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/*******************************************************************************
* Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
*
* 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 MAXIM INTEGRATED 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.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************
*/
#include "cmsis.h"
#include "gpio_regs.h"
#include "clkman_regs.h"
/* Application developer should override where necessary with different external HFX source */
#ifndef __SYSTEM_HFX
#define __SYSTEM_HFX 24000000
#endif
//******************************************************************************
// This function will get called early in system initialization
void low_level_init(void)
{
/* wait for the RO to stabilize */
while (!(MXC_CLKMAN->intfl & MXC_F_CLKMAN_INTFL_RING_STABLE));
/* Configure and enable the oscillator */
if (!(MXC_CLKMAN->clk_config & MXC_F_CLKMAN_CLK_CONFIG_HFX_ENABLE)) {
MXC_CLKMAN->clk_config = (0x4 << MXC_F_CLKMAN_CLK_CONFIG_HFX_GM_ADJUST_POS);
/* Enable the external crystal */
MXC_CLKMAN->clk_config |= MXC_F_CLKMAN_CLK_CONFIG_HFX_ENABLE;
}
/* Wait for external crystal to stabilize */
for (volatile int waitcnt = 0; waitcnt < 0x4000; waitcnt++); // 0x4000 ~10ms 0x10000 ~35ms, 0x20000 ~75ms
/* Configure the PLL */
uint32_t clk_config = MXC_CLKMAN->clk_config;
clk_config = (clk_config & ~MXC_F_CLKMAN_CLK_CONFIG_PLL_INPUT_SELECT) | (MXC_E_CLKMAN_PLL_INPUT_SELECT_HFX << MXC_F_CLKMAN_CLK_CONFIG_PLL_INPUT_SELECT_POS);
#if (__SYSTEM_HFX == 8000000)
clk_config = (clk_config & ~MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT) | (MXC_E_CLKMAN_PLL_DIVISOR_SELECT_8MHZ << MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT_POS);
#elif (__SYSTEM_HFX == 12000000)
clk_config = (clk_config & ~MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT) | (MXC_E_CLKMAN_PLL_DIVISOR_SELECT_12MHZ << MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT_POS);
#elif (__SYSTEM_HFX == 24000000)
clk_config = (clk_config & ~MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT) | (MXC_E_CLKMAN_PLL_DIVISOR_SELECT_24MHZ << MXC_F_CLKMAN_CLK_CONFIG_PLL_DIVISOR_SELECT_POS);
#else
#error Invalid __SYSTEM_HFX setting
#endif
clk_config |= MXC_F_CLKMAN_CLK_CONFIG_PLL_8MHZ_ENABLE;
clk_config &= ~MXC_F_CLKMAN_CLK_CONFIG_PLL_BYPASS;
clk_config = (clk_config & ~MXC_F_CLKMAN_CLK_CONFIG_PLL_STABILITY_COUNT) | (MXC_E_CLKMAN_STABILITY_COUNT_2_13_CLKS << MXC_F_CLKMAN_CLK_CONFIG_PLL_STABILITY_COUNT_POS);
MXC_CLKMAN->clk_config = clk_config;
/* Enable the PLL and wait for stable */
MXC_CLKMAN->clk_config |= (MXC_F_CLKMAN_CLK_CONFIG_PLL_ENABLE | MXC_F_CLKMAN_CLK_CONFIG_PLL_RESET_N);
while (!(MXC_CLKMAN->intfl & MXC_F_CLKMAN_INTFL_PLL_STABLE));
/* Switch to the PLL */
MXC_CLKMAN->clk_ctrl = (MXC_CLKMAN->clk_ctrl & ~MXC_F_CLKMAN_CLK_CTRL_SYSTEM_SOURCE_SELECT) |
((MXC_E_CLKMAN_SYSTEM_SOURCE_SELECT_PLL_48MHZ_DIV_2 << MXC_F_CLKMAN_CLK_CTRL_SYSTEM_SOURCE_SELECT_POS));
}
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