rcc.c

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/** @defgroup rcc_file RCC peripheral API
 *
 * @ingroup peripheral_apis
 * This library supports the Reset and Clock Control System in the STM32 series
 * of ARM Cortex Microcontrollers by ST Microelectronics.
 *
 * LGPL License Terms @ref lgpl_license
 */
#include <stddef.h>
#include <libopencm3/cm3/assert.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/pwr.h>
#include <libopencm3/stm32/flash.h>
 
#define HZ_PER_MHZ                      1000000UL
#define HZ_PER_KHZ                      1000UL
 
/* Local private copy of the clock configuration for providing user with clock tree data. */
static struct {
        uint16_t sysclk_mhz;
        uint16_t cpu_mhz;
        uint16_t hclk_mhz;
        struct {
                uint16_t pclk1_mhz;             /* APB1 clock. */
                uint16_t pclk2_mhz;             /* APB2 clock. */
                uint16_t pclk3_mhz;             /* APB3 clock. */
                uint16_t pclk4_mhz;             /* APB4 clock. */
        } per;
        struct pll_clocks {                     /* Each PLL output set of data. */
                uint16_t p_mhz;
                uint16_t q_mhz;
                uint16_t r_mhz;
        } pll1, pll2, pll3;
        uint16_t hse_khz;                       /* This can't exceed 50MHz */
} rcc_clock_tree = {
        .sysclk_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .cpu_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .hclk_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .per.pclk1_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .per.pclk2_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .per.pclk3_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ,
        .per.pclk4_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ
};
 
static void rcc_configure_pll(uint32_t clkin, const struct pll_config *config, int pll_num) {
        /* Only concern ourselves with the PLL if the input clock is enabled. */
        if (config->divm == 0 || pll_num < 1 || pll_num > 3) {
                return;
        }
 
        struct pll_clocks *pll_tree_ptr;
        if (pll_num == 1) {
                pll_tree_ptr = &rcc_clock_tree.pll1;
        } else if (pll_num == 2) {
                pll_tree_ptr = &rcc_clock_tree.pll2;
        } else {
                pll_tree_ptr = &rcc_clock_tree.pll3;
        }
 
        /* Let's write all of the dividers as specified. */
        RCC_PLLDIVR(pll_num)  = 0;
        RCC_PLLDIVR(pll_num) |= RCC_PLLNDIVR_DIVN(config->divn);
 
        /* Setup the PLL config values for this PLL. */
        uint8_t vco_addshift = 4 * (pll_num - 1);               /* Values spaced by 4 for PLL 1/2/3 */
 
        /* Set the PLL input frequency range. */
        uint32_t pll_clk_mhz = (clkin / config->divm) / HZ_PER_MHZ;
        if (pll_clk_mhz > 2 && pll_clk_mhz <= 4) {
                RCC_PLLCFGR |= (RCC_PLLCFGR_PLLRGE_2_4MHZ << RCC_PLLCFGR_PLL1RGE_SHIFT) << vco_addshift;
        } else if (pll_clk_mhz > 4 && pll_clk_mhz <= 8) {
                RCC_PLLCFGR |= (RCC_PLLCFGR_PLLRGE_4_8MHZ << RCC_PLLCFGR_PLL1RGE_SHIFT) << vco_addshift;
        } else if (pll_clk_mhz > 8) {
                RCC_PLLCFGR |= (RCC_PLLCFGR_PLLRGE_8_16MHZ << RCC_PLLCFGR_PLL1RGE_SHIFT) << vco_addshift;
        }
 
        /* Set the VCO output frequency range. */
        uint32_t pll_vco_clk_mhz = (pll_clk_mhz * config->divn);
        if (pll_vco_clk_mhz <= 420) {
                RCC_PLLCFGR |= (RCC_PLLCFGR_PLL1VCO_MED << vco_addshift);
        }
 
