arch/arm/mach-omap2/timer.c - kernel/msm-4.9 - Gitiles

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

 #include <asm/arch_timer.h>
 #include "omap_hwmod.h"
 #include "omap_device.h"
 #include <plat/counter-32k.h>
 #include <plat/dmtimer.h>
 #include "omap-pm.h"

 #include "soc.h"
 #include "common.h"
 #include "powerdomain.h"

 /* Parent clocks, eventually these will come from the clock framework */

 #define OMAP2_MPU_SOURCE	"sys_ck"
 #define OMAP3_MPU_SOURCE	OMAP2_MPU_SOURCE
 #define OMAP4_MPU_SOURCE	"sys_clkin_ck"
 #define OMAP2_32K_SOURCE	"func_32k_ck"
 #define OMAP3_32K_SOURCE	"omap_32k_fck"
 #define OMAP4_32K_SOURCE	"sys_32k_ck"

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

 /* Clockevent code */

 static struct omap_dm_timer clkev;
 static struct clock_event_device clockevent_gpt;

 static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = &clockevent_gpt;

 	__omap_dm_timer_write_status(&clkev, OMAP_TIMER_INT_OVERFLOW);

 	evt->event_handler(evt);
 	return IRQ_HANDLED;
 }

 static struct irqaction omap2_gp_timer_irq = {
 	.name		= "gp_timer",
 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 	.handler	= omap2_gp_timer_interrupt,
 };

 static int omap2_gp_timer_set_next_event(unsigned long cycles,
 					 struct clock_event_device *evt)
 {
 	__omap_dm_timer_load_start(&clkev, OMAP_TIMER_CTRL_ST,
 				   0xffffffff - cycles, OMAP_TIMER_POSTED);

 	return 0;
 }

 static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
 				    struct clock_event_device *evt)
 {
 	u32 period;

 	__omap_dm_timer_stop(&clkev, OMAP_TIMER_POSTED, clkev.rate);

 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
 		period = clkev.rate / HZ;
 		period -= 1;
 		/* Looks like we need to first set the load value separately */
 		__omap_dm_timer_write(&clkev, OMAP_TIMER_LOAD_REG,
 				      0xffffffff - period, OMAP_TIMER_POSTED);
 		__omap_dm_timer_load_start(&clkev,
 					OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
 					0xffffffff - period, OMAP_TIMER_POSTED);
 		break;
 	case CLOCK_EVT_MODE_ONESHOT:
 		break;
 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
 	case CLOCK_EVT_MODE_RESUME:
 		break;
 	}
 }

 static struct clock_event_device clockevent_gpt = {
 	.name		= "gp_timer",
 	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.rating		= 300,
 	.set_next_event	= omap2_gp_timer_set_next_event,
 	.set_mode	= omap2_gp_timer_set_mode,
 };

 static struct property device_disabled = {
 	.name = "status",
 	.length = sizeof("disabled"),
 	.value = "disabled",
 };

 static struct of_device_id omap_timer_match[] __initdata = {
 	{ .compatible = "ti,omap2-timer", },
 	{ }
 };

 /**
  * 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(struct of_device_id *match,
 						     const char *property)
 {
 	struct device_node *np;

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

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

 		of_add_property(np, &device_disabled);
 		return np;
 	}

 	return NULL;
 }

 /**
  * omap_dmtimer_init - initialisation function when device tree is used
  *
  * For secure OMAP3 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())
 		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");
 		if (np)
 			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,
 						int gptimer_id,
 						const char *fck_source,
 						const char *property,
 						int posted)
 {
 	char name[10]; /* 10 = sizeof("gptXX_Xck0") */
 	const char *oh_name;
 	struct device_node *np;
 	struct omap_hwmod *oh;
 	struct resource irq, mem;
 	int r = 0;

 	if (of_have_populated_dt()) {
 		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)
 			return -ENODEV;

