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v3.5.6
  1/*
  2 * linux/arch/arm/mach-omap2/timer.c
  3 *
  4 * OMAP2 GP timer support.
  5 *
  6 * Copyright (C) 2009 Nokia Corporation
  7 *
  8 * Update to use new clocksource/clockevent layers
  9 * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
 10 * Copyright (C) 2007 MontaVista Software, Inc.
 11 *
 12 * Original driver:
 13 * Copyright (C) 2005 Nokia Corporation
 14 * Author: Paul Mundt <paul.mundt@nokia.com>
 15 *         Juha Yrjölä <juha.yrjola@nokia.com>
 16 * OMAP Dual-mode timer framework support by Timo Teras
 17 *
 18 * Some parts based off of TI's 24xx code:
 19 *
 20 * Copyright (C) 2004-2009 Texas Instruments, Inc.
 21 *
 22 * Roughly modelled after the OMAP1 MPU timer code.
 23 * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
 24 *
 25 * This file is subject to the terms and conditions of the GNU General Public
 26 * License. See the file "COPYING" in the main directory of this archive
 27 * for more details.
 28 */
 29#include <linux/init.h>
 30#include <linux/time.h>
 31#include <linux/interrupt.h>
 32#include <linux/err.h>
 33#include <linux/clk.h>
 34#include <linux/delay.h>
 35#include <linux/irq.h>
 36#include <linux/clocksource.h>
 37#include <linux/clockchips.h>
 38#include <linux/slab.h>
 
 
 
 
 
 
 39
 40#include <asm/mach/time.h>
 41#include <plat/dmtimer.h>
 42#include <asm/smp_twd.h>
 43#include <asm/sched_clock.h>
 44#include "common.h"
 45#include <plat/omap_hwmod.h>
 46#include <plat/omap_device.h>
 47#include <plat/omap-pm.h>
 48
 49#include "powerdomain.h"
 50
 51/* Parent clocks, eventually these will come from the clock framework */
 
 
 
 52
 53#define OMAP2_MPU_SOURCE	"sys_ck"
 54#define OMAP3_MPU_SOURCE	OMAP2_MPU_SOURCE
 55#define OMAP4_MPU_SOURCE	"sys_clkin_ck"
 56#define OMAP2_32K_SOURCE	"func_32k_ck"
 57#define OMAP3_32K_SOURCE	"omap_32k_fck"
 58#define OMAP4_32K_SOURCE	"sys_32k_ck"
 59
 60#ifdef CONFIG_OMAP_32K_TIMER
 61#define OMAP2_CLKEV_SOURCE	OMAP2_32K_SOURCE
 62#define OMAP3_CLKEV_SOURCE	OMAP3_32K_SOURCE
 63#define OMAP4_CLKEV_SOURCE	OMAP4_32K_SOURCE
 64#define OMAP3_SECURE_TIMER	12
 65#else
 66#define OMAP2_CLKEV_SOURCE	OMAP2_MPU_SOURCE
 67#define OMAP3_CLKEV_SOURCE	OMAP3_MPU_SOURCE
 68#define OMAP4_CLKEV_SOURCE	OMAP4_MPU_SOURCE
 69#define OMAP3_SECURE_TIMER	1
 70#endif
 71
 72/* MAX_GPTIMER_ID: number of GPTIMERs on the chip */
 73#define MAX_GPTIMER_ID		12
 74
 75static u32 sys_timer_reserved;
 
 
 
 76
 77/* Clockevent code */
 78
 79static struct omap_dm_timer clkev;
 80static struct clock_event_device clockevent_gpt;
 81
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 82static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
 83{
 84	struct clock_event_device *evt = &clockevent_gpt;
 85
 86	__omap_dm_timer_write_status(&clkev, OMAP_TIMER_INT_OVERFLOW);
 87
 88	evt->event_handler(evt);
 89	return IRQ_HANDLED;
 90}
 91
 92static struct irqaction omap2_gp_timer_irq = {
 93	.name		= "gp_timer",
 94	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 95	.handler	= omap2_gp_timer_interrupt,
 96};
 97
 98static int omap2_gp_timer_set_next_event(unsigned long cycles,
 99					 struct clock_event_device *evt)
100{
101	__omap_dm_timer_load_start(&clkev, OMAP_TIMER_CTRL_ST,
102						0xffffffff - cycles, 1);
103
104	return 0;
105}
106
107static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
108				    struct clock_event_device *evt)
 
 
 
 
 
109{
110	u32 period;
111
112	__omap_dm_timer_stop(&clkev, 1, clkev.rate);
113
114	switch (mode) {
115	case CLOCK_EVT_MODE_PERIODIC:
116		period = clkev.rate / HZ;
117		period -= 1;
118		/* Looks like we need to first set the load value separately */
119		__omap_dm_timer_write(&clkev, OMAP_TIMER_LOAD_REG,
120					0xffffffff - period, 1);
121		__omap_dm_timer_load_start(&clkev,
122					OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
123						0xffffffff - period, 1);
124		break;
125	case CLOCK_EVT_MODE_ONESHOT:
126		break;
127	case CLOCK_EVT_MODE_UNUSED:
128	case CLOCK_EVT_MODE_SHUTDOWN:
129	case CLOCK_EVT_MODE_RESUME:
130		break;
131	}
 
 
 
 
 
 
 
 
132}
133
134static struct clock_event_device clockevent_gpt = {
135	.name		= "gp_timer",
136	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
137	.shift		= 32,
138	.set_next_event	= omap2_gp_timer_set_next_event,
139	.set_mode	= omap2_gp_timer_set_mode,
 
 
 
140};
141
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
142static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
143						int gptimer_id,
144						const char *fck_source)
 
