/*
 * Copyright (c) 2014-2015, Freescale Semiconductor, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * o Redistributions of source code must retain the above copyright notice, this list
 *   of conditions and the following disclaimer.
 *
 * o Redistributions in binary form must reproduce the above copyright notice, this
 *   list of conditions and the following disclaimer in the documentation and/or
 *   other materials provided with the distribution.
 *
 * o Neither the name of Freescale Semiconductor, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "bootloader_common.h"
#include "bootloader/bl_context.h"
#include "property/property.h"
#include "fsl_device_registers.h"
#include "utilities/fsl_assert.h"

////////////////////////////////////////////////////////////////////////////////
// Definitions
////////////////////////////////////////////////////////////////////////////////

// Clock mode types
typedef enum _target_clock_mode
{
    kClockMode_FEI = 0,
    kClockMode_FEE = 1,
    kClockMode_Default = kClockMode_FEI,
} target_clock_mode_t;

////////////////////////////////////////////////////////////////////////////////
// Prototypes
////////////////////////////////////////////////////////////////////////////////

// This function implements clock mode switch between FEI and PEE mode used in this bootloader
void clock_mode_switch(const target_clock_mode_t currentMode, const target_clock_mode_t expectedMode);

////////////////////////////////////////////////////////////////////////////////
// Code
////////////////////////////////////////////////////////////////////////////////

// See bootloader_common.h for documentation on this function.
void configure_clocks(bootloader_clock_option_t option)
{
#if BL_TARGET_FLASH

    static target_clock_mode_t s_currentClockMode = kClockMode_FEI;
    static uint32_t s_defaultClockDivider;

    if (option == kClockOption_EnterBootloader)
    {
        s_defaultClockDivider = SIM->CLKDIV1;

        // General procedure to be implemented:
        // 1. Read clock flags and divider from bootloader config in property store
        bootloader_configuration_data_t *config = &g_bootloaderContext.propertyInterface->store->configurationData;
        uint8_t options = config->clockFlags;

        // Check if the USB HID peripheral is enabled. If it is enabled, we always
        // use the 48MHz IRC.
        bool isUsbEnabled = config->enabledPeripherals & kPeripheralType_USB_HID;

        // 2. If NOT High Speed and USB isn't enabled, do nothing (use reset clock config)
        if ((options & kClockFlag_HighSpeed) && (!isUsbEnabled))
        {
            // Get actual Core clock.
            SystemCoreClock =
                kDefaultClock / (((SIM->CLKDIV1 & SIM_CLKDIV1_OUTDIV1_MASK) >> SIM_CLKDIV1_OUTDIV1_SHIFT) + 1);

            // High speed flag is set (meaning disabled), so just use default clocks.
            return;
        }

        // 3. Set OUTDIV1 based on divider in config. OUTDIV4 starts out at /1.
        // The divider values are masked by the maximum bits per divider.
        uint32_t div1 = ((~config->clockDivider) & (SIM_CLKDIV1_OUTDIV1_MASK >> SIM_CLKDIV1_OUTDIV1_SHIFT)) + 1;

        // 4. Get MCGOUTCLK
        uint32_t McgOutClk = kHIRC;

        // 5. Keep core clock up kMinCoreClockWithUsbSupport if usb is supported.
        uint32_t freq = McgOutClk;
        // If USB is enabled, the CPU clock must not be allowed to go below 20 MHz
        if (isUsbEnabled)
        {
            while ((freq / div1) < kMinCoreClockWithUsbSupport)
            {
                --div1;
            }
        }

        // 6. Keep core clock below kMaxCoreClock
        while ((freq / div1) > kMaxCoreClock)
        {
            ++div1;
        }

        assert((div1 >= kDivider_Min) && (div1 <= kDivider_Max));

        uint32_t div2 = div1;
        uint32_t div4 = div1;

        // 7. Keep bus freq below max.
        //
        // The bus clock is divided by OUTDIV2:
        //      MCGOUTCLK -> OUTDIV2 -> bus_clk
        freq = McgOutClk;
        while ((freq / div2) > kMaxBusClock)
        {
            // Increase bus clock divider.
            ++div2;
        }
        assert((div2 >= kDivider_Min) && (div2 <= kDivider_Max));