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

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

 		of_node_put(np);
 	} else {
 		if (omap_dm_timer_reserve_systimer(gptimer_id))
 			return -ENODEV;

 		sprintf(name, "timer%d", gptimer_id);
 		oh_name = name;
 	}

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

 	if (!of_have_populated_dt()) {
 		r = omap_hwmod_get_resource_byname(oh, IORESOURCE_IRQ, NULL,
 						   &irq);
 		if (r)
 			return -ENXIO;
 		timer->irq = irq.start;

 		r = omap_hwmod_get_resource_byname(oh, IORESOURCE_MEM, NULL,
 						   &mem);
 		if (r)
 			return -ENXIO;

 		/* Static mapping, never released */
 		timer->io_base = ioremap(mem.start, mem.end - mem.start);
 	}

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

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

 	/* FIXME: Need to remove hard-coded test on timer ID */
 	if (gptimer_id != 12) {
 		struct clk *src;

 		src = clk_get(NULL, fck_source);
 		if (IS_ERR(src)) {
 			r = -EINVAL;
 		} else {
 			r = clk_set_parent(timer->fclk, src);
 			if (IS_ERR_VALUE(r))
 				pr_warn("%s: %s cannot set source\n",
 					__func__, oh->name);
 			clk_put(src);
 		}
 	}

 	omap_hwmod_setup_one(oh_name);
 	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;
 }

 static void __init omap2_gp_clockevent_init(int gptimer_id,
 						const char *fck_source,
 						const char *property)
 {
 	int res;

 	clkev.errata = omap_dm_timer_get_errata();

 	/*
 	 * 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(&clkev, OMAP_TIMER_ERRATA_I103_I767);

 	res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source, property,
 				     OMAP_TIMER_POSTED);
 	BUG_ON(res);

 	omap2_gp_timer_irq.dev_id = &clkev;
 	setup_irq(clkev.irq, &omap2_gp_timer_irq);

 	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);

 	clockevent_gpt.cpumask = cpu_possible_mask;
 	clockevent_gpt.irq = omap_dm_timer_get_irq(&clkev);
 	clockevents_config_and_register(&clockevent_gpt, clkev.rate,
 					3, /* Timer internal resynch latency */
 					0xffffffff);

 	pr_info("OMAP clockevent source: GPTIMER%d at %lu Hz\n",
 		gptimer_id, clkev.rate);
 }

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

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

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

 static u32 notrace dmtimer_read_sched_clock(void)
 {
 	if (clksrc.reserved)
 		return __omap_dm_timer_read_counter(&clksrc,
 						    OMAP_TIMER_NONPOSTED);

 	return 0;
 }

 static struct of_device_id omap_counter_match[] __initdata = {
 	{ .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;
 	void __iomem *vbase;
 	const char *oh_name = "counter_32k";

 	/*
 	 * If device-tree is present, then search the DT blob
 	 * to see if the 32kHz counter is supported.
 	 */
 	if (of_have_populated_dt()) {
 		np = omap_get_timer_dt(omap_counter_match, NULL);
 		if (!np)
 			return -ENODEV;

 		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);

 	if (np) {
 		vbase = of_iomap(np, 0);
 		of_node_put(np);
 	} else {
 		vbase = omap_hwmod_get_mpu_rt_va(oh);
 	}

 	if (!vbase) {
 		pr_warn("%s: failed to get counter_32k resource\n", __func__);
 		return -ENXIO;
 	}

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

 	ret = omap_init_clocksource_32k(vbase);
 	if (ret) {
 		pr_warn("%s: failed to initialize counter_32k as a clocksource (%d)\n",
 							__func__, ret);
 		omap_hwmod_idle(oh);
 	}

 	return ret;
 }

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

 	clksrc.errata = omap_dm_timer_get_errata();

 	res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source, NULL,
 				     OMAP_TIMER_NONPOSTED);
 	BUG_ON(res);

 	__omap_dm_timer_load_start(&clksrc,
 				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
 				   OMAP_TIMER_NONPOSTED);
 	setup_sched_clock(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: GPTIMER%d at %lu Hz\n",
 			gptimer_id, clksrc.rate);
 }