 
145{
146	char name[10]; /* 10 = sizeof("gptXX_Xck0") */
 
147	struct omap_hwmod *oh;
148	struct resource irq_rsrc, mem_rsrc;
149	size_t size;
150	int res = 0;
151	int r;
152
153	sprintf(name, "timer%d", gptimer_id);
154	omap_hwmod_setup_one(name);
155	oh = omap_hwmod_lookup(name);
156	if (!oh)
157		return -ENODEV;
158
159	r = omap_hwmod_get_resource_byname(oh, IORESOURCE_IRQ, NULL, &irq_rsrc);
160	if (r)
161		return -ENXIO;
162	timer->irq = irq_rsrc.start;
 
 
 
163
164	r = omap_hwmod_get_resource_byname(oh, IORESOURCE_MEM, NULL, &mem_rsrc);
165	if (r)
166		return -ENXIO;
167	timer->phys_base = mem_rsrc.start;
168	size = mem_rsrc.end - mem_rsrc.start;
169
170	/* Static mapping, never released */
171	timer->io_base = ioremap(timer->phys_base, size);
 
 
 
 
 
 
 
 
 
 
172	if (!timer->io_base)
173		return -ENXIO;
174
 
 
175	/* After the dmtimer is using hwmod these clocks won't be needed */
176	sprintf(name, "gpt%d_fck", gptimer_id);
177	timer->fclk = clk_get(NULL, name);
178	if (IS_ERR(timer->fclk))
179		return -ENODEV;
180
181	omap_hwmod_enable(oh);
 
 
182
183	sys_timer_reserved |= (1 << (gptimer_id - 1));
 
184
185	if (gptimer_id != 12) {
186		struct clk *src;
187
188		src = clk_get(NULL, fck_source);
189		if (IS_ERR(src)) {
190			res = -EINVAL;
191		} else {
192			res = __omap_dm_timer_set_source(timer->fclk, src);
193			if (IS_ERR_VALUE(res))
194				pr_warning("%s: timer%i cannot set source\n",
195						__func__, gptimer_id);
196			clk_put(src);
197		}
198	}
199	__omap_dm_timer_init_regs(timer);
200	__omap_dm_timer_reset(timer, 1, 1);
201	timer->posted = 1;
202
203	timer->rate = clk_get_rate(timer->fclk);
 
204
 
 
 
 
 
205	timer->reserved = 1;
206
207	return res;
208}
209
 
 
 
 
 
 
210static void __init omap2_gp_clockevent_init(int gptimer_id,
211						const char *fck_source)
 
212{
213	int res;
214
215	res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source);
 
 
 
 
 
 
 
 
 
 
 
216	BUG_ON(res);
217
218	omap2_gp_timer_irq.dev_id = (void *)&clkev;
219	setup_irq(clkev.irq, &omap2_gp_timer_irq);
220
221	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
222
223	clockevent_gpt.mult = div_sc(clkev.rate, NSEC_PER_SEC,
224				     clockevent_gpt.shift);
225	clockevent_gpt.max_delta_ns =
226		clockevent_delta2ns(0xffffffff, &clockevent_gpt);
227	clockevent_gpt.min_delta_ns =
228		clockevent_delta2ns(3, &clockevent_gpt);
229		/* Timer internal resynch latency. */
 
 
230
231	clockevent_gpt.cpumask = cpumask_of(0);
232	clockevents_register_device(&clockevent_gpt);
 
233
234	pr_info("OMAP clockevent source: GPTIMER%d at %lu Hz\n",
235		gptimer_id, clkev.rate);
236}
237
238/* Clocksource code */
239static struct omap_dm_timer clksrc;
240static bool use_gptimer_clksrc;
241
242/*
243 * clocksource
244 */
245static cycle_t clocksource_read_cycles(struct clocksource *cs)
246{
247	return (cycle_t)__omap_dm_timer_read_counter(&clksrc, 1);
 
248}
249
250static struct clocksource clocksource_gpt = {
251	.name		= "gp_timer",
252	.rating		= 300,
253	.read		= clocksource_read_cycles,
254	.mask		= CLOCKSOURCE_MASK(32),
255	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
256};
257
258static u32 notrace dmtimer_read_sched_clock(void)
259{
260	if (clksrc.reserved)
261		return __omap_dm_timer_read_counter(&clksrc, 1);
 
262
263	return 0;
264}
265
266#ifdef CONFIG_OMAP_32K_TIMER
 
 
 
 
267/* Setup free-running counter for clocksource */
268static int __init omap2_sync32k_clocksource_init(void)
269{
270	int ret;
 
271	struct omap_hwmod *oh;
272	void __iomem *vbase;
273	const char *oh_name = "counter_32k";
274
275	/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
276	 * First check hwmod data is available for sync32k counter
277	 */
278	oh = omap_hwmod_lookup(oh_name);
279	if (!oh || oh->slaves_cnt == 0)
280		return -ENODEV;
281
282	omap_hwmod_setup_one(oh_name);
283
284	vbase = omap_hwmod_get_mpu_rt_va(oh);
285	if (!vbase) {
286		pr_warn("%s: failed to get counter_32k resource\n", __func__);
287		return -ENXIO;
288	}
289
290	ret = omap_hwmod_enable(oh);
291	if (ret) {
292		pr_warn("%s: failed to enable counter_32k module (%d)\n",
293							__func__, ret);
294		return ret;
295	}
296
297	ret = omap_init_clocksource_32k(vbase);
298	if (ret) {
299		pr_warn("%s: failed to initialize counter_32k as a clocksource (%d)\n",
300							__func__, ret);
301		omap_hwmod_idle(oh);
302	}
303
304	return ret;
305}
306#else
307static inline int omap2_sync32k_clocksource_init(void)
 
 
 
 
 
 
 
 
 
 
308{
309	return -ENODEV;
 
 
 
 
 
310}
311#endif
312
313static void __init omap2_gptimer_clocksource_init(int gptimer_id,
314						const char *fck_source)
 
315{
316	int res;
317
318	res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
319	BUG_ON(res);
320
321	__omap_dm_timer_load_start(&clksrc,
322			OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1);
323	setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate);
 