        // 8. Keep flash freq below max.
        //
        // The flash clock is diveded by OUTDIV4:
        //      MCGOUTCLK -> OUTDIV4 ->flash_clk
        freq = McgOutClk;
        while ((freq / div4) > kMaxFlashClock)
        {
            // Increase bus/flash clock divider.
            ++div4;
        }
        assert((div4 >= kDivider_Min) && (div4 <= kDivider_Max));

        if ((div1 == 1) && ((div2 > 8) || (div4 > 8)))
        {
            return;
        }

        // 9. Now set the dividers
        SIM->CLKDIV1 = SIM_CLKDIV1_OUTDIV1(div1 - 1) | SIM_CLKDIV1_OUTDIV2(div2 - 1) |
                       SIM_CLKDIV1_OUTDIV4(div4 - 1); /* Update system prescalers */

        // 10. Update SystemCoreClock global.
        SystemCoreClock = McgOutClk / div1;

        clock_mode_switch(s_currentClockMode, kClockMode_FEE);
        s_currentClockMode = kClockMode_FEE;
    }
    else if (option == kClockOption_ExitBootloader)
    {
        // Restore from FEE mode to FEI mode
        clock_mode_switch(s_currentClockMode, kClockMode_FEI);

        // Restore clock divider
        SIM->CLKDIV1 = s_defaultClockDivider;
    }

#endif // BL_TARGET_FLASH
}

void clock_mode_switch(const target_clock_mode_t currentMode, const target_clock_mode_t expectedMode)
{
    // Note: here only implements clock switch between FEI and FEE,
    // The other modes are not supported.
    assert(currentMode == kClockMode_FEE || currentMode == kClockMode_FEI);
    assert(expectedMode == kClockMode_FEE || expectedMode == kClockMode_FEI);

    if (currentMode == expectedMode)
    {
        return;
    }

    if (expectedMode == kClockMode_FEE)
    {
        uint8_t tmp;
        /* Switch to FEE mode */
        tmp = MCG->C2;
        tmp &= (uint8_t)~MCG_C2_RANGE_MASK;
        tmp |= MCG_C2_RANGE(2);
        MCG->C2 = tmp; /* MCG_C2: RANGE = 2 */

        tmp = MCG->C1;
        tmp &= (uint8_t) ~(MCG_C1_FRDIV_MASK | MCG_C1_IREFS_MASK);
        tmp |= MCG_C1_FRDIV(6);
        MCG->C1 = tmp; // FRDIV=6, RANGE=2, divide IRC48M with 1280, switch to external reference clock.

        tmp = MCG->C4;
        tmp &= (uint8_t)~MCG_C4_DRST_DRS_MASK;
        tmp |= MCG_C4_DRST_DRS(1);
        MCG->C4 = tmp; // Multiply with 1280, MCGOUTCLK is 48Mhz

        tmp = MCG->C7;
        tmp &= (uint8_t)~MCG_C7_OSCSEL_MASK;
        tmp |= MCG_C7_OSCSEL(2);
        MCG->C7 = tmp; // Select IRC48M as Oscillator.

        while (MCG->S & MCG_S_IREFST_MASK)
            ; // Wait until external reference clock is ready.
    }
    else if (expectedMode == kClockMode_FEI)
    {
        MCG->C1 |= MCG_C1_IREFS_MASK; // Switch to internal reference clock.
        while (!(MCG->S & MCG_S_IREFST_MASK))
            ; // Wait until internal reference clock is ready.

        // Restore registers to default value out of reset.
        MCG->C1 = 0x04U;
        MCG->C2 = 0x80U;

        MCG->C4 &= (uint8_t)MCG_C4_DRST_DRS_MASK;
        MCG->C7 = 0;
    }
}

////////////////////////////////////////////////////////////////////////////////
// EOF
////////////////////////////////////////////////////////////////////////////////