keychron_qmk_firmware/platforms/avr/bootloader.c

#include <stdint.h>
#include <stdbool.h>
#include <avr/io.h>
#include <avr/eeprom.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>
#include <util/delay.h>
#include "bootloader.h"
#include <avr/boot.h>

#ifdef PROTOCOL_LUFA
#    include <LUFA/Drivers/USB/USB.h>
#endif

/** \brief Bootloader Size in *bytes*
 *
 * AVR Boot section size are defined by setting BOOTSZ fuse in fact. Consult with your MCU datasheet.
 * Note that 'Word'(2 bytes) size and address are used in datasheet while TMK uses 'Byte'.
 *
 * Size of Bootloaders in bytes:
 *   Atmel DFU loader(ATmega32U4)   4096
 *   Atmel DFU loader(AT90USB128)   8192
 *   LUFA bootloader(ATmega32U4)    4096
 *   Arduino Caterina(ATmega32U4)   4096
 *   USBaspLoader(ATmega***)        2048
 *   Teensy   halfKay(ATmega32U4)   512
 *   Teensy++ halfKay(AT90USB128)   1024
 *
 * AVR Boot section is located at the end of Flash memory like the followings.
 *
 * byte     Atmel/LUFA(ATMega32u4)          byte     Atmel(AT90SUB128)
 * 0x0000   +---------------+               0x00000  +---------------+
 *          |               |                        |               |
 *          |               |                        |               |
 *          |  Application  |                        |  Application  |
 *          |               |                        |               |
 *          =               =                        =               =
 *          |               | 32KB-4KB               |               | 128KB-8KB
 * 0x7000   +---------------+               0x1E000  +---------------+
 *          |  Bootloader   | 4KB                    |  Bootloader   | 8KB
 * 0x7FFF   +---------------+               0x1FFFF  +---------------+
 *
 *
 * byte     Teensy(ATMega32u4)              byte     Teensy++(AT90SUB128)
 * 0x0000   +---------------+               0x00000  +---------------+
 *          |               |                        |               |
 *          |               |                        |               |
 *          |  Application  |                        |  Application  |
 *          |               |                        |               |
 *          =               =                        =               =
 *          |               | 32KB-512B              |               | 128KB-1KB
 * 0x7E00   +---------------+               0x1FC00  +---------------+
 *          |  Bootloader   | 512B                   |  Bootloader   | 1KB
 * 0x7FFF   +---------------+               0x1FFFF  +---------------+
 */
#define FLASH_SIZE (FLASHEND + 1L)

#if !defined(BOOTLOADER_SIZE)
uint16_t bootloader_start;
#endif

// compatibility between ATMega8 and ATMega88
#if !defined(MCUCSR)
#    if defined(MCUSR)
#        define MCUCSR MCUSR
#    endif
#endif

/** \brief Entering the Bootloader via Software
 *
 * http://www.fourwalledcubicle.com/files/LUFA/Doc/120730/html/_page__software_bootloader_start.html
 */
#define BOOTLOADER_RESET_KEY 0xB007B007
uint32_t reset_key __attribute__((section(".noinit,\"aw\",@nobits;")));

/** \brief initialize MCU status by watchdog reset
 *
 * FIXME: needs doc
 */
__attribute__((weak)) void bootloader_jump(void) {
#if !defined(BOOTLOADER_SIZE)
    uint8_t high_fuse = boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS);

    if (high_fuse & ~(FUSE_BOOTSZ0 & FUSE_BOOTSZ1)) {
        bootloader_start = (FLASH_SIZE - 512) >> 1;
    } else if (high_fuse & ~(FUSE_BOOTSZ1)) {
        bootloader_start = (FLASH_SIZE - 1024) >> 1;
    } else if (high_fuse & ~(FUSE_BOOTSZ0)) {
        bootloader_start = (FLASH_SIZE - 2048) >> 1;
    } else {
        bootloader_start = (FLASH_SIZE - 4096) >> 1;
    }
#endif