 #ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
 /*
  * 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)
 {
 	void __iomem *base;
 	static struct clk *sys_clk;
 	unsigned long rate;
 	unsigned int reg, 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_ck");
 	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);
 	/* Numerator/denumerator values refer TRM Realtime Counter section */
 	switch (rate) {
 	case 1200000:
 		num = 64;
 		den = 125;
 		break;
 	case 1300000:
 		num = 768;
 		den = 1625;
 		break;
 	case 19200000:
 		num = 8;
 		den = 25;
 		break;
 	case 2600000:
 		num = 384;
 		den = 1625;
 		break;
 	case 2700000:
 		num = 256;
 		den = 1125;
 		break;
 	case 38400000:
 	default:
 		/* Program it for 38.4 MHz */
 		num = 4;
 		den = 25;
 		break;
 	}

 	/* Program numerator and denumerator registers */
 	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
 			NUMERATOR_DENUMERATOR_MASK;
 	reg |= num;
 	__raw_writel(reg, base + INCREMENTER_NUMERATOR_OFFSET);

 	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
 			NUMERATOR_DENUMERATOR_MASK;
 	reg |= den;
 	__raw_writel(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);

 	iounmap(base);
 }
 #else
 static inline void __init realtime_counter_init(void)
 {}
 #endif

 #define OMAP_SYS_GP_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop,	\
 			       clksrc_nr, clksrc_src)			\
 void __init omap##name##_gptimer_timer_init(void)			\
 {									\
 	if (omap_clk_init)						\
 		omap_clk_init();					\
 	omap_dmtimer_init();						\
 	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop);	\
 	omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src);	\
 }

 #define OMAP_SYS_32K_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop,	\
 				clksrc_nr, clksrc_src)			\
 void __init omap##name##_sync32k_timer_init(void)		\
 {									\
 	if (omap_clk_init)						\
 		omap_clk_init();					\
 	omap_dmtimer_init();						\
 	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop);	\
 	/* Enable the use of clocksource="gp_timer" kernel parameter */	\
 	if (use_gptimer_clksrc)						\
 		omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src);\
 	else								\
 		omap2_sync32k_clocksource_init();			\
 }

 #ifdef CONFIG_ARCH_OMAP2
 OMAP_SYS_32K_TIMER_INIT(2, 1, OMAP2_32K_SOURCE, "ti,timer-alwon",
 			2, OMAP2_MPU_SOURCE);
 #endif /* CONFIG_ARCH_OMAP2 */

 #ifdef CONFIG_ARCH_OMAP3
 OMAP_SYS_32K_TIMER_INIT(3, 1, OMAP3_32K_SOURCE, "ti,timer-alwon",
 			2, OMAP3_MPU_SOURCE);
 OMAP_SYS_32K_TIMER_INIT(3_secure, 12, OMAP3_32K_SOURCE, "ti,timer-secure",
 			2, OMAP3_MPU_SOURCE);
 OMAP_SYS_GP_TIMER_INIT(3_gp, 1, OMAP3_MPU_SOURCE, "ti,timer-alwon",
 		       2, OMAP3_MPU_SOURCE);
 #endif /* CONFIG_ARCH_OMAP3 */

 #ifdef CONFIG_SOC_AM33XX
 OMAP_SYS_GP_TIMER_INIT(3_am33xx, 1, OMAP4_MPU_SOURCE, "ti,timer-alwon",
 		       2, OMAP4_MPU_SOURCE);
 #endif /* CONFIG_SOC_AM33XX */

 #ifdef CONFIG_ARCH_OMAP4
 OMAP_SYS_32K_TIMER_INIT(4, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
 			2, OMAP4_MPU_SOURCE);
 #ifdef CONFIG_LOCAL_TIMERS
 static DEFINE_TWD_LOCAL_TIMER(twd_local_timer, OMAP44XX_LOCAL_TWD_BASE, 29);
 void __init omap4_local_timer_init(void)
 {
 	omap4_sync32k_timer_init();
 	/* Local timers are not supprted on OMAP4430 ES1.0 */
 	if (omap_rev() != OMAP4430_REV_ES1_0) {
 		int err;

 		if (of_have_populated_dt()) {
 			twd_local_timer_of_register();
 			return;
 		}

 		err = twd_local_timer_register(&twd_local_timer);
 		if (err)
 			pr_err("twd_local_timer_register failed %d\n", err);
 	}
 }
 #else /* CONFIG_LOCAL_TIMERS */
 void __init omap4_local_timer_init(void)
 {
 	omap4_sync32k_timer_init();
 }
 #endif /* CONFIG_LOCAL_TIMERS */
 #endif /* CONFIG_ARCH_OMAP4 */