324
325	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
326		pr_err("Could not register clocksource %s\n",
327			clocksource_gpt.name);
328	else
329		pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
330			gptimer_id, clksrc.rate);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
331}
332
333static void __init omap2_clocksource_init(int gptimer_id,
334						const char *fck_source)
335{
336	/*
337	 * First give preference to kernel parameter configuration
338	 * by user (clocksource="gp_timer").
339	 *
340	 * In case of missing kernel parameter for clocksource,
341	 * first check for availability for 32k-sync timer, in case
342	 * of failure in finding 32k_counter module or registering
343	 * it as clocksource, execution will fallback to gp-timer.
344	 */
345	if (use_gptimer_clksrc == true)
346		omap2_gptimer_clocksource_init(gptimer_id, fck_source);
347	else if (omap2_sync32k_clocksource_init())
348		/* Fall back to gp-timer code */
349		omap2_gptimer_clocksource_init(gptimer_id, fck_source);
350}
351
352#define OMAP_SYS_TIMER_INIT(name, clkev_nr, clkev_src,			\
353				clksrc_nr, clksrc_src)			\
354static void __init omap##name##_timer_init(void)			\
355{									\
356	omap2_gp_clockevent_init((clkev_nr), clkev_src);		\
357	omap2_clocksource_init((clksrc_nr), clksrc_src);		\
358}
359
360#define OMAP_SYS_TIMER(name)						\
361struct sys_timer omap##name##_timer = {					\
362	.init	= omap##name##_timer_init,				\
363};
364
365#ifdef CONFIG_ARCH_OMAP2
366OMAP_SYS_TIMER_INIT(2, 1, OMAP2_CLKEV_SOURCE, 2, OMAP2_MPU_SOURCE)
367OMAP_SYS_TIMER(2)
368#endif
369
370#ifdef CONFIG_ARCH_OMAP3
371OMAP_SYS_TIMER_INIT(3, 1, OMAP3_CLKEV_SOURCE, 2, OMAP3_MPU_SOURCE)
372OMAP_SYS_TIMER(3)
373OMAP_SYS_TIMER_INIT(3_secure, OMAP3_SECURE_TIMER, OMAP3_CLKEV_SOURCE,
374			2, OMAP3_MPU_SOURCE)
375OMAP_SYS_TIMER(3_secure)
376#endif
377
378#ifdef CONFIG_ARCH_OMAP4
379#ifdef CONFIG_LOCAL_TIMERS
380static DEFINE_TWD_LOCAL_TIMER(twd_local_timer,
381			      OMAP44XX_LOCAL_TWD_BASE,
382			      OMAP44XX_IRQ_LOCALTIMER);
383#endif
384
385static void __init omap4_timer_init(void)
 
 
386{
387	omap2_gp_clockevent_init(1, OMAP4_CLKEV_SOURCE);
388	omap2_clocksource_init(2, OMAP4_MPU_SOURCE);
389#ifdef CONFIG_LOCAL_TIMERS
390	/* Local timers are not supprted on OMAP4430 ES1.0 */
391	if (omap_rev() != OMAP4430_REV_ES1_0) {
392		int err;
393
394		err = twd_local_timer_register(&twd_local_timer);
395		if (err)
396			pr_err("twd_local_timer_register failed %d\n", err);
397	}
398#endif
399}
400OMAP_SYS_TIMER(4)
401#endif
402
403/**
404 * omap2_dm_timer_set_src - change the timer input clock source
405 * @pdev:	timer platform device pointer
406 * @source:	array index of parent clock source
407 */
408static int omap2_dm_timer_set_src(struct platform_device *pdev, int source)
409{
410	int ret;
411	struct dmtimer_platform_data *pdata = pdev->dev.platform_data;
412	struct clk *fclk, *parent;
413	char *parent_name = NULL;
414
415	fclk = clk_get(&pdev->dev, "fck");
416	if (IS_ERR_OR_NULL(fclk)) {
417		dev_err(&pdev->dev, "%s: %d: clk_get() FAILED\n",
418				__func__, __LINE__);
419		return -EINVAL;
420	}
421
422	switch (source) {
423	case OMAP_TIMER_SRC_SYS_CLK:
424		parent_name = "sys_ck";
425		break;
 
