u-boot/arch/arm/cpu/arm1136/mx35/timer.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2007
* Sascha Hauer, Pengutronix
*
* (C) Copyright 2008-2009 Freescale Semiconductor, Inc.
*/
#include <common.h>
#include <asm/io.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/crm_regs.h>
/* General purpose timers bitfields */
#define GPTCR_SWR (1<<15) /* Software reset */
#define GPTCR_FRR (1<<9) /* Freerun / restart */
#define GPTCR_CLKSOURCE_32 (4<<6) /* Clock source */
#define GPTCR_TEN (1) /* Timer enable */
/*
* nothing really to do with interrupts, just starts up a counter.
* The 32KHz 32-bit timer overruns in 134217 seconds
*/
int timer_init(void)
{
int i;
struct gpt_regs *gpt = (struct gpt_regs *)GPT1_BASE_ADDR;
struct ccm_regs *ccm = (struct ccm_regs *)CCM_BASE_ADDR;
/* setup GP Timer 1 */
writel(GPTCR_SWR, &gpt->ctrl);
writel(readl(&ccm->cgr1) | 3 << MXC_CCM_CGR1_GPT_OFFSET, &ccm->cgr1);
for (i = 0; i < 100; i++)
writel(0, &gpt->ctrl); /* We have no udelay by now */
writel(0, &gpt->pre); /* prescaler = 1 */
/* Freerun Mode, 32KHz input */
writel(readl(&gpt->ctrl) | GPTCR_CLKSOURCE_32 | GPTCR_FRR,
&gpt->ctrl);
writel(readl(&gpt->ctrl) | GPTCR_TEN, &gpt->ctrl);
return 0;
}