit_ma = d;
+		return EC_SUCCESS;
 	} else
 		return EC_ERROR_PARAM1;
 }
 
 DECLARE_CONSOLE_COMMAND(charger, command_charger,
-			"[input | current | voltage] [newval]",
+			"[input | current | voltage | dptf] [newval]",
 			"Get or set charger param(s)",
 			NULL);
diff --git a/include/dptf.h b/include/dptf.h
index f611acb361..6797806e18 100644
--- a/include/dptf.h
+++ b/include/dptf.h
@@ -8,26 +8,44 @@
 #ifndef __CROS_EC_DPTF_H
 #define __CROS_EC_DPTF_H
 
-/* 0-100% sets fixed duty cycle, out of range means let the EC drive */
+/**
+ * Set fan duty target.
+ *
+ * 0-100% sets fixed duty cycle, out of range means let the EC drive.
+ */
 void dptf_set_fan_duty_target(int pct);
 
-/* 0-100% if in duty mode. -1 if not */
+/**
+ * Return 0-100% if in duty mode. -1 if not.
+ */
 int dptf_get_fan_duty_target(void);
 
 /* Thermal thresholds may be set for each temp sensor. */
 #define DPTF_THRESHOLDS_PER_SENSOR 2
 #define DPTF_THRESHOLD_HYSTERESIS 2
 
-/* Set/enable the thresholds */
+/**
+ * Set/enable the thresholds.
+ */
 void dptf_set_temp_threshold(int sensor_id,	/* zero-based sensor index */
 			     int temp,		/* in degrees K */
 			     int idx,		/* which threshold (0 or 1) */
 			     int enable);	/* true = on, false = off */
 
-/*
+/**
  * Return the ID of a temp sensor that has crossed its threshold since the last
-   time we asked. -1 means none.
+ * time we asked. -1 means none.
  */
 int dptf_query_next_sensor_event(void);
 
+/**
+ * Set charging current limit, in mA.  -1 means no limit.
+ */
+void dptf_set_charging_current_limit(int ma);
+
+/**
+ * Get charging current limit, in mA, or -1 if not DPTF-limiting.
+ */
+int dptf_get_charging_current_limit(void);
+
 #endif	/* __CROS_EC_DPTF_H */
diff --git a/include/ec_commands.h b/include/ec_commands.h
index e4652bed89..3d557eb6d4 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -1971,6 +1971,14 @@ struct ec_params_reboot_ec {
  *   write 0x1 to [0x07]    --  disable threshold 1
  */
 
+/* DPTF battery charging current limit */
+#define EC_ACPI_MEM_CHARGING_LIMIT     0x08
+
+/* Charging limit is specified in 64 mA steps */
+#define EC_ACPI_MEM_CHARGING_LIMIT_STEP_MA   64
+/* Value to disable DPTF battery charging limit */
+#define EC_ACPI_MEM_CHARGING_LIMIT_DISABLED  0xff
+
 /* Current version of ACPI memory address space */
 #define EC_ACPI_MEM_VERSION_CURRENT 1