 
426
427	case OMAP_TIMER_SRC_32_KHZ:
428		parent_name = "32k_ck";
429		break;
430
431	case OMAP_TIMER_SRC_EXT_CLK:
432		if (pdata->timer_ip_version == OMAP_TIMER_IP_VERSION_1) {
433			parent_name = "alt_ck";
434			break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
435		}
436		dev_err(&pdev->dev, "%s: %d: invalid clk src.\n",
437			__func__, __LINE__);
438		clk_put(fclk);
439		return -EINVAL;
440	}
441
442	parent = clk_get(&pdev->dev, parent_name);
443	if (IS_ERR_OR_NULL(parent)) {
444		dev_err(&pdev->dev, "%s: %d: clk_get() %s FAILED\n",
445			__func__, __LINE__, parent_name);
446		clk_put(fclk);
447		return -EINVAL;
448	}
449
450	ret = clk_set_parent(fclk, parent);
451	if (IS_ERR_VALUE(ret)) {
452		dev_err(&pdev->dev, "%s: clk_set_parent() to %s FAILED\n",
453			__func__, parent_name);
454		ret = -EINVAL;
455	}
456
457	clk_put(parent);
458	clk_put(fclk);
459
460	return ret;
461}
462
463/**
464 * omap_timer_init - build and register timer device with an
465 * associated timer hwmod
466 * @oh:	timer hwmod pointer to be used to build timer device
467 * @user:	parameter that can be passed from calling hwmod API
468 *
469 * Called by omap_hwmod_for_each_by_class to register each of the timer
470 * devices present in the system. The number of timer devices is known
471 * by parsing through the hwmod database for a given class name. At the
472 * end of function call memory is allocated for timer device and it is
473 * registered to the framework ready to be proved by the driver.
474 */
475static int __init omap_timer_init(struct omap_hwmod *oh, void *unused)
476{
477	int id;
478	int ret = 0;
479	char *name = "omap_timer";
480	struct dmtimer_platform_data *pdata;
481	struct platform_device *pdev;
482	struct omap_timer_capability_dev_attr *timer_dev_attr;
483	struct powerdomain *pwrdm;
484
485	pr_debug("%s: %s\n", __func__, oh->name);
486
487	/* on secure device, do not register secure timer */
488	timer_dev_attr = oh->dev_attr;
489	if (omap_type() != OMAP2_DEVICE_TYPE_GP && timer_dev_attr)
490		if (timer_dev_attr->timer_capability == OMAP_TIMER_SECURE)
491			return ret;
492
493	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
494	if (!pdata) {
495		pr_err("%s: No memory for [%s]\n", __func__, oh->name);
496		return -ENOMEM;
497	}
498
499	/*
500	 * Extract the IDs from name field in hwmod database
501	 * and use the same for constructing ids' for the
502	 * timer devices. In a way, we are avoiding usage of
503	 * static variable witin the function to do the same.
504	 * CAUTION: We have to be careful and make sure the
505	 * name in hwmod database does not change in which case
506	 * we might either make corresponding change here or
507	 * switch back static variable mechanism.
508	 */
509	sscanf(oh->name, "timer%2d", &id);
510
511	pdata->set_timer_src = omap2_dm_timer_set_src;
512	pdata->timer_ip_version = oh->class->rev;
513
514	/* Mark clocksource and clockevent timers as reserved */
515	if ((sys_timer_reserved >> (id - 1)) & 0x1)
516		pdata->reserved = 1;
517
518	pwrdm = omap_hwmod_get_pwrdm(oh);
519	pdata->loses_context = pwrdm_can_ever_lose_context(pwrdm);
520#ifdef CONFIG_PM
521	pdata->get_context_loss_count = omap_pm_get_dev_context_loss_count;
522#endif
523	pdev = omap_device_build(name, id, oh, pdata, sizeof(*pdata),
524				 NULL, 0, 0);
525
526	if (IS_ERR(pdev)) {
527		pr_err("%s: Can't build omap_device for %s: %s.\n",
528			__func__, name, oh->name);
529		ret = -EINVAL;
530	}
531
532	kfree(pdata);
533
534	return ret;
535}
536
537/**
538 * omap2_dm_timer_init - top level regular device initialization
539 *
540 * Uses dedicated hwmod api to parse through hwmod database for
541 * given class name and then build and register the timer device.
542 */
543static int __init omap2_dm_timer_init(void)
544{
545	int ret;
546
547	ret = omap_hwmod_for_each_by_class("timer", omap_timer_init, NULL);
548	if (unlikely(ret)) {
549		pr_err("%s: device registration failed.\n", __func__);
550		return -EINVAL;
551	}
552
553	return 0;
554}
555arch_initcall(omap2_dm_timer_init);
556
557/**
558 * omap2_override_clocksource - clocksource override with user configuration
559 *
560 * Allows user to override default clocksource, using kernel parameter
561 *   clocksource="gp_timer"	(For all OMAP2PLUS architectures)
562 *
563 * Note that, here we are using same standard kernel parameter "clocksource=",
564 * and not introducing any OMAP specific interface.
565 */
566static int __init omap2_override_clocksource(char *str)
567{
568	if (!str)
569		return 0;
570	/*
571	 * For OMAP architecture, we only have two options
572	 *    - sync_32k (default)
573	 *    - gp_timer (sys_clk based)
574	 */
575	if (!strcmp(str, "gp_timer"))
576		use_gptimer_clksrc = true;
577
578	return 0;
579}
580early_param("clocksource", omap2_override_clocksource);
v5.4
  1/*
  2 * linux/arch/arm/mach-omap2/timer.c
  3 *
  4 * OMAP2 GP timer support.
  5 *
  6 * Copyright (C) 2009 Nokia Corporation
  7 *
  8 * Update to use new clocksource/clockevent layers
  9 * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
 10 * Copyright (C) 2007 MontaVista Software, Inc.
 11 *
 12 * Original driver:
 13 * Copyright (C) 2005 Nokia Corporation
 14 * Author: Paul Mundt <paul.mundt@nokia.com>
 15 *         Juha Yrjölä <juha.yrjola@nokia.com>
 16 * OMAP Dual-mode timer framework support by Timo Teras
 17 *
 18 * Some parts based off of TI's 24xx code:
 19 *
 20 * Copyright (C) 2004-2009 Texas Instruments, Inc.
 21 *
 22 * Roughly modelled after the OMAP1 MPU timer code.
 23 * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
 24 *
 25 * This file is subject to the terms and conditions of the GNU General Public
 26 * License. See the file "COPYING" in the main directory of this archive
 27 * for more details.
 28 */
 29#include <linux/init.h>
 30#include <linux/time.h>
 31#include <linux/interrupt.h>
 32#include <linux/err.h>
 33#include <linux/clk.h>
 34#include <linux/delay.h>
 35#include <linux/irq.h>
 36#include <linux/clocksource.h>
 37#include <linux/clockchips.h>
 38#include <linux/slab.h>
 39#include <linux/of.h>
 40#include <linux/of_address.h>
 41#include <linux/of_irq.h>
 42#include <linux/platform_device.h>
 43#include <linux/platform_data/dmtimer-omap.h>
 44#include <linux/sched_clock.h>
 45
 46#include <asm/mach/time.h>
 
 
 
 
 
 
 
 
 
