xref: /openbmc/linux/arch/arm/mach-omap2/timer.c (revision 840ef8b7cc584a23c4f9d05352f4dbaf8e56e5ab)
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 
45 #include <asm/mach/time.h>
46 #include <asm/smp_twd.h>
47 #include <asm/sched_clock.h>
48 
49 #include <asm/arch_timer.h>
50 #include "omap_hwmod.h"
51 #include "omap_device.h"
52 #include <plat/counter-32k.h>
53 #include <plat/dmtimer.h>
54 #include "omap-pm.h"
55 
56 #include "soc.h"
57 #include "common.h"
58 #include "powerdomain.h"
59 
60 /* Parent clocks, eventually these will come from the clock framework */
61 
62 #define OMAP2_MPU_SOURCE	"sys_ck"
63 #define OMAP3_MPU_SOURCE	OMAP2_MPU_SOURCE
64 #define OMAP4_MPU_SOURCE	"sys_clkin_ck"
65 #define OMAP2_32K_SOURCE	"func_32k_ck"
66 #define OMAP3_32K_SOURCE	"omap_32k_fck"
67 #define OMAP4_32K_SOURCE	"sys_32k_ck"
68 
69 #define REALTIME_COUNTER_BASE				0x48243200
70 #define INCREMENTER_NUMERATOR_OFFSET			0x10
71 #define INCREMENTER_DENUMERATOR_RELOAD_OFFSET		0x14
72 #define NUMERATOR_DENUMERATOR_MASK			0xfffff000
73 
74 /* Clockevent code */
75 
76 static struct omap_dm_timer clkev;
77 static struct clock_event_device clockevent_gpt;
78 
79 static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
80 {
81 	struct clock_event_device *evt = &clockevent_gpt;
82 
83 	__omap_dm_timer_write_status(&clkev, OMAP_TIMER_INT_OVERFLOW);
84 
85 	evt->event_handler(evt);
86 	return IRQ_HANDLED;
87 }
88 
89 static struct irqaction omap2_gp_timer_irq = {
90 	.name		= "gp_timer",
91 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
92 	.handler	= omap2_gp_timer_interrupt,
93 };
94 
95 static int omap2_gp_timer_set_next_event(unsigned long cycles,
96 					 struct clock_event_device *evt)
97 {
98 	__omap_dm_timer_load_start(&clkev, OMAP_TIMER_CTRL_ST,
99 				   0xffffffff - cycles, OMAP_TIMER_POSTED);
100 
101 	return 0;
102 }
103 
104 static void omap2_gp_timer_set_mode(enum clock_event_mode mode,
105 				    struct clock_event_device *evt)
106 {
107 	u32 period;
108 
109 	__omap_dm_timer_stop(&clkev, OMAP_TIMER_POSTED, clkev.rate);
110 
111 	switch (mode) {
112 	case CLOCK_EVT_MODE_PERIODIC:
113 		period = clkev.rate / HZ;
114 		period -= 1;
115 		/* Looks like we need to first set the load value separately */
116 		__omap_dm_timer_write(&clkev, OMAP_TIMER_LOAD_REG,
117 				      0xffffffff - period, OMAP_TIMER_POSTED);
118 		__omap_dm_timer_load_start(&clkev,
119 					OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
120 					0xffffffff - period, OMAP_TIMER_POSTED);
121 		break;
122 	case CLOCK_EVT_MODE_ONESHOT:
123 		break;
124 	case CLOCK_EVT_MODE_UNUSED:
125 	case CLOCK_EVT_MODE_SHUTDOWN:
126 	case CLOCK_EVT_MODE_RESUME:
127 		break;
128 	}
129 }
130 
131 static struct clock_event_device clockevent_gpt = {
132 	.name		= "gp_timer",
133 	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
134 	.rating		= 300,
135 	.set_next_event	= omap2_gp_timer_set_next_event,
136 	.set_mode	= omap2_gp_timer_set_mode,
137 };
138 
139 static struct property device_disabled = {
140 	.name = "status",
141 	.length = sizeof("disabled"),
142 	.value = "disabled",
143 };
144 
145 static struct of_device_id omap_timer_match[] __initdata = {
146 	{ .compatible = "ti,omap2-timer", },
147 	{ }
148 };
149 
150 /**
151  * omap_get_timer_dt - get a timer using device-tree
152  * @match	- device-tree match structure for matching a device type
153  * @property	- optional timer property to match
154  *
155  * Helper function to get a timer during early boot using device-tree for use
156  * as kernel system timer. Optionally, the property argument can be used to
157  * select a timer with a specific property. Once a timer is found then mark
158  * the timer node in device-tree as disabled, to prevent the kernel from
159  * registering this timer as a platform device and so no one else can use it.
