#include <proxmark3.h>

struct common_area common_area __attribute__((section(".commonarea")));
unsigned int start_addr, end_addr, bootrom_unlocked; 
extern char _bootrom_start, _bootrom_end, _flash_start, _flash_end;

static void ConfigClocks(void)
{
    // we are using a 16 MHz crystal as the basis for everything
    // slow clock runs at 32Khz typical regardless of crystal

    // enable system clock and USB clock
    PMC_SYS_CLK_ENABLE = PMC_SYS_CLK_PROCESSOR_CLK | PMC_SYS_CLK_UDP_CLK;

	// enable the clock to the following peripherals
    PMC_PERIPHERAL_CLK_ENABLE =
        (1<<PERIPH_PIOA) |
        (1<<PERIPH_ADC) |
        (1<<PERIPH_SPI) |
        (1<<PERIPH_SSC) |
        (1<<PERIPH_PWMC) |
        (1<<PERIPH_UDP);

	// worst case scenario, with 16Mhz xtal startup delay is 14.5ms
	// with a slow clock running at it worst case (max) frequency of 42khz
	// max startup delay = (14.5ms*42k)/8 = 76 = 0x4C round up to 0x50

	// enable main oscillator and set startup delay
    PMC_MAIN_OSCILLATOR = PMC_MAIN_OSCILLATOR_ENABLE |
        PMC_MAIN_OSCILLATOR_STARTUP_DELAY(0x50);

	// wait for main oscillator to stabilize
	while ( !(PMC_INTERRUPT_STATUS & PMC_MAIN_OSCILLATOR_STABILIZED) )
		;

    // minimum PLL clock frequency is 80 MHz in range 00 (96 here so okay)
    // frequency is crystal * multiplier / divisor = 16Mhz * 12 / 2 = 96Mhz
    PMC_PLL = PMC_PLL_DIVISOR(2) | PMC_PLL_COUNT_BEFORE_LOCK(0x50) |
        PMC_PLL_FREQUENCY_RANGE(0) | PMC_PLL_MULTIPLIER(12) |
        PMC_PLL_USB_DIVISOR(1);

	// wait for PLL to lock
	while ( !(PMC_INTERRUPT_STATUS & PMC_MAIN_OSCILLATOR_PLL_LOCK) )
		;

	// we want a master clock (MCK) to be PLL clock / 2 = 96Mhz / 2 = 48Mhz
	// as per datasheet, this register must be programmed in two operations
	// when changing to PLL, program the prescaler first then the source
    PMC_MASTER_CLK = PMC_CLK_PRESCALE_DIV_2;

	// wait for main clock ready signal
	while ( !(PMC_INTERRUPT_STATUS & PMC_MAIN_OSCILLATOR_MCK_READY) )
		;

	// set the source to PLL
    PMC_MASTER_CLK = PMC_CLK_SELECTION_PLL_CLOCK | PMC_CLK_PRESCALE_DIV_2;

	// wait for main clock ready signal
	while ( !(PMC_INTERRUPT_STATUS & PMC_MAIN_OSCILLATOR_MCK_READY) )
		;
}

static void Fatal(void)
{
    for(;;);
}

void UsbPacketReceived(BYTE *packet, int len)
{
    int i, dont_ack=0;
    UsbCommand *c = (UsbCommand *)packet;
    volatile DWORD *p;

    if(len != sizeof(*c)) {
        Fatal();
    }

    switch(c->cmd) {
        case CMD_DEVICE_INFO:
            dont_ack = 1;
            c->cmd = CMD_DEVICE_INFO;
            c->ext1 = DEVICE_INFO_FLAG_BOOTROM_PRESENT | DEVICE_INFO_FLAG_CURRENT_MODE_BOOTROM | 
                DEVICE_INFO_FLAG_UNDERSTANDS_START_FLASH;
            if(common_area.flags.osimage_present) c->ext1 |= DEVICE_INFO_FLAG_OSIMAGE_PRESENT;
            UsbSendPacket(packet, len);
            break;

        case CMD_SETUP_WRITE:
            /* The temporary write buffer of the embedded flash controller is mapped to the
             * whole memory region, only the last 8 bits are decoded.
             */
            p = (volatile DWORD *)&_flash_start;
            for(i = 0; i < 12; i++) {
                p[i+c->ext1] = c->d.asDwords[i];
            }
            break;

        case CMD_FINISH_WRITE:
            p = (volatile DWORD *)&_flash_start;
            for(i = 0; i < 4; i++) {
                p[i+60] = c->d.asDwords[i];
            }

