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cpu/stm32f4: implement stmclk functions

master
Vincent Dupont 6 years ago
parent
commit
22399d4b06
  1. 126
      cpu/stm32f4/cpu.c
  2. 177
      cpu/stm32f4/stmclk.c

126
cpu/stm32f4/cpu.c

@ -20,28 +20,9 @@
#include <stdint.h>
#include "cpu.h"
#include "periph_conf.h"
#include "stmclk.h"
#include "periph/init.h"
/* Check the source to be used for the PLL */
#if defined(CLOCK_HSI) && defined(CLOCK_HSE)
#error "Only provide one of two CLOCK_HSI/CLOCK_HSE"
#elif CLOCK_HSI
#define CLOCK_CR_SOURCE RCC_CR_HSION
#define CLOCK_CR_SOURCE_RDY RCC_CR_HSIRDY
#define CLOCK_PLL_SOURCE RCC_PLLCFGR_PLLSRC_HSI
#define CLOCK_DISABLE_HSI 0
#elif CLOCK_HSE
#define CLOCK_CR_SOURCE RCC_CR_HSEON
#define CLOCK_CR_SOURCE_RDY RCC_CR_HSERDY
#define CLOCK_PLL_SOURCE RCC_PLLCFGR_PLLSRC_HSE
#define CLOCK_DISABLE_HSI 1
#else
#error "Please provide CLOCK_HSI or CLOCK_HSE in boards/NAME/includes/perhip_cpu.h"
#endif
static void cpu_clock_init(void);
/**
* @brief Initialize the CPU, set IRQ priorities
*/
@ -50,110 +31,7 @@ void cpu_init(void)
/* initialize the Cortex-M core */
cortexm_init();
/* initialize the clock system */
cpu_clock_init();
stmclk_init_sysclk();
/* trigger static peripheral initialization */
periph_init();
}
/**
* @brief Configure the controllers clock system
*
* The clock initialization make the following assumptions:
* - the external HSE clock from an external oscillator is used as base clock
* - the internal PLL circuit is used for clock refinement
*
* Use the following formulas to calculate the needed values:
*
* SYSCLK = ((XTAL_SPEED / CLOCK_PLL_M) * CLOCK_PLL_N) / CLOCK_PLL_P
* USB, SDIO and RNG Clock = ((XTAL_SPEED / CLOCK_PLL_M) * CLOCK_PLL_N) / CLOCK_PLL_Q
*
* The actual used values are specified in the board's `periph_conf.h` file.
*
* NOTE: currently there is not timeout for initialization of PLL and other locks
* -> when wrong values are chosen, the initialization could stall
*/
static void cpu_clock_init(void)
{
/* reset clock configuration register */
RCC->CFGR = 0;
/* disable HSE, CSS and PLL */
RCC->CR &= ~(RCC_CR_HSEON | RCC_CR_HSEBYP | RCC_CR_CSSON | RCC_CR_PLLON);
/* disable all clock interrupts */
RCC->CIR = 0;
/* enable the high speed clock */
RCC->CR |= CLOCK_CR_SOURCE;
/* wait for the high speed clock source to be ready */
while (!(RCC->CR & CLOCK_CR_SOURCE_RDY)) {}
/* setup power module */
/* enable the power module */
periph_clk_en(APB1, RCC_APB1ENR_PWREN);
/* set the voltage scaling to 1 to enable the maximum frequency */
PWR->CR |= PWR_CR_VOS_1;
/* setup the peripheral bus prescalers */
/* set the AHB clock divider */
RCC->CFGR &= ~RCC_CFGR_HPRE;
RCC->CFGR |= CLOCK_AHB_DIV;
/* set the APB2 (high speed) bus clock divider */
RCC->CFGR &= ~RCC_CFGR_PPRE2;
RCC->CFGR |= CLOCK_APB2_DIV;
/* set the APB1 (low speed) bus clock divider */
RCC->CFGR &= ~RCC_CFGR_PPRE1;
RCC->CFGR |= CLOCK_APB1_DIV;
/* configure the PLL */
/* reset PLL config register */
RCC->PLLCFGR = 0;
/* set high speed clock as source for the PLL */
RCC->PLLCFGR |= CLOCK_PLL_SOURCE;
/* set division factor for main PLL input clock */
RCC->PLLCFGR |= (CLOCK_PLL_M & 0x3F);
/* set main PLL multiplication factor for VCO */
RCC->PLLCFGR |= (CLOCK_PLL_N & 0x1FF) << 6;
/* set main PLL division factor for main system clock */
RCC->PLLCFGR |= (((CLOCK_PLL_P & 0x03) >> 1) - 1) << 16;
/* set main PLL division factor for USB OTG FS, SDIO and RNG clocks */
RCC->PLLCFGR |= (CLOCK_PLL_Q & 0x0F) << 24;
/* enable PLL again */
RCC->CR |= RCC_CR_PLLON;
/* wait until PLL is stable */
while(!(RCC->CR & RCC_CR_PLLRDY)) {}
/* configure flash latency */
/* reset flash access control register */
FLASH->ACR = 0;
/* enable instruction cache */
FLASH->ACR |= FLASH_ACR_ICEN;
/* enable data cache */
FLASH->ACR |= FLASH_ACR_DCEN;
/* enable pre-fetch buffer */
// FLASH->ACR |= FLASH_ACR_PRFTEN;
/* set flash latency */
FLASH->ACR &= ~FLASH_ACR_LATENCY;
FLASH->ACR |= CLOCK_FLASH_LATENCY;
/* configure the sysclock and the peripheral clocks */
/* set sysclock to be driven by the PLL clock */
RCC->CFGR &= ~RCC_CFGR_SW;
RCC->CFGR |= RCC_CFGR_SW_PLL;
/* wait for sysclock to be stable */
while (!(RCC->CFGR & RCC_CFGR_SWS_PLL)) {}
#if CLOCK_DISABLE_HSI
/* disable the HSI if we use the HSE */
RCC->CR &= ~(RCC_CR_HSION);
while (RCC->CR & RCC_CR_HSIRDY) {}
#endif
}

