cpu/armv7m/systick-timer.c

1 // SPDX-License-Identifier: GPL-2.0+
3  * ARM Cortex M3/M4/M7 SysTick timer driver
6  * Based on arch/arm/mach-stm32/stm32f1/timer.c
13  * The SysTick timer is a 24-bit count down timer. The clock can be either the
29 /* SysTick Base Address - fixed for all Cortex M3, M4 and M7 devices */
47 /* read the 24-bit timer */
53 	return TIMER_MAX_VAL - readl(&systick->current_val);  in read_timer()
61 	writel(TIMER_MAX_VAL, &systick->reload_val);  in timer_init()
63 	writel(0, &systick->current_val);  in timer_init()
65 	cal = readl(&systick->calibration);  in timer_init()
68 		writel(SYSTICK_CTRL_EN | SYSTICK_CTRL_CPU_CLK, &systick->ctrl);  in timer_init()
71 		writel(SYSTICK_CTRL_EN, &systick->ctrl);  in timer_init()
78 	gd->arch.timer_rate_hz = CONFIG_SYS_HZ_CLOCK;  in timer_init()
80 	gd->arch.timer_rate_hz = (cal & SYSTICK_CAL_TENMS_MASK) * 100;  in timer_init()
83 	gd->arch.tbl = 0;  in timer_init()
84 	gd->arch.tbu = 0;  in timer_init()
85 	gd->arch.lastinc = read_timer();  in timer_init()
90 /* return milli-seconds timer value */
95 	return (ulong)((t / gd->arch.timer_rate_hz)) - base;  in get_timer()
102 	if (now >= gd->arch.lastinc)  in get_ticks()
103 		gd->arch.tbl += (now - gd->arch.lastinc);  in get_ticks()
105 		gd->arch.tbl += (TIMER_MAX_VAL - gd->arch.lastinc) + now;  in get_ticks()
107 	gd->arch.lastinc = now;  in get_ticks()
109 	return gd->arch.tbl;  in get_ticks()
114 	return gd->arch.timer_rate_hz;  in get_tbclk()