160  */
161 static struct device_node * __init omap_get_timer_dt(struct of_device_id *match,
162 						     const char *property)
163 {
164 	struct device_node *np;
165 
166 	for_each_matching_node(np, match) {
167 		if (!of_device_is_available(np))
168 			continue;
169 
170 		if (property && !of_get_property(np, property, NULL))
171 			continue;
172 
173 		of_add_property(np, &device_disabled);
174 		return np;
175 	}
176 
177 	return NULL;
178 }
179 
180 /**
181  * omap_dmtimer_init - initialisation function when device tree is used
182  *
183  * For secure OMAP3 devices, timers with device type "timer-secure" cannot
184  * be used by the kernel as they are reserved. Therefore, to prevent the
185  * kernel registering these devices remove them dynamically from the device
186  * tree on boot.
187  */
188 static void __init omap_dmtimer_init(void)
189 {
190 	struct device_node *np;
191 
192 	if (!cpu_is_omap34xx())
193 		return;
194 
195 	/* If we are a secure device, remove any secure timer nodes */
196 	if ((omap_type() != OMAP2_DEVICE_TYPE_GP)) {
197 		np = omap_get_timer_dt(omap_timer_match, "ti,timer-secure");
198 		if (np)
199 			of_node_put(np);
200 	}
201 }
202 
203 /**
204  * omap_dm_timer_get_errata - get errata flags for a timer
205  *
206  * Get the timer errata flags that are specific to the OMAP device being used.
207  */
208 static u32 __init omap_dm_timer_get_errata(void)
209 {
210 	if (cpu_is_omap24xx())
211 		return 0;
212 
213 	return OMAP_TIMER_ERRATA_I103_I767;
214 }
215 
216 static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
217 						int gptimer_id,
218 						const char *fck_source,
219 						const char *property,
220 						int posted)
221 {
222 	char name[10]; /* 10 = sizeof("gptXX_Xck0") */
223 	const char *oh_name;
224 	struct device_node *np;
225 	struct omap_hwmod *oh;
226 	struct resource irq, mem;
227 	int r = 0;
228 
229 	if (of_have_populated_dt()) {
230 		np = omap_get_timer_dt(omap_timer_match, property);
231 		if (!np)
232 			return -ENODEV;
233 
234 		of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
235 		if (!oh_name)
236 			return -ENODEV;
237 
238 		timer->irq = irq_of_parse_and_map(np, 0);
239 		if (!timer->irq)
240 			return -ENXIO;
241 
242 		timer->io_base = of_iomap(np, 0);
243 
244 		of_node_put(np);
245 	} else {
246 		if (omap_dm_timer_reserve_systimer(gptimer_id))
247 			return -ENODEV;
248 
249 		sprintf(name, "timer%d", gptimer_id);
250 		oh_name = name;
251 	}
252 
253 	oh = omap_hwmod_lookup(oh_name);
254 	if (!oh)
255 		return -ENODEV;
256 
257 	if (!of_have_populated_dt()) {
258 		r = omap_hwmod_get_resource_byname(oh, IORESOURCE_IRQ, NULL,
259 						   &irq);
260 		if (r)
261 			return -ENXIO;
262 		timer->irq = irq.start;
263 
264 		r = omap_hwmod_get_resource_byname(oh, IORESOURCE_MEM, NULL,
265 						   &mem);
266 		if (r)
267 			return -ENXIO;
268 
269 		/* Static mapping, never released */
270 		timer->io_base = ioremap(mem.start, mem.end - mem.start);
271 	}
272 
273 	if (!timer->io_base)
274 		return -ENXIO;
275 
276 	/* After the dmtimer is using hwmod these clocks won't be needed */
277 	timer->fclk = clk_get(NULL, omap_hwmod_get_main_clk(oh));
278 	if (IS_ERR(timer->fclk))
279 		return -ENODEV;
280 