177
cpu/stm32f4/stmclk.c

@ -0,0 +1,177 @@
/*
* Copyright (C) 2017 Freie Universität Berlin
* 2017 OTA keys S.A.
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_stm32f4
* @{
*
* @file
* @brief Implementation of STM32 clock configuration
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Vincent Dupont <vincent@otakeys.com>
* @}
*/
#include "cpu.h"
#include "stmclk.h"
#include "periph_conf.h"
/* make sure we have all needed information about the clock configuration */
#ifndef CLOCK_HSE
#error "Please provide CLOCK_HSE in your board's perhip_conf.h"
#endif
#ifndef CLOCK_LSE
#error "Please provide CLOCK_LSE in your board's periph_conf.h"
#endif
/**
* @name PLL configuration
* @{
*/
/* figure out which input to use */
#if (CLOCK_HSE)
#define PLL_IN CLOCK_HSE
#define PLL_SRC RCC_PLLCFGR_PLLSRC_HSE
#else
#define PLL_IN (16000000U) /* HSI fixed @ 16MHz */
#define PLL_SRC RCC_PLLCFGR_PLLSRC_HSI
#endif
#ifndef P
/* we fix P to 2 (so the PLL output equals 2 * CLOCK_CORECLOCK) */
#define P (2U)
#if ((P != 2) && (P != 4) && (P != 6) && (P != 8))
#error "PLL configuration: PLL P value is invalid"
#endif
#endif /* P */
/* the recommended input clock for the PLL should be 2MHz */
#define M (PLL_IN / 2000000U)
#if ((M < 2) || (M > 63))
#error "PLL configuration: PLL M value is out of range"
#endif
/* next we multiply the input freq to 2 * CORECLOCK */
#define N (P * CLOCK_CORECLOCK / 2000000U)
#if ((N < 50) || (N > 432))
#error "PLL configuration: PLL N value is out of range"
#endif
/* finally we need to set Q, so that the USB clock is 48MHz */
#define Q ((P * CLOCK_CORECLOCK) / 48000000U)
#if ((Q * 48000000U) != (P * CLOCK_CORECLOCK))
#error "PLL configuration: USB frequency is not 48MHz"
#endif
/* now we get the actual bitfields */
#define PLL_P (((P / 2) - 1) << RCC_PLLCFGR_PLLP_Pos)
#define PLL_M (M << RCC_PLLCFGR_PLLM_Pos)
#define PLL_N (N << RCC_PLLCFGR_PLLN_Pos)
#define PLL_Q (Q << RCC_PLLCFGR_PLLQ_Pos)
/** @} */
/**
* @name Deduct the needed flash wait states from the core clock frequency
* @{
*/
#define FLASH_WAITSTATES (CLOCK_CORECLOCK / 30000000U)
/** @} */
void stmclk_init_sysclk(void)
{
/* disable any interrupts. Global interrupts could be enabled if this is
* called from some kind of bootloader... */
