rt-thread/libcpu/arm/lpc122x/CMSIS/system_LPC122x.c

/******************************************************************************
 * @file:    system_LPC122x.c
 * @purpose: CMSIS Cortex-M0 Device Peripheral Access Layer Source File
 *           for the NXP LPC122x Device Series 
 * @version: V1.0
 * @date:    26. Nov. 2008
 *----------------------------------------------------------------------------
 *
 * Copyright (C) 2008 ARM Limited. All rights reserved.
 *
 * ARM Limited (ARM) is supplying this software for use with Cortex-M3 
 * processor based microcontrollers.  This file can be freely distributed 
 * within development tools that are supporting such ARM based processors. 
 *
 * THIS SOFTWARE IS PROVIDED "AS IS".  NO WARRANTIES, WHETHER EXPRESS, IMPLIED
 * OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
 * ARM SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR
 * CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
 *
 ******************************************************************************/
#include <stdint.h>
#include "LPC122x.h"

/*
//-------- <<< Use Configuration Wizard in Context Menu >>> ------------------
*/

/*--------------------- Clock Configuration ----------------------------------
//
// <e> Clock Configuration
//   <h> System Controls and Status Register (SCS)
//     <o1.4>    OSCRANGE: Main Oscillator Range Select
//                     <0=>  1 MHz to 20 MHz
//                     <1=> 15 MHz to 24 MHz
//     <e1.5>       OSCEN: Main Oscillator Enable
//     </e>
//   </h>
//
//   <h> Clock Source Select Register (CLKSRCSEL)
//     <o2.0..1>   CLKSRC: PLL Clock Source Selection
//                     <0=> Internal RC oscillator
//                     <1=> Main oscillator
//                     <2=> RTC oscillator
//   </h>
//
//   <e3> PLL0 Configuration (Main PLL)
//     <h> PLL0 Configuration Register (PLL0CFG)
//                     <i> F_cco0 = (2 * M * F_in) / N
//                     <i> F_in must be in the range of 32 kHz to 50 MHz
//                     <i> F_cco0 must be in the range of 275 MHz to 550 MHz
//       <o4.0..14>  MSEL: PLL Multiplier Selection
//                     <6-32768><#-1>
//                     <i> M Value
//       <o4.16..23> NSEL: PLL Divider Selection
//                     <1-256><#-1>
//                     <i> N Value
//     </h>
//   </e>
//
//
//   <h> CPU Clock Configuration Register (CCLKCFG)
//     <o7.0..7>  CCLKSEL: Divide Value for CPU Clock from PLL0
//                     <0-255>
//                     <i> Divide is CCLKSEL + 1. Only 0 and odd values are valid.
//   </h>
//
//
// </e>
*/
#define CLOCK_SETUP           1

#define SYS_PLL_SETUP         1
#define SYS_PLLSRCSEL_Val     0x00000001
#define SYS_PLL_M_Val         0x00000003
#define SYS_PLL_P_Val         0x00000001
#define MAIN_CLKSRCSEL_Val    0x00000003
#define SYS_AHB_DIV_Val       0x01			/* 1 through 255, 0 will disable the output. */

/*
//-------- <<< end of configuration section >>> ------------------------------
*/

/*----------------------------------------------------------------------------
  DEFINES
 *----------------------------------------------------------------------------*/
    
/*----------------------------------------------------------------------------
  Define clocks
 *----------------------------------------------------------------------------*/
#define XTAL        (12000000UL)        /* Oscillator frequency               */
#define OSC_CLK     (      XTAL)        /* Main oscillator frequency          */
#define IRC_OSC     ( 4000000UL)        /* Internal RC oscillator frequency   */
#define WDT_OSC     (  250000UL)        /* WDT oscillator frequency           */

/*----------------------------------------------------------------------------
  Clock Variable definitions
 *----------------------------------------------------------------------------*/
uint32_t ClockSource = IRC_OSC;
uint32_t SystemFrequency = IRC_OSC; /*!< System Clock Frequency (Core Clock)  */
uint32_t SystemAHBFrequency = IRC_OSC;

/**
 * Misc. clock generation modules
 *
 * @param  none
 * @return none
 *
 * @brief  Setup the microcontroller system.
 *         Initialize the System and update the SystemFrequency variable.
 */
void SystemPLL_Setup ( void )
{
  uint32_t regVal;

