RCC refactor.

Older refactor commit e4807a5010f59ab863ad2c96dc14caf65bf1ae60 used
bit-banding in rcc_clk_init() to set RCC_CR_HSEON, which doesn't work
for some reason.  Not going to try to figure out why.

3 files changed, 563 insertions, 178 deletions

diff --git a/libmaple/dac.c b/libmaple/dac.c
index ef3a9f9..0f44bb4 100644
--- a/libmaple/dac.c
+++ b/libmaple/dac.c
@@ -26,6 +26,8 @@
 #include "gpio.h"
 #include "dac.h"
 
+#ifdef STM32_HIGH_DENSITY
+
 /**
  * @brief DAC peripheral routines.
  */
@@ -108,3 +110,5 @@ void dac_disable_channel(uint8 channel) {
         break;
     }
 }
+
+#endif  /* STM32_HIGH_DENSITY */
diff --git a/libmaple/rcc.c b/libmaple/rcc.c
index 6445958..327e3ad 100644
--- a/libmaple/rcc.c
+++ b/libmaple/rcc.c
@@ -30,6 +30,7 @@
 #include "libmaple.h"
 #include "flash.h"
 #include "rcc.h"
+#include "bitband.h"
 
 enum {
     APB1,
@@ -42,15 +43,13 @@ struct rcc_dev_info {
     const uint8 line_num;
 };
 
-/* device descriptor tables  */
+/* Device descriptor table, maps rcc_clk_id onto bus and enable/reset
+ * register bit numbers. */
 static const struct rcc_dev_info rcc_dev_table[] = {
     [RCC_GPIOA]  = { .clk_domain = APB2, .line_num = 2 },
     [RCC_GPIOB]  = { .clk_domain = APB2, .line_num = 3 },
     [RCC_GPIOC]  = { .clk_domain = APB2, .line_num = 4 },
     [RCC_GPIOD]  = { .clk_domain = APB2, .line_num = 5 },
-    [RCC_GPIOE]  = { .clk_domain = APB2, .line_num = 6 }, // High-density only
-    [RCC_GPIOF]  = { .clk_domain = APB2, .line_num = 7 }, // High-density only
-    [RCC_GPIOG]  = { .clk_domain = APB2, .line_num = 8 }, // High-density only
     [RCC_AFIO]   = { .clk_domain = APB2, .line_num = 0 },
     [RCC_ADC1]   = { .clk_domain = APB2, .line_num = 9 },
     [RCC_ADC2]   = { .clk_domain = APB2, .line_num = 10 },
@@ -58,26 +57,43 @@ static const struct rcc_dev_info rcc_dev_table[] = {
     [RCC_USART1] = { .clk_domain = APB2, .line_num = 14 },
     [RCC_USART2] = { .clk_domain = APB1, .line_num = 17 },
     [RCC_USART3] = { .clk_domain = APB1, .line_num = 18 },
-    [RCC_UART4]  = { .clk_domain = APB1, .line_num = 19 }, // High-density only
-    [RCC_UART5]  = { .clk_domain = APB1, .line_num = 20 }, // High-density only
     [RCC_TIMER1] = { .clk_domain = APB2, .line_num = 11 },
     [RCC_TIMER2] = { .clk_domain = APB1, .line_num = 0 },
     [RCC_TIMER3] = { .clk_domain = APB1, .line_num = 1 },
     [RCC_TIMER4] = { .clk_domain = APB1, .line_num = 2 },
-    [RCC_TIMER5] = { .clk_domain = APB1, .line_num = 3 }, // High-density only
-    [RCC_TIMER6] = { .clk_domain = APB1, .line_num = 4 }, // High-density only
-    [RCC_TIMER7] = { .clk_domain = APB1, .line_num = 5 }, // High-density only
-    [RCC_TIMER8] = { .clk_domain = APB2, .line_num = 13 }, // High-density only
     [RCC_SPI1]   = { .clk_domain = APB2, .line_num = 12 },
     [RCC_SPI2]   = { .clk_domain = APB1, .line_num = 14 },
-    [RCC_FSMC]   = { .clk_domain = AHB,  .line_num = 8 }, // High-density only
-    [RCC_DAC]    = { .clk_domain = APB1, .line_num = 29 }, // High-density only
     [RCC_DMA1]   = { .clk_domain = AHB,  .line_num = 0 },
-    [RCC_DMA2]   = { .clk_domain = AHB,  .line_num = 1 }, // High-density only
     [RCC_PWR]    = { .clk_domain = APB1, .line_num = 28},
     [RCC_BKP]    = { .clk_domain = APB1, .line_num = 27},
-    [RCC_I2C1]   = { .clk_domain = APB1, .line_num = 21 }, // High-density only
-    [RCC_I2C2]   = { .clk_domain = APB1, .line_num = 22 }, // High-density only
+    [RCC_I2C1]   = { .clk_domain = APB1, .line_num = 21 },
+    [RCC_CRC]    = { .clk_domain = AHB,  .line_num = 6},
+    [RCC_FLITF]  = { .clk_domain = AHB,  .line_num = 4},
+    [RCC_SRAM]   = { .clk_domain = AHB,  .line_num = 2},
+#if defined(STM32_HIGH_DENSITY) || defined(STM32_XL_DENSITY)
+    [RCC_GPIOE]  = { .clk_domain = APB2, .line_num = 6 },
+    [RCC_GPIOF]  = { .clk_domain = APB2, .line_num = 7 },
+    [RCC_GPIOG]  = { .clk_domain = APB2, .line_num = 8 },
+    [RCC_UART4]  = { .clk_domain = APB1, .line_num = 19 },
+    [RCC_UART5]  = { .clk_domain = APB1, .line_num = 20 },
+    [RCC_TIMER5] = { .clk_domain = APB1, .line_num = 3 },
+    [RCC_TIMER6] = { .clk_domain = APB1, .line_num = 4 },
+    [RCC_TIMER7] = { .clk_domain = APB1, .line_num = 5 },
+    [RCC_TIMER8] = { .clk_domain = APB2, .line_num = 13 },
+    [RCC_FSMC]   = { .clk_domain = AHB,  .line_num = 8 },
+    [RCC_DAC]    = { .clk_domain = APB1, .line_num = 29 },
+    [RCC_DMA2]   = { .clk_domain = AHB,  .line_num = 1 },
+    [RCC_I2C2]   = { .clk_domain = APB1, .line_num = 22 },
+    [RCC_SDIO]   = { .clk_domain = AHB,  .line_num = 10 },
+#endif
+#ifdef STM32_XL_DENSITY
+    [RCC_TIMER9]  = { .clk_domain = APB2, .line_num = 19 },
+    [RCC_TIMER10] = { .clk_domain = APB2, .line_num = 20 },
+    [RCC_TIMER11] = { .clk_domain = APB2, .line_num = 21 },
+    [RCC_TIMER12] = { .clk_domain = APB1, .line_num = 6 },
+    [RCC_TIMER13] = { .clk_domain = APB1, .line_num = 7 },
+    [RCC_TIMER14] = { .clk_domain = APB1, .line_num = 8 },
+#endif
 };
 
