kernel_xiaomi_sm8250/arch/arm/mach-omap2/timer.c

/*
 * linux/arch/arm/mach-omap2/timer.c
 *
 * OMAP2 GP timer support.
 *
 * Copyright (C) 2009 Nokia Corporation
 *
 * Update to use new clocksource/clockevent layers
 * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
 * Copyright (C) 2007 MontaVista Software, Inc.
 *
 * Original driver:
 * Copyright (C) 2005 Nokia Corporation
 * Author: Paul Mundt <paul.mundt@nokia.com>
 *         Juha Yrjölä <juha.yrjola@nokia.com>
 * OMAP Dual-mode timer framework support by Timo Teras
 *
 * Some parts based off of TI's 24xx code:
 *
 * Copyright (C) 2004-2009 Texas Instruments, Inc.
 *
 * Roughly modelled after the OMAP1 MPU timer code.
 * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/platform_data/dmtimer-omap.h>
#include <linux/sched_clock.h>

#include <asm/mach/time.h>
#include <asm/smp_twd.h>

#include "omap_hwmod.h"
#include "omap_device.h"
#include <plat/counter-32k.h>
#include <clocksource/timer-ti-dm.h>

#include "soc.h"
#include "common.h"
#include "control.h"
#include "powerdomain.h"
#include "omap-secure.h"

#define REALTIME_COUNTER_BASE				0x48243200
#define INCREMENTER_NUMERATOR_OFFSET			0x10
#define INCREMENTER_DENUMERATOR_RELOAD_OFFSET		0x14
#define NUMERATOR_DENUMERATOR_MASK			0xfffff000

/* Clockevent code */

/* Clockevent hwmod for am335x and am437x suspend */
static struct omap_hwmod *clockevent_gpt_hwmod;

/* Clockesource hwmod for am437x suspend */
static struct omap_hwmod *clocksource_gpt_hwmod;

struct dmtimer_clockevent {
	struct clock_event_device dev;
	struct omap_dm_timer timer;
};

static struct dmtimer_clockevent clockevent;

static struct omap_dm_timer *to_dmtimer(struct clock_event_device *clockevent)
{
	struct dmtimer_clockevent *clkevt =
		container_of(clockevent, struct dmtimer_clockevent, dev);
	struct omap_dm_timer *timer = &clkevt->timer;

	return timer;
}

#ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
static unsigned long arch_timer_freq;

void set_cntfreq(void)
{
	omap_smc1(OMAP5_DRA7_MON_SET_CNTFRQ_INDEX, arch_timer_freq);
}
#endif

static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
{
	struct dmtimer_clockevent *clkevt = dev_id;
	struct clock_event_device *evt = &clkevt->dev;
	struct omap_dm_timer *timer = &clkevt->timer;

	__omap_dm_timer_write_status(timer, OMAP_TIMER_INT_OVERFLOW);
	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static int omap2_gp_timer_set_next_event(unsigned long cycles,
					 struct clock_event_device *evt)
{
	struct omap_dm_timer *timer = to_dmtimer(evt);

	__omap_dm_timer_load_start(timer, OMAP_TIMER_CTRL_ST,
				   0xffffffff - cycles, OMAP_TIMER_POSTED);

	return 0;
}

static int omap2_gp_timer_shutdown(struct clock_event_device *evt)
{
	struct omap_dm_timer *timer = to_dmtimer(evt);

	__omap_dm_timer_stop(timer, OMAP_TIMER_POSTED, timer->rate);

	return 0;
}

static int omap2_gp_timer_set_periodic(struct clock_event_device *evt)
{
	struct omap_dm_timer *timer = to_dmtimer(evt);
	u32 period;