281 	/* FIXME: Need to remove hard-coded test on timer ID */
282 	if (gptimer_id != 12) {
283 		struct clk *src;
284 
285 		src = clk_get(NULL, fck_source);
286 		if (IS_ERR(src)) {
287 			r = -EINVAL;
288 		} else {
289 			r = clk_set_parent(timer->fclk, src);
290 			if (IS_ERR_VALUE(r))
291 				pr_warn("%s: %s cannot set source\n",
292 					__func__, oh->name);
293 			clk_put(src);
294 		}
295 	}
296 
297 	omap_hwmod_setup_one(oh_name);
298 	omap_hwmod_enable(oh);
299 	__omap_dm_timer_init_regs(timer);
300 
301 	if (posted)
302 		__omap_dm_timer_enable_posted(timer);
303 
304 	/* Check that the intended posted configuration matches the actual */
305 	if (posted != timer->posted)
306 		return -EINVAL;
307 
308 	timer->rate = clk_get_rate(timer->fclk);
309 	timer->reserved = 1;
310 
311 	return r;
312 }
313 
314 static void __init omap2_gp_clockevent_init(int gptimer_id,
315 						const char *fck_source,
316 						const char *property)
317 {
318 	int res;
319 
320 	clkev.errata = omap_dm_timer_get_errata();
321 
322 	/*
323 	 * For clock-event timers we never read the timer counter and
324 	 * so we are not impacted by errata i103 and i767. Therefore,
325 	 * we can safely ignore this errata for clock-event timers.
326 	 */
327 	__omap_dm_timer_override_errata(&clkev, OMAP_TIMER_ERRATA_I103_I767);
328 
329 	res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source, property,
330 				     OMAP_TIMER_POSTED);
331 	BUG_ON(res);
332 
333 	omap2_gp_timer_irq.dev_id = &clkev;
334 	setup_irq(clkev.irq, &omap2_gp_timer_irq);
335 
336 	__omap_dm_timer_int_enable(&clkev, OMAP_TIMER_INT_OVERFLOW);
337 
338 	clockevent_gpt.cpumask = cpu_possible_mask;
339 	clockevent_gpt.irq = omap_dm_timer_get_irq(&clkev);
340 	clockevents_config_and_register(&clockevent_gpt, clkev.rate,
341 					3, /* Timer internal resynch latency */
342 					0xffffffff);
343 
344 	pr_info("OMAP clockevent source: GPTIMER%d at %lu Hz\n",
345 		gptimer_id, clkev.rate);
346 }
347 
348 /* Clocksource code */
349 static struct omap_dm_timer clksrc;
350 static bool use_gptimer_clksrc;
351 
352 /*
353  * clocksource
354  */
355 static cycle_t clocksource_read_cycles(struct clocksource *cs)
356 {
357 	return (cycle_t)__omap_dm_timer_read_counter(&clksrc,
358 						     OMAP_TIMER_NONPOSTED);
359 }
360 
361 static struct clocksource clocksource_gpt = {
362 	.name		= "gp_timer",
363 	.rating		= 300,
364 	.read		= clocksource_read_cycles,
365 	.mask		= CLOCKSOURCE_MASK(32),
366 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
367 };
368 
369 static u32 notrace dmtimer_read_sched_clock(void)
370 {
371 	if (clksrc.reserved)
372 		return __omap_dm_timer_read_counter(&clksrc,
373 						    OMAP_TIMER_NONPOSTED);
374 
375 	return 0;
376 }
377 
378 static struct of_device_id omap_counter_match[] __initdata = {
379 	{ .compatible = "ti,omap-counter32k", },
380 	{ }
381 };
382 
383 /* Setup free-running counter for clocksource */
384 static int __init __maybe_unused omap2_sync32k_clocksource_init(void)
385 {
386 	int ret;
387 	struct device_node *np = NULL;
388 	struct omap_hwmod *oh;
389 	void __iomem *vbase;
390 	const char *oh_name = "counter_32k";
391 
392 	/*
393 	 * If device-tree is present, then search the DT blob
394 	 * to see if the 32kHz counter is supported.
