src/mainboard/google/kukui/boardid.c

   1 /*
   2  * This file is part of the coreboot project.
   3  *
   4  * Copyright 2018 MediaTek Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <assert.h>
  17 #include <boardid.h>
  18 #include <soc/auxadc.h>
  19 #include <stddef.h>
  20
  21 static uint32_t get_index(unsigned int channel, uint32_t *cached_id)
  22 {
  23         static const int voltages[] = {
  24         /* ID : Voltage (unit: uV) */
  25         /*  0 : */   74000,
  26         /*  1 : */  212000,
  27         /*  2 : */  319000,
  28         /*  3 : */  429000,
  29         /*  4 : */  542000,
  30         /*  5 : */  666000,
  31         /*  6 : */  781000,
  32         /*  7 : */  900000,
  33         /*  8 : */ 1023000,
  34         /*  9 : */ 1137000,
  35         /* 10 : */ 1240000,
  36         /* 11 : */ 1343000,
  37         /* 12 : */ 1457000,
  38         /* 13 : */ 1576000,
  39         /* 14 : */ 1684000,
  40         /* 15 : */ 1800000,
  41         };
  42
  43         uint32_t id;
  44
  45         if (*cached_id != BOARD_ID_INIT)
  46                 return *cached_id;
  47
  48         int value = auxadc_get_voltage(channel);
  49         /* Find the closest voltage */
  50         for (id = 0; id < ARRAY_SIZE(voltages) - 1; id++)
  51                 if (value < (voltages[id] + voltages[id + 1]) / 2)
  52                         break;
  53
  54         const int tolerance = 10000; /* 10,000 uV */
  55         assert(ABS(value - voltages[id]) < tolerance);
  56
  57         *cached_id = id;
  58         return id;
  59 }
  60
  61 uint32_t board_id(void)
  62 {
  63         static uint32_t cached_board_id = BOARD_ID_INIT;
  64         return get_index(4, &cached_board_id);
  65 }
  66
  67 uint32_t ram_code(void)
  68 {
  69         static uint32_t cached_ram_code = BOARD_ID_INIT;
  70         return get_index(3, &cached_ram_code);
  71 }