Merge pull request #7159 from OTAkeys/pr/stmclk_f2

cpu/stm32f2: implement stmclk interface for stm32f2

boards/nucleo144-f207/include/periph_conf.h

@@ -31,22 +31,21 @@ extern "C" {
  * @name    Clock system configuration
  * @{
  */
-#define CLOCK_HSE           (8000000U)          /* external oscillator */
-#define CLOCK_CORECLOCK     (120000000U)        /* desired core clock frequency */
-
-/* the actual PLL values are automatically generated */
-#define CLOCK_PLL_M         (CLOCK_HSE / 1000000)
-#define CLOCK_PLL_N         ((CLOCK_CORECLOCK / 1000000) * 2)
-#define CLOCK_PLL_P         (2U)
-#define CLOCK_PLL_Q         (CLOCK_PLL_N / 48)
-#define CLOCK_AHB_DIV       RCC_CFGR_HPRE_DIV1
-#define CLOCK_APB1_DIV      RCC_CFGR_PPRE1_DIV4
-#define CLOCK_APB2_DIV      RCC_CFGR_PPRE2_DIV2
-#define CLOCK_FLASH_LATENCY FLASH_ACR_LATENCY_5WS
-
-/* bus clocks for simplified peripheral initialization, UPDATE MANUALLY! */
+/* 0: no external high speed crystal available
+ * else: actual crystal frequency [in Hz] */
+#define CLOCK_HSE           (8000000U)
+/* 0: no external low speed crystal available,
+ * 1: external crystal available (always 32.768kHz) */
+#define CLOCK_LSE           (1)
+/* give the target core clock (HCLK) frequency [in Hz],
+ * maximum: 120MHz */
+#define CLOCK_CORECLOCK     (120000000U)
+/* peripheral clock setup */
+#define CLOCK_AHB_DIV       RCC_CFGR_HPRE_DIV1      /* min 25MHz */
 #define CLOCK_AHB           (CLOCK_CORECLOCK / 1)
+#define CLOCK_APB1_DIV      RCC_CFGR_PPRE1_DIV4     /* max 30MHz */
 #define CLOCK_APB1          (CLOCK_CORECLOCK / 4)
+#define CLOCK_APB2_DIV      RCC_CFGR_PPRE2_DIV2     /* max 60MHz */
 #define CLOCK_APB2          (CLOCK_CORECLOCK / 2)
 /** @} */
 

cpu/stm32f2/cpu.c

@@ -18,108 +18,15 @@
  */
 
 #include "cpu.h"
-#include "periph_conf.h"
+#include "stmclk.h"
 #include "periph/init.h"
 