 47
 48#include "omap_hwmod.h"
 49#include "omap_device.h"
 50#include <plat/counter-32k.h>
 51#include <clocksource/timer-ti-dm.h>
 52
 53#include "soc.h"
 54#include "common.h"
 55#include "control.h"
 56#include "powerdomain.h"
 57#include "omap-secure.h"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 58
 59#define REALTIME_COUNTER_BASE				0x48243200
 60#define INCREMENTER_NUMERATOR_OFFSET			0x10
 61#define INCREMENTER_DENUMERATOR_RELOAD_OFFSET		0x14
 62#define NUMERATOR_DENUMERATOR_MASK			0xfffff000
 63
 64/* Clockevent code */
 65
 66static struct omap_dm_timer clkev;
 67static struct clock_event_device clockevent_gpt;
 68
 69/* Clockevent hwmod for am335x and am437x suspend */
 70static struct omap_hwmod *clockevent_gpt_hwmod;
 71
 72/* Clockesource hwmod for am437x suspend */
 73static struct omap_hwmod *clocksource_gpt_hwmod;
 74
 75#ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
 76static unsigned long arch_timer_freq;
 77
 78void set_cntfreq(void)
 79{
 80	omap_smc1(OMAP5_DRA7_MON_SET_CNTFRQ_INDEX, arch_timer_freq);
 81}
 82#endif
 83
 84static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
 85{
 86	struct clock_event_device *evt = &clockevent_gpt;
 87
 88	__omap_dm_timer_write_status(&clkev, OMAP_TIMER_INT_OVERFLOW);
 89
 90	evt->event_handler(evt);
 91	return IRQ_HANDLED;
 92}
 93
 94static struct irqaction omap2_gp_timer_irq = {
 95	.name		= "gp_timer",
 96	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
 97	.handler	= omap2_gp_timer_interrupt,
 98};
 99
100static int omap2_gp_timer_set_next_event(unsigned long cycles,
101					 struct clock_event_device *evt)
102{
103	__omap_dm_timer_load_start(&clkev, OMAP_TIMER_CTRL_ST,
104				   0xffffffff - cycles, OMAP_TIMER_POSTED);
105
106	return 0;
107}
108
109static int omap2_gp_timer_shutdown(struct clock_event_device *evt)
110{
111	__omap_dm_timer_stop(&clkev, OMAP_TIMER_POSTED, clkev.rate);
112	return 0;
113}
114
115static int omap2_gp_timer_set_periodic(struct clock_event_device *evt)
116{
117	u32 period;
118
119	__omap_dm_timer_stop(&clkev, OMAP_TIMER_POSTED, clkev.rate);
120
121	period = clkev.rate / HZ;
122	period -= 1;
123	/* Looks like we need to first set the load value separately */
124	__omap_dm_timer_write(&clkev, OMAP_TIMER_LOAD_REG, 0xffffffff - period,
125			      OMAP_TIMER_POSTED);
126	__omap_dm_timer_load_start(&clkev,
127				   OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
128				   0xffffffff - period, OMAP_TIMER_POSTED);
129	return 0;
130}
131
132static void omap_clkevt_idle(struct clock_event_device *unused)
133{
134	if (!clockevent_gpt_hwmod)
135		return;
136
137	omap_hwmod_idle(clockevent_gpt_hwmod);
138}
139
140static void omap_clkevt_unidle(struct clock_event_device *unused)
141{
142	if (!clockevent_gpt_hwmod)
143		return;
144
145	omap_hwmod_enable(clockevent_gpt_hwmod);
146	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
147}
148
149static struct clock_event_device clockevent_gpt = {
150	.features		= CLOCK_EVT_FEAT_PERIODIC |
151				  CLOCK_EVT_FEAT_ONESHOT,
152	.rating			= 300,
153	.set_next_event		= omap2_gp_timer_set_next_event,
154	.set_state_shutdown	= omap2_gp_timer_shutdown,
155	.set_state_periodic	= omap2_gp_timer_set_periodic,
156	.set_state_oneshot	= omap2_gp_timer_shutdown,
157	.tick_resume		= omap2_gp_timer_shutdown,
158};
159
160static const struct of_device_id omap_timer_match[] __initconst = {
161	{ .compatible = "ti,omap2420-timer", },
162	{ .compatible = "ti,omap3430-timer", },
163	{ .compatible = "ti,omap4430-timer", },
164	{ .compatible = "ti,omap5430-timer", },
165	{ .compatible = "ti,dm814-timer", },
166	{ .compatible = "ti,dm816-timer", },
167	{ .compatible = "ti,am335x-timer", },
168	{ .compatible = "ti,am335x-timer-1ms", },
169	{ }
170};
171
172static int omap_timer_add_disabled_property(struct device_node *np)
173{
174	struct property *prop;
175
176	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
177	if (!prop)
178		return -ENOMEM;
179
180	prop->name = "status";
181	prop->value = "disabled";
182	prop->length = strlen(prop->value);
183
184	return of_add_property(np, prop);
185}
186
187static int omap_timer_update_dt(struct device_node *np)
188{
189	int error = 0;
190
191	if (!of_device_is_compatible(np, "ti,omap-counter32k")) {
192		error = omap_timer_add_disabled_property(np);
193		if (error)
194			return error;
195	}
196
197	/* No parent interconnect target module configured? */
198	if (of_get_property(np, "ti,hwmods", NULL))
199		return error;
200
201	/* Tag parent interconnect target module disabled */
202	error = omap_timer_add_disabled_property(np->parent);
203	if (error)
204		return error;
205
206	return 0;
207}
208
209/**
210 * omap_get_timer_dt - get a timer using device-tree
211 * @match	- device-tree match structure for matching a device type
212 * @property	- optional timer property to match
213 *
214 * Helper function to get a timer during early boot using device-tree for use
215 * as kernel system timer. Optionally, the property argument can be used to
216 * select a timer with a specific property. Once a timer is found then mark
217 * the timer node in device-tree as disabled, to prevent the kernel from
218 * registering this timer as a platform device and so no one else can use it.
219 */
220static struct device_node * __init omap_get_timer_dt(const struct of_device_id *match,
221						     const char *property)
222{
223	struct device_node *np;
224	int error;
225
226	for_each_matching_node(np, match) {
227		if (!of_device_is_available(np))
228			continue;
229
230		if (property && !of_get_property(np, property, NULL))
231			continue;
232
233		if (!property && (of_get_property(np, "ti,timer-alwon", NULL) ||
234				  of_get_property(np, "ti,timer-dsp", NULL) ||
235				  of_get_property(np, "ti,timer-pwm", NULL) ||
236				  of_get_property(np, "ti,timer-secure", NULL)))
237			continue;
238
239		error = omap_timer_update_dt(np);
240		WARN(error, "%s: Could not update dt: %i\n", __func__, error);
241
242		return np;
243	}
244
245	return NULL;
246}
247
248/**
249 * omap_dmtimer_init - initialisation function when device tree is used
250 *
251 * For secure OMAP3/DRA7xx devices, timers with device type "timer-secure"
252 * cannot be used by the kernel as they are reserved. Therefore, to prevent the
253 * kernel registering these devices remove them dynamically from the device
254 * tree on boot.
255 */
256static void __init omap_dmtimer_init(void)
257{
258	struct device_node *np;
259
260	if (!cpu_is_omap34xx() && !soc_is_dra7xx())
261		return;
262
263	/* If we are a secure device, remove any secure timer nodes */
264	if ((omap_type() != OMAP2_DEVICE_TYPE_GP)) {
265		np = omap_get_timer_dt(omap_timer_match, "ti,timer-secure");
266		of_node_put(np);
267	}
268}
269
270/**
271 * omap_dm_timer_get_errata - get errata flags for a timer
272 *
273 * Get the timer errata flags that are specific to the OMAP device being used.
274 */
275static u32 __init omap_dm_timer_get_errata(void)
276{
277	if (cpu_is_omap24xx())
278		return 0;
279
280	return OMAP_TIMER_ERRATA_I103_I767;
281}
282
283static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
284					 const char *fck_source,
285					 const char *property,
286					 const char **timer_name,
287					 int posted)
288{
289	const char *oh_name = NULL;
290	struct device_node *np;
291	struct omap_hwmod *oh;
292	struct clk *src;
293	int r = 0;
294
295	np = omap_get_timer_dt(omap_timer_match, property);
296	if (!np)
 