	__omap_dm_timer_stop(timer, OMAP_TIMER_POSTED, timer->rate);

	period = timer->rate / HZ;
	period -= 1;
	/* Looks like we need to first set the load value separately */
	__omap_dm_timer_write(timer, OMAP_TIMER_LOAD_REG, 0xffffffff - period,
			      OMAP_TIMER_POSTED);
	__omap_dm_timer_load_start(timer,
				   OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
				   0xffffffff - period, OMAP_TIMER_POSTED);
	return 0;
}

static void omap_clkevt_idle(struct clock_event_device *unused)
{
	if (!clockevent_gpt_hwmod)
		return;

	omap_hwmod_idle(clockevent_gpt_hwmod);
}

static void omap_clkevt_unidle(struct clock_event_device *evt)
{
	struct omap_dm_timer *timer = to_dmtimer(evt);

	if (!clockevent_gpt_hwmod)
		return;

	omap_hwmod_enable(clockevent_gpt_hwmod);
	__omap_dm_timer_int_enable(timer, OMAP_TIMER_INT_OVERFLOW);
}

static const struct of_device_id omap_timer_match[] __initconst = {
	{ .compatible = "ti,omap2420-timer", },
	{ .compatible = "ti,omap3430-timer", },
	{ .compatible = "ti,omap4430-timer", },
	{ .compatible = "ti,omap5430-timer", },
	{ .compatible = "ti,dm814-timer", },
	{ .compatible = "ti,dm816-timer", },
	{ .compatible = "ti,am335x-timer", },
	{ .compatible = "ti,am335x-timer-1ms", },
	{ }
};

static int omap_timer_add_disabled_property(struct device_node *np)
{
	struct property *prop;

	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
	if (!prop)
		return -ENOMEM;

	prop->name = "status";
	prop->value = "disabled";
	prop->length = strlen(prop->value);

	return of_add_property(np, prop);
}

static int omap_timer_update_dt(struct device_node *np)
{
	int error = 0;

	if (!of_device_is_compatible(np, "ti,omap-counter32k")) {
		error = omap_timer_add_disabled_property(np);
		if (error)
			return error;
	}

	/* No parent interconnect target module configured? */
	if (of_get_property(np, "ti,hwmods", NULL))
		return error;

	/* Tag parent interconnect target module disabled */
	error = omap_timer_add_disabled_property(np->parent);
	if (error)
		return error;

	return 0;
}

/**
 * omap_get_timer_dt - get a timer using device-tree
 * @match	- device-tree match structure for matching a device type
 * @property	- optional timer property to match
 *
 * Helper function to get a timer during early boot using device-tree for use
 * as kernel system timer. Optionally, the property argument can be used to
 * select a timer with a specific property. Once a timer is found then mark
 * the timer node in device-tree as disabled, to prevent the kernel from
 * registering this timer as a platform device and so no one else can use it.
 */
static struct device_node * __init omap_get_timer_dt(const struct of_device_id *match,
						     const char *property)
{
	struct device_node *np;
	int error;

	for_each_matching_node(np, match) {
		if (!of_device_is_available(np))
			continue;

		if (property && !of_get_property(np, property, NULL))
			continue;

		if (!property && (of_get_property(np, "ti,timer-alwon", NULL) ||
				  of_get_property(np, "ti,timer-dsp", NULL) ||
				  of_get_property(np, "ti,timer-pwm", NULL) ||
				  of_get_property(np, "ti,timer-secure", NULL)))
			continue;

		error = omap_timer_update_dt(np);
		WARN(error, "%s: Could not update dt: %i\n", __func__, error);

		return np;
	}

	return NULL;
}

/**
 * omap_dmtimer_init - initialisation function when device tree is used
 *
 * For secure OMAP3/DRA7xx devices, timers with device type "timer-secure"
 * cannot be used by the kernel as they are reserved. Therefore, to prevent the
 * kernel registering these devices remove them dynamically from the device
 * tree on boot.
 */
static void __init omap_dmtimer_init(void)
{
	struct device_node *np;

	if (!cpu_is_omap34xx() && !soc_is_dra7xx())
		return;

