/*
* OMAP 32ksynctimer/counter_32k-related code
*
* Copyright (C) 2009 Texas Instruments
* Copyright (C) 2010 Nokia Corporation
* Tony Lindgren <tony@atomide.com>
* Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* NOTE: This timer is not the same timer as the old OMAP1 MPU timer.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <plat/common.h>
#include <plat/board.h>
#include <plat/clock.h>
/*
* 32KHz clocksource ... always available, on pretty most chips except
* OMAP 730 and 1510. Other timers could be used as clocksources, with
* higher resolution in free-running counter modes (e.g. 12 MHz xtal),
* but systems won't necessarily want to spend resources that way.
*/
#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
#if !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX))
#include <linux/clocksource.h>
/*
* offset_32k holds the init time counter value. It is then subtracted
* from every counter read to achieve a counter that counts time from the
* kernel boot (needed for sched_clock()).
*/
static u32 offset_32k __read_mostly;
#ifdef CONFIG_ARCH_OMAP16XX
static cycle_t omap16xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k;
}
#else
#define omap16xx_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP2420
static cycle_t omap2420_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2420_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP2430
static cycle_t omap2430_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2430_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP3
static cycle_t omap34xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap34xx_32k_read NULL
#endif
#ifdef CONFIG_ARCH_OMAP4
static cycle_t omap44xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap44xx_32k_read NULL
#endif
/*
* Kernel assumes that sched_clock can be called early but may not have
* things ready yet.
*/
static cycle_t omap_32k_read_dummy(struct clocksource *cs)
{
return 0;
}
static struct clocksource clocksource_32k = {
.name = "32k_counter",
.rating = 250,
.read = omap_32k_read_dummy,
.mask = CLOCKSOURCE_MASK(32),
.shift = 10,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Returns current time from boot in nsecs. It's OK for this to wrap
* around for now, as it's just a relative time stamp.
*/
unsigned long long sched_clock(void)
{
return clocksource_cyc2ns(clocksource_32k.read(&clocksource_32k),
clocksource_32k.mult, clocksource_32k.shift);
}
/**
* read_persistent_clock - Return time from a persistent clock.
*
* Reads the time from a source which isn't disabled during PM, the
* 32k sync timer. Convert the cycles elapsed since last read into
* nsecs and adds to a monotonically increasing timespec.
*/
static struct timespec persistent_ts;
static cycles_t cycles, last_cycles;
void read_persistent_clock(struct timespec *ts)
{
unsigned long long nsecs;
cycles_t delta;
struct timespec *tsp = &persistent_ts;
last_cycles = cycles;
cycles = clocksource_32k.read(&clocksource_32k);
delta = cycles - last_cycles;
nsecs = clocksource_cyc2ns(delta,
clocksource_32k.mult, clocksource_32k.shift);
timespec_add_ns(tsp, nsecs);
*ts = *tsp;
}
static int __init omap_init_clocksource_32k(void)
{
static char err[] __initdata = KERN_ERR
"%s: can't register clocksource!\n";
if (cpu_is_omap16xx() || cpu_class_is_omap2()) {
struct clk *sync_32k_ick;
if (cpu_is_omap16xx())
clocksource_32k.read = omap16xx_32k_read;
else if (cpu_is_omap2420())
clocksource_32k.read = omap2420_32k_read;
else if (cpu_is_omap2430())
clocksource_32k.read = omap2430_32k_read;
else if (cpu_is_omap34xx())
clocksource_32k.read = omap34xx_32k_read;
else if (cpu_is_omap44xx())
clocksource_32k.read = omap44xx_32k_read;
else
return -ENODEV;
sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
if (sync_32k_ick)
clk_enable(sync_32k_ick);
clocksource_32k.mult = clocksource_hz2mult(32768,
clocksource_32k.shift);
offset_32k = clocksource_32k.read(&clocksource_32k);
if (clocksource_register(&clocksource_32k))
printk(err, clocksource_32k.name);
}
return 0;
}
arch_initcall(omap_init_clocksource_32k);
#endif /* !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX)) */