 #ifdef CONFIG_SOC_OMAP5
 OMAP_SYS_32K_TIMER_INIT(5, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
 			2, OMAP4_MPU_SOURCE);
 void __init omap5_realtime_timer_init(void)
 {
 	int err;

 	omap5_sync32k_timer_init();
 	realtime_counter_init();

 	err = arch_timer_of_register();
 	if (err)
 		pr_err("%s: arch_timer_register failed %d\n", __func__, err);
 }
 #endif /* CONFIG_SOC_OMAP5 */

 /**
  * omap_timer_init - build and register timer device with an
  * associated timer hwmod
  * @oh:	timer hwmod pointer to be used to build timer device
  * @user:	parameter that can be passed from calling hwmod API
  *
  * Called by omap_hwmod_for_each_by_class to register each of the timer
  * devices present in the system. The number of timer devices is known
  * by parsing through the hwmod database for a given class name. At the
  * end of function call memory is allocated for timer device and it is
  * registered to the framework ready to be proved by the driver.
  */
 static int __init omap_timer_init(struct omap_hwmod *oh, void *unused)
 {
 	int id;
 	int ret = 0;
 	char *name = "omap_timer";
 	struct dmtimer_platform_data *pdata;
 	struct platform_device *pdev;
 	struct omap_timer_capability_dev_attr *timer_dev_attr;

 	pr_debug("%s: %s\n", __func__, oh->name);

 	/* on secure device, do not register secure timer */
 	timer_dev_attr = oh->dev_attr;
 	if (omap_type() != OMAP2_DEVICE_TYPE_GP && timer_dev_attr)
 		if (timer_dev_attr->timer_capability == OMAP_TIMER_SECURE)
 			return ret;

 	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
 	if (!pdata) {
 		pr_err("%s: No memory for [%s]\n", __func__, oh->name);
 		return -ENOMEM;
 	}

 	/*
 	 * Extract the IDs from name field in hwmod database
 	 * and use the same for constructing ids' for the
 	 * timer devices. In a way, we are avoiding usage of
 	 * static variable witin the function to do the same.
 	 * CAUTION: We have to be careful and make sure the
 	 * name in hwmod database does not change in which case
 	 * we might either make corresponding change here or
 	 * switch back static variable mechanism.
 	 */
 	sscanf(oh->name, "timer%2d", &id);

 	if (timer_dev_attr)
 		pdata->timer_capability = timer_dev_attr->timer_capability;

 	pdata->timer_errata = omap_dm_timer_get_errata();
 	pdata->get_context_loss_count = omap_pm_get_dev_context_loss_count;

 	pdev = omap_device_build(name, id, oh, pdata, sizeof(*pdata));

 	if (IS_ERR(pdev)) {
 		pr_err("%s: Can't build omap_device for %s: %s.\n",
 			__func__, name, oh->name);
 		ret = -EINVAL;
 	}

 	kfree(pdata);

 	return ret;
 }

 /**
  * omap2_dm_timer_init - top level regular device initialization
  *
  * Uses dedicated hwmod api to parse through hwmod database for
  * given class name and then build and register the timer device.
  */
 static int __init omap2_dm_timer_init(void)
 {
 	int ret;

 	/* If dtb is there, the devices will be created dynamically */
 	if (of_have_populated_dt())
 		return -ENODEV;

 	ret = omap_hwmod_for_each_by_class("timer", omap_timer_init, NULL);
 	if (unlikely(ret)) {
 		pr_err("%s: device registration failed.\n", __func__);
 		return -EINVAL;
 	}

 	return 0;
 }
 omap_arch_initcall(omap2_dm_timer_init);

