1 files changed, 107 insertions, 0 deletions
diff --git a/baseboard/asurada/board_id.c b/baseboard/asurada/board_id.c
new file mode 100644
index 0000000000..78cc9455c4
--- /dev/null
+++ b/baseboard/asurada/board_id.c
@@ -0,0 +1,107 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "adc.h"
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "timer.h"
+#include "util.h"
+
+/**
+ * Conversion based on following table:
+ *
+ * ID | Rp   | Rd   | Voltage
+ *    | kOhm | kOhm | mV
+ * ---+------+------+--------
+ *  0 | 51.1 |  2.2 | 136.2
+ *  1 | 51.1 | 6.81 | 388.1
+ *  2 | 51.1 |   11 | 584.5
+ *  3 | 57.6 |   18 | 785.7
+ *  4 | 51.1 |   22 | 993.2
+ *  5 | 51.1 |   30 | 1220.7
+ *  6 | 51.1 | 39.2 | 1432.6
+ *  7 |   56 |   56 | 1650.0
+ *  8 |   47 | 61.9 | 1875.8
+ *  9 |   47 | 80.6 | 2084.5
+ * 10 |   56 |  124 | 2273.3
+ * 11 | 51.1 |  150 | 2461.5
+ * 12 |   47 |  200 | 2672.1
+ * 13 |   47 |  330 | 2888.6
+ * 14 |   47 |  680 | 3086.7
+ */
+const static int voltage_map[] = {
+	136,
+	388,
+	584,
+	785,
+	993,
+	1220,
+	1432,
+	1650,
+	1875,
+	2084,
+	2273,
+	2461,
+	2672,
+	2888,
+	3086,
+};
+
+const int threshold_mv = 100;
+
+/**
+ * Convert ADC value to board id using the voltage table above.
+ *
+ * @param ch	ADC channel to read, usually ADC_BOARD_ID_0 or ADC_BOARD_ID_1.
+ *
+ * @return	a non-negative board id, or negative value if error.
+ */
+static int adc_value_to_numeric_id(enum adc_channel ch)
+{
+	int mv;
+
+	gpio_set_level(GPIO_EN_EC_ID_ODL, 0);
+	/* Wait to allow cap charge */
+	msleep(10);
+
+	mv = adc_read_channel(ch);
+	if (mv == ADC_READ_ERROR)
+		mv = adc_read_channel(ch);
+
+	gpio_set_level(GPIO_EN_EC_ID_ODL, 1);
+
+	if (mv == ADC_READ_ERROR)
+		return -EC_ERROR_UNKNOWN;
+
+	for (int i = 0; i < ARRAY_SIZE(voltage_map); i++) {
+		if (IN_RANGE(mv, voltage_map[i] - threshold_mv,
+			     voltage_map[i] + threshold_mv))
+			return i;
+	}
+
+	return -EC_ERROR_UNKNOWN;
+}
+
+static int version = -1;
+
+/* b/163963220: Cache ADC value before board_hibernate_late() reads it */
+static void board_version_init(void)
+{
+	version = adc_value_to_numeric_id(ADC_BOARD_ID_0);
+	if (version < 0) {
+		ccprints("WARN:BOARD_ID_0");
+		ccprints("Assuming board id = 0");
+
+		version = 0;
+	}
+}
+DECLARE_HOOK(HOOK_INIT, board_version_init, HOOK_PRIO_INIT_ADC + 1);
+
+int board_get_version(void)
+{
+	return version;
+}