 /**
@@ -87,35 +103,38 @@ static const struct rcc_dev_info rcc_dev_table[] = {
  * @param pll_src pll clock source, must be HSE
  * @param pll_mul pll multiplier
  */
-void rcc_clk_init(uint32 sysclk_src, uint32 pll_src, uint32 pll_mul) {
+void rcc_clk_init(rcc_sysclk_src sysclk_src,
+                  rcc_pllsrc pll_src,
+                  rcc_pll_multiplier pll_mul) {
+    uint32 cfgr;
+    uint32 cr;
+
     /* Assume that we're going to clock the chip off the PLL, fed by
      * the HSE */
     ASSERT(sysclk_src == RCC_CLKSRC_PLL &&
            pll_src    == RCC_PLLSRC_HSE);
 
-    uint32 cfgr = 0;
-    uint32 cr = RCC_READ_CR();
-
-    cfgr =  (pll_src | pll_mul);
-    RCC_WRITE_CFGR(cfgr);
+    RCC_BASE->CFGR = pll_src | pll_mul;
 
-    /* Turn on the HSE  */
+    /* Turn on the HSE */
+    /* FIXME WTF why doesn't bit-banding work here? */
+    cr = RCC_BASE->CR;
     cr |= RCC_CR_HSEON;
-    RCC_WRITE_CR(cr);
-    while (!(RCC_READ_CR() & RCC_CR_HSERDY))
+    RCC_BASE->CR = cr;
+    while (!(RCC_BASE->CR & RCC_CR_HSERDY))
         ;
 
     /* Now the PLL  */
     cr |= RCC_CR_PLLON;
-    RCC_WRITE_CR(cr);
-    while (!(RCC_READ_CR() & RCC_CR_PLLRDY))
+    RCC_BASE->CR = cr;
+    while (!(RCC_BASE->CR & RCC_CR_PLLRDY))
         ;
 
     /* Finally, let's switch over to the PLL  */
     cfgr &= ~RCC_CFGR_SW;
     cfgr |= RCC_CFGR_SW_PLL;
-    RCC_WRITE_CFGR(cfgr);
-    while ((RCC_READ_CFGR() & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL)
+    RCC_BASE->CFGR = cfgr;
+    while ((RCC_BASE->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL)
         ;
 }
 
@@ -124,15 +143,35 @@ void rcc_clk_init(uint32 sysclk_src, uint32 pll_src, uint32 pll_mul) {
  * @param device Clock ID of the device to turn on.
  */
 void rcc_clk_enable(rcc_clk_id device) {
-    static const uint32 enable_regs[] = {
-        [APB1] = RCC_APB1ENR,
-        [APB2] = RCC_APB2ENR,
-        [AHB] = RCC_AHBENR,
+    static const __io uint32* enable_regs[] = {
+        [APB1] = &RCC_BASE->APB1ENR,
+        [APB2] = &RCC_BASE->APB2ENR,
+        [AHB] = &RCC_BASE->AHBENR,
+    };
+
+    uint8 clk_domain = rcc_dev_table[device].clk_domain;
+    __io uint32* enr = (__io uint32*)enable_regs[clk_domain];
+    uint8 lnum = rcc_dev_table[device].line_num;
+
+    bb_peri_set_bit(enr, lnum, 1);
+}
+
+/**
+ * @brief reset a device
+ * @param device Clock ID of the device to reset.
+ */
+void rcc_reset_dev(rcc_clk_id device) {
+    static const __io uint32* reset_regs[] = {
+        [APB1] = &RCC_BASE->APB1RSTR,
+        [APB2] = &RCC_BASE->APB2RSTR,
     };
 
     uint8 clk_domain = rcc_dev_table[device].clk_domain;
+    __io void* addr = (__io void*)reset_regs[clk_domain];
+    uint8 lnum = rcc_dev_table[device].line_num;
 
-    __set_bits(enable_regs[clk_domain], BIT(rcc_dev_table[device].line_num));
+    bb_peri_set_bit(addr, lnum, 1);
+    bb_peri_set_bit(addr, lnum, 0);
 }
 
 /**
@@ -140,7 +179,7 @@ void rcc_clk_enable(rcc_clk_id device) {
  * @param prescaler prescaler to set
  * @param divider prescaler divider
  */
-void rcc_set_prescaler(uint32 prescaler, uint32 divider) {
+void rcc_set_prescaler(rcc_prescaler prescaler, uint32 divider) {
     static const uint32 masks[] = {
         [RCC_PRESCALER_AHB] = RCC_CFGR_HPRE,
         [RCC_PRESCALER_APB1] = RCC_CFGR_PPRE1,
@@ -149,25 +188,8 @@ void rcc_set_prescaler(uint32 prescaler, uint32 divider) {
         [RCC_PRESCALER_ADC] = RCC_CFGR_ADCPRE,
     };
 
-    uint32 cfgr = RCC_READ_CFGR();
-
+    uint32 cfgr = RCC_BASE->CFGR;
     cfgr &= ~masks[prescaler];
     cfgr |= divider;
-    RCC_WRITE_CFGR(cfgr);
-}
-
-/**
- * @brief reset a device
- * @param device Clock ID of the device to reset.
- */
-void rcc_reset_dev(rcc_clk_id device) {
-    static const uint32 reset_regs[] = {
-        [APB1] = RCC_APB1RSTR,
-        [APB2] = RCC_APB2RSTR,
-    };
-
-    uint8 clk_domain = rcc_dev_table[device].clk_domain;
-
-    __set_bits(reset_regs[clk_domain], BIT(rcc_dev_table[device].line_num));
-    __clear_bits(reset_regs[clk_domain], BIT(rcc_dev_table[device].line_num));
+    RCC_BASE->CFGR = cfgr;
 }
diff --git a/libmaple/rcc.h b/libmaple/rcc.h
index dcb9ea2..e6fa196 100644
--- a/libmaple/rcc.h
+++ b/libmaple/rcc.h
@@ -36,127 +36,402 @@
 extern "C"{
 #endif
 