-#ifdef HSI_VALUE
-# define RCC_CR_SOURCE          RCC_CR_HSION
-# define RCC_CR_SOURCE_RDY      RCC_CR_HSIRDY
-# define RCC_PLL_SOURCE         RCC_PLLCFGR_PLLSRC_HSI
-#else
-# define RCC_CR_SOURCE          RCC_CR_HSEON
-# define RCC_CR_SOURCE_RDY      RCC_CR_HSERDY
-# define RCC_PLL_SOURCE         RCC_PLLCFGR_PLLSRC_HSE
-#endif
-
-static void clk_init(void);
-
 void cpu_init(void)
 {
     /* initialize the Cortex-M core */
     cortexm_init();
     /* initialize system clocks */
-    clk_init();
+    stmclk_init_sysclk();
     /* trigger static peripheral initialization */
     periph_init();
 }
-
-/**
- * @brief Configure the clock system of the stm32f2
- *
- */
-static void clk_init(void)
-{
-    /* Reset the RCC clock configuration to the default reset state(for debug purpose) */
-    /* Set HSION bit */
-    RCC->CR |= 0x00000001U;
-    /* Reset SW, HPRE, PPRE1, PPRE2, ADCPRE and MCO bits */
-    RCC->CFGR = 0x00000000U;
-    /* Reset HSEON, CSSON and PLLON bits */
-    RCC->CR &= 0xFEF6FFFFU;
-    /* Reset PLLCFGR register */
-    RCC->PLLCFGR = 0x24003010U;
-    /* Reset HSEBYP bit */
-    RCC->CR &= 0xFFFBFFFFU;
-    /* Disable all interrupts and clear pending bits  */
-    RCC->CIR = 0x00000000U;
-
-    /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration */
-    /* Enable the high speed clock source */
-    RCC->CR |= RCC_CR_SOURCE;
-    /* Wait till hish speed clock source is ready,
-     * NOTE: the MCU will stay here forever if no HSE clock is connected */
-    while ((RCC->CR & RCC_CR_SOURCE_RDY) == 0);
-    /* Configure Flash prefetch, Instruction cache, Data cache and wait state */
-    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN | FLASH_ACR_DCEN;
-    /* Flash 2 wait state */
-    FLASH->ACR &= ~((uint32_t)FLASH_ACR_LATENCY);
-    FLASH->ACR |= (uint32_t)CLOCK_FLASH_LATENCY;
-    /* HCLK = SYSCLK */
-    RCC->CFGR |= (uint32_t)CLOCK_AHB_DIV;
-    /* PCLK2 = HCLK */
-    RCC->CFGR |= (uint32_t)CLOCK_APB2_DIV;
-    /* PCLK1 = HCLK */
-    RCC->CFGR |= (uint32_t)CLOCK_APB1_DIV;
-
-    /* reset PLL config register */
-    RCC->PLLCFGR &= ~((uint32_t)(RCC_PLLCFGR_PLLSRC | RCC_PLLCFGR_PLLN | RCC_PLLCFGR_PLLM | RCC_PLLCFGR_PLLP | RCC_PLLCFGR_PLLQ));
-    /* set HSE as source for the PLL */
-    RCC->PLLCFGR |= RCC_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;
-
-#ifdef ENABLE_PLLI2S_MCO2
-    /* reset PLL I2S config register */
-    RCC->PLLI2SCFGR = 0x00000000U;
-    /* set PLL I2S division factor */
-    RCC->PLLI2SCFGR |= (CLOCK_PLL_I2S_R & 0x07) << 28;
-    /* set PLL I2S multiplication factor */
-    RCC->PLLI2SCFGR |= (CLOCK_PLL_I2S_N & 0x1FF) << 6;
-
-    /* MCO2 output is PLLI2S */
-    RCC->CFGR |= (uint32_t) RCC_CFGR_MCO2_0;
-    RCC->CFGR &= ~(uint32_t) RCC_CFGR_MCO2_1;
-    /* MCO2 prescaler div by 5 */
-    RCC->CFGR |= (uint32_t) ((CLOCK_MC02_PRE + 4 - 2) & 0x7) << 27;
-    /* enable PLL I2S clock */
-    RCC->CR |= RCC_CR_PLLI2SON;
-    /* wait till PLL I2S clock is ready */
-    while ((RCC->CR & RCC_CR_PLLI2SRDY) == 0) {}
-#endif
-
-    /* Enable PLL */
-    RCC->CR |= RCC_CR_PLLON;
-    /* Wait till PLL is ready */
-    while ((RCC->CR & RCC_CR_PLLRDY) == 0);
-    /* Select PLL as system clock source */
-    RCC->CFGR &= ~((uint32_t)(RCC_CFGR_SW));
-    RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;
-    /* Wait till PLL is used as system clock source */
-    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL);
-}

cpu/stm32f2/stmclk.c

@@ -0,0 +1,200 @@
+/*
+ * 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_stm32f2
+ * @{
+ *
+ * @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
+
+#define RCC_PLLCFGR_PLLP_Pos    (16U)
+#define RCC_PLLCFGR_PLLM_Pos    (0U)
+#define RCC_PLLCFGR_PLLN_Pos    (6U)
+#define RCC_PLLCFGR_PLLQ_Pos    (24U)
+/* 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) != 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
+
+#ifdef ENABLE_PLLI2S_MCO2
+    /* reset PLL I2S config register */
+    RCC->PLLI2SCFGR = 0x00000000U;
+    /* set PLL I2S division factor */
+    RCC->PLLI2SCFGR |= (CLOCK_PLL_I2S_R & 0x07) << 28;
+    /* set PLL I2S multiplication factor */
+    RCC->PLLI2SCFGR |= (CLOCK_PLL_I2S_N & 0x1FF) << 6;
+
+    /* MCO2 output is PLLI2S */
+    RCC->CFGR |= (uint32_t) RCC_CFGR_MCO2_0;
+    RCC->CFGR &= ~(uint32_t) RCC_CFGR_MCO2_1;
+    /* MCO2 prescaler div by 5 */
+    RCC->CFGR |= (uint32_t) ((CLOCK_MC02_PRE + 4 - 2) & 0x7) << 27;
+    /* enable PLL I2S clock */
+    RCC->CR |= RCC_CR_PLLI2SON;
+    /* wait till PLL I2S clock is ready */
+    while ((RCC->CR & RCC_CR_PLLI2SRDY) == 0) {}
+#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) != 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) != 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);
+}