	/* If we are a secure device, remove any secure timer nodes */
	if ((omap_type() != OMAP2_DEVICE_TYPE_GP)) {
		np = omap_get_timer_dt(omap_timer_match, "ti,timer-secure");
		of_node_put(np);
	}
}

/**
 * omap_dm_timer_get_errata - get errata flags for a timer
 *
 * Get the timer errata flags that are specific to the OMAP device being used.
 */
static u32 __init omap_dm_timer_get_errata(void)
{
	if (cpu_is_omap24xx())
		return 0;

	return OMAP_TIMER_ERRATA_I103_I767;
}

static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
					 const char *fck_source,
					 const char *property,
					 const char **timer_name,
					 int posted)
{
	const char *oh_name = NULL;
	struct device_node *np;
	struct omap_hwmod *oh;
	struct clk *src;
	int r = 0;

	np = omap_get_timer_dt(omap_timer_match, property);
	if (!np)
		return -ENODEV;

	of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
	if (!oh_name) {
		of_property_read_string_index(np->parent, "ti,hwmods", 0,
					      &oh_name);
		if (!oh_name)
			return -ENODEV;
	}

	timer->irq = irq_of_parse_and_map(np, 0);
	if (!timer->irq)
		return -ENXIO;

	timer->io_base = of_iomap(np, 0);

	timer->fclk = of_clk_get_by_name(np, "fck");

	of_node_put(np);

	oh = omap_hwmod_lookup(oh_name);
	if (!oh)
		return -ENODEV;

	*timer_name = oh->name;

	if (!timer->io_base)
		return -ENXIO;

	omap_hwmod_setup_one(oh_name);

	/* After the dmtimer is using hwmod these clocks won't be needed */
	if (IS_ERR_OR_NULL(timer->fclk))
		timer->fclk = clk_get(NULL, omap_hwmod_get_main_clk(oh));
	if (IS_ERR(timer->fclk))
		return PTR_ERR(timer->fclk);

	src = clk_get(NULL, fck_source);
	if (IS_ERR(src))
		return PTR_ERR(src);

	WARN(clk_set_parent(timer->fclk, src) < 0,
	     "Cannot set timer parent clock, no PLL clock driver?");

	clk_put(src);

	omap_hwmod_enable(oh);
	__omap_dm_timer_init_regs(timer);

	if (posted)
		__omap_dm_timer_enable_posted(timer);

	/* Check that the intended posted configuration matches the actual */
	if (posted != timer->posted)
		return -EINVAL;

	timer->rate = clk_get_rate(timer->fclk);
	timer->reserved = 1;

	return r;
}

#if !defined(CONFIG_SMP) && defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
void tick_broadcast(const struct cpumask *mask)
{
}
#endif

static void __init dmtimer_clkevt_init_common(struct dmtimer_clockevent *clkevt,
					      int gptimer_id,
					      const char *fck_source,
					      unsigned int features,
					      const struct cpumask *cpumask,
					      const char *property,
					      int rating, const char *name)
{
	struct omap_dm_timer *timer = &clkevt->timer;
	int res;

	timer->id = gptimer_id;
	timer->errata = omap_dm_timer_get_errata();
	clkevt->dev.features = features;
	clkevt->dev.rating = rating;
	clkevt->dev.set_next_event = omap2_gp_timer_set_next_event;
	clkevt->dev.set_state_shutdown = omap2_gp_timer_shutdown;
	clkevt->dev.set_state_periodic = omap2_gp_timer_set_periodic;
	clkevt->dev.set_state_oneshot = omap2_gp_timer_shutdown;
	clkevt->dev.tick_resume = omap2_gp_timer_shutdown;

