[coreboot-gerrit] Change in coreboot[master]: mb/google/asurada: Get ram id from AUX_IN3

[Yidi Lin (Code Review)]

Hello CK HU,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/46391

to review the following change.

Change subject: mb/google/asurada: Get ram id from AUX_IN3
......................................................................

mb/google/asurada: Get ram id from AUX_IN3

Mapping the voltage of AUX_IN3 to ram id.

Signed-off-by: CK Hu 
Change-Id: Iaadabea1b6aa91c48b137f7c6784ab7ee0adc473
---
M src/mainboard/google/asurada/boardid.c
1 file changed, 55 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/91/46391/1

diff --git a/src/mainboard/google/asurada/boardid.c b/src/mainboard/google/asurada/boardid.c
index 2c8efcd..6dc1f7a 100644
--- a/src/mainboard/google/asurada/boardid.c
+++ b/src/mainboard/google/asurada/boardid.c
@@ -1,9 +1,58 @@
 /* SPDX-License-Identifier: GPL-2.0-only */

+#include <assert.h>
 #include <boardid.h>
+#include <console/console.h>
+#include <soc/auxadc.h>

/* board_id is provided by ec/google/chromeec/ec_boardid.c */

+#define ADC_LEVELS 15
+
+enum {
+	RAM_ID_CHANNEL = 3,
+};
+
+static const 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,
+	/* 12 : */ 1457500,
+	/* 13 : */ 1575600,
+	/* 14 : */ 1683600,
+};
+
+static const int *adc_voltages[] = {
+	[RAM_ID_CHANNEL] = ram_voltages,
+};
+
+static uint32_t get_adc_index(unsigned int channel)
+{
+	int value = auxadc_get_voltage(channel);
+
+	assert(channel < ARRAY_SIZE(adc_voltages));
+	const 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[%d]: Raw value=%d ID=%d\n", channel, value, id);
+	return id;
+}
+
 uint32_t sku_id(void)
 {
    return 0;
@@ -11,5 +60,10 @@

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_CHANNEL);
+
+	return cached_ram_code;
 }