1 /*
2  * Copyright (C) 2007-2009 ST-Ericsson AB
3  * License terms: GNU General Public License (GPL) version 2
4  * Timer COH 901 328, runs the OS timer interrupt.
5  * Author: Linus Walleij <linus.walleij@stericsson.com>
6  */
7 #include <linux/interrupt.h>
8 #include <linux/time.h>
9 #include <linux/timex.h>
10 #include <linux/clockchips.h>
11 #include <linux/clocksource.h>
12 #include <linux/types.h>
13 #include <linux/io.h>
14 #include <linux/clk.h>
15 #include <linux/err.h>
16 #include <linux/irq.h>
17 #include <linux/delay.h>
18 #include <linux/of_address.h>
19 #include <linux/of_irq.h>
20 #include <linux/sched_clock.h>
21 
22 /* Generic stuff */
23 #include <asm/mach/map.h>
24 #include <asm/mach/time.h>
25 
26 /*
27  * APP side special timer registers
28  * This timer contains four timers which can fire an interrupt each.
29  * OS (operating system) timer @ 32768 Hz
30  * DD (device driver) timer @ 1 kHz
31  * GP1 (general purpose 1) timer @ 1MHz
32  * GP2 (general purpose 2) timer @ 1MHz
33  */
34 
35 /* Reset OS Timer 32bit (-/W) */
36 #define U300_TIMER_APP_ROST					(0x0000)
37 #define U300_TIMER_APP_ROST_TIMER_RESET				(0x00000000)
38 /* Enable OS Timer 32bit (-/W) */
39 #define U300_TIMER_APP_EOST					(0x0004)
40 #define U300_TIMER_APP_EOST_TIMER_ENABLE			(0x00000000)
41 /* Disable OS Timer 32bit (-/W) */
42 #define U300_TIMER_APP_DOST					(0x0008)
43 #define U300_TIMER_APP_DOST_TIMER_DISABLE			(0x00000000)
44 /* OS Timer Mode Register 32bit (-/W) */
45 #define U300_TIMER_APP_SOSTM					(0x000c)
46 #define U300_TIMER_APP_SOSTM_MODE_CONTINUOUS			(0x00000000)
47 #define U300_TIMER_APP_SOSTM_MODE_ONE_SHOT			(0x00000001)
48 /* OS Timer Status Register 32bit (R/-) */
49 #define U300_TIMER_APP_OSTS					(0x0010)
50 #define U300_TIMER_APP_OSTS_TIMER_STATE_MASK			(0x0000000F)
51 #define U300_TIMER_APP_OSTS_TIMER_STATE_IDLE			(0x00000001)
52 #define U300_TIMER_APP_OSTS_TIMER_STATE_ACTIVE			(0x00000002)
53 #define U300_TIMER_APP_OSTS_ENABLE_IND				(0x00000010)
54 #define U300_TIMER_APP_OSTS_MODE_MASK				(0x00000020)
55 #define U300_TIMER_APP_OSTS_MODE_CONTINUOUS			(0x00000000)
56 #define U300_TIMER_APP_OSTS_MODE_ONE_SHOT			(0x00000020)
57 #define U300_TIMER_APP_OSTS_IRQ_ENABLED_IND			(0x00000040)
58 #define U300_TIMER_APP_OSTS_IRQ_PENDING_IND			(0x00000080)
59 /* OS Timer Current Count Register 32bit (R/-) */
60 #define U300_TIMER_APP_OSTCC					(0x0014)
61 /* OS Timer Terminal Count Register 32bit (R/W) */
62 #define U300_TIMER_APP_OSTTC					(0x0018)
63 /* OS Timer Interrupt Enable Register 32bit (-/W) */
64 #define U300_TIMER_APP_OSTIE					(0x001c)
65 #define U300_TIMER_APP_OSTIE_IRQ_DISABLE			(0x00000000)
66 #define U300_TIMER_APP_OSTIE_IRQ_ENABLE				(0x00000001)
67 /* OS Timer Interrupt Acknowledge Register 32bit (-/W) */
68 #define U300_TIMER_APP_OSTIA					(0x0020)
69 #define U300_TIMER_APP_OSTIA_IRQ_ACK				(0x00000080)
70 
71 /* Reset DD Timer 32bit (-/W) */
72 #define U300_TIMER_APP_RDDT					(0x0040)
73 #define U300_TIMER_APP_RDDT_TIMER_RESET				(0x00000000)
74 /* Enable DD Timer 32bit (-/W) */
75 #define U300_TIMER_APP_EDDT					(0x0044)
76 #define U300_TIMER_APP_EDDT_TIMER_ENABLE			(0x00000000)
77 /* Disable DD Timer 32bit (-/W) */
78 #define U300_TIMER_APP_DDDT					(0x0048)
79 #define U300_TIMER_APP_DDDT_TIMER_DISABLE			(0x00000000)
80 /* DD Timer Mode Register 32bit (-/W) */
81 #define U300_TIMER_APP_SDDTM					(0x004c)
82 #define U300_TIMER_APP_SDDTM_MODE_CONTINUOUS			(0x00000000)
83 #define U300_TIMER_APP_SDDTM_MODE_ONE_SHOT			(0x00000001)