            /* Check that the address that we are supposed to write to is within our allowed region */
            if( ((c->ext1+FLASH_PAGE_SIZE_BYTES-1) >= end_addr) || (c->ext1 < start_addr) ) {
                /* Disallow write */
                dont_ack = 1;
                c->cmd = CMD_NACK;
                UsbSendPacket(packet, len);
            } else {
                /* Translate address to flash page and do flash, update here for the 512k part */
                MC_FLASH_COMMAND = MC_FLASH_COMMAND_KEY |
                    MC_FLASH_COMMAND_PAGEN((c->ext1-(int)&_flash_start)/FLASH_PAGE_SIZE_BYTES) |
                    FCMD_WRITE_PAGE;
            }
            while(!(MC_FLASH_STATUS & MC_FLASH_STATUS_READY))
                ;
            break;

        case CMD_HARDWARE_RESET:
            USB_D_PLUS_PULLUP_OFF();
            RSTC_CONTROL = RST_CONTROL_KEY | RST_CONTROL_PROCESSOR_RESET;
            break;
        
        case CMD_START_FLASH:
            if(c->ext3 == START_FLASH_MAGIC) bootrom_unlocked = 1;
            else bootrom_unlocked = 0;
            {
                int prot_start = (int)&_bootrom_start;
                int prot_end = (int)&_bootrom_end;
                int allow_start = (int)&_flash_start;
                int allow_end = (int)&_flash_end;
                int cmd_start = c->ext1;
                int cmd_end = c->ext2;
                
                /* Only allow command if the bootrom is unlocked, or the parameters are outside of the protected
                 * bootrom area. In any case they must be within the flash area.
                 */
                if( (bootrom_unlocked || ((cmd_start >= prot_end) || (cmd_end < prot_start)))
                    && (cmd_start >= allow_start) && (cmd_end <= allow_end) ) {
                    start_addr = cmd_start;
                    end_addr = cmd_end;
                } else {
                    start_addr = end_addr = 0;
                    dont_ack = 1;
                    c->cmd = CMD_NACK;
                    UsbSendPacket(packet, len);
                }
            }
            break;
        
        default:
            Fatal();
            break;
    }

    if(!dont_ack) {
        c->cmd = CMD_ACK;
        UsbSendPacket(packet, len);
    }
}

static void flash_mode(int externally_entered)
{
	start_addr = 0;
	end_addr = 0;
	bootrom_unlocked = 0;
	
	UsbStart();
	for(;;) {
		WDT_HIT();
		
		UsbPoll(TRUE);
		
		if(!externally_entered && !BUTTON_PRESS()) {
			/* Perform a reset to leave flash mode */
			USB_D_PLUS_PULLUP_OFF();
			LED_B_ON();
			RSTC_CONTROL = RST_CONTROL_KEY | RST_CONTROL_PROCESSOR_RESET;
			for(;;);
		}
		if(externally_entered && BUTTON_PRESS()) {
			/* Let the user's button press override the automatic leave */
			externally_entered = 0;
		}
	}
}

extern char _osimage_entry;
void BootROM(void)
{
    //------------
    // First set up all the I/O pins; GPIOs configured directly, other ones
    // just need to be assigned to the appropriate peripheral.

