u-boot/drivers/timer/omap-timer.c

/*
 * TI OMAP timer driver
 *
 * Copyright (C) 2015, Texas Instruments, Incorporated
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#include <common.h>
#include <dm.h>
#include <errno.h>
#include <timer.h>
#include <asm/io.h>
#include <asm/arch/clock.h>

DECLARE_GLOBAL_DATA_PTR;

/* Timer register bits */
#define TCLR_START			BIT(0)	/* Start=1 */
#define TCLR_AUTO_RELOAD		BIT(1)	/* Auto reload */
#define TCLR_PRE_EN			BIT(5)	/* Pre-scaler enable */
#define TCLR_PTV_SHIFT			(2)	/* Pre-scaler shift value */

#define TIMER_CLOCK             (V_SCLK / (2 << CONFIG_SYS_PTV))

struct omap_gptimer_regs {
	unsigned int tidr;		/* offset 0x00 */
	unsigned char res1[12];
	unsigned int tiocp_cfg;		/* offset 0x10 */
	unsigned char res2[12];
	unsigned int tier;		/* offset 0x20 */
	unsigned int tistatr;		/* offset 0x24 */
	unsigned int tistat;		/* offset 0x28 */
	unsigned int tisr;		/* offset 0x2c */
	unsigned int tcicr;		/* offset 0x30 */
	unsigned int twer;		/* offset 0x34 */
	unsigned int tclr;		/* offset 0x38 */
	unsigned int tcrr;		/* offset 0x3c */
	unsigned int tldr;		/* offset 0x40 */
	unsigned int ttgr;		/* offset 0x44 */
	unsigned int twpc;		/* offset 0x48 */
	unsigned int tmar;		/* offset 0x4c */
	unsigned int tcar1;		/* offset 0x50 */
	unsigned int tscir;		/* offset 0x54 */
	unsigned int tcar2;		/* offset 0x58 */
};

/* Omap Timer Priv */
struct omap_timer_priv {
	struct omap_gptimer_regs *regs;
};

static int omap_timer_get_count(struct udevice *dev, u64 *count)
{
	struct omap_timer_priv *priv = dev_get_priv(dev);

	*count = readl(&priv->regs->tcrr);

	return 0;
}

static int omap_timer_probe(struct udevice *dev)
{
	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
	struct omap_timer_priv *priv = dev_get_priv(dev);

	uc_priv->clock_rate = TIMER_CLOCK;

	/* start the counter ticking up, reload value on overflow */
	writel(0, &priv->regs->tldr);
	/* enable timer */
	writel((CONFIG_SYS_PTV << 2) | TCLR_PRE_EN | TCLR_AUTO_RELOAD |
	       TCLR_START, &priv->regs->tclr);

	return 0;
}

static int omap_timer_ofdata_to_platdata(struct udevice *dev)
{
	struct omap_timer_priv *priv = dev_get_priv(dev);

	priv->regs = map_physmem(dev_get_addr(dev),
				 sizeof(struct omap_gptimer_regs), MAP_NOCACHE);

	return 0;
}


static const struct timer_ops omap_timer_ops = {
	.get_count = omap_timer_get_count,
};

static const struct udevice_id omap_timer_ids[] = {
	{ .compatible = "ti,am335x-timer" },
	{ .compatible = "ti,am4372-timer" },
	{ .compatible = "ti,omap5430-timer" },
	{}
};

U_BOOT_DRIVER(omap_timer) = {
	.name	= "omap_timer",
	.id	= UCLASS_TIMER,
	.of_match = omap_timer_ids,
	.ofdata_to_platdata = omap_timer_ofdata_to_platdata,
	.priv_auto_alloc_size = sizeof(struct omap_timer_priv),
	.probe = omap_timer_probe,
	.ops	= &omap_timer_ops,
	.flags = DM_FLAG_PRE_RELOC,
};