-/* registers  */
-#define RCC_BASE               0x40021000
-#define RCC_CR                 (RCC_BASE + 0x0)
-#define RCC_CFGR               (RCC_BASE + 0x4)
-#define RCC_CIR                (RCC_BASE + 0x8)
-#define RCC_APB2RSTR           (RCC_BASE + 0xC)
-#define RCC_APB1RSTR           (RCC_BASE + 0x10)
-#define RCC_AHBENR             (RCC_BASE + 0x14)
-#define RCC_APB2ENR            (RCC_BASE + 0x18)
-#define RCC_APB1ENR            (RCC_BASE + 0x1C)
-#define RCC_BDCR               (RCC_BASE + 0x20)
-#define RCC_CSR                (RCC_BASE + 0x24)
-#define RCC_AHBSTR             (RCC_BASE + 0x28)
-#define RCC_CFGR2              (RCC_BASE + 0x2C)
-
-#define RCC_CFGR_USBPRE        (0x1 << 22)
-#define RCC_CFGR_ADCPRE        (0x3 << 14)
-#define RCC_CFGR_PPRE1         (0x7 << 8)
-#define RCC_CFGR_PPRE2         (0x7 << 11)
-#define RCC_CFGR_HPRE          (0xF << 4)
-#define RCC_CFGR_PLLSRC        (0x1 << 16)
-
-#define RCC_CFGR_SWS           (0x3 << 2)
-#define RCC_CFGR_SWS_PLL       (0x2 << 2)
-#define RCC_CFGR_SWS_HSE       (0x1 << 2)
-
-#define RCC_CFGR_SW            (0x3 << 0)
-#define RCC_CFGR_SW_PLL        (0x2 << 0)
-#define RCC_CFGR_SW_HSE        (0x1 << 0)
-
-/* CR status bits  */
-#define RCC_CR_HSEON           (0x1 << 16)
-#define RCC_CR_HSERDY          (0x1 << 17)
-#define RCC_CR_PLLON           (0x1 << 24)
-#define RCC_CR_PLLRDY          (0x1 << 25)
-
-#define RCC_WRITE_CFGR(val)    __write(RCC_CFGR, val)
-#define RCC_READ_CFGR()        __read(RCC_CFGR)
-
-#define RCC_WRITE_CR(val)      __write(RCC_CR, val)
-#define RCC_READ_CR()          __read(RCC_CR)
-
-/* sysclk source  */
-#define RCC_CLKSRC_HSI                          (0x0)
-#define RCC_CLKSRC_HSE                          (0x1)
-#define RCC_CLKSRC_PLL                          (0x2)
-
-/* pll entry clock source  */
-#define RCC_PLLSRC_HSE                          (0x1 << 16)
-#define RCC_PLLSRC_HSI_DIV_2                    (0x0 << 16)
-
-/* adc prescaler dividers  */
-#define RCC_ADCPRE_PCLK_DIV_2                   (0x0 << 14)
-#define RCC_ADCPRE_PCLK_DIV_4                   (0x1 << 14)
-#define RCC_ADCPRE_PCLK_DIV_6                   (0x2 << 14)
-#define RCC_ADCPRE_PCLK_DIV_8                   (0x3 << 14)
-
-/* apb1 prescaler dividers  */
-#define RCC_APB1_HCLK_DIV_1                     (0x0 << 8)
-#define RCC_APB1_HCLK_DIV_2                     (0x4 << 8)
-#define RCC_APB1_HCLK_DIV_4                     (0x5 << 8)
-#define RCC_APB1_HCLK_DIV_8                     (0x6 << 8)
-#define RCC_APB1_HCLK_DIV_16                    (0x7 << 8)
-
-/* apb2 prescaler dividers  */
-#define RCC_APB2_HCLK_DIV_1                     (0x0 << 11)
-#define RCC_APB2_HCLK_DIV_2                     (0x4 << 11)
-#define RCC_APB2_HCLK_DIV_4                     (0x5 << 11)
-#define RCC_APB2_HCLK_DIV_8                     (0x6 << 11)
-#define RCC_APB2_HCLK_DIV_16                    (0x7 << 11)
-
-/* ahb prescaler dividers  */
-#define RCC_AHB_SYSCLK_DIV_1                    (0x0 << 4)
-#define RCC_AHB_SYSCLK_DIV_2                    (0x8 << 4)
-#define RCC_AHB_SYSCLK_DIV_4                    (0x9 << 4)
-#define RCC_AHB_SYSCLK_DIV_8                    (0xA << 4)
-#define RCC_AHB_SYSCLK_DIV_16                   (0xB << 4)
-#define RCC_AHB_SYSCLK_DIV_32                   (0xC << 4)
-#define RCC_AHB_SYSCLK_DIV_64                   (0xD << 4)
-#define RCC_AHB_SYSCLK_DIV_128                  (0xD << 4)
-#define RCC_AHB_SYSCLK_DIV_256                  (0xE << 4)
-#define RCC_AHB_SYSCLK_DIV_512                  (0xF << 4)
-
-/* pll multipliers  */
-#define RCC_PLLMUL_2                            (0x0 << 18)
-#define RCC_PLLMUL_3                            (0x1 << 18)
-#define RCC_PLLMUL_4                            (0x2 << 18)
-#define RCC_PLLMUL_5                            (0x3 << 18)
-#define RCC_PLLMUL_6                            (0x4 << 18)
-#define RCC_PLLMUL_7                            (0x5 << 18)
-#define RCC_PLLMUL_8                            (0x6 << 18)
-#define RCC_PLLMUL_9                            (0x7 << 18)
-#define RCC_PLLMUL_10                           (0x8 << 18)
-#define RCC_PLLMUL_11                           (0x9 << 18)
-#define RCC_PLLMUL_12                           (0xA << 18)
-#define RCC_PLLMUL_13                           (0xB << 18)
-#define RCC_PLLMUL_14                           (0xC << 18)
-#define RCC_PLLMUL_15                           (0xD << 18)
-#define RCC_PLLMUL_16                           (0xE << 18)
-
-
-/* prescalers */
-enum {
-    RCC_PRESCALER_AHB,
-    RCC_PRESCALER_APB1,
-    RCC_PRESCALER_APB2,
-    RCC_PRESCALER_USB,
-    RCC_PRESCALER_ADC
-};
+/** RCC register map type */
+typedef struct rcc_reg_map {
+    __io uint32 CR;             /**< Clock control register */
+    __io uint32 CFGR;           /**< Clock configuration register */
+    __io uint32 CIR;            /**< Clock interrupt register */
+    __io uint32 APB2RSTR;       /**< APB2 peripheral reset register */
+    __io uint32 APB1RSTR;       /**< APB1 peripheral reset register */
+    __io uint32 AHBENR;         /**< AHB peripheral clock enable register */
+    __io uint32 APB2ENR;        /**< APB2 peripheral clock enable register */
+    __io uint32 APB1ENR;        /**< APB1 peripheral clock enable register */
+    __io uint32 BDCR;           /**< Backup domain control register */
+    __io uint32 CSR;            /**< Control/status register */
+} rcc_reg_map;
+
+/** RCC register map base pointer */
+#define RCC_BASE                        ((rcc_reg_map*)0x40021000)
 