  LPC_SYSCON->PRESETCTRL  &= ~0x00008000;		  /* Disable 1-Cycle Read Mode */

  ClockSource = OSC_CLK;
  LPC_SYSCON->SYSPLLCLKSEL = SYS_PLLSRCSEL_Val;    /* Select system OSC */
  LPC_SYSCON->SYSPLLCLKUEN = 0x01;                 /* Update clock source */
  LPC_SYSCON->SYSPLLCLKUEN = 0x00;                 /* toggle Update register once */
  LPC_SYSCON->SYSPLLCLKUEN = 0x01;
  while ( !(LPC_SYSCON->SYSPLLCLKUEN & 0x01) ); /* Wait until updated */

  regVal = LPC_SYSCON->SYSPLLCTRL;
  regVal &= ~0x1FF;
  LPC_SYSCON->SYSPLLCTRL = (regVal | (SYS_PLL_P_Val<<5) | SYS_PLL_M_Val);
  
  /* Enable main system clock, main system clock bit 7 in PDRUNCFG. */
  LPC_SYSCON->PDRUNCFG &= ~(0x1<<7);
  while ( !(LPC_SYSCON->SYSPLLSTAT & 0x01) );	/* Wait until it's locked */

  LPC_SYSCON->MAINCLKSEL = MAIN_CLKSRCSEL_Val;	/* Select PLL clock output */
  LPC_SYSCON->MAINCLKUEN = 0x01;		/* Update MCLK clock source */
  LPC_SYSCON->MAINCLKUEN = 0x00;		/* Toggle update register once */
  LPC_SYSCON->MAINCLKUEN = 0x01;
  while ( !(LPC_SYSCON->MAINCLKUEN & 0x01) );	/* Wait until updated */

  LPC_SYSCON->SYSAHBCLKDIV = SYS_AHB_DIV_Val;	/* SYS AHB clock, 0 will disable output */

#if SYS_PLL_SETUP
  /* If the SYS PLL output is selected as the main clock. Even if SYS PLL is 
  configured and enabled, it doesn't mean it will be selected as the MAIN clock 
  source. Be careful with MAINCLKSEL value. If SYS PLL is not selected, System
  Frequence should be the same as either IRC, external OSC(SYS), or WDT OSC clock. */
  SystemFrequency = ClockSource * (SYS_PLL_M_Val+1);
#else
  SystemFrequency = ClockSource;
#endif
  SystemAHBFrequency = (uint32_t)(SystemFrequency/SYS_AHB_DIV_Val);
  return;
}

/**
 * Initialize the system
 *
 * @param  none
 * @return none
 *
 * @brief  Setup the microcontroller system.
 *         Initialize the System and update the SystemFrequency variable.
 */
void SystemInit (void)
{
  uint32_t i;

#ifdef __DEBUG_RAM    
  LPC_SYSCON->SYSMEMREMAP = 0x1;		/* remap to internal RAM */ 
#else
#ifdef __DEBUG_FLASH    
  LPC_SYSCON->SYSMEMREMAP = 0x2;		/* remap to internal flash */
#endif
#endif

#if 1
  /* First, below lines are for debugging only. For future release, WDT is 
  enabled by bootrom, thus, unless a feed to WDT continuously, or WDT timeout 
  will occur. If it's happen, WDT interrupt will be pending until a INT_CLEAR
  is applied. Below logic is to prevent system from going to the WDT interrupt
  during debugging. 
  Second, all the peripheral clocks seem to be enabled by bootrom, it's
  not consistent with the UM. In below lines, only SYS, ROM, RAM, FLASHREG,
  FLASHARRAY, and I2C are enabled per UM dated July 14th. */
  LPC_WDT->MOD = 0x00;  
  LPC_WDT->FEED = 0xAA;		/* Feeding sequence */
  LPC_WDT->FEED = 0x55;
  
  NVIC->ICPR[0] |= 0xFFFFFFFF; 
  LPC_SYSCON->SYSAHBCLKCTRL = 0x00000001F;
#endif   

#if (CLOCK_SETUP)                       /* Clock Setup */
  /* bit 0 default is crystal bypass, 
  bit1 0=0~20Mhz crystal input, 1=15~50Mhz crystal input. */
  LPC_SYSCON->SYSOSCCTRL = 0x00;

  /* main system OSC run is cleared, bit 5 in PDRUNCFG register */
  LPC_SYSCON->PDRUNCFG &= ~(0x1<<5);
  /* Wait 200us for OSC to be stablized, no status 
  indication, dummy wait. */
  for ( i = 0; i < 0x100; i++ );

#if (SYS_PLL_SETUP)
  SystemPLL_Setup();  
#endif

#endif	/* endif CLOCK_SETUP */

  /* System clock to the IOCON needs to be enabled or
  most of the I/O related peripherals won't work. */
  LPC_SYSCON->SYSAHBCLKCTRL |= (1<<16);
  return;
}