        /* Setup the enable bits for the PLL outputs. */
        uint8_t diven_addshift = 3 * (pll_num - 1);             /* Values spaced by 3 for PLL1/2/3 */
        if (config->divp > 0) {
                RCC_PLLDIVR(pll_num) |= RCC_PLLNDIVR_DIVP(config->divp);
                RCC_PLLCFGR |= (RCC_PLLCFGR_DIVP1EN << diven_addshift);
                pll_tree_ptr->p_mhz = pll_vco_clk_mhz / config->divp;
        }
        if (config->divq > 0) {
                RCC_PLLDIVR(pll_num) |= RCC_PLLNDIVR_DIVQ(config->divq);
                RCC_PLLCFGR |= (RCC_PLLCFGR_DIVQ1EN << diven_addshift);
                pll_tree_ptr->q_mhz = pll_vco_clk_mhz / config->divq;
        }
        if (config->divr > 0) {
                RCC_PLLDIVR(pll_num) |= RCC_PLLNDIVR_DIVR(config->divr);
                RCC_PLLCFGR |= (RCC_PLLCFGR_DIVR1EN << diven_addshift);
                pll_tree_ptr->r_mhz = pll_vco_clk_mhz / config->divr;
        }
 
        /* Attempt to enable and lock PLL. */
        uint8_t cr_addshift = 2 * (pll_num - 1);
        RCC_CR |= RCC_CR_PLL1ON << cr_addshift;
        while (!(RCC_CR & (RCC_CR_PLL1RDY << cr_addshift)));
}
 
static void rcc_set_and_enable_plls(const struct rcc_pll_config *config) {
        /* It is assumed that this function is entered with PLLs disabled and not
         * running. Setup PLL1/2/3 with configurations specified in the config. */
        RCC_PLLCKSELR = RCC_PLLCKSELR_DIVM1(config->pll1.divm) |
                                        RCC_PLLCKSELR_DIVM2(config->pll2.divm) |
                                        RCC_PLLCKSELR_DIVM3(config->pll3.divm) |
                                        config->pll_source;
 
        uint32_t clkin = (config->pll_source == RCC_PLLCKSELR_PLLSRC_HSI)
                ? RCC_HSI_BASE_FREQUENCY : config->hse_frequency;
 
        RCC_PLLCFGR = 0;
        rcc_configure_pll(clkin, &config->pll1, 1);
        rcc_configure_pll(clkin, &config->pll2, 2);
        rcc_configure_pll(clkin, &config->pll3, 3);
}
 
/* This is a helper to calculate dividers that go 2/4/8/16/64/128/256/512.
 * These dividers also use the top bit as an "enable". */
static uint16_t rcc_prediv_log_skip32_div(uint16_t clk_mhz, uint32_t div_val) {
        if (div_val < 0x8) {
                return clk_mhz;
        } else if (div_val <= RCC_D1CFGR_D1CPRE_DIV16) {
                return clk_mhz >> (div_val - 7);
        } else {
                return clk_mhz >> (div_val - 6);
        }
}
 
/* This is a helper to help calculate simple 3-bit log dividers with top bit
 * used as enable bit. */
static uint16_t rcc_prediv_3bit_log_div(uint16_t clk_mhz, uint32_t div_val) {
        if (div_val < 0x4) {
                return clk_mhz;
        } else {
                return clk_mhz >> (div_val - 3);
        }
}
 
static void rcc_clock_setup_domain1(const struct rcc_pll_config *config) {
        RCC_D1CFGR = 0;
        RCC_D1CFGR |= RCC_D1CFGR_D1CPRE(config->core_pre)  |
                RCC_D1CFGR_D1HPRE(config->hpre) | RCC_D1CFGR_D1PPRE(config->ppre3);
 