 /*
- * Identifies bus and clock line for a device
+ * Register bit definitions
+ */
+
+/* Clock control register */
+
+#define RCC_CR_PLLRDY_BIT               25
+#define RCC_CR_PLLON_BIT                24
+#define RCC_CR_CSSON_BIT                19
+#define RCC_CR_HSEBYP_BIT               18
+#define RCC_CR_HSERDY_BIT               17
+#define RCC_CR_HSEON_BIT                16
+#define RCC_CR_HSIRDY_BIT               1
+#define RCC_CR_HSION_BIT                0
+
+#define RCC_CR_PLLRDY                   BIT(RCC_CR_PLLRDY_BIT)
+#define RCC_CR_PLLON                    BIT(RCC_CR_PLLON_BIT)
+#define RCC_CR_CSSON                    BIT(RCC_CR_CSSON_BIT)
+#define RCC_CR_HSEBYP                   BIT(RCC_CR_HSEBYP_BIT)
+#define RCC_CR_HSERDY                   BIT(RCC_CR_HSERDY_BIT)
+#define RCC_CR_HSEON                    BIT(RCC_CR_HSEON_BIT)
+#define RCC_CR_HSICAL                   (0xFF << 8)
+#define RCC_CR_HSITRIM                  (0x1F << 3)
+#define RCC_CR_HSIRDY                   BIT(RCC_CR_HSIRDY_BIT)
+#define RCC_CR_HSION                    BIT(RCC_CR_HSION_BIT)
+
+/* Clock configuration register */
+
+#define RCC_CFGR_USBPRE_BIT             22
+#define RCC_CFGR_PLLXTPRE_BIT           17
+#define RCC_CFGR_PLLSRC_BIT             16
+
+#define RCC_CFGR_MCO                    (0x3 << 24)
+#define RCC_CFGR_USBPRE                 BIT(RCC_CFGR_USBPRE_BIT)
+#define RCC_CFGR_PLLMUL                 (0xF << 18)
+#define RCC_CFGR_PLLXTPRE               BIT(RCC_CFGR_PLLXTPRE_BIT)
+#define RCC_CFGR_PLLSRC                 BIT(RCC_CFGR_PLLSRC_BIT)
+#define RCC_CFGR_ADCPRE                 (0x3 << 14)
+#define RCC_CFGR_PPRE2                  (0x7 << 11)
+#define RCC_CFGR_PPRE1                  (0x7 << 8)
+#define RCC_CFGR_HPRE                   (0xF << 4)
+#define RCC_CFGR_SWS                    (0x3 << 2)
+#define RCC_CFGR_SWS_PLL                (0x2 << 2)
+#define RCC_CFGR_SWS_HSE                (0x1 << 2)
+#define RCC_CFGR_SW                     0x3
+#define RCC_CFGR_SW_PLL                 0x2
+#define RCC_CFGR_SW_HSE                 0x1
+
+/* Clock interrupt register */
+
+#define RCC_CIR_CSSC_BIT                23
+#define RCC_CIR_PLLRDYC_BIT             20
+#define RCC_CIR_HSERDYC_BIT             19
+#define RCC_CIR_HSIRDYC_BIT             18
+#define RCC_CIR_LSERDYC_BIT             17
+#define RCC_CIR_LSIRDYC_BIT             16
+#define RCC_CIR_PLLRDYIE_BIT            12
+#define RCC_CIR_HSERDYIE_BIT            11
+#define RCC_CIR_HSIRDYIE_BIT            10
+#define RCC_CIR_LSERDYIE_BIT            9
+#define RCC_CIR_LSIRDYIE_BIT            8
+#define RCC_CIR_CSSF_BIT                7
+#define RCC_CIR_PLLRDYF_BIT             4
+#define RCC_CIR_HSERDYF_BIT             3
+#define RCC_CIR_HSIRDYF_BIT             2
+#define RCC_CIR_LSERDYF_BIT             1
+#define RCC_CIR_LSIRDYF_BIT             0
+
+#define RCC_CIR_CSSC                    BIT(RCC_CIR_CSSC_BIT)
+#define RCC_CIR_PLLRDYC                 BIT(RCC_CIR_PLLRDYC_BIT)
+#define RCC_CIR_HSERDYC                 BIT(RCC_CIR_HSERDYC_BIT)
+#define RCC_CIR_HSIRDYC                 BIT(RCC_CIR_HSIRDYC_BIT)
+#define RCC_CIR_LSERDYC                 BIT(RCC_CIR_LSERDYC_BIT)
+#define RCC_CIR_LSIRDYC                 BIT(RCC_CIR_LSIRDYC_BIT)
+#define RCC_CIR_PLLRDYIE                BIT(RCC_CIR_PLLRDYIE_BIT)
+#define RCC_CIR_HSERDYIE                BIT(RCC_CIR_HSERDYIE_BIT)
+#define RCC_CIR_HSIRDYIE                BIT(RCC_CIR_HSIRDYIE_BIT)
+#define RCC_CIR_LSERDYIE                BIT(RCC_CIR_LSERDYIE_BIT)
+#define RCC_CIR_LSIRDYIE                BIT(RCC_CIR_LSIRDYIE_BIT)
+#define RCC_CIR_CSSF                    BIT(RCC_CIR_CSSF_BIT)
+#define RCC_CIR_PLLRDYF                 BIT(RCC_CIR_PLLRDYF_BIT)
+#define RCC_CIR_HSERDYF                 BIT(RCC_CIR_HSERDYF_BIT)
+#define RCC_CIR_HSIRDYF                 BIT(RCC_CIR_HSIRDYF_BIT)
+#define RCC_CIR_LSERDYF                 BIT(RCC_CIR_LSERDYF_BIT)
+#define RCC_CIR_LSIRDYF                 BIT(RCC_CIR_LSIRDYF_BIT)
+
+/* APB2 peripheral reset register */
+
+#define RCC_APB2RSTR_TIM11RST_BIT       21
+#define RCC_APB2RSTR_TIM10RST_BIT       20
+#define RCC_APB2RSTR_TIM9RST_BIT        19
+#define RCC_APB2RSTR_ADC3RST_BIT        15
+#define RCC_APB2RSTR_USART1RST_BIT      14
+#define RCC_APB2RSTR_TIM8RST_BIT        13
+#define RCC_APB2RSTR_SPI1RST_BIT        12
+#define RCC_APB2RSTR_TIM1RST_BIT        11
+#define RCC_APB2RSTR_ADC2RST_BIT        10
+#define RCC_APB2RSTR_ADC1RST_BIT        9
+#define RCC_APB2RSTR_IOPGRST_BIT        8
+#define RCC_APB2RSTR_IOPFRST_BIT        7
+#define RCC_APB2RSTR_IOPERST_BIT        6
+#define RCC_APB2RSTR_IOPDRST_BIT        5
+#define RCC_APB2RSTR_IOPCRST_BIT        4
+#define RCC_APB2RSTR_IOPBRST_BIT        3
+#define RCC_APB2RSTR_IOPARST_BIT        2