395 	 */
396 	if (of_have_populated_dt()) {
397 		np = omap_get_timer_dt(omap_counter_match, NULL);
398 		if (!np)
399 			return -ENODEV;
400 
401 		of_property_read_string_index(np, "ti,hwmods", 0, &oh_name);
402 		if (!oh_name)
403 			return -ENODEV;
404 	}
405 
406 	/*
407 	 * First check hwmod data is available for sync32k counter
408 	 */
409 	oh = omap_hwmod_lookup(oh_name);
410 	if (!oh || oh->slaves_cnt == 0)
411 		return -ENODEV;
412 
413 	omap_hwmod_setup_one(oh_name);
414 
415 	if (np) {
416 		vbase = of_iomap(np, 0);
417 		of_node_put(np);
418 	} else {
419 		vbase = omap_hwmod_get_mpu_rt_va(oh);
420 	}
421 
422 	if (!vbase) {
423 		pr_warn("%s: failed to get counter_32k resource\n", __func__);
424 		return -ENXIO;
425 	}
426 
427 	ret = omap_hwmod_enable(oh);
428 	if (ret) {
429 		pr_warn("%s: failed to enable counter_32k module (%d)\n",
430 							__func__, ret);
431 		return ret;
432 	}
433 
434 	ret = omap_init_clocksource_32k(vbase);
435 	if (ret) {
436 		pr_warn("%s: failed to initialize counter_32k as a clocksource (%d)\n",
437 							__func__, ret);
438 		omap_hwmod_idle(oh);
439 	}
440 
441 	return ret;
442 }
443 
444 static void __init omap2_gptimer_clocksource_init(int gptimer_id,
445 						const char *fck_source)
446 {
447 	int res;
448 
449 	clksrc.errata = omap_dm_timer_get_errata();
450 
451 	res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source, NULL,
452 				     OMAP_TIMER_NONPOSTED);
453 	BUG_ON(res);
454 
455 	__omap_dm_timer_load_start(&clksrc,
456 				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
457 				   OMAP_TIMER_NONPOSTED);
458 	setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate);
459 
460 	if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
461 		pr_err("Could not register clocksource %s\n",
462 			clocksource_gpt.name);
463 	else
464 		pr_info("OMAP clocksource: GPTIMER%d at %lu Hz\n",
465 			gptimer_id, clksrc.rate);
466 }
467 
468 #ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
469 /*
470  * The realtime counter also called master counter, is a free-running
471  * counter, which is related to real time. It produces the count used
472  * by the CPU local timer peripherals in the MPU cluster. The timer counts
473  * at a rate of 6.144 MHz. Because the device operates on different clocks
474  * in different power modes, the master counter shifts operation between
475  * clocks, adjusting the increment per clock in hardware accordingly to
476  * maintain a constant count rate.
477  */
478 static void __init realtime_counter_init(void)
479 {
480 	void __iomem *base;
481 	static struct clk *sys_clk;
482 	unsigned long rate;
483 	unsigned int reg, num, den;
484 
485 	base = ioremap(REALTIME_COUNTER_BASE, SZ_32);
486 	if (!base) {
487 		pr_err("%s: ioremap failed\n", __func__);
488 		return;
489 	}
490 	sys_clk = clk_get(NULL, "sys_clkin_ck");
491 	if (IS_ERR(sys_clk)) {
492 		pr_err("%s: failed to get system clock handle\n", __func__);
493 		iounmap(base);
494 		return;
495 	}
496 
497 	rate = clk_get_rate(sys_clk);
498 	/* Numerator/denumerator values refer TRM Realtime Counter section */
499 	switch (rate) {
500 	case 1200000:
501 		num = 64;
502 		den = 125;
503 		break;
504 	case 1300000:
505 		num = 768;
506 		den = 1625;
507 		break;
508 	case 19200000:
509 		num = 8;
510 		den = 25;
511 		break;
512 	case 2600000:
513 		num = 384;
514 		den = 1625;
515 		break;
516 	case 2700000:
517 		num = 256;
518 		den = 1125;
519 		break;
520 	case 38400000:
521 	default:
522 		/* Program it for 38.4 MHz */
523 		num = 4;
524 		den = 25;
525 		break;
526 	}
527 
528 	/* Program numerator and denumerator registers */
529 	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
530 			NUMERATOR_DENUMERATOR_MASK;
531 	reg |= num;
532 	__raw_writel(reg, base + INCREMENTER_NUMERATOR_OFFSET);
533 
534 	reg = __raw_readl(base + INCREMENTER_NUMERATOR_OFFSET) &