        /* Update our clock values in our tree based on the config values. */
        rcc_clock_tree.cpu_mhz =
                rcc_prediv_log_skip32_div(rcc_clock_tree.sysclk_mhz, config->core_pre);
        rcc_clock_tree.hclk_mhz =
                rcc_prediv_log_skip32_div(rcc_clock_tree.cpu_mhz, config->hpre);
        rcc_clock_tree.per.pclk3_mhz =
                rcc_prediv_3bit_log_div(rcc_clock_tree.hclk_mhz, config->ppre3);
}
 
static void rcc_clock_setup_domain2(const struct rcc_pll_config *config) {
        RCC_D2CFGR  = 0;
        RCC_D2CFGR |= RCC_D2CFGR_D2PPRE1(config->ppre1) |
                RCC_D2CFGR_D2PPRE2(config->ppre2);
 
        /* Update our clock values in our tree based on the config values. */
        rcc_clock_tree.per.pclk2_mhz =
                rcc_prediv_3bit_log_div(rcc_clock_tree.hclk_mhz, config->ppre2);
        rcc_clock_tree.per.pclk1_mhz =
                rcc_prediv_3bit_log_div(rcc_clock_tree.hclk_mhz, config->ppre1);
}
 
static void rcc_clock_setup_domain3(const struct rcc_pll_config *config) {
        RCC_D3CFGR &= 0;
        RCC_D3CFGR |= RCC_D3CFGR_D3PPRE(config->ppre4);
 
        /* Update our clock values in our tree based on the config values. */
        rcc_clock_tree.per.pclk4_mhz =
                rcc_prediv_3bit_log_div(rcc_clock_tree.hclk_mhz, config->ppre4);
}
 
void rcc_clock_setup_pll(const struct rcc_pll_config *config) {
        /* First, set system clock to utilize HSI, then disable all but HSI. */
        RCC_CR |= RCC_CR_HSION;
        RCC_CFGR &= ~(RCC_CFGR_SW_MASK << RCC_CFGR_SW_SHIFT);
        while (((RCC_CFGR >> RCC_CFGR_SWS_SHIFT) & RCC_CFGR_SWS_MASK) != RCC_CFGR_SWS_HSI);
        RCC_CR = RCC_CR_HSION;
 
        /* Now that we're safely running on HSI, let's setup the power system for scaling. */
        pwr_set_mode(config->power_mode, config->smps_level);
        pwr_set_vos_scale(config->voltage_scale);
 
        /* Set flash waitstates. Enable flash prefetch if we have at least 1WS */
        flash_set_ws(config->flash_waitstates);
        if (config->flash_waitstates > FLASH_ACR_LATENCY_0WS) {
                flash_prefetch_enable();
        } else {
                flash_prefetch_disable();
        }
 
        /* User has specified an external oscillator, make sure we turn it on. */
        if (config->hse_frequency > 0) {
                RCC_CR |= RCC_CR_HSEON;
                while (!(RCC_CR & RCC_CR_HSERDY));
                rcc_clock_tree.hse_khz = config->hse_frequency / HZ_PER_KHZ;
        }
 
        /* Set, enable and lock all of the pll from the config. */
        rcc_set_and_enable_plls(config);
 
        /* Populate our base sysclk settings for use with domain clocks. */
        if (config->sysclock_source == RCC_PLL) {
                rcc_clock_tree.sysclk_mhz = rcc_clock_tree.pll1.p_mhz;
        } else if (config->sysclock_source == RCC_HSE) {
                rcc_clock_tree.sysclk_mhz = config->hse_frequency / HZ_PER_MHZ;
        } else {
                rcc_clock_tree.sysclk_mhz = RCC_HSI_BASE_FREQUENCY / HZ_PER_MHZ;
        }
 
        /* PLL's are set, now we need to get everything switched over the correct domains. */
        rcc_clock_setup_domain1(config);
        rcc_clock_setup_domain2(config);
        rcc_clock_setup_domain3(config);
 