 /**
  * 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);
	/*
	* 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 <asm/mach/time.h>
	#include <asm/smp_twd.h>
	#include <asm/sched_clock.h>

	#include <asm/arch_timer.h>
	#include "omap_hwmod.h"
	#include "omap_device.h"
	#include <plat/counter-32k.h>
	#include <plat/dmtimer.h>
	#include "omap-pm.h"

	#include "soc.h"
	#include "common.h"
	#include "powerdomain.h"

	/* Parent clocks, eventually these will come from the clock framework */

	#define OMAP2_MPU_SOURCE "sys_ck"
	#define OMAP3_MPU_SOURCE OMAP2_MPU_SOURCE
	#define OMAP4_MPU_SOURCE "sys_clkin_ck"
	#define OMAP2_32K_SOURCE "func_32k_ck"
	#define OMAP3_32K_SOURCE "omap_32k_fck"
	#define OMAP4_32K_SOURCE "sys_32k_ck"

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

	/* Clockevent code */

	static struct omap_dm_timer clkev;
	static struct clock_event_device clockevent_gpt;

	static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
	{
	struct clock_event_device *evt = &clockevent_gpt;

	__omap_dm_timer_write_status(&clkev, OMAP_TIMER_INT_OVERFLOW);

	evt->event_handler(evt);
	return IRQ_HANDLED;
	}

	static struct irqaction omap2_gp_timer_irq = {
	.name = "gp_timer",
	.flags = IRQF_DISABLED \| IRQF_TIMER \| IRQF_IRQPOLL,
	.handler = omap2_gp_timer_interrupt,
	};

	static int omap2_gp_timer_set_next_event(unsigned long cycles,
	struct clock_event_device *evt)
	{
	__omap_dm_timer_load_start(&clkev, OMAP_TIMER_CTRL_ST,
	0xffffffff - cycles, OMAP_TIMER_POSTED);

	return 0;
	}

	static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
	struct clock_event_device *evt)
	{
	u32 period;

	__omap_dm_timer_stop(&clkev, OMAP_TIMER_POSTED, clkev.rate);

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
	period = clkev.rate / HZ;
	period -= 1;
	/* Looks like we need to first set the load value separately */
	__omap_dm_timer_write(&clkev, OMAP_TIMER_LOAD_REG,
	0xffffffff - period, OMAP_TIMER_POSTED);
	__omap_dm_timer_load_start(&clkev,
	OMAP_TIMER_CTRL_AR \| OMAP_TIMER_CTRL_ST,
	0xffffffff - period, OMAP_TIMER_POSTED);
	break;
	case CLOCK_EVT_MODE_ONESHOT:
	break;
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
	case CLOCK_EVT_MODE_RESUME:
	break;
	}
	}

	static struct clock_event_device clockevent_gpt = {
	.name = "gp_timer",
	.features = CLOCK_EVT_FEAT_PERIODIC \| CLOCK_EVT_FEAT_ONESHOT,
	.rating = 300,
	.set_next_event = omap2_gp_timer_set_next_event,
	.set_mode = omap2_gp_timer_set_mode,
	};

	static struct property device_disabled = {
	.name = "status",
	.length = sizeof("disabled"),
	.value = "disabled",
	};

	static struct of_device_id omap_timer_match[] __initdata = {
	{ .compatible = "ti,omap2-timer", },
	{ }
	};

	/**
	* 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(struct of_device_id *match,
	const char *property)
	{
	struct device_node *np;

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

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

	of_add_property(np, &device_disabled);
	return np;
	}

	return NULL;
	}

	/**
	* omap_dmtimer_init - initialisation function when device tree is used
	*
	* For secure OMAP3 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())
	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");
	if (np)
	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,
	int gptimer_id,
	const char *fck_source,
	const char *property,
	int posted)
	{
	char name[10]; /* 10 = sizeof("gptXX_Xck0") */
	const char *oh_name;
	struct device_node *np;
	struct omap_hwmod *oh;
	struct resource irq, mem;
	int r = 0;

	if (of_have_populated_dt()) {
	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)
	return -ENODEV;

