/*
 * Author: Carlo Caione <carlo@carlocaione.org>
 *
 * Based on clocksource for nomadik
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */


#include <common.h>
#include <clock.h>
#include <io.h>
#include <init.h>
#include <driver.h>
#include <errno.h>
#include <linux/clk.h>
#include <linux/err.h>

/* Registers */
#define ST_CLO	0x04

static __iomem void *stc_base;

static uint64_t stc_read_cycles(void)
{
	return readl(stc_base + ST_CLO);
}

static struct clocksource bcm2835_stc = {
	.read = stc_read_cycles,
	.mask = CLOCKSOURCE_MASK(32),
};

static int bcm2835_cs_probe(struct device_d *dev)
{
	static struct clk *stc_clk;
	u32 rate;
	int ret;

	stc_clk = clk_get(dev, NULL);
	if (IS_ERR(stc_clk)) {
		ret = PTR_ERR(stc_clk);
		dev_err(dev, "clock not found: %d\n", ret);
		return ret;
	}

	ret = clk_enable(stc_clk);
	if (ret) {
		dev_err(dev, "clock failed to enable: %d\n", ret);
		clk_put(stc_clk);
		return ret;
	}

	rate = clk_get_rate(stc_clk);
	stc_base = dev_request_mem_region(dev, 0);
	if (IS_ERR(stc_base))
		return PTR_ERR(stc_base);

	clocks_calc_mult_shift(&bcm2835_stc.mult, &bcm2835_stc.shift, rate, NSEC_PER_SEC, 60);

	return init_clock(&bcm2835_stc);
}

static __maybe_unused struct of_device_id bcm2835_cs_dt_ids[] = {
	{
		.compatible = "brcm,bcm2835-system-timer",
	}, {
		/* sentinel */
	}
};

static struct driver_d bcm2835_cs_driver = {
	.name = "bcm2835-cs",
	.probe = bcm2835_cs_probe,
	.of_compatible = DRV_OF_COMPAT(bcm2835_cs_dt_ids),
};

static int bcm2835_cs_init(void)
{
	return platform_driver_register(&bcm2835_cs_driver);
}
core_initcall(bcm2835_cs_init);
