power.c

/*
 * Copyright (C) 2018 bzt (bztsrc@github)
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 */

#include "gpio.h"
#include "mbox.h"
#include "delays.h"

#define PM_RSTC ((volatile unsigned int *)(MMIO_BASE + 0x0010001c))
#define PM_RSTS ((volatile unsigned int *)(MMIO_BASE + 0x00100020))
#define PM_WDOG ((volatile unsigned int *)(MMIO_BASE + 0x00100024))
#define PM_WDOG_MAGIC 0x5a000000
#define PM_RSTC_FULLRST 0x00000020

/**
 * Shutdown the board
 */
void power_off()
{
    unsigned long r;

    // power off devices one by one
    for (r = 0; r < 16; r++)
    {
        mbox[0] = 8 * 4;
        mbox[1] = MBOX_REQUEST;
        mbox[2] = MBOX_TAG_SETPOWER; // set power state
        mbox[3] = 8;
        mbox[4] = 8;
        mbox[5] = (unsigned int)r; // device id
        mbox[6] = 0;               // bit 0: off, bit 1: no wait
        mbox[7] = MBOX_TAG_LAST;
        mbox_call(MBOX_CH_PROP);
    }

    // power off gpio pins (but not VCC pins)
    *GPFSEL0 = 0;
    *GPFSEL1 = 0;
    *GPFSEL2 = 0;
    *GPFSEL3 = 0;
    *GPFSEL4 = 0;
    *GPFSEL5 = 0;
    *GPPUD = 0;
    wait_cycles(150);
    *GPPUDCLK0 = 0xffffffff;
    *GPPUDCLK1 = 0xffffffff;
    wait_cycles(150);
    *GPPUDCLK0 = 0;
    *GPPUDCLK1 = 0; // flush GPIO setup

    // power off the SoC (GPU + CPU)
    r = *PM_RSTS;
    r &= ~0xfffffaaa;
    r |= 0x555; // partition 63 used to indicate halt
    *PM_RSTS = PM_WDOG_MAGIC | r;
    *PM_WDOG = PM_WDOG_MAGIC | 10;
    *PM_RSTC = PM_WDOG_MAGIC | PM_RSTC_FULLRST;
}

/**
 * Reboot
 */
void reset(int partition)
{
    // the register values are weird, the partition number must be converted
    // to hex, then padded with 0's every other bit, so for example, partition
    // 63 (which actually means halt), is turned into "111111", which is then
    // turned into "0b0101010101" and those bits are set in PM_RSTS
    unsigned int partitionBitField = 0;
    switch (partition)
    {
    case 1:
        // first partition is "0"
        partitionBitField = 0b0;
        break;
    case 2:
        partitionBitField = 0b100;
        break;
    case 3:
        partitionBitField = 0b100;
        break;
    case 4:
        partitionBitField = 0b101;
        break;
        // etc. etc.
    }
    unsigned int r;
    // trigger a restart by instructing the GPU to boot from partition 0
    r = *PM_RSTS;
    r &= ~0xfffffaaa;

    // set the bit field for which partition to boot from
    r |= partitionBitField;

    *PM_RSTS = PM_WDOG_MAGIC | r;
    *PM_WDOG = PM_WDOG_MAGIC | 10;
    *PM_RSTC = PM_WDOG_MAGIC | PM_RSTC_FULLRST;
}