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

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

	of_node_put(np);
	} else {
	if (omap_dm_timer_reserve_systimer(gptimer_id))
	return -ENODEV;

	sprintf(name, "timer%d", gptimer_id);
	oh_name = name;
	}

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

	if (!of_have_populated_dt()) {
	r = omap_hwmod_get_resource_byname(oh, IORESOURCE_IRQ, NULL,
	&irq);
	if (r)
	return -ENXIO;
	timer->irq = irq.start;

	r = omap_hwmod_get_resource_byname(oh, IORESOURCE_MEM, NULL,
	&mem);
	if (r)
	return -ENXIO;

	/* Static mapping, never released */
	timer->io_base = ioremap(mem.start, mem.end - mem.start);
	}

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

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

	/* FIXME: Need to remove hard-coded test on timer ID */
	if (gptimer_id != 12) {
	struct clk *src;

	src = clk_get(NULL, fck_source);
	if (IS_ERR(src)) {
	r = -EINVAL;
	} else {
	r = clk_set_parent(timer->fclk, src);
	if (IS_ERR_VALUE(r))
	pr_warn("%s: %s cannot set source\n",
	__func__, oh->name);
	clk_put(src);
	}
	}

	omap_hwmod_setup_one(oh_name);
	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;
	}

	static void __init omap2_gp_clockevent_init(int gptimer_id,
	const char *fck_source,
	const char *property)
	{
	int res;

	clkev.errata = omap_dm_timer_get_errata();

	/*
	* 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(&clkev, OMAP_TIMER_ERRATA_I103_I767);

	res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source, property,
	OMAP_TIMER_POSTED);
	BUG_ON(res);

	omap2_gp_timer_irq.dev_id = &clkev;
	setup_irq(clkev.irq, &omap2_gp_timer_irq);

	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);

	clockevent_gpt.cpumask = cpu_possible_mask;
	clockevent_gpt.irq = omap_dm_timer_get_irq(&clkev);
	clockevents_config_and_register(&clockevent_gpt, clkev.rate,
	3, /* Timer internal resynch latency */
	0xffffffff);

	pr_info("OMAP clockevent source: GPTIMER%d at %lu Hz\n",
	gptimer_id, clkev.rate);
	}

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

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

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

	static u32 notrace dmtimer_read_sched_clock(void)
	{
	if (clksrc.reserved)
	return __omap_dm_timer_read_counter(&clksrc,
	OMAP_TIMER_NONPOSTED);

	return 0;
	}

	static struct of_device_id omap_counter_match[] __initdata = {
	{ .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;
	void __iomem *vbase;
	const char *oh_name = "counter_32k";

	/*
	* If device-tree is present, then search the DT blob
	* to see if the 32kHz counter is supported.
	*/
	if (of_have_populated_dt()) {
	np = omap_get_timer_dt(omap_counter_match, NULL);
	if (!np)
	return -ENODEV;

	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);

	if (np) {
	vbase = of_iomap(np, 0);
	of_node_put(np);
	} else {
	vbase = omap_hwmod_get_mpu_rt_va(oh);
	}

	if (!vbase) {
	pr_warn("%s: failed to get counter_32k resource\n", __func__);
	return -ENXIO;
	}

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

	ret = omap_init_clocksource_32k(vbase);
	if (ret) {
	pr_warn("%s: failed to initialize counter_32k as a clocksource (%d)\n",
	__func__, ret);
	omap_hwmod_idle(oh);
	}

	return ret;
	}

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

	clksrc.errata = omap_dm_timer_get_errata();

	res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source, NULL,
	OMAP_TIMER_NONPOSTED);
	BUG_ON(res);

	__omap_dm_timer_load_start(&clksrc,
	OMAP_TIMER_CTRL_ST \| OMAP_TIMER_CTRL_AR, 0,
	OMAP_TIMER_NONPOSTED);
	setup_sched_clock(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: GPTIMER%d at %lu Hz\n",
	gptimer_id, clksrc.rate);
	}