	/*
	 * For clock-event timers we never read the timer counter and
	 * so we are not impacted by errata i103 and i767. Therefore,
	 * we can safely ignore this errata for clock-event timers.
	 */
	__omap_dm_timer_override_errata(timer, OMAP_TIMER_ERRATA_I103_I767);

	res = omap_dm_timer_init_one(timer, fck_source, property,
				     &clkevt->dev.name, OMAP_TIMER_POSTED);
	BUG_ON(res);

	clkevt->dev.cpumask = cpumask;
	clkevt->dev.irq = omap_dm_timer_get_irq(timer);

	if (request_irq(clkevt->dev.irq, omap2_gp_timer_interrupt,
			IRQF_TIMER | IRQF_IRQPOLL, name, clkevt))
		pr_err("Failed to request irq %d (gp_timer)\n", clkevt->dev.irq);

	__omap_dm_timer_int_enable(timer, OMAP_TIMER_INT_OVERFLOW);

	if (soc_is_am33xx() || soc_is_am43xx()) {
		clkevt->dev.suspend = omap_clkevt_idle;
		clkevt->dev.resume = omap_clkevt_unidle;

		clockevent_gpt_hwmod =
			omap_hwmod_lookup(clkevt->dev.name);
	}

	pr_info("OMAP clockevent source: %s at %lu Hz\n", clkevt->dev.name,
		timer->rate);
}

/* Clocksource code */
static struct omap_dm_timer clksrc;
static bool use_gptimer_clksrc __initdata;

/*
 * clocksource
 */
static u64 clocksource_read_cycles(struct clocksource *cs)
{
	return (u64)__omap_dm_timer_read_counter(&clksrc,
						     OMAP_TIMER_NONPOSTED);
}

static struct clocksource clocksource_gpt = {
	.rating		= 300,
	.read		= clocksource_read_cycles,
	.mask		= CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
};

static u64 notrace dmtimer_read_sched_clock(void)
{
	if (clksrc.reserved)
		return __omap_dm_timer_read_counter(&clksrc,
						    OMAP_TIMER_NONPOSTED);

	return 0;
}

static const struct of_device_id omap_counter_match[] __initconst = {
	{ .compatible = "ti,omap-counter32k", },
	{ }
};

/* Setup free-running counter for clocksource */
static int __init __maybe_unused omap2_sync32k_clocksource_init(void)
{
	int ret;
	struct device_node *np = NULL;
	struct omap_hwmod *oh;
	const char *oh_name = "counter_32k";

	/*
	 * See if the 32kHz counter is supported.
	 */
	np = omap_get_timer_dt(omap_counter_match, NULL);
	if (!np)
		return -ENODEV;

	of_property_read_string_index(np->parent, "ti,hwmods", 0, &oh_name);
	if (!oh_name) {
		of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
		if (!oh_name)
			return -ENODEV;
	}

	/*
	 * First check hwmod data is available for sync32k counter
	 */
	oh = omap_hwmod_lookup(oh_name);
	if (!oh || oh->slaves_cnt == 0)
		return -ENODEV;

	omap_hwmod_setup_one(oh_name);

	ret = omap_hwmod_enable(oh);
	if (ret) {
		pr_warn("%s: failed to enable counter_32k module (%d)\n",
							__func__, ret);
		return ret;
	}

	return ret;
}

static unsigned int omap2_gptimer_clksrc_load;

static void omap2_gptimer_clksrc_suspend(struct clocksource *unused)
{
	omap2_gptimer_clksrc_load =
		__omap_dm_timer_read_counter(&clksrc, OMAP_TIMER_NONPOSTED);

	omap_hwmod_idle(clocksource_gpt_hwmod);
}

static void omap2_gptimer_clksrc_resume(struct clocksource *unused)
{
	omap_hwmod_enable(clocksource_gpt_hwmod);