        /* TODO: Configure custom kernel mappings. */
 
        /* Domains dividers are all configured, now we can switchover to PLL. */
        RCC_CFGR |= RCC_CFGR_SW_PLL1;
        uint32_t cfgr_sws = ((RCC_CFGR >> RCC_CFGR_SWS_SHIFT) & RCC_CFGR_SWS_MASK);
        while(cfgr_sws != RCC_CFGR_SWS_PLL1) {
                cfgr_sws = ((RCC_CFGR >> RCC_CFGR_SWS_SHIFT) & RCC_CFGR_SWS_MASK);
        }
}
 
uint32_t rcc_get_bus_clk_freq(enum rcc_clock_source source) {
        uint32_t clksel;
        switch (source) {
                case RCC_SYSCLK:
                        return rcc_clock_tree.sysclk_mhz * HZ_PER_MHZ;
                case RCC_CPUCLK:
                case RCC_SYSTICKCLK:
                        return rcc_clock_tree.cpu_mhz * HZ_PER_MHZ;
                case RCC_AHBCLK:
                case RCC_HCLK3:
                        return rcc_clock_tree.hclk_mhz * HZ_PER_MHZ;
                case RCC_APB1CLK:
                        return rcc_clock_tree.per.pclk1_mhz * HZ_PER_MHZ;
                case RCC_APB2CLK:
                        return rcc_clock_tree.per.pclk2_mhz * HZ_PER_MHZ;
                case RCC_APB3CLK:
                        return rcc_clock_tree.per.pclk3_mhz * HZ_PER_MHZ;
                case RCC_APB4CLK:
                        return rcc_clock_tree.per.pclk4_mhz * HZ_PER_MHZ;
                case RCC_PERCLK:
                        clksel = (RCC_D1CCIPR >> RCC_D1CCIPR_CKPERSEL_SHIFT) & RCC_D1CCIPR_CKPERSEL_MASK;
                        if (clksel == RCC_D1CCIPR_CKPERSEL_HSI) {
                                return RCC_HSI_BASE_FREQUENCY;
                        } else if (clksel == RCC_D1CCIPR_CKPERSEL_HSE) {
                                return rcc_clock_tree.hse_khz * HZ_PER_KHZ;
                        } else {
                                return 0U;
                        }
                default:
                        cm3_assert_not_reached();
                        return 0U;
        }
}
 
uint32_t rcc_get_usart_clk_freq(uint32_t usart)
{
        uint32_t clksel, pclk;
        if (usart == USART1_BASE || usart == USART6_BASE) {
                pclk = rcc_clock_tree.per.pclk2_mhz * HZ_PER_MHZ;;
                clksel = (RCC_D2CCIP2R >> RCC_D2CCIP2R_USART16SEL_SHIFT) & RCC_D2CCIP2R_USARTSEL_MASK;
        } else {
                pclk = rcc_clock_tree.per.pclk1_mhz * HZ_PER_MHZ;
                clksel = (RCC_D2CCIP2R >> RCC_D2CCIP2R_USART234578SEL_SHIFT) & RCC_D2CCIP2R_USARTSEL_MASK;
        }
 
        /* Based on extracted clksel value, return the clock. */
        switch(clksel) {
        case RCC_D2CCIP2R_USARTSEL_PCLK:
                return pclk;
        case RCC_D2CCIP2R_USARTSEL_PLL2Q:
                return rcc_clock_tree.pll2.q_mhz * HZ_PER_MHZ;
        case RCC_D2CCIP2R_USARTSEL_PLL3Q:
                return rcc_clock_tree.pll3.q_mhz * HZ_PER_MHZ;
        case RCC_D2CCIP2R_USARTSEL_HSI:
                return RCC_HSI_BASE_FREQUENCY;
        case RCC_D2CCIP2R_USARTSEL_CSI:
                return 4000000;
        case RCC_D2CCIP2R_USARTSEL_LSE:
                return 32768;
        }
        cm3_assert_not_reached();
}
 
