From ef53634d9a68c93b123f792dc4a0336346b82b8c Mon Sep 17 00:00:00 2001 From: Rex-BC Chen Date: Mon, 31 May 2021 21:44:05 +0800 Subject: mb/google/cherry: Get RAM code from ADC On Chromebooks the RAM code is implemented by the resistor straps that we can read and decode from ADC. For Cherry the RAM code can be read from ADC channel 2 and 3. Signed-off-by: Rex-BC Chen Change-Id: I4f28bc1c567cb886bd90d930219981a6206b9bb9 Reviewed-on: https://review.coreboot.org/c/coreboot/+/55156 Tested-by: build bot (Jenkins) Reviewed-by: Yu-Ping Wu --- src/mainboard/google/cherry/boardid.c | 60 ++++++++++++++++++++++++++++++++++- 1 file changed, 59 insertions(+), 1 deletion(-) 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 #include +#include +#include + +#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; } -- cgit v1.2.3