+#define RCC_APB2RSTR_AFIORST_BIT        0
+
+#define RCC_APB2RSTR_TIM11RST           BIT(RCC_APB2RSTR_TIM11RST_BIT)
+#define RCC_APB2RSTR_TIM10RST           BIT(RCC_APB2RSTR_TIM10RST_BIT)
+#define RCC_APB2RSTR_TIM9RST            BIT(RCC_APB2RSTR_TIM9RST_BIT)
+#define RCC_APB2RSTR_ADC3RST            BIT(RCC_APB2RSTR_ADC3RST_BIT)
+#define RCC_APB2RSTR_USART1RST          BIT(RCC_APB2RSTR_USART1RST_BIT)
+#define RCC_APB2RSTR_TIM8RST            BIT(RCC_APB2RSTR_TIM8RST_BIT)
+#define RCC_APB2RSTR_SPI1RST            BIT(RCC_APB2RSTR_SPI1RST_BIT)
+#define RCC_APB2RSTR_TIM1RST            BIT(RCC_APB2RSTR_TIM1RST_BIT)
+#define RCC_APB2RSTR_ADC2RST            BIT(RCC_APB2RSTR_ADC2RST_BIT)
+#define RCC_APB2RSTR_ADC1RST            BIT(RCC_APB2RSTR_ADC1RST_BIT)
+#define RCC_APB2RSTR_IOPGRST            BIT(RCC_APB2RSTR_IOPGRST_BIT)
+#define RCC_APB2RSTR_IOPFRST            BIT(RCC_APB2RSTR_IOPFRST_BIT)
+#define RCC_APB2RSTR_IOPERST            BIT(RCC_APB2RSTR_IOPERST_BIT)
+#define RCC_APB2RSTR_IOPDRST            BIT(RCC_APB2RSTR_IOPDRST_BIT)
+#define RCC_APB2RSTR_IOPCRST            BIT(RCC_APB2RSTR_IOPCRST_BIT)
+#define RCC_APB2RSTR_IOPBRST            BIT(RCC_APB2RSTR_IOPBRST_BIT)
+#define RCC_APB2RSTR_IOPARST            BIT(RCC_APB2RSTR_IOPARST_BIT)
+#define RCC_APB2RSTR_AFIORST            BIT(RCC_APB2RSTR_AFIORST_BIT)
+
+/* APB1 peripheral reset register */
+
+#define RCC_APB1RSTR_DACRST_BIT         29
+#define RCC_APB1RSTR_PWRRST_BIT         28
+#define RCC_APB1RSTR_BKPRST_BIT         27
+#define RCC_APB1RSTR_CANRST_BIT         25
+#define RCC_APB1RSTR_USBRST_BIT         23
+#define RCC_APB1RSTR_I2C2RST_BIT        22
+#define RCC_APB1RSTR_I2C1RST_BIT        21
+#define RCC_APB1RSTR_UART5RST_BIT       20
+#define RCC_APB1RSTR_UART4RST_BIT       19
+#define RCC_APB1RSTR_USART3RST_BIT      18
+#define RCC_APB1RSTR_USART2RST_BIT      17
+#define RCC_APB1RSTR_SPI3RST_BIT        15
+#define RCC_APB1RSTR_SPI2RST_BIT        14
+#define RCC_APB1RSTR_WWDRST_BIT         11
+#define RCC_APB1RSTR_TIM14RST_BIT       8
+#define RCC_APB1RSTR_TIM13RST_BIT       7
+#define RCC_APB1RSTR_TIM12RST_BIT       6
+#define RCC_APB1RSTR_TIM7RST_BIT        5
+#define RCC_APB1RSTR_TIM6RST_BIT        4
+#define RCC_APB1RSTR_TIM5RST_BIT        3
+#define RCC_APB1RSTR_TIM4RST_BIT        2
+#define RCC_APB1RSTR_TIM3RST_BIT        1
+#define RCC_APB1RSTR_TIM2RST_BIT        0
+
+#define RCC_APB1RSTR_DACRST             BIT(RCC_APB1RSTR_DACRST_BIT)
+#define RCC_APB1RSTR_PWRRST             BIT(RCC_APB1RSTR_PWRRST_BIT)
+#define RCC_APB1RSTR_BKPRST             BIT(RCC_APB1RSTR_BKPRST_BIT)
+#define RCC_APB1RSTR_CANRST             BIT(RCC_APB1RSTR_CANRST_BIT)
+#define RCC_APB1RSTR_USBRST             BIT(RCC_APB1RSTR_USBRST_BIT)
+#define RCC_APB1RSTR_I2C2RST            BIT(RCC_APB1RSTR_I2C2RST_BIT)
+#define RCC_APB1RSTR_I2C1RST            BIT(RCC_APB1RSTR_I2C1RST_BIT)
+#define RCC_APB1RSTR_UART5RST           BIT(RCC_APB1RSTR_UART5RST_BIT)
+#define RCC_APB1RSTR_UART4RST           BIT(RCC_APB1RSTR_UART4RST_BIT)
+#define RCC_APB1RSTR_USART3RST          BIT(RCC_APB1RSTR_USART3RST_BIT)
+#define RCC_APB1RSTR_USART2RST          BIT(RCC_APB1RSTR_USART2RST_BIT)
+#define RCC_APB1RSTR_SPI3RST            BIT(RCC_APB1RSTR_SPI3RST_BIT)
+#define RCC_APB1RSTR_SPI2RST            BIT(RCC_APB1RSTR_SPI2RST_BIT)
+#define RCC_APB1RSTR_WWDRST             BIT(RCC_APB1RSTR_WWDRST_BIT)
+#define RCC_APB1RSTR_TIM14RST           BIT(RCC_APB1RSTR_TIM14RST_BIT)
+#define RCC_APB1RSTR_TIM13RST           BIT(RCC_APB1RSTR_TIM13RST_BIT)
+#define RCC_APB1RSTR_TIM12RST           BIT(RCC_APB1RSTR_TIM12RST_BIT)
+#define RCC_APB1RSTR_TIM7RST            BIT(RCC_APB1RSTR_TIM7RST_BIT)
+#define RCC_APB1RSTR_TIM6RST            BIT(RCC_APB1RSTR_TIM6RST_BIT)
+#define RCC_APB1RSTR_TIM5RST            BIT(RCC_APB1RSTR_TIM5RST_BIT)
+#define RCC_APB1RSTR_TIM4RST            BIT(RCC_APB1RSTR_TIM4RST_BIT)
+#define RCC_APB1RSTR_TIM3RST            BIT(RCC_APB1RSTR_TIM3RST_BIT)
+#define RCC_APB1RSTR_TIM2RST            BIT(RCC_APB1RSTR_TIM2RST_BIT)
+
+/* AHB peripheral clock enable register */
+
+#define RCC_AHBENR_SDIOEN_BIT           10
+#define RCC_AHBENR_FSMCEN_BIT           8
+#define RCC_AHBENR_CRCEN_BIT            7
+#define RCC_AHBENR_FLITFEN_BIT          4
+#define RCC_AHBENR_SRAMEN_BIT           2
+#define RCC_AHBENR_DMA2EN_BIT           1
+#define RCC_AHBENR_DMA1EN_BIT           0
+
+#define RCC_AHBENR_SDIOEN               BIT(RCC_AHBENR_SDIOEN_BIT)
+#define RCC_AHBENR_FSMCEN               BIT(RCC_AHBENR_FSMCEN_BIT)
+#define RCC_AHBENR_CRCEN                BIT(RCC_AHBENR_CRCEN_BIT)
+#define RCC_AHBENR_FLITFEN              BIT(RCC_AHBENR_FLITFEN_BIT)
+#define RCC_AHBENR_SRAMEN               BIT(RCC_AHBENR_SRAMEN_BIT)