	#ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
	/*
	* 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)
	{
	void __iomem *base;
	static struct clk *sys_clk;
	unsigned long rate;
	unsigned int reg, 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_ck");
	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);
	/* Numerator/denumerator values refer TRM Realtime Counter section */
	switch (rate) {
	case 1200000:
	num = 64;
	den = 125;
	break;
	case 1300000:
	num = 768;
	den = 1625;
	break;
	case 19200000:
	num = 8;
	den = 25;
	break;
	case 2600000:
	num = 384;
	den = 1625;
	break;
	case 2700000:
	num = 256;
	den = 1125;
	break;
	case 38400000:
	default:
	/* Program it for 38.4 MHz */
	num = 4;
	den = 25;
	break;
	}

	/* Program numerator and denumerator registers */
	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
	NUMERATOR_DENUMERATOR_MASK;
	reg \|= num;
	__raw_writel(reg, base + INCREMENTER_NUMERATOR_OFFSET);

	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
	NUMERATOR_DENUMERATOR_MASK;
	reg \|= den;
	__raw_writel(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);

	iounmap(base);
	}
	#else
	static inline void __init realtime_counter_init(void)
	{}
	#endif

	#define OMAP_SYS_GP_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop, \
	clksrc_nr, clksrc_src) \
	void __init omap##name##_gptimer_timer_init(void) \
	{ \
	if (omap_clk_init) \
	omap_clk_init(); \
	omap_dmtimer_init(); \
	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop); \
	omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src); \
	}

	#define OMAP_SYS_32K_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop, \
	clksrc_nr, clksrc_src) \
	void __init omap##name##_sync32k_timer_init(void) \
	{ \
	if (omap_clk_init) \
	omap_clk_init(); \
	omap_dmtimer_init(); \
	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop); \
	/* Enable the use of clocksource="gp_timer" kernel parameter */ \
	if (use_gptimer_clksrc) \
	omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src);\
	else \
	omap2_sync32k_clocksource_init(); \
	}

	#ifdef CONFIG_ARCH_OMAP2
	OMAP_SYS_32K_TIMER_INIT(2, 1, OMAP2_32K_SOURCE, "ti,timer-alwon",
	2, OMAP2_MPU_SOURCE);
	#endif /* CONFIG_ARCH_OMAP2 */

	#ifdef CONFIG_ARCH_OMAP3
	OMAP_SYS_32K_TIMER_INIT(3, 1, OMAP3_32K_SOURCE, "ti,timer-alwon",
	2, OMAP3_MPU_SOURCE);
	OMAP_SYS_32K_TIMER_INIT(3_secure, 12, OMAP3_32K_SOURCE, "ti,timer-secure",
	2, OMAP3_MPU_SOURCE);
	OMAP_SYS_GP_TIMER_INIT(3_gp, 1, OMAP3_MPU_SOURCE, "ti,timer-alwon",
	2, OMAP3_MPU_SOURCE);
	#endif /* CONFIG_ARCH_OMAP3 */

	#ifdef CONFIG_SOC_AM33XX
	OMAP_SYS_GP_TIMER_INIT(3_am33xx, 1, OMAP4_MPU_SOURCE, "ti,timer-alwon",
	2, OMAP4_MPU_SOURCE);
	#endif /* CONFIG_SOC_AM33XX */

	#ifdef CONFIG_ARCH_OMAP4
	OMAP_SYS_32K_TIMER_INIT(4, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
	2, OMAP4_MPU_SOURCE);
	#ifdef CONFIG_LOCAL_TIMERS
	static DEFINE_TWD_LOCAL_TIMER(twd_local_timer, OMAP44XX_LOCAL_TWD_BASE, 29);
	void __init omap4_local_timer_init(void)
	{
	omap4_sync32k_timer_init();
	/* Local timers are not supprted on OMAP4430 ES1.0 */
	if (omap_rev() != OMAP4430_REV_ES1_0) {
	int err;

	if (of_have_populated_dt()) {
	twd_local_timer_of_register();
	return;
	}

	err = twd_local_timer_register(&twd_local_timer);
	if (err)
	pr_err("twd_local_timer_register failed %d\n", err);
	}
	}
	#else /* CONFIG_LOCAL_TIMERS */
	void __init omap4_local_timer_init(void)
	{
	omap4_sync32k_timer_init();
	}
	#endif /* CONFIG_LOCAL_TIMERS */
	#endif /* CONFIG_ARCH_OMAP4 */