uint32_t rcc_get_timer_clk_freq(uint32_t timer __attribute__((unused)))
{
        if (timer >= LPTIM2_BASE && timer <= LPTIM5_BASE) {
                /* TODO: Read LPTIMxSEL values from D3CCIPR to determine clock source. */
                return rcc_clock_tree.per.pclk4_mhz * HZ_PER_MHZ;
        } else if (timer >= TIM1_BASE && timer <= HRTIM_BASE) {
                return rcc_clock_tree.per.pclk2_mhz * HZ_PER_MHZ;
        } else {
                return rcc_clock_tree.per.pclk1_mhz * HZ_PER_MHZ;
        }
}
 
uint32_t rcc_get_i2c_clk_freq(uint32_t i2c)
{
        if (i2c == I2C4_BASE) {
                /* TODO: Read I2C4SEL from D3CCIPR to determine clock source. */
                return rcc_clock_tree.per.pclk3_mhz * HZ_PER_MHZ;
        } else {
                /* TODO: Read I2C123SEL from D2CCIP2R to determine clock source. */
                return rcc_clock_tree.per.pclk1_mhz * HZ_PER_MHZ;
        }
}
 
uint32_t rcc_get_spi_clk_freq(uint32_t spi)
{
        if (spi == SPI4_BASE || spi == SPI5_BASE) {
                uint32_t clksel =
                        (RCC_D2CCIP1R >> RCC_D2CCIP1R_SPI45SEL_SHIFT) & RCC_D2CCIP1R_SPI45SEL_MASK;
                if (clksel == RCC_D2CCIP1R_SPI45SEL_APB4){
                        return rcc_clock_tree.per.pclk2_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI45SEL_PLL2Q){
                        return rcc_clock_tree.pll2.q_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI45SEL_PLL3Q){
                        return rcc_clock_tree.pll3.q_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI45SEL_HSI){
                        return RCC_HSI_BASE_FREQUENCY;
                } else if (clksel == RCC_D2CCIP1R_SPI45SEL_HSE) {
                        return rcc_clock_tree.hse_khz * HZ_PER_KHZ;
                } else {
                        return 0U;
                }
        } else {
                uint32_t clksel =
                        (RCC_D2CCIP1R >> RCC_D2CCIP1R_SPI123SEL_SHIFT) & RCC_D2CCIP1R_SPI123SEL_MASK;
                if (clksel == RCC_D2CCIP1R_SPI123SEL_PLL1Q) {
                        return rcc_clock_tree.pll1.q_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI123SEL_PLL2P) {
                        return rcc_clock_tree.pll2.p_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI123SEL_PLL3P) {
                        return rcc_clock_tree.pll3.p_mhz * HZ_PER_MHZ;
                } else if (clksel == RCC_D2CCIP1R_SPI123SEL_PERCK) {
                        return rcc_get_bus_clk_freq(RCC_PERCLK);
                } else {
                        return 0U;
                }
        }
}
 
uint32_t rcc_get_fdcan_clk_freq(uint32_t fdcan __attribute__((unused)))
{
        uint32_t clksel =
                (RCC_D2CCIP1R >> RCC_D2CCIP1R_FDCANSEL_SHIFT) & RCC_D2CCIP1R_FDCANSEL_MASK;
        if (clksel == RCC_D2CCIP1R_FDCANSEL_HSE) {
                return rcc_clock_tree.hse_khz * HZ_PER_KHZ;
        } else if (clksel == RCC_D2CCIP1R_FDCANSEL_PLL1Q) {
                return rcc_clock_tree.pll1.q_mhz * HZ_PER_MHZ;
        } else if (clksel == RCC_D2CCIP1R_FDCANSEL_PLL2Q) {
                return rcc_clock_tree.pll2.q_mhz * HZ_PER_MHZ;
        } else {
                return 0U;
        }
}
 
void rcc_set_peripheral_clk_sel(uint32_t periph, uint32_t sel) {
        volatile uint32_t *reg;
        uint32_t mask;
        uint32_t val;
 
