google/kukui: Add board id support

Get board id from AUXIN4 and RAM code from AUXIN3.

BUG=b:80501386
BRANCH=none
TEST=AUXIN4 is 0.074v and AUXIN3 is 0.212v on P0.
     AUXIN4 is 0.212v and AUXIN3 is 0.212v on P1.

Change-Id: I50533e851d2fae66ae8c5e4e1aa36708d9058e94
Signed-off-by: Tristan Shieh <tristan.shieh@mediatek.com>
Reviewed-on: https://review.coreboot.org/29062
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/src/mainboard/google/kukui/boardid.c b/src/mainboard/google/kukui/boardid.c
new file mode 100644
index 0000000000..26ae82f3a6
--- /dev/null
+++ b/src/mainboard/google/kukui/boardid.c
@@ -0,0 +1,68 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2018 MediaTek Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <assert.h>
+#include <boardid.h>
+#include <soc/auxadc.h>
+#include <stddef.h>
+
+static uint32_t get_index(unsigned int channel, uint32_t *cached_id)
+{
+	static const int voltages[] = {
+	/* ID : Voltage (unit: uV) */
+	/*  0 : */   74000,
+	/*  1 : */  212000,
+	/*  2 : */  319000,
+	/*  3 : */  429000,
+	/*  4 : */  542000,
+	/*  5 : */  666000,
+	/*  6 : */  781000,
+	/*  7 : */  900000,
+	/*  8 : */ 1023000,
+	/*  9 : */ 1137000,
+	/* 10 : */ 1240000,
+	/* 11 : */ 1343000,
+	/* 12 : */ 1457000
+	};
+
+	uint32_t id;
+
+	if (*cached_id != BOARD_ID_UNKNOWN)
+		return *cached_id;
+
+	int value = auxadc_get_voltage(channel);
+	/* Find the closest voltage */
+	for (id = 0; id < ARRAY_SIZE(voltages) - 1; id++)
+		if (value < (voltages[id] + voltages[id + 1]) / 2)
+			break;
+
+	const int tolerance = 10000; /* 10,000 uV */
+	assert(ABS(value - voltages[id]) < tolerance);
+
+	*cached_id = id;
+	return id;
+}
+
+uint32_t board_id(void)
+{
+	static uint32_t cached_board_id = BOARD_ID_UNKNOWN;
+	return get_index(4, &cached_board_id);
+}
+
+uint32_t ram_code(void)
+{
+	static uint32_t cached_ram_code = BOARD_ID_UNKNOWN;
+	return get_index(3, &cached_ram_code);
+}