    // Something like this might work, but it compiled larger than the block above
    // bootloader_start = FLASH_SIZE - (256 << (~high_fuse & 0b110 >> 1));

#if defined(BOOTLOADER_HALFKAY)
    //  http://www.pjrc.com/teensy/jump_to_bootloader.html
    cli();
    // disable watchdog, if enabled (it's not)
    // disable all peripherals
    // a shutdown call might make sense here
    UDCON  = 1;
    USBCON = (1 << FRZCLK);  // disable USB
    UCSR1B = 0;
    _delay_ms(5);
#    if defined(__AVR_AT90USB162__)  // Teensy 1.0
    EIMSK  = 0;
    PCICR  = 0;
    SPCR   = 0;
    ACSR   = 0;
    EECR   = 0;
    TIMSK0 = 0;
    TIMSK1 = 0;
    UCSR1B = 0;
    DDRB   = 0;
    DDRC   = 0;
    DDRD   = 0;
    PORTB  = 0;
    PORTC  = 0;
    PORTD  = 0;
    asm volatile("jmp 0x3E00");
#    elif defined(__AVR_ATmega32U4__)   // Teensy 2.0
    EIMSK  = 0;
    PCICR  = 0;
    SPCR   = 0;
    ACSR   = 0;
    EECR   = 0;
    ADCSRA = 0;
    TIMSK0 = 0;
    TIMSK1 = 0;
    TIMSK3 = 0;
    TIMSK4 = 0;
    UCSR1B = 0;
    TWCR   = 0;
    DDRB   = 0;
    DDRC   = 0;
    DDRD   = 0;
    DDRE   = 0;
    DDRF   = 0;
    TWCR   = 0;
    PORTB  = 0;
    PORTC  = 0;
    PORTD  = 0;
    PORTE  = 0;
    PORTF  = 0;
    asm volatile("jmp 0x7E00");
#    elif defined(__AVR_AT90USB646__)   // Teensy++ 1.0
    EIMSK  = 0;
    PCICR  = 0;
    SPCR   = 0;
    ACSR   = 0;
    EECR   = 0;
    ADCSRA = 0;
    TIMSK0 = 0;
    TIMSK1 = 0;
    TIMSK2 = 0;
    TIMSK3 = 0;
    UCSR1B = 0;
    TWCR   = 0;
    DDRA   = 0;
    DDRB   = 0;
    DDRC   = 0;
    DDRD   = 0;
    DDRE   = 0;
    DDRF   = 0;
    PORTA  = 0;
    PORTB  = 0;
    PORTC  = 0;
    PORTD  = 0;
    PORTE  = 0;
    PORTF  = 0;
    asm volatile("jmp 0xFC00");
#    elif defined(__AVR_AT90USB1286__)  // Teensy++ 2.0
    EIMSK  = 0;
    PCICR  = 0;
    SPCR   = 0;
    ACSR   = 0;
    EECR   = 0;
    ADCSRA = 0;
    TIMSK0 = 0;
    TIMSK1 = 0;
    TIMSK2 = 0;
    TIMSK3 = 0;
    UCSR1B = 0;
    TWCR   = 0;
    DDRA   = 0;
    DDRB   = 0;
    DDRC   = 0;
    DDRD   = 0;
    DDRE   = 0;
    DDRF   = 0;
    PORTA  = 0;
    PORTB  = 0;
    PORTC  = 0;
    PORTD  = 0;
    PORTE  = 0;
    PORTF  = 0;
    asm volatile("jmp 0x1FC00");
#    endif

#elif defined(BOOTLOADER_CATERINA)
    // this block may be optional
    // TODO: figure it out

    uint16_t *const bootKeyPtr = (uint16_t *)0x0800;

    // Value used by Caterina bootloader use to determine whether to run the
    // sketch or the bootloader programmer.
    uint16_t bootKey = 0x7777;