	#ifdef CONFIG_SOC_OMAP5
	OMAP_SYS_32K_TIMER_INIT(5, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
	2, OMAP4_MPU_SOURCE);
	void __init omap5_realtime_timer_init(void)
	{
	int err;

	omap5_sync32k_timer_init();
	realtime_counter_init();

	err = arch_timer_of_register();
	if (err)
	pr_err("%s: arch_timer_register failed %d\n", __func__, err);
	}
	#endif /* CONFIG_SOC_OMAP5 */

	/**
	* omap_timer_init - build and register timer device with an
	* associated timer hwmod
	* @oh: timer hwmod pointer to be used to build timer device
	* @user: parameter that can be passed from calling hwmod API
	*
	* Called by omap_hwmod_for_each_by_class to register each of the timer
	* devices present in the system. The number of timer devices is known
	* by parsing through the hwmod database for a given class name. At the
	* end of function call memory is allocated for timer device and it is
	* registered to the framework ready to be proved by the driver.
	*/
	static int __init omap_timer_init(struct omap_hwmod oh, void unused)
	{
	int id;
	int ret = 0;
	char *name = "omap_timer";
	struct dmtimer_platform_data *pdata;
	struct platform_device *pdev;
	struct omap_timer_capability_dev_attr *timer_dev_attr;

	pr_debug("%s: %s\n", __func__, oh->name);

	/* on secure device, do not register secure timer */
	timer_dev_attr = oh->dev_attr;
	if (omap_type() != OMAP2_DEVICE_TYPE_GP && timer_dev_attr)
	if (timer_dev_attr->timer_capability == OMAP_TIMER_SECURE)
	return ret;

	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
	if (!pdata) {
	pr_err("%s: No memory for [%s]\n", __func__, oh->name);
	return -ENOMEM;
	}

	/*
	* Extract the IDs from name field in hwmod database
	* and use the same for constructing ids' for the
	* timer devices. In a way, we are avoiding usage of
	* static variable witin the function to do the same.
	* CAUTION: We have to be careful and make sure the
	* name in hwmod database does not change in which case
	* we might either make corresponding change here or
	* switch back static variable mechanism.
	*/
	sscanf(oh->name, "timer%2d", &id);

	if (timer_dev_attr)
	pdata->timer_capability = timer_dev_attr->timer_capability;

	pdata->timer_errata = omap_dm_timer_get_errata();
	pdata->get_context_loss_count = omap_pm_get_dev_context_loss_count;

	pdev = omap_device_build(name, id, oh, pdata, sizeof(*pdata));

	if (IS_ERR(pdev)) {
	pr_err("%s: Can't build omap_device for %s: %s.\n",
	__func__, name, oh->name);
	ret = -EINVAL;
	}

	kfree(pdata);

	return ret;
	}

	/**
	* omap2_dm_timer_init - top level regular device initialization
	*
	* Uses dedicated hwmod api to parse through hwmod database for
	* given class name and then build and register the timer device.
	*/
	static int __init omap2_dm_timer_init(void)
	{
	int ret;

	/* If dtb is there, the devices will be created dynamically */
	if (of_have_populated_dt())
	return -ENODEV;

	ret = omap_hwmod_for_each_by_class("timer", omap_timer_init, NULL);
	if (unlikely(ret)) {
	pr_err("%s: device registration failed.\n", __func__);
	return -EINVAL;
	}

	return 0;
	}
	omap_arch_initcall(omap2_dm_timer_init);

	/**
	* 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);