	__omap_dm_timer_load_start(&clksrc,
				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR,
				   omap2_gptimer_clksrc_load,
				   OMAP_TIMER_NONPOSTED);
}

static void __init omap2_gptimer_clocksource_init(int gptimer_id,
						  const char *fck_source,
						  const char *property)
{
	int res;

	clksrc.id = gptimer_id;
	clksrc.errata = omap_dm_timer_get_errata();

	res = omap_dm_timer_init_one(&clksrc, fck_source, property,
				     &clocksource_gpt.name,
				     OMAP_TIMER_NONPOSTED);

	if (soc_is_am43xx()) {
		clocksource_gpt.suspend = omap2_gptimer_clksrc_suspend;
		clocksource_gpt.resume = omap2_gptimer_clksrc_resume;

		clocksource_gpt_hwmod =
			omap_hwmod_lookup(clocksource_gpt.name);
	}

	BUG_ON(res);

	__omap_dm_timer_load_start(&clksrc,
				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
				   OMAP_TIMER_NONPOSTED);
	sched_clock_register(dmtimer_read_sched_clock, 32, clksrc.rate);

	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
		pr_err("Could not register clocksource %s\n",
			clocksource_gpt.name);
	else
		pr_info("OMAP clocksource: %s at %lu Hz\n",
			clocksource_gpt.name, clksrc.rate);
}

static void __init __omap_sync32k_timer_init(int clkev_nr, const char *clkev_src,
		const char *clkev_prop, int clksrc_nr, const char *clksrc_src,
		const char *clksrc_prop, bool gptimer)
{
	omap_clk_init();
	omap_dmtimer_init();
	dmtimer_clkevt_init_common(&clockevent, clkev_nr, clkev_src,
				   CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
				   cpu_possible_mask, clkev_prop, 300, "clockevent");
	clockevents_config_and_register(&clockevent.dev, clockevent.timer.rate,
					3, /* Timer internal resynch latency */
					0xffffffff);

	/* Enable the use of clocksource="gp_timer" kernel parameter */
	if (use_gptimer_clksrc || gptimer)
		omap2_gptimer_clocksource_init(clksrc_nr, clksrc_src,
						clksrc_prop);
	else
		omap2_sync32k_clocksource_init();
}

void __init omap_init_time(void)
{
	__omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",
			2, "timer_sys_ck", NULL, false);

	timer_probe();
}

#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM43XX)
void __init omap3_secure_sync32k_timer_init(void)
{
	__omap_sync32k_timer_init(12, "secure_32k_fck", "ti,timer-secure",
			2, "timer_sys_ck", NULL, false);

	timer_probe();
}
#endif /* CONFIG_ARCH_OMAP3 */

#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) || \
	defined(CONFIG_SOC_AM43XX)
void __init omap3_gptimer_timer_init(void)
{
	__omap_sync32k_timer_init(2, "timer_sys_ck", NULL,
			1, "timer_sys_ck", "ti,timer-alwon", true);
	if (of_have_populated_dt())
		timer_probe();
}
#endif

#if defined(CONFIG_ARCH_OMAP4) || defined(CONFIG_SOC_OMAP5) ||		\
	defined(CONFIG_SOC_DRA7XX)
static void __init omap4_sync32k_timer_init(void)
{
	__omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",
			2, "sys_clkin_ck", NULL, false);
}

void __init omap4_local_timer_init(void)
{
	omap4_sync32k_timer_init();
	timer_probe();
}
#endif

#if defined(CONFIG_SOC_OMAP5) || defined(CONFIG_SOC_DRA7XX)

/*
 * The realtime counter also called master counter, is a free-running
 * counter, which is related to real time. It produces the count used
 * by the CPU local timer peripherals in the MPU cluster. The timer counts
 * at a rate of 6.144 MHz. Because the device operates on different clocks
 * in different power modes, the master counter shifts operation between
 * clocks, adjusting the increment per clock in hardware accordingly to
 * maintain a constant count rate.
 */
static void __init realtime_counter_init(void)
{
#ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
	void __iomem *base;
	static struct clk *sys_clk;
	unsigned long rate;
	unsigned int reg;
	unsigned long long num, den;

