uf2-stm32f/bl.c

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 *
 *   Copyright (c) 2012-2014 PX4 Development Team. All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *    used to endorse or promote products derived from this software
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/**
 * @file bl.c
 *
 * Common bootloader logic.
 *
 * Aside from the header includes below, this file should have no board-specific logic.
 */
#include "hw_config.h"

#include <inttypes.h>
#include <stdlib.h>

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/flash.h>

#include <libopencm3/cm3/scb.h>
#include <libopencm3/cm3/systick.h>

#include "bl.h"
#include "usb.h"

inline void cinit(void *config, uint8_t interface) {
    if (interface == USB) {
        return usb_cinit();
    }
}

inline void cfini(void) {
    usb_cfini();
}

static enum led_state { LED_BLINK, LED_ON, LED_OFF } _led_state;

void sys_tick_handler(void);

static void do_jump(uint32_t stacktop, uint32_t entrypoint) {
    asm volatile("msr msp, %0	\n"
                 "bx	%1	\n"
                 :
                 : "r"(stacktop), "r"(entrypoint)
                 :);

    // just to keep noreturn happy
    for (;;)
        ;
}

void jump_to_app() {
    const uint32_t *app_base = (const uint32_t *)APP_LOAD_ADDRESS;

    /*
     * We refuse to program the first word of the app until the upload is marked
     * complete by the host.  So if it's not 0xffffffff, we should try booting it.
     */
    if (app_base[0] == 0xffffffff) {
        return;
    }

    // first word is stack base - needs to be in RAM region and word-aligned
    if ((app_base[0] & 0xff000003) != 0x20000000) {
        return;
    }

    /*
     * The second word of the app is the entrypoint; it must point within the
     * flash area (or we have a bad flash).
     */
    if (app_base[1] < APP_LOAD_ADDRESS) {
        return;
    }

    if (app_base[1] >= (APP_LOAD_ADDRESS + BOARD_FLASH_SIZE)) {
        return;
    }

    /* just for paranoia's sake */
    flash_lock();

    /* kill the systick interrupt */
    systick_interrupt_disable();
    systick_counter_disable();

    /* deinitialise the interface */
    cfini();

    /* reset the clock */
    clock_deinit();

    /* deinitialise the board */
    board_deinit();

    /* switch exception handlers to the application */
    SCB_VTOR = APP_LOAD_ADDRESS;

    /* extract the stack and entrypoint from the app vector table and go */
    do_jump(app_base[0], app_base[1]);
}

volatile unsigned timer[NTIMERS];
void ghostfat_1ms();

static int16_t blOn, blDl = 40, blDir = 1;
static int ledToBlink = LED_BOOTLOADER;

void sys_tick_handler(void) {
    unsigned i;

    ghostfat_1ms();

    for (i = 0; i < NTIMERS; i++)
        if (timer[i] > 0) {
            timer[i]--;
        }

    if ((_led_state == LED_BLINK) && (timer[TIMER_LED] == 0)) {
        if (blOn) {
            led_off(ledToBlink);
            timer[TIMER_LED] = blDl / 3;
            blDl += blDir;
            if (blDl > 60)
                blDir = -1;
            else if (blDl < 20)
                blDir = 1;
        } else {
            led_on(ledToBlink);
            timer[TIMER_LED] = 1;
        }
        blOn = !blOn;
    }
}

void delay(unsigned msec) {
    timer[TIMER_DELAY] = msec;

    while (timer[TIMER_DELAY] > 0)
        ;
}

static void led_set(enum led_state state) {
    _led_state = state;

    switch (state) {
    case LED_OFF:
        led_off(LED_BOOTLOADER);
        break;

    case LED_ON:
        led_on(LED_BOOTLOADER);
        break;

    case LED_BLINK:
        /* restart the blink state machine ASAP */
        timer[TIMER_LED] = 0;
        break;
    }
}

#if 0
static uint32_t crc32(const uint8_t *src, unsigned len, unsigned state) {
    static uint32_t crctab[256];

    /* check whether we have generated the CRC table yet */
    /* this is much smaller than a static table */
    if (crctab[1] == 0) {
        for (unsigned i = 0; i < 256; i++) {
            uint32_t c = i;

            for (unsigned j = 0; j < 8; j++) {
                if (c & 1) {
                    c = 0xedb88320U ^ (c >> 1);

                } else {
                    c = c >> 1;
                }
            }

            crctab[i] = c;
        }
    }

    for (unsigned i = 0; i < len; i++) {
        state = crctab[(state ^ src[i]) & 0xff] ^ (state >> 8);
    }

    return state;
}
#endif

void usb_enumerated() {
    timer[TIMER_BL_WAIT] = hf2_mode ? 10 * 1000 : 24 * 3600 * 1000;
    if (ledToBlink == LED_BOOTLOADER) {
        led_off(ledToBlink);
        ledToBlink = LED_ACTIVITY;
    }
}

int screen_on;

void start_systick() {
    /* (re)start the timer system */
    systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
    systick_set_reload(board_info.systick_mhz * 1000); /* 1ms tick, magic number */
    systick_interrupt_enable();
    systick_counter_enable();
}

void bootloader(unsigned timeout) {
    start_systick();
    
    /* if we are working with a timeout, start it running */
    if (timeout) {
        timer[TIMER_BL_WAIT] = timeout;
    }

    /* make the LED blink while we are idle */
    led_set(LED_BLINK);
    led_off(LED_ACTIVITY);

    while (true) {
        if (timeout && !timer[TIMER_BL_WAIT]) {
            return;
        }

        if (hasScreen() &&
            (!timeout || timer[TIMER_BL_WAIT] > 10000 || hf2_mode)) {
            if (!screen_on) {
                screen_on = 1;
                screen_init();
                if (hf2_mode)
                    draw_hf2();
                else
                    draw_drag();
            }
        }

        usb_callback();
    }
}