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/**
* @file
* @brief Provide @ref clocksource functionality for OMAP
*
* @ref clocksource provides a neat architecture. all we do is
* To loop in with Sync 32Khz clock ticking away at 32768hz on OMAP.
* Sync 32Khz clock is an always ON clock.
*
* (C) Copyright 2008
* Texas Instruments, <www.ti.com>
* Nishanth Menon <x0nishan@ti.com>
*
* 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 <init.h>
#include <io.h>
#include <mach/omap3-silicon.h>
#include <mach/omap4-silicon.h>
#include <mach/clocks.h>
#include <mach/timers.h>
#include <mach/sys_info.h>
#include <mach/syslib.h>
/** Sync 32Khz Timer registers */
#define S32K_CR 0x10
#define S32K_FREQUENCY 32768
static void __iomem *timerbase;
/**
* @brief Provide a simple clock read
*
* Nothing is simpler.. read direct from clock and provide it
* to the caller.
*
* @return S32K clock counter
*/
static uint64_t s32k_clocksource_read(void)
{
return readl(timerbase + S32K_CR);
}
/* A bit obvious isn't it? */
static struct clocksource s32k_cs = {
.read = s32k_clocksource_read,
.mask = CLOCKSOURCE_MASK(32),
.shift = 10,
};
/**
* @brief Initialize the Clock
*
* There is nothing to do on OMAP as SYNC32K clock is
* always on, and we do a simple data structure initialization.
* 32K clock gives 32768 ticks a seconds
*
* @return result of @ref init_clock
*/
static int omap_32ktimer_probe(struct device_d *dev)
{
struct resource *iores;
/* one timer is enough */
if (timerbase)
return 0;
iores = dev_request_mem_resource(dev, 0);
if (IS_ERR(iores))
return PTR_ERR(iores);
timerbase = IOMEM(iores->start);
s32k_cs.mult = clocksource_hz2mult(S32K_FREQUENCY, s32k_cs.shift);
return init_clock(&s32k_cs);
}
static __maybe_unused struct of_device_id omap_32ktimer_dt_ids[] = {
{
.compatible = "ti,omap-counter32k",
}, {
/* sentinel */
}
};
static struct driver_d omap_32ktimer_driver = {
.name = "omap-32ktimer",
.probe = omap_32ktimer_probe,
.of_compatible = DRV_OF_COMPAT(omap_32ktimer_dt_ids),
};
static int omap_32ktimer_init(void)
{
return platform_driver_register(&omap_32ktimer_driver);
}
postcore_initcall(omap_32ktimer_init);
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