    *bootKeyPtr = bootKey;

    // setup watchdog timeout
    wdt_enable(WDTO_60MS);

    while (1) {
    }  // wait for watchdog timer to trigger

#elif defined(BOOTLOADER_USBASP)
    // Taken with permission of Stephan Baerwolf from https://github.com/tinyusbboard/API/blob/master/apipage.c
    wdt_enable(WDTO_15MS);
    wdt_reset();
    asm volatile("cli                    \n\t"
                 "ldi    r29 ,       %[ramendhi] \n\t"
                 "ldi    r28 ,       %[ramendlo] \n\t"
#    if (FLASHEND > 131071)
                 "ldi    r18 ,       %[bootaddrhi]   \n\t"
                 "st     Y+,         r18     \n\t"
#    endif
                 "ldi    r18 ,       %[bootaddrme]   \n\t"
                 "st     Y+,     r18     \n\t"
                 "ldi    r18 ,       %[bootaddrlo]   \n\t"
                 "st     Y+,     r18     \n\t"
                 "out    %[mcucsrio],    __zero_reg__    \n\t"
                 "bootloader_startup_loop%=:         \n\t"
                 "rjmp bootloader_startup_loop%=     \n\t"
                 :
                 : [mcucsrio] "I"(_SFR_IO_ADDR(MCUCSR)),
#    if (FLASHEND > 131071)
                   [ramendhi] "M"(((RAMEND - 2) >> 8) & 0xff), [ramendlo] "M"(((RAMEND - 2) >> 0) & 0xff), [bootaddrhi] "M"((((FLASH_SIZE - BOOTLOADER_SIZE) >> 1) >> 16) & 0xff),
#    else
                   [ramendhi] "M"(((RAMEND - 1) >> 8) & 0xff), [ramendlo] "M"(((RAMEND - 1) >> 0) & 0xff),
#    endif
                   [bootaddrme] "M"((((FLASH_SIZE - BOOTLOADER_SIZE) >> 1) >> 8) & 0xff), [bootaddrlo] "M"((((FLASH_SIZE - BOOTLOADER_SIZE) >> 1) >> 0) & 0xff));

#else  // Assume remaining boards are DFU, even if the flag isn't set

#    if !(defined(__AVR_ATmega32A__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__) || defined(__AVR_ATtiny85__))  // no USB - maybe BOOTLOADER_BOOTLOADHID instead though?
    UDCON  = 1;
    USBCON = (1 << FRZCLK);  // disable USB
    UCSR1B = 0;
    _delay_ms(5);  // 5 seems to work fine
#    endif

#    ifdef BOOTLOADER_BOOTLOADHID
    // force bootloadHID to stay in bootloader mode, so that it waits
    // for a new firmware to be flashed
    eeprom_write_byte((uint8_t *)1, 0x00);
#    endif

    // watchdog reset
    reset_key = BOOTLOADER_RESET_KEY;
    wdt_enable(WDTO_250MS);
    for (;;)
        ;
#endif
}

/* this runs before main() */
void bootloader_jump_after_watchdog_reset(void) __attribute__((used, naked, section(".init3")));
void bootloader_jump_after_watchdog_reset(void) {
#ifndef BOOTLOADER_HALFKAY
    if ((MCUCSR & (1 << WDRF)) && reset_key == BOOTLOADER_RESET_KEY) {
        reset_key = 0;

        // My custom USBasploader requires this to come up.
        MCUCSR = 0;

        // Seems like Teensy halfkay loader requires clearing WDRF and disabling watchdog.
        MCUCSR &= ~(1 << WDRF);
        wdt_disable();

// This is compled into 'icall', address should be in word unit, not byte.
#    ifdef BOOTLOADER_SIZE
        ((void (*)(void))((FLASH_SIZE - BOOTLOADER_SIZE) >> 1))();
#    else
        asm("ijmp" ::"z"(bootloader_start));
#    endif
    }
#endif
}