	base = ioremap(REALTIME_COUNTER_BASE, SZ_32);
	if (!base) {
		pr_err("%s: ioremap failed\n", __func__);
		return;
	}
	sys_clk = clk_get(NULL, "sys_clkin");
	if (IS_ERR(sys_clk)) {
		pr_err("%s: failed to get system clock handle\n", __func__);
		iounmap(base);
		return;
	}

	rate = clk_get_rate(sys_clk);
	clk_put(sys_clk);

	if (soc_is_dra7xx()) {
		/*
		 * Errata i856 says the 32.768KHz crystal does not start at
		 * power on, so the CPU falls back to an emulated 32KHz clock
		 * based on sysclk / 610 instead. This causes the master counter
		 * frequency to not be 6.144MHz but at sysclk / 610 * 375 / 2
		 * (OR sysclk * 75 / 244)
		 *
		 * This affects at least the DRA7/AM572x 1.0, 1.1 revisions.
		 * Of course any board built without a populated 32.768KHz
		 * crystal would also need this fix even if the CPU is fixed
		 * later.
		 *
		 * Either case can be detected by using the two speedselect bits
		 * If they are not 0, then the 32.768KHz clock driving the
		 * coarse counter that corrects the fine counter every time it
		 * ticks is actually rate/610 rather than 32.768KHz and we
		 * should compensate to avoid the 570ppm (at 20MHz, much worse
		 * at other rates) too fast system time.
		 */
		reg = omap_ctrl_readl(DRA7_CTRL_CORE_BOOTSTRAP);
		if (reg & DRA7_SPEEDSELECT_MASK) {
			num = 75;
			den = 244;
			goto sysclk1_based;
		}
	}

	/* Numerator/denumerator values refer TRM Realtime Counter section */
	switch (rate) {
	case 12000000:
		num = 64;
		den = 125;
		break;
	case 13000000:
		num = 768;
		den = 1625;
		break;
	case 19200000:
		num = 8;
		den = 25;
		break;
	case 20000000:
		num = 192;
		den = 625;
		break;
	case 26000000:
		num = 384;
		den = 1625;
		break;
	case 27000000:
		num = 256;
		den = 1125;
		break;
	case 38400000:
	default:
		/* Program it for 38.4 MHz */
		num = 4;
		den = 25;
		break;
	}

sysclk1_based:
	/* Program numerator and denumerator registers */
	reg = readl_relaxed(base + INCREMENTER_NUMERATOR_OFFSET) &
			NUMERATOR_DENUMERATOR_MASK;
	reg |= num;
	writel_relaxed(reg, base + INCREMENTER_NUMERATOR_OFFSET);

	reg = readl_relaxed(base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET) &
			NUMERATOR_DENUMERATOR_MASK;
	reg |= den;
	writel_relaxed(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);

	arch_timer_freq = DIV_ROUND_UP_ULL(rate * num, den);
	set_cntfreq();

	iounmap(base);
#endif
}

void __init omap5_realtime_timer_init(void)
{
	omap4_sync32k_timer_init();
	realtime_counter_init();

	timer_probe();
}
#endif /* CONFIG_SOC_OMAP5 || CONFIG_SOC_DRA7XX */

/**
 * omap2_override_clocksource - clocksource override with user configuration
 *
 * Allows user to override default clocksource, using kernel parameter
 *   clocksource="gp_timer"	(For all OMAP2PLUS architectures)
 *
 * Note that, here we are using same standard kernel parameter "clocksource=",
 * and not introducing any OMAP specific interface.
 */
static int __init omap2_override_clocksource(char *str)
{
	if (!str)
		return 0;
	/*
	 * For OMAP architecture, we only have two options
	 *    - sync_32k (default)
	 *    - gp_timer (sys_clk based)
	 */
	if (!strcmp(str, "gp_timer"))
		use_gptimer_clksrc = true;

	return 0;
}
early_param("clocksource", omap2_override_clocksource);