 
 
 
297		return -ENODEV;
298
299	of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
300	if (!oh_name) {
301		of_property_read_string_index(np->parent, "ti,hwmods", 0,
302					      &oh_name);
303		if (!oh_name)
304			return -ENODEV;
305	}
306
307	timer->irq = irq_of_parse_and_map(np, 0);
308	if (!timer->irq)
309		return -ENXIO;
 
 
310
311	timer->io_base = of_iomap(np, 0);
312
313	timer->fclk = of_clk_get_by_name(np, "fck");
314
315	of_node_put(np);
316
317	oh = omap_hwmod_lookup(oh_name);
318	if (!oh)
319		return -ENODEV;
320
321	*timer_name = oh->name;
322
323	if (!timer->io_base)
324		return -ENXIO;
325
326	omap_hwmod_setup_one(oh_name);
327
328	/* After the dmtimer is using hwmod these clocks won't be needed */
329	if (IS_ERR_OR_NULL(timer->fclk))
330		timer->fclk = clk_get(NULL, omap_hwmod_get_main_clk(oh));
331	if (IS_ERR(timer->fclk))
332		return PTR_ERR(timer->fclk);
333
334	src = clk_get(NULL, fck_source);
335	if (IS_ERR(src))
336		return PTR_ERR(src);
337
338	WARN(clk_set_parent(timer->fclk, src) < 0,
339	     "Cannot set timer parent clock, no PLL clock driver?");
340
341	clk_put(src);
 
342
343	omap_hwmod_enable(oh);
 
 
 
 
 
 
 
 
 
 
344	__omap_dm_timer_init_regs(timer);
 
 
345
346	if (posted)
347		__omap_dm_timer_enable_posted(timer);
348
349	/* Check that the intended posted configuration matches the actual */
350	if (posted != timer->posted)
351		return -EINVAL;
352
353	timer->rate = clk_get_rate(timer->fclk);
354	timer->reserved = 1;
355
356	return r;
357}
358
359#if !defined(CONFIG_SMP) && defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
360void tick_broadcast(const struct cpumask *mask)
361{
362}
363#endif
364
365static void __init omap2_gp_clockevent_init(int gptimer_id,
366						const char *fck_source,
367						const char *property)
368{
369	int res;
370
371	clkev.id = gptimer_id;
372	clkev.errata = omap_dm_timer_get_errata();
373
374	/*
375	 * For clock-event timers we never read the timer counter and
376	 * so we are not impacted by errata i103 and i767. Therefore,
377	 * we can safely ignore this errata for clock-event timers.
378	 */
379	__omap_dm_timer_override_errata(&clkev, OMAP_TIMER_ERRATA_I103_I767);
380
381	res = omap_dm_timer_init_one(&clkev, fck_source, property,
382				     &clockevent_gpt.name, OMAP_TIMER_POSTED);
383	BUG_ON(res);
384
385	omap2_gp_timer_irq.dev_id = &clkev;
386	setup_irq(clkev.irq, &omap2_gp_timer_irq);
387
388	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
389
390	clockevent_gpt.cpumask = cpu_possible_mask;
391	clockevent_gpt.irq = omap_dm_timer_get_irq(&clkev);
392	clockevents_config_and_register(&clockevent_gpt, clkev.rate,
393					3, /* Timer internal resynch latency */
394					0xffffffff);
395
396	if (soc_is_am33xx() || soc_is_am43xx()) {
397		clockevent_gpt.suspend = omap_clkevt_idle;
398		clockevent_gpt.resume = omap_clkevt_unidle;
399
400		clockevent_gpt_hwmod =
401			omap_hwmod_lookup(clockevent_gpt.name);
402	}
403
404	pr_info("OMAP clockevent source: %s at %lu Hz\n", clockevent_gpt.name,
405		clkev.rate);
406}
407
408/* Clocksource code */
409static struct omap_dm_timer clksrc;
410static bool use_gptimer_clksrc __initdata;
411
412/*
413 * clocksource
414 */
415static u64 clocksource_read_cycles(struct clocksource *cs)
416{
417	return (u64)__omap_dm_timer_read_counter(&clksrc,
418						     OMAP_TIMER_NONPOSTED);
419}
420
421static struct clocksource clocksource_gpt = {
 