535 			NUMERATOR_DENUMERATOR_MASK;
536 	reg |= den;
537 	__raw_writel(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);
538 
539 	iounmap(base);
540 }
541 #else
542 static inline void __init realtime_counter_init(void)
543 {}
544 #endif
545 
546 #define OMAP_SYS_GP_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop,	\
547 			       clksrc_nr, clksrc_src)			\
548 void __init omap##name##_gptimer_timer_init(void)			\
549 {									\
550 	omap_dmtimer_init();						\
551 	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop);	\
552 	omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src);	\
553 }
554 
555 #define OMAP_SYS_32K_TIMER_INIT(name, clkev_nr, clkev_src, clkev_prop,	\
556 				clksrc_nr, clksrc_src)			\
557 void __init omap##name##_sync32k_timer_init(void)		\
558 {									\
559 	omap_dmtimer_init();						\
560 	omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop);	\
561 	/* Enable the use of clocksource="gp_timer" kernel parameter */	\
562 	if (use_gptimer_clksrc)						\
563 		omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src);\
564 	else								\
565 		omap2_sync32k_clocksource_init();			\
566 }
567 
568 #ifdef CONFIG_ARCH_OMAP2
569 OMAP_SYS_32K_TIMER_INIT(2, 1, OMAP2_32K_SOURCE, "ti,timer-alwon",
570 			2, OMAP2_MPU_SOURCE);
571 #endif /* CONFIG_ARCH_OMAP2 */
572 
573 #ifdef CONFIG_ARCH_OMAP3
574 OMAP_SYS_32K_TIMER_INIT(3, 1, OMAP3_32K_SOURCE, "ti,timer-alwon",
575 			2, OMAP3_MPU_SOURCE);
576 OMAP_SYS_32K_TIMER_INIT(3_secure, 12, OMAP3_32K_SOURCE, "ti,timer-secure",
577 			2, OMAP3_MPU_SOURCE);
578 OMAP_SYS_GP_TIMER_INIT(3_gp, 1, OMAP3_MPU_SOURCE, "ti,timer-alwon",
579 		       2, OMAP3_MPU_SOURCE);
580 #endif /* CONFIG_ARCH_OMAP3 */
581 
582 #ifdef CONFIG_SOC_AM33XX
583 OMAP_SYS_GP_TIMER_INIT(3_am33xx, 1, OMAP4_MPU_SOURCE, "ti,timer-alwon",
584 		       2, OMAP4_MPU_SOURCE);
585 #endif /* CONFIG_SOC_AM33XX */
586 
587 #ifdef CONFIG_ARCH_OMAP4
588 OMAP_SYS_32K_TIMER_INIT(4, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
589 			2, OMAP4_MPU_SOURCE);
590 #ifdef CONFIG_LOCAL_TIMERS
591 static DEFINE_TWD_LOCAL_TIMER(twd_local_timer, OMAP44XX_LOCAL_TWD_BASE, 29);
592 void __init omap4_local_timer_init(void)
593 {
594 	omap4_sync32k_timer_init();
595 	/* Local timers are not supprted on OMAP4430 ES1.0 */
596 	if (omap_rev() != OMAP4430_REV_ES1_0) {
597 		int err;
598 
599 		if (of_have_populated_dt()) {
600 			twd_local_timer_of_register();
601 			return;
602 		}
603 
604 		err = twd_local_timer_register(&twd_local_timer);
605 		if (err)
606 			pr_err("twd_local_timer_register failed %d\n", err);
607 	}
608 }
609 #else /* CONFIG_LOCAL_TIMERS */
610 void __init omap4_local_timer_init(void)
611 {
612 	omap4_sync32k_timer_init();
613 }
614 #endif /* CONFIG_LOCAL_TIMERS */
615 #endif /* CONFIG_ARCH_OMAP4 */
616 
617 #ifdef CONFIG_SOC_OMAP5
618 OMAP_SYS_32K_TIMER_INIT(5, 1, OMAP4_32K_SOURCE, "ti,timer-alwon",
619 			2, OMAP4_MPU_SOURCE);
620 void __init omap5_realtime_timer_init(void)
621 {
622 	int err;
623 
624 	omap5_sync32k_timer_init();
625 	realtime_counter_init();
626 
627 	err = arch_timer_of_register();
628 	if (err)
629 		pr_err("%s: arch_timer_register failed %d\n", __func__, err);
630 }
631 #endif /* CONFIG_SOC_OMAP5 */
632 
633 /**
634  * omap_timer_init - build and register timer device with an
635  * associated timer hwmod
636  * @oh:	timer hwmod pointer to be used to build timer device
637  * @user:	parameter that can be passed from calling hwmod API
638  *
639  * Called by omap_hwmod_for_each_by_class to register each of the timer
640  * devices present in the system. The number of timer devices is known
641  * by parsing through the hwmod database for a given class name. At the
642  * end of function call memory is allocated for timer device and it is
643  * registered to the framework ready to be proved by the driver.
