1 files changed, 59 insertions, 1 deletions
diff --git a/src/mainboard/google/cherry/boardid.c b/src/mainboard/google/cherry/boardid.c
index 34d7692557..a51eee8f42 100644
--- a/src/mainboard/google/cherry/boardid.c
+++ b/src/mainboard/google/cherry/boardid.c
@@ -1,8 +1,66 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <assert.h>
 #include <boardid.h>
+#include <console/console.h>
+#include <soc/auxadc.h>
+
+#define ADC_LEVELS 12
+
+enum {
+	/* RAM IDs */
+	RAM_ID_HIGH_CHANNEL = 3,
+	RAM_ID_LOW_CHANNEL = 2,
+};
+
+static const unsigned int ram_voltages[ADC_LEVELS] = {
+	/* ID : Voltage (unit: uV) */
+	[0]  =   74300,
+	[1]  =  211700,
+	[2]  =  318800,
+	[3]  =  428600,
+	[4]  =  541700,
+	[5]  =  665800,
+	[6]  =  781400,
+	[7]  =  900000,
+	[8]  = 1023100,
+	[9]  = 1137000,
+	[10] = 1240000,
+	[11] = 1342600,
+};
+
+static const unsigned int *adc_voltages[] = {
+	[RAM_ID_HIGH_CHANNEL] = ram_voltages,
+	[RAM_ID_LOW_CHANNEL] = ram_voltages,
+};
+
+static uint32_t get_adc_index(unsigned int channel)
+{
+	unsigned int value = auxadc_get_voltage_uv(channel);
+
+	assert(channel < ARRAY_SIZE(adc_voltages));
+	const unsigned int *voltages = adc_voltages[channel];
+	assert(voltages);
+
+	/* Find the closest voltage */
+	uint32_t id;
+	for (id = 0; id < ADC_LEVELS - 1; id++)
+		if (value < (voltages[id] + voltages[id + 1]) / 2)
+			break;
+
+	printk(BIOS_DEBUG, "ADC[%u]: Raw value=%u ID=%u\n", channel, value, id);
+	return id;
+}
 
 uint32_t ram_code(void)
 {
-	return 0;
+	static uint32_t cached_ram_code = BOARD_ID_INIT;
+
+	if (cached_ram_code == BOARD_ID_INIT) {
+		cached_ram_code = (get_adc_index(RAM_ID_HIGH_CHANNEL) << 4 |
+				   get_adc_index(RAM_ID_LOW_CHANNEL));
+		printk(BIOS_DEBUG, "RAM Code: %#02x\n", cached_ram_code);
+	}
+
+	return cached_ram_code;
 }