    // Kill all the pullups, especially the one on USB D+; leave them for
    // the unused pins, though.
    PIO_NO_PULL_UP_ENABLE =     (1 << GPIO_USB_PU)          |
                                (1 << GPIO_LED_A)           |
                                (1 << GPIO_LED_B)           |
                                (1 << GPIO_LED_C)           |
                                (1 << GPIO_LED_D)           |
                                (1 << GPIO_FPGA_DIN)        |
                                (1 << GPIO_FPGA_DOUT)       |
                                (1 << GPIO_FPGA_CCLK)       |
                                (1 << GPIO_FPGA_NINIT)      |
                                (1 << GPIO_FPGA_NPROGRAM)   |
                                (1 << GPIO_FPGA_DONE)       |
                                (1 << GPIO_MUXSEL_HIPKD)    |
                                (1 << GPIO_MUXSEL_HIRAW)    |
                                (1 << GPIO_MUXSEL_LOPKD)    |
                                (1 << GPIO_MUXSEL_LORAW)    |
                                (1 << GPIO_RELAY)	        |
                                (1 << GPIO_NVDD_ON);
                                // (and add GPIO_FPGA_ON)
	// These pins are outputs
    PIO_OUTPUT_ENABLE =         (1 << GPIO_LED_A)           |
                                (1 << GPIO_LED_B)           |
                                (1 << GPIO_LED_C)           |
                                (1 << GPIO_LED_D)           |
                                (1 << GPIO_RELAY)	        |
                                (1 << GPIO_NVDD_ON);
	// PIO controls the following pins
    PIO_ENABLE =                (1 << GPIO_USB_PU)          |
                                (1 << GPIO_LED_A)           |
                                (1 << GPIO_LED_B)           |
                                (1 << GPIO_LED_C)           |
                                (1 << GPIO_LED_D);

    USB_D_PLUS_PULLUP_OFF();
    LED_D_OFF();
    LED_C_ON();
    LED_B_OFF();
    LED_A_OFF();
    
    // if 512K FLASH part - TODO make some defines :)
    if ((DBGU_CIDR | 0xf00) == 0xa00) {
	    MC_FLASH_MODE0 = MC_FLASH_MODE_FLASH_WAIT_STATES(1) |
	    MC_FLASH_MODE_MASTER_CLK_IN_MHZ(0x48);
	    MC_FLASH_MODE1 = MC_FLASH_MODE_FLASH_WAIT_STATES(1) |
	    MC_FLASH_MODE_MASTER_CLK_IN_MHZ(0x48);
    } else {
	    MC_FLASH_MODE0 = MC_FLASH_MODE_FLASH_WAIT_STATES(0) |
	    MC_FLASH_MODE_MASTER_CLK_IN_MHZ(48);
    }
    
    // Initialize all system clocks
    ConfigClocks();
    
    LED_A_ON();
    
    int common_area_present = 0;
    switch(RSTC_STATUS & RST_STATUS_TYPE_MASK) {
    case RST_STATUS_TYPE_WATCHDOG:
    case RST_STATUS_TYPE_SOFTWARE:
    case RST_STATUS_TYPE_USER:
	    /* In these cases the common_area in RAM should be ok, retain it if it's there */
	    if(common_area.magic == COMMON_AREA_MAGIC && common_area.version == 1) {
		    common_area_present = 1;
	    }
	    break;
    default: /* Otherwise, initialize it from scratch */
	    break;
    }
    
    if(!common_area_present){
	    /* Common area not ok, initialize it */
	    int i; for(i=0; i<sizeof(common_area); i++) { /* Makeshift memset, no need to drag util.c into this */
		    ((char*)&common_area)[i] = 0;
	    }
	    common_area.magic = COMMON_AREA_MAGIC;
	    common_area.version = 1;
	    common_area.flags.bootrom_present = 1;
    }
    
    common_area.flags.bootrom_present = 1;
    if(common_area.command == COMMON_AREA_COMMAND_ENTER_FLASH_MODE) {
	    common_area.command = COMMON_AREA_COMMAND_NONE;
	    flash_mode(1);
    } else if(BUTTON_PRESS()) {
	    flash_mode(0);
    } else {
	    // jump to Flash address of the osimage entry point (LSBit set for thumb mode)
	    asm("bx %0\n" : : "r" ( ((int)&_osimage_entry) | 0x1 ) );
    }
}