+#define RCC_AHBENR_DMA2EN               BIT(RCC_AHBENR_DMA2EN_BIT)
+#define RCC_AHBENR_DMA1EN               BIT(RCC_AHBENR_DMA1EN_BIT)
+
+/* APB2 peripheral clock enable register */
+
+#define RCC_APB2ENR_TIM11EN_BIT         21
+#define RCC_APB2ENR_TIM10EN_BIT         20
+#define RCC_APB2ENR_TIM9EN_BIT          19
+#define RCC_APB2ENR_ADC3EN_BIT          15
+#define RCC_APB2ENR_USART1EN_BIT        14
+#define RCC_APB2ENR_TIM8EN_BIT          13
+#define RCC_APB2ENR_SPI1EN_BIT          12
+#define RCC_APB2ENR_TIM1EN_BIT          11
+#define RCC_APB2ENR_ADC2EN_BIT          10
+#define RCC_APB2ENR_ADC1EN_BIT          9
+#define RCC_APB2ENR_IOPGEN_BIT          8
+#define RCC_APB2ENR_IOPFEN_BIT          7
+#define RCC_APB2ENR_IOPEEN_BIT          6
+#define RCC_APB2ENR_IOPDEN_BIT          5
+#define RCC_APB2ENR_IOPCEN_BIT          4
+#define RCC_APB2ENR_IOPBEN_BIT          3
+#define RCC_APB2ENR_IOPAEN_BIT          2
+#define RCC_APB2ENR_AFIOEN_BIT          0
+
+#define RCC_APB2ENR_TIM11EN             BIT(RCC_APB2ENR_TIM11EN_BIT)
+#define RCC_APB2ENR_TIM10EN             BIT(RCC_APB2ENR_TIM10EN_BIT)
+#define RCC_APB2ENR_TIM9EN              BIT(RCC_APB2ENR_TIM9EN_BIT)
+#define RCC_APB2ENR_ADC3EN              BIT(RCC_APB2ENR_ADC3EN_BIT)
+#define RCC_APB2ENR_USART1EN            BIT(RCC_APB2ENR_USART1EN_BIT)
+#define RCC_APB2ENR_TIM8EN              BIT(RCC_APB2ENR_TIM8EN_BIT)
+#define RCC_APB2ENR_SPI1EN              BIT(RCC_APB2ENR_SPI1EN_BIT)
+#define RCC_APB2ENR_TIM1EN              BIT(RCC_APB2ENR_TIM1EN_BIT)
+#define RCC_APB2ENR_ADC2EN              BIT(RCC_APB2ENR_ADC2EN_BIT)
+#define RCC_APB2ENR_ADC1EN              BIT(RCC_APB2ENR_ADC1EN_BIT)
+#define RCC_APB2ENR_IOPGEN              BIT(RCC_APB2ENR_IOPGEN_BIT)
+#define RCC_APB2ENR_IOPFEN              BIT(RCC_APB2ENR_IOPFEN_BIT)
+#define RCC_APB2ENR_IOPEEN              BIT(RCC_APB2ENR_IOPEEN_BIT)
+#define RCC_APB2ENR_IOPDEN              BIT(RCC_APB2ENR_IOPDEN_BIT)
+#define RCC_APB2ENR_IOPCEN              BIT(RCC_APB2ENR_IOPCEN_BIT)
+#define RCC_APB2ENR_IOPBEN              BIT(RCC_APB2ENR_IOPBEN_BIT)
+#define RCC_APB2ENR_IOPAEN              BIT(RCC_APB2ENR_IOPAEN_BIT)
+#define RCC_APB2ENR_AFIOEN              BIT(RCC_APB2ENR_AFIOEN_BIT)
+
+/* APB1 peripheral clock enable register */
+
+#define RCC_APB1ENR_DACEN_BIT           29
+#define RCC_APB1ENR_PWREN_BIT           28
+#define RCC_APB1ENR_BKPEN_BIT           27
+#define RCC_APB1ENR_CANEN_BIT           25
+#define RCC_APB1ENR_USBEN_BIT           23
+#define RCC_APB1ENR_I2C2EN_BIT          22
+#define RCC_APB1ENR_I2C1EN_BIT          21
+#define RCC_APB1ENR_UART5EN_BIT         20
+#define RCC_APB1ENR_UART4EN_BIT         19
+#define RCC_APB1ENR_USART3EN_BIT        18
+#define RCC_APB1ENR_USART2EN_BIT        17
+#define RCC_APB1ENR_SPI3EN_BIT          15
+#define RCC_APB1ENR_SPI2EN_BIT          14
+#define RCC_APB1ENR_WWDEN_BIT           11
+#define RCC_APB1ENR_TIM14EN_BIT         8
+#define RCC_APB1ENR_TIM13EN_BIT         7
+#define RCC_APB1ENR_TIM12EN_BIT         6
+#define RCC_APB1ENR_TIM7EN_BIT          5
+#define RCC_APB1ENR_TIM6EN_BIT          4
+#define RCC_APB1ENR_TIM5EN_BIT          3
+#define RCC_APB1ENR_TIM4EN_BIT          2
+#define RCC_APB1ENR_TIM3EN_BIT          1
+#define RCC_APB1ENR_TIM2EN_BIT          0
+
+#define RCC_APB1ENR_DACEN               BIT(RCC_APB1ENR_DACEN_BIT)
+#define RCC_APB1ENR_PWREN               BIT(RCC_APB1ENR_PWREN_BIT)
+#define RCC_APB1ENR_BKPEN               BIT(RCC_APB1ENR_BKPEN_BIT)
+#define RCC_APB1ENR_CANEN               BIT(RCC_APB1ENR_CANEN_BIT)
+#define RCC_APB1ENR_USBEN               BIT(RCC_APB1ENR_USBEN_BIT)
+#define RCC_APB1ENR_I2C2EN              BIT(RCC_APB1ENR_I2C2EN_BIT)
+#define RCC_APB1ENR_I2C1EN              BIT(RCC_APB1ENR_I2C1EN_BIT)
+#define RCC_APB1ENR_UART5EN             BIT(RCC_APB1ENR_UART5EN_BIT)
+#define RCC_APB1ENR_UART4EN             BIT(RCC_APB1ENR_UART4EN_BIT)
+#define RCC_APB1ENR_USART3EN            BIT(RCC_APB1ENR_USART3EN_BIT)
+#define RCC_APB1ENR_USART2EN            BIT(RCC_APB1ENR_USART2EN_BIT)
+#define RCC_APB1ENR_SPI3EN              BIT(RCC_APB1ENR_SPI3EN_BIT)
+#define RCC_APB1ENR_SPI2EN              BIT(RCC_APB1ENR_SPI2EN_BIT)
+#define RCC_APB1ENR_WWDEN               BIT(RCC_APB1ENR_WWDEN_BIT)
+#define RCC_APB1ENR_TIM14EN             BIT(RCC_APB1ENR_TIM14EN_BIT)
+#define RCC_APB1ENR_TIM13EN             BIT(RCC_APB1ENR_TIM13EN_BIT)
+#define RCC_APB1ENR_TIM12EN             BIT(RCC_APB1ENR_TIM12EN_BIT)
+#define RCC_APB1ENR_TIM7EN              BIT(RCC_APB1ENR_TIM7EN_BIT)
+#define RCC_APB1ENR_TIM6EN              BIT(RCC_APB1ENR_TIM6EN_BIT)
+#define RCC_APB1ENR_TIM5EN              BIT(RCC_APB1ENR_TIM5EN_BIT)
+#define RCC_APB1ENR_TIM4EN              BIT(RCC_APB1ENR_TIM4EN_BIT)
+#define RCC_APB1ENR_TIM3EN              BIT(RCC_APB1ENR_TIM3EN_BIT)
