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    /*
     * (C) Copyright 2015
     * Kamil Lulko, <rev13@wp.pl>
     *
     * SPDX-License-Identifier:	GPL-2.0+
     */
    
    #include <common.h>
    #include <asm/io.h>
    #include <asm/armv7m.h>
    #include <asm/arch/stm32.h>
    
    DECLARE_GLOBAL_DATA_PTR;
    
    #define STM32_TIM2_BASE	(STM32_APB1PERIPH_BASE + 0x0000)
    
    #define RCC_APB1ENR_TIM2EN	(1 << 0)
    
    struct stm32_tim2_5 {
    	u32 cr1;
    	u32 cr2;
    	u32 smcr;
    	u32 dier;
    	u32 sr;
    	u32 egr;
    	u32 ccmr1;
    	u32 ccmr2;
    	u32 ccer;
    	u32 cnt;
    	u32 psc;
    	u32 arr;
    	u32 reserved1;
    	u32 ccr1;
    	u32 ccr2;
    	u32 ccr3;
    	u32 ccr4;
    	u32 reserved2;
    	u32 dcr;
    	u32 dmar;
    	u32 or;
    };
    
    #define TIM_CR1_CEN	(1 << 0)
    
    #define TIM_EGR_UG	(1 << 0)
    
    int timer_init(void)
    {
    	struct stm32_tim2_5 *tim = (struct stm32_tim2_5 *)STM32_TIM2_BASE;
    
    	setbits_le32(&STM32_RCC->apb1enr, RCC_APB1ENR_TIM2EN);
    
    	if (clock_get(CLOCK_AHB) == clock_get(CLOCK_APB1))
    		writel((clock_get(CLOCK_APB1) / CONFIG_SYS_HZ_CLOCK) - 1,
    		       &tim->psc);
    	else
    		writel(((clock_get(CLOCK_APB1) * 2) / CONFIG_SYS_HZ_CLOCK) - 1,
    		       &tim->psc);
    
    	writel(0xFFFFFFFF, &tim->arr);
    	writel(TIM_CR1_CEN, &tim->cr1);
    	setbits_le32(&tim->egr, TIM_EGR_UG);
    
    	gd->arch.tbl = 0;
    	gd->arch.tbu = 0;
    	gd->arch.lastinc = 0;
    
    	return 0;
    }
    
    ulong get_timer(ulong base)
    {
    	return (get_ticks() / (CONFIG_SYS_HZ_CLOCK / CONFIG_SYS_HZ)) - base;
    }
    
    unsigned long long get_ticks(void)
    {
    	struct stm32_tim2_5 *tim = (struct stm32_tim2_5 *)STM32_TIM2_BASE;
    	u32 now;
    
    	now = readl(&tim->cnt);
    
    	if (now >= gd->arch.lastinc)
    		gd->arch.tbl += (now - gd->arch.lastinc);
    	else
    		gd->arch.tbl += (0xFFFFFFFF - gd->arch.lastinc) + now;
    
    	gd->arch.lastinc = now;
    
    	return gd->arch.tbl;
    }
    
    void reset_timer(void)
    {
    	struct stm32_tim2_5 *tim = (struct stm32_tim2_5 *)STM32_TIM2_BASE;
    
    	gd->arch.lastinc = readl(&tim->cnt);
    	gd->arch.tbl = 0;
    }
    
    /* delay x useconds */
    void __udelay(ulong usec)
    {
    	unsigned long long start;
    
    	start = get_ticks();		/* get current timestamp */
    	while ((get_ticks() - start) < usec)
    		;			/* loop till time has passed */
    }
    
    /*
     * This function is derived from PowerPC code (timebase clock frequency).
     * On ARM it returns the number of timer ticks per second.
     */
    ulong get_tbclk(void)
    {
    	return CONFIG_SYS_HZ_CLOCK;
    }