422	.rating		= 300,
423	.read		= clocksource_read_cycles,
424	.mask		= CLOCKSOURCE_MASK(32),
425	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
426};
427
428static u64 notrace dmtimer_read_sched_clock(void)
429{
430	if (clksrc.reserved)
431		return __omap_dm_timer_read_counter(&clksrc,
432						    OMAP_TIMER_NONPOSTED);
433
434	return 0;
435}
436
437static const struct of_device_id omap_counter_match[] __initconst = {
438	{ .compatible = "ti,omap-counter32k", },
439	{ }
440};
441
442/* Setup free-running counter for clocksource */
443static int __init __maybe_unused omap2_sync32k_clocksource_init(void)
444{
445	int ret;
446	struct device_node *np = NULL;
447	struct omap_hwmod *oh;
 
448	const char *oh_name = "counter_32k";
449
450	/*
451	 * See if the 32kHz counter is supported.
452	 */
453	np = omap_get_timer_dt(omap_counter_match, NULL);
454	if (!np)
455		return -ENODEV;
456
457	of_property_read_string_index(np->parent, "ti,hwmods", 0, &oh_name);
458	if (!oh_name) {
459		of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
460		if (!oh_name)
461			return -ENODEV;
462	}
463
464	/*
465	 * First check hwmod data is available for sync32k counter
466	 */
467	oh = omap_hwmod_lookup(oh_name);
468	if (!oh || oh->slaves_cnt == 0)
469		return -ENODEV;
470
471	omap_hwmod_setup_one(oh_name);
472
 
 
 
 
 
 
473	ret = omap_hwmod_enable(oh);
474	if (ret) {
475		pr_warn("%s: failed to enable counter_32k module (%d)\n",
476							__func__, ret);
477		return ret;
478	}
479
 
 
 
 
 
 
 
480	return ret;
481}
482
483static unsigned int omap2_gptimer_clksrc_load;
484
485static void omap2_gptimer_clksrc_suspend(struct clocksource *unused)
486{
487	omap2_gptimer_clksrc_load =
488		__omap_dm_timer_read_counter(&clksrc, OMAP_TIMER_NONPOSTED);
489
490	omap_hwmod_idle(clocksource_gpt_hwmod);
491}
492
493static void omap2_gptimer_clksrc_resume(struct clocksource *unused)
494{
495	omap_hwmod_enable(clocksource_gpt_hwmod);
496
497	__omap_dm_timer_load_start(&clksrc,
498				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR,
499				   omap2_gptimer_clksrc_load,
500				   OMAP_TIMER_NONPOSTED);
501}
 
502
503static void __init omap2_gptimer_clocksource_init(int gptimer_id,
504						  const char *fck_source,
505						  const char *property)
506{
507	int res;
508
509	clksrc.id = gptimer_id;
510	clksrc.errata = omap_dm_timer_get_errata();
511
512	res = omap_dm_timer_init_one(&clksrc, fck_source, property,
513				     &clocksource_gpt.name,
514				     OMAP_TIMER_NONPOSTED);
515
516	if (soc_is_am43xx()) {
517		clocksource_gpt.suspend = omap2_gptimer_clksrc_suspend;
518		clocksource_gpt.resume = omap2_gptimer_clksrc_resume;
519
520		clocksource_gpt_hwmod =
521			omap_hwmod_lookup(clocksource_gpt.name);
522	}
523
524	BUG_ON(res);
525
526	__omap_dm_timer_load_start(&clksrc,
527				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
528				   OMAP_TIMER_NONPOSTED);
529	sched_clock_register(dmtimer_read_sched_clock, 32, clksrc.rate);
530
531	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
532		pr_err("Could not register clocksource %s\n",
533			clocksource_gpt.name);
534	else
535		pr_info("OMAP clocksource: %s at %lu Hz\n",
536			clocksource_gpt.name, clksrc.rate);
537}
538
539static void __init __omap_sync32k_timer_init(int clkev_nr, const char *clkev_src,
540		const char *clkev_prop, int clksrc_nr, const char *clksrc_src,
541		const char *clksrc_prop, bool gptimer)
542{
543	omap_clk_init();
544	omap_dmtimer_init();
545	omap2_gp_clockevent_init(clkev_nr, clkev_src, clkev_prop);
546
547	/* Enable the use of clocksource="gp_timer" kernel parameter */
548	if (use_gptimer_clksrc || gptimer)
549		omap2_gptimer_clocksource_init(clksrc_nr, clksrc_src,
550						clksrc_prop);
551	else
552		omap2_sync32k_clocksource_init();
553}
554
555void __init omap_init_time(void)
 
556{
557	__omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",
558			2, "timer_sys_ck", NULL, false);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
559
560	timer_probe();
561}
 
 
562
563#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM43XX)
564void __init omap3_secure_sync32k_timer_init(void)
565{
566	__omap_sync32k_timer_init(12, "secure_32k_fck", "ti,timer-secure",
567			2, "timer_sys_ck", NULL, false);
 
 
568
569	timer_probe();
570}
571#endif /* CONFIG_ARCH_OMAP3 */
 
 
 
572
573#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) || \
574	defined(CONFIG_SOC_AM43XX)
575void __init omap3_gptimer_timer_init(void)
576{
577	__omap_sync32k_timer_init(2, "timer_sys_ck", NULL,
578			1, "timer_sys_ck", "ti,timer-alwon", true);
579	if (of_have_populated_dt())
580		timer_probe();
 