644  */
645 static int __init omap_timer_init(struct omap_hwmod *oh, void *unused)
646 {
647 	int id;
648 	int ret = 0;
649 	char *name = "omap_timer";
650 	struct dmtimer_platform_data *pdata;
651 	struct platform_device *pdev;
652 	struct omap_timer_capability_dev_attr *timer_dev_attr;
653 
654 	pr_debug("%s: %s\n", __func__, oh->name);
655 
656 	/* on secure device, do not register secure timer */
657 	timer_dev_attr = oh->dev_attr;
658 	if (omap_type() != OMAP2_DEVICE_TYPE_GP && timer_dev_attr)
659 		if (timer_dev_attr->timer_capability == OMAP_TIMER_SECURE)
660 			return ret;
661 
662 	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
663 	if (!pdata) {
664 		pr_err("%s: No memory for [%s]\n", __func__, oh->name);
665 		return -ENOMEM;
666 	}
667 
668 	/*
669 	 * Extract the IDs from name field in hwmod database
670 	 * and use the same for constructing ids' for the
671 	 * timer devices. In a way, we are avoiding usage of
672 	 * static variable witin the function to do the same.
673 	 * CAUTION: We have to be careful and make sure the
674 	 * name in hwmod database does not change in which case
675 	 * we might either make corresponding change here or
676 	 * switch back static variable mechanism.
677 	 */
678 	sscanf(oh->name, "timer%2d", &id);
679 
680 	if (timer_dev_attr)
681 		pdata->timer_capability = timer_dev_attr->timer_capability;
682 
683 	pdata->timer_errata = omap_dm_timer_get_errata();
684 	pdata->get_context_loss_count = omap_pm_get_dev_context_loss_count;
685 
686 	pdev = omap_device_build(name, id, oh, pdata, sizeof(*pdata));
687 
688 	if (IS_ERR(pdev)) {
689 		pr_err("%s: Can't build omap_device for %s: %s.\n",
690 			__func__, name, oh->name);
691 		ret = -EINVAL;
692 	}
693 
694 	kfree(pdata);
695 
696 	return ret;
697 }
698 
699 /**
700  * omap2_dm_timer_init - top level regular device initialization
701  *
702  * Uses dedicated hwmod api to parse through hwmod database for
703  * given class name and then build and register the timer device.
704  */
705 static int __init omap2_dm_timer_init(void)
706 {
707 	int ret;
708 
709 	/* If dtb is there, the devices will be created dynamically */
710 	if (of_have_populated_dt())
711 		return -ENODEV;
712 
713 	ret = omap_hwmod_for_each_by_class("timer", omap_timer_init, NULL);
714 	if (unlikely(ret)) {
715 		pr_err("%s: device registration failed.\n", __func__);
716 		return -EINVAL;
717 	}
718 
719 	return 0;
720 }
721 omap_arch_initcall(omap2_dm_timer_init);
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  */
732 static 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 }
746 early_param("clocksource", omap2_override_clocksource);
747