        switch (periph) {
                case FDCAN1_BASE:
                case FDCAN2_BASE:
                        reg = &RCC_D2CCIP1R;
                        mask = RCC_D2CCIP1R_FDCANSEL_MASK << RCC_D2CCIP1R_FDCANSEL_SHIFT;
                        val = sel << RCC_D2CCIP1R_FDCANSEL_SHIFT;
                        break;
                case RNG_BASE:
                  reg = &RCC_D2CCIP2R;
                  mask = RCC_D2CCIP2R_RNGSEL_MASK << RCC_D2CCIP2R_RNGSEL_SHIFT;
                  val = sel << RCC_D2CCIP2R_RNGSEL_SHIFT;
                  break;
                case SPI1_BASE:
                case SPI2_BASE:
                case SPI3_BASE:
                        reg = &RCC_D2CCIP2R;
                        mask = RCC_D2CCIP1R_SPI123SEL_MASK << RCC_D2CCIP1R_SPI123SEL_SHIFT;
                        val = sel << RCC_D2CCIP1R_SPI123SEL_SHIFT;
                        break;
                case SPI4_BASE:
                case SPI5_BASE:
                        reg = &RCC_D2CCIP1R;
                        mask = RCC_D2CCIP1R_SPI45SEL_MASK << RCC_D2CCIP1R_SPI45SEL_SHIFT;
                        val = sel << RCC_D2CCIP1R_SPI45SEL_SHIFT;
                        break;
                case USART1_BASE:
                case USART6_BASE:
                        reg = &RCC_D2CCIP2R;
                        mask = RCC_D2CCIP2R_USARTSEL_MASK << RCC_D2CCIP2R_USART16SEL_SHIFT;
                        val = sel << RCC_D2CCIP2R_USART16SEL_SHIFT;
                        break;
                case USART2_BASE:
                case USART3_BASE:
                case UART4_BASE:
                case UART5_BASE:
                case UART7_BASE:
                case UART8_BASE:
                        reg = &RCC_D2CCIP2R;
                        mask = RCC_D2CCIP2R_USARTSEL_MASK << RCC_D2CCIP2R_USART234578SEL_SHIFT;
                        val = sel << RCC_D2CCIP2R_USART234578SEL_SHIFT;
                        break;
 
                default:
                        cm3_assert_not_reached();
                        return;
        }
 
        // Update the register value by masking and oring in new values.
        uint32_t regval = (*reg & mask) | val;
        *reg = regval;
}
 
void rcc_set_fdcan_clksel(uint8_t clksel) {
        RCC_D2CCIP1R &= ~(RCC_D2CCIP1R_FDCANSEL_MASK << RCC_D2CCIP1R_FDCANSEL_SHIFT);
        RCC_D2CCIP1R |= clksel << RCC_D2CCIP1R_FDCANSEL_SHIFT;
}
 
void rcc_set_rng_clksel(uint8_t clksel) {
        RCC_D2CCIP2R &= ~(RCC_D2CCIP2R_RNGSEL_MASK << RCC_D2CCIP2R_RNGSEL_SHIFT);
        RCC_D2CCIP2R |= clksel << RCC_D2CCIP2R_RNGSEL_SHIFT;
}
 
void rcc_set_spi123_clksel(uint8_t clksel) {
        RCC_D2CCIP1R &= ~(RCC_D2CCIP1R_SPI123SEL_MASK << RCC_D2CCIP1R_SPI123SEL_SHIFT);
        RCC_D2CCIP1R |= clksel << RCC_D2CCIP1R_SPI123SEL_SHIFT;
}
 
void rcc_set_spi45_clksel(uint8_t clksel) {
        RCC_D2CCIP1R &= ~(RCC_D2CCIP1R_SPI45SEL_MASK << RCC_D2CCIP1R_SPI45SEL_SHIFT);
        RCC_D2CCIP1R |= clksel << RCC_D2CCIP1R_SPI45SEL_SHIFT;
}