unsigned is = irq_disable();
RCC->CIR = 0;
/* enable HSI clock for the duration of initialization */
stmclk_enable_hsi();
/* use HSI as system clock while we do any further configuration and
* configure the AHB and APB clock dividers as configure by the board */
RCC->CFGR = (RCC_CFGR_SW_HSI | CLOCK_AHB_DIV |
CLOCK_APB1_DIV | CLOCK_APB2_DIV);
while ((RCC->CFGR & RCC_CFGR_SWS_Msk) != RCC_CFGR_SWS_HSI) {}
/* we enable I+D cashes, pre-fetch, and we set the actual number of
* needed flash wait states */
FLASH->ACR = (FLASH_ACR_ICEN | FLASH_ACR_DCEN | FLASH_ACR_PRFTEN | FLASH_WAITSTATES);
/* disable all active clocks except HSI -> resets the clk configuration */
RCC->CR = (RCC_CR_HSION | RCC_CR_HSITRIM_4);
/* if configured, we need to enable the HSE clock now */
#if (CLOCK_HSE)
RCC->CR |= (RCC_CR_HSEON);
while (!(RCC->CR & RCC_CR_HSERDY)) {}
#endif
/* now we can safely configure and start the PLL */
RCC->PLLCFGR = (PLL_SRC | PLL_M | PLL_N | PLL_P | PLL_Q);
RCC->CR |= (RCC_CR_PLLON);
while (!(RCC->CR & RCC_CR_PLLRDY)) {}
/* now that the PLL is running, we use it as system clock */
RCC->CFGR |= (RCC_CFGR_SW_PLL);
while ((RCC->CFGR & RCC_CFGR_SWS_Msk) != RCC_CFGR_SWS_PLL) {}
stmclk_disable_hsi();
irq_restore(is);
}
void stmclk_enable_hsi(void)
{
RCC->CR |= (RCC_CR_HSION);
while (!(RCC->CR & RCC_CR_HSIRDY)) {}
}
void stmclk_disable_hsi(void)
{
if ((RCC->CFGR & RCC_CFGR_SWS_Msk) != RCC_CFGR_SWS_HSI) {
RCC->CR &= ~(RCC_CR_HSION);
}
}
void stmclk_enable_lfclk(void)
{
/* configure the low speed clock domain (LSE vs LSI) */
#if CLOCK_LSE
/* allow write access to backup domain */
stmclk_bdp_unlock();
/* enable LSE */
RCC->BDCR |= RCC_BDCR_LSEON;
while (!(RCC->BDCR & RCC_BDCR_LSERDY)) {}
/* disable write access to back domain when done */
stmclk_bdp_lock();
#else
RCC->CSR |= RCC_CSR_LSION;
while (!(RCC->CSR & RCC_CSR_LSIRDY)) {}
#endif
}
void stmclk_disable_lfclk(void)
{
#if CLOCK_LSE
stmclk_bdp_unlock();
RCC->BDCR &= ~(RCC_BDCR_LSEON);
stmclk_bdp_lock();
#else
RCC->CSR &= ~(RCC_CSR_LSION);
#endif
}
void stmclk_bdp_unlock(void)
{
periph_clk_en(APB1, RCC_APB1ENR_PWREN);
PWR->CR |= PWR_CR_DBP;
}
void stmclk_bdp_lock(void)
{
PWR->CR &= ~(PWR_CR_DBP);
periph_clk_dis(APB1, RCC_APB1ENR_PWREN);
}
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