+#define RCC_APB1ENR_TIM2EN              BIT(RCC_APB1ENR_TIM2EN_BIT)
+
+/* Backup domain control register */
+
+#define RCC_BDCR_BDRST_BIT              16
+#define RCC_BDCR_RTCEN_BIT              15
+#define RCC_BDCR_LSEBYP_BIT             2
+#define RCC_BDCR_LSERDY_BIT             1
+#define RCC_BDCR_LSEON_BIT              0
+
+#define RCC_BDCR_BDRST                  BIT(RCC_BDCR_BDRST_BIT)
+#define RCC_BDCR_RTCEN                  BIT(RCC_BDCR_RTC_BIT)
+#define RCC_BDCR_RTCSEL                 (0x3 << 8)
+#define RCC_BDCR_RTCSEL_NONE            (0x0 << 8)
+#define RCC_BDCR_RTCSEL_LSE             (0x1 << 8)
+#define RCC_BDCR_RTCSEL_HSE             (0x3 << 8)
+#define RCC_BDCR_LSEBYP                 BIT(RCC_BDCR_LSEBYP_BIT)
+#define RCC_BDCR_LSERDY                 BIT(RCC_BDCR_LSERDY_BIT)
+#define RCC_BDCR_LSEON                  BIT(RCC_BDCR_LSEON_BIT)
+
+/* Control/status register */
+
+#define RCC_CSR_LPWRRSTF_BIT            31
+#define RCC_CSR_WWDGRSTF_BIT            30
+#define RCC_CSR_IWDGRSTF_BIT            29
+#define RCC_CSR_SFTRSTF_BIT             28
+#define RCC_CSR_PORRSTF_BIT             27
+#define RCC_CSR_PINRSTF_BIT             26
+#define RCC_CSR_RMVF_BIT                24
+#define RCC_CSR_LSIRDY_BIT              1
+#define RCC_CSR_LSION_BIT               0
+
+#define RCC_CSR_LPWRRSTF                BIT(RCC_CSR_LPWRRSTF_BIT)
+#define RCC_CSR_WWDGRSTF                BIT(RCC_CSR_WWDGRSTF_BIT)
+#define RCC_CSR_IWDGRSTF                BIT(RCC_CSR_IWDGRSTF_BIT)
+#define RCC_CSR_SFTRSTF                 BIT(RCC_CSR_SFTRSTF_BIT)
+#define RCC_CSR_PORRSTF                 BIT(RCC_CSR_PORRSTF_BIT)
+#define RCC_CSR_PINRSTF                 BIT(RCC_CSR_PINRSTF_BIT)
+#define RCC_CSR_RMVF                    BIT(RCC_CSR_RMVF_BIT)
+#define RCC_CSR_LSIRDY                  BIT(RCC_CSR_LSIRDY_BIT)
+#define RCC_CSR_LSION                   BIT(RCC_CSR_LSION_BIT)
+
+/*
+ * Convenience routines
+ */
+
+/**
+ * SYSCLK sources
+ * @see rcc_clk_init()
+ */
+typedef enum rcc_sysclk_src {
+    RCC_CLKSRC_HSI = 0x0,
+    RCC_CLKSRC_HSE = 0x1,
+    RCC_CLKSRC_PLL = 0x2,
+} rcc_sysclk_src;
+
+/**
+ * PLL entry clock source
+ * @see rcc_clk_init()
+ */
+typedef enum rcc_pllsrc {
+    RCC_PLLSRC_HSE = (0x1 << 16),
+    RCC_PLLSRC_HSI_DIV_2 = (0x0 << 16)
+} rcc_pllsrc;
+
+/**
+ * PLL multipliers
+ * @see rcc_clk_init()
+ */
+typedef enum rcc_pll_multiplier {
+    RCC_PLLMUL_2 = (0x0 << 18),
+    RCC_PLLMUL_3 = (0x1 << 18),
+    RCC_PLLMUL_4 = (0x2 << 18),
+    RCC_PLLMUL_5 = (0x3 << 18),
+    RCC_PLLMUL_6 = (0x4 << 18),
+    RCC_PLLMUL_7 = (0x5 << 18),
+    RCC_PLLMUL_8 = (0x6 << 18),
+    RCC_PLLMUL_9 = (0x7 << 18),
+    RCC_PLLMUL_10 = (0x8 << 18),
+    RCC_PLLMUL_11 = (0x9 << 18),
+    RCC_PLLMUL_12 = (0xA << 18),
+    RCC_PLLMUL_13 = (0xB << 18),
+    RCC_PLLMUL_14 = (0xC << 18),
+    RCC_PLLMUL_15 = (0xD << 18),
+    RCC_PLLMUL_16 = (0xE << 18),
+} rcc_pll_multiplier;
+
+/**
+ * @brief Identifies bus and clock line for a device
+ *
+ * Also generally useful as a unique identifier for that device.
  */
 typedef enum {
     RCC_GPIOA,
     RCC_GPIOB,
     RCC_GPIOC,
     RCC_GPIOD,
-    RCC_GPIOE,       // High-density devices only (Maple Native)
-    RCC_GPIOF,       // High-density devices only (Maple Native)
-    RCC_GPIOG,       // High-density devices only (Maple Native)
     RCC_AFIO,
     RCC_ADC1,
     RCC_ADC2,
@@ -164,32 +439,116 @@ typedef enum {
     RCC_USART1,
     RCC_USART2,
     RCC_USART3,
-    RCC_UART4,      // High-density devices only (Maple Native)
-    RCC_UART5,      // High-density devices only (Maple Native)
     RCC_TIMER1,
     RCC_TIMER2,
     RCC_TIMER3,
     RCC_TIMER4,
-    RCC_TIMER5,      // High-density devices only (Maple Native)
-    RCC_TIMER6,      // High-density devices only (Maple Native)
-    RCC_TIMER7,      // High-density devices only (Maple Native)
-    RCC_TIMER8,      // High-density devices only (Maple Native)
     RCC_SPI1,
     RCC_SPI2,
-    RCC_FSMC,        // High-density devices only (Maple Native)
-    RCC_DAC,         // High-density devices only (Maple Native)
     RCC_DMA1,
-    RCC_DMA2,        // High-density devices only (Maple Native)
     RCC_PWR,
     RCC_BKP,
     RCC_I2C1,
-    RCC_I2C2
+    RCC_CRC,
+    RCC_FLITF,
+    RCC_SRAM,
+#if defined(STM32_HIGH_DENSITY) || defined(STM32_XL_DENSITY)
+    RCC_GPIOE,
+    RCC_GPIOF,
+    RCC_GPIOG,
+    RCC_UART4,
+    RCC_UART5,
+    RCC_TIMER5,
+    RCC_TIMER6,
+    RCC_TIMER7,
+    RCC_TIMER8,
+    RCC_FSMC,
+    RCC_DAC,
+    RCC_DMA2,
+    RCC_I2C2,
+    RCC_SDIO,
+#endif
+#ifdef STM32_XL_DENSITY
+    RCC_TIMER9,
+    RCC_TIMER10,
+    RCC_TIMER11,
+    RCC_TIMER12,
+    RCC_TIMER13,
+    RCC_TIMER14,
+#endif
 } rcc_clk_id;
 