 
 
 
 
 
 
 
581}
 
582#endif
583
584#if defined(CONFIG_ARCH_OMAP4) || defined(CONFIG_SOC_OMAP5) ||		\
585	defined(CONFIG_SOC_DRA7XX)
586static void __init omap4_sync32k_timer_init(void)
 
 
 
587{
588	__omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",
589			2, "sys_clkin_ck", NULL, false);
590}
 
 
 
 
 
 
 
 
591
592void __init omap4_local_timer_init(void)
593{
594	omap4_sync32k_timer_init();
595	timer_probe();
596}
597#endif
598
599#if defined(CONFIG_SOC_OMAP5) || defined(CONFIG_SOC_DRA7XX)
 
 
600
601/*
602 * The realtime counter also called master counter, is a free-running
603 * counter, which is related to real time. It produces the count used
604 * by the CPU local timer peripherals in the MPU cluster. The timer counts
605 * at a rate of 6.144 MHz. Because the device operates on different clocks
606 * in different power modes, the master counter shifts operation between
607 * clocks, adjusting the increment per clock in hardware accordingly to
608 * maintain a constant count rate.
609 */
610static void __init realtime_counter_init(void)
611{
612#ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
613	void __iomem *base;
614	static struct clk *sys_clk;
615	unsigned long rate;
616	unsigned int reg;
617	unsigned long long num, den;
618
619	base = ioremap(REALTIME_COUNTER_BASE, SZ_32);
620	if (!base) {
621		pr_err("%s: ioremap failed\n", __func__);
622		return;
623	}
624	sys_clk = clk_get(NULL, "sys_clkin");
625	if (IS_ERR(sys_clk)) {
626		pr_err("%s: failed to get system clock handle\n", __func__);
627		iounmap(base);
628		return;
629	}
630
631	rate = clk_get_rate(sys_clk);
632
633	if (soc_is_dra7xx()) {
634		/*
635		 * Errata i856 says the 32.768KHz crystal does not start at
636		 * power on, so the CPU falls back to an emulated 32KHz clock
637		 * based on sysclk / 610 instead. This causes the master counter
638		 * frequency to not be 6.144MHz but at sysclk / 610 * 375 / 2
639		 * (OR sysclk * 75 / 244)
640		 *
641		 * This affects at least the DRA7/AM572x 1.0, 1.1 revisions.
642		 * Of course any board built without a populated 32.768KHz
643		 * crystal would also need this fix even if the CPU is fixed
644		 * later.
645		 *
646		 * Either case can be detected by using the two speedselect bits
647		 * If they are not 0, then the 32.768KHz clock driving the
648		 * coarse counter that corrects the fine counter every time it
649		 * ticks is actually rate/610 rather than 32.768KHz and we
650		 * should compensate to avoid the 570ppm (at 20MHz, much worse
651		 * at other rates) too fast system time.
652		 */
653		reg = omap_ctrl_readl(DRA7_CTRL_CORE_BOOTSTRAP);
654		if (reg & DRA7_SPEEDSELECT_MASK) {
655			num = 75;
656			den = 244;
657			goto sysclk1_based;
658		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
659	}
660
661	/* Numerator/denumerator values refer TRM Realtime Counter section */
662	switch (rate) {
663	case 12000000:
664		num = 64;
665		den = 125;
666		break;
667	case 13000000:
668		num = 768;
669		den = 1625;
670		break;
671	case 19200000:
672		num = 8;
673		den = 25;
674		break;
675	case 20000000:
676		num = 192;
677		den = 625;
678		break;
679	case 26000000:
680		num = 384;
681		den = 1625;
682		break;
683	case 27000000:
684		num = 256;
685		den = 1125;
686		break;
687	case 38400000:
688	default:
689		/* Program it for 38.4 MHz */
690		num = 4;
691		den = 25;
692		break;
 
 
 
 
 
 
 
 
693	}
694
695sysclk1_based:
696	/* Program numerator and denumerator registers */
697	reg = readl_relaxed(base + INCREMENTER_NUMERATOR_OFFSET) &
698			NUMERATOR_DENUMERATOR_MASK;
699	reg |= num;
700	writel_relaxed(reg, base + INCREMENTER_NUMERATOR_OFFSET);
701
702	reg = readl_relaxed(base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET) &
703			NUMERATOR_DENUMERATOR_MASK;
704	reg |= den;
705	writel_relaxed(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);
706
707	arch_timer_freq = DIV_ROUND_UP_ULL(rate * num, den);
708	set_cntfreq();
709
710	iounmap(base);
 
 
 
 
 
 
 
711#endif
 
 
 
 
 
 
 
 
 
 
 
 
712}
713
714void __init omap5_realtime_timer_init(void)
 
 
 
 
 
 
715{
716	omap4_sync32k_timer_init();
717	realtime_counter_init();
 
 
 
 
 
718
719	timer_probe();
720}
721#endif /* CONFIG_SOC_OMAP5 || CONFIG_SOC_DRA7XX */
722
723/**
724 * omap2_override_clocksource - clocksource override with user configuration
725 *
726 * Allows user to override default clocksource, using kernel parameter
727 *   clocksource="gp_timer"	(For all OMAP2PLUS architectures)
728 *
729 * Note that, here we are using same standard kernel parameter "clocksource=",
730 * and not introducing any OMAP specific interface.
731 */
732static int __init omap2_override_clocksource(char *str)
733{
734	if (!str)
735		return 0;
736	/*
737	 * For OMAP architecture, we only have two options
738	 *    - sync_32k (default)
739	 *    - gp_timer (sys_clk based)
740	 */
741	if (!strcmp(str, "gp_timer"))
742		use_gptimer_clksrc = true;
743
744	return 0;
745}
746early_param("clocksource", omap2_override_clocksource);