-void rcc_clk_init(uint32 sysclk_src, uint32 pll_src, uint32 pll_mul);
+void rcc_clk_init(rcc_sysclk_src sysclk_src,
+                  rcc_pllsrc pll_src,
+                  rcc_pll_multiplier pll_mul);
 void rcc_clk_enable(rcc_clk_id device);
 void rcc_reset_dev(rcc_clk_id device);
-void rcc_set_prescaler(uint32 prescaler, uint32 divider);
+
+/**
+ * Prescaler identifiers
+ * @see rcc_set_prescaler()
+ */
+typedef enum rcc_prescaler {
+    RCC_PRESCALER_AHB,
+    RCC_PRESCALER_APB1,
+    RCC_PRESCALER_APB2,
+    RCC_PRESCALER_USB,
+    RCC_PRESCALER_ADC
+} rcc_prescaler;
+
+/**
+ * ADC prescaler dividers
+ * @see rcc_set_prescaler()
+ */
+typedef enum adc_prescaler_divider {
+    RCC_ADCPRE_PCLK_DIV_2 = 0x0 << 14,
+    RCC_ADCPRE_PCLK_DIV_4 = 0x1 << 14,
+    RCC_ADCPRE_PCLK_DIV_6 = 0x2 << 14,
+    RCC_ADCPRE_PCLK_DIV_8 = 0x3 << 14,
+} adc_prescaler_divider;
+
+/**
+ * APB1 prescaler dividers
+ * @see rcc_set_prescaler()
+ */
+typedef enum apb1_prescaler_divider {
+    RCC_APB1_HCLK_DIV_1 = 0x0 << 8,
+    RCC_APB1_HCLK_DIV_2 = 0x4 << 8,
+    RCC_APB1_HCLK_DIV_4 = 0x5 << 8,
+    RCC_APB1_HCLK_DIV_8 = 0x6 << 8,
+    RCC_APB1_HCLK_DIV_16 = 0x7 << 8,
+} apb1_prescaler_divider;
+
+/**
+ * APB2 prescaler dividers
+ * @see rcc_set_prescaler()
+ */
+typedef enum apb2_prescaler_divider {
+    RCC_APB2_HCLK_DIV_1 = 0x0 << 11,
+    RCC_APB2_HCLK_DIV_2 = 0x4 << 11,
+    RCC_APB2_HCLK_DIV_4 = 0x5 << 11,
+    RCC_APB2_HCLK_DIV_8 = 0x6 << 11,
+    RCC_APB2_HCLK_DIV_16 = 0x7 << 11,
+} apb2_prescaler_divider;
+
+/**
+ * AHB prescaler dividers
+ * @see rcc_set_prescaler()
+ */
+typedef enum ahb_prescaler_divider {
+    RCC_AHB_SYSCLK_DIV_1 = 0x0 << 4,
+    RCC_AHB_SYSCLK_DIV_2 = 0x8 << 4,
+    RCC_AHB_SYSCLK_DIV_4 = 0x9 << 4,
+    RCC_AHB_SYSCLK_DIV_8 = 0xA << 4,
+    RCC_AHB_SYSCLK_DIV_16 = 0xB << 4,
+    RCC_AHB_SYSCLK_DIV_32 = 0xC << 4,
+    RCC_AHB_SYSCLK_DIV_64 = 0xD << 4,
+    RCC_AHB_SYSCLK_DIV_128 = 0xD << 4,
+    RCC_AHB_SYSCLK_DIV_256 = 0xE << 4,
+    RCC_AHB_SYSCLK_DIV_512 = 0xF << 4,
+} ahb_prescaler_divider;
+
+void rcc_set_prescaler(rcc_prescaler prescaler, uint32 divider);
 
 #ifdef __cplusplus
 } // extern "C"