84 /* DD Timer Status Register 32bit (R/-) */
85 #define U300_TIMER_APP_DDTS					(0x0050)
86 #define U300_TIMER_APP_DDTS_TIMER_STATE_MASK			(0x0000000F)
87 #define U300_TIMER_APP_DDTS_TIMER_STATE_IDLE			(0x00000001)
88 #define U300_TIMER_APP_DDTS_TIMER_STATE_ACTIVE			(0x00000002)
89 #define U300_TIMER_APP_DDTS_ENABLE_IND				(0x00000010)
90 #define U300_TIMER_APP_DDTS_MODE_MASK				(0x00000020)
91 #define U300_TIMER_APP_DDTS_MODE_CONTINUOUS			(0x00000000)
92 #define U300_TIMER_APP_DDTS_MODE_ONE_SHOT			(0x00000020)
93 #define U300_TIMER_APP_DDTS_IRQ_ENABLED_IND			(0x00000040)
94 #define U300_TIMER_APP_DDTS_IRQ_PENDING_IND			(0x00000080)
95 /* DD Timer Current Count Register 32bit (R/-) */
96 #define U300_TIMER_APP_DDTCC					(0x0054)
97 /* DD Timer Terminal Count Register 32bit (R/W) */
98 #define U300_TIMER_APP_DDTTC					(0x0058)
99 /* DD Timer Interrupt Enable Register 32bit (-/W) */
100 #define U300_TIMER_APP_DDTIE					(0x005c)
101 #define U300_TIMER_APP_DDTIE_IRQ_DISABLE			(0x00000000)
102 #define U300_TIMER_APP_DDTIE_IRQ_ENABLE				(0x00000001)
103 /* DD Timer Interrupt Acknowledge Register 32bit (-/W) */
104 #define U300_TIMER_APP_DDTIA					(0x0060)
105 #define U300_TIMER_APP_DDTIA_IRQ_ACK				(0x00000080)
106 
107 /* Reset GP1 Timer 32bit (-/W) */
108 #define U300_TIMER_APP_RGPT1					(0x0080)
109 #define U300_TIMER_APP_RGPT1_TIMER_RESET			(0x00000000)
110 /* Enable GP1 Timer 32bit (-/W) */
111 #define U300_TIMER_APP_EGPT1					(0x0084)
112 #define U300_TIMER_APP_EGPT1_TIMER_ENABLE			(0x00000000)
113 /* Disable GP1 Timer 32bit (-/W) */
114 #define U300_TIMER_APP_DGPT1					(0x0088)
115 #define U300_TIMER_APP_DGPT1_TIMER_DISABLE			(0x00000000)
116 /* GP1 Timer Mode Register 32bit (-/W) */
117 #define U300_TIMER_APP_SGPT1M					(0x008c)
118 #define U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS			(0x00000000)
119 #define U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT			(0x00000001)
120 /* GP1 Timer Status Register 32bit (R/-) */
121 #define U300_TIMER_APP_GPT1S					(0x0090)
122 #define U300_TIMER_APP_GPT1S_TIMER_STATE_MASK			(0x0000000F)
123 #define U300_TIMER_APP_GPT1S_TIMER_STATE_IDLE			(0x00000001)
124 #define U300_TIMER_APP_GPT1S_TIMER_STATE_ACTIVE			(0x00000002)
125 #define U300_TIMER_APP_GPT1S_ENABLE_IND				(0x00000010)
126 #define U300_TIMER_APP_GPT1S_MODE_MASK				(0x00000020)
127 #define U300_TIMER_APP_GPT1S_MODE_CONTINUOUS			(0x00000000)
128 #define U300_TIMER_APP_GPT1S_MODE_ONE_SHOT			(0x00000020)
129 #define U300_TIMER_APP_GPT1S_IRQ_ENABLED_IND			(0x00000040)
130 #define U300_TIMER_APP_GPT1S_IRQ_PENDING_IND			(0x00000080)
131 /* GP1 Timer Current Count Register 32bit (R/-) */
132 #define U300_TIMER_APP_GPT1CC					(0x0094)
133 /* GP1 Timer Terminal Count Register 32bit (R/W) */
134 #define U300_TIMER_APP_GPT1TC					(0x0098)
135 /* GP1 Timer Interrupt Enable Register 32bit (-/W) */
136 #define U300_TIMER_APP_GPT1IE					(0x009c)
137 #define U300_TIMER_APP_GPT1IE_IRQ_DISABLE			(0x00000000)
138 #define U300_TIMER_APP_GPT1IE_IRQ_ENABLE			(0x00000001)
139 /* GP1 Timer Interrupt Acknowledge Register 32bit (-/W) */
140 #define U300_TIMER_APP_GPT1IA					(0x00a0)
141 #define U300_TIMER_APP_GPT1IA_IRQ_ACK				(0x00000080)
142 
143 /* Reset GP2 Timer 32bit (-/W) */
144 #define U300_TIMER_APP_RGPT2					(0x00c0)
145 #define U300_TIMER_APP_RGPT2_TIMER_RESET			(0x00000000)
146 /* Enable GP2 Timer 32bit (-/W) */
147 #define U300_TIMER_APP_EGPT2					(0x00c4)
148 #define U300_TIMER_APP_EGPT2_TIMER_ENABLE			(0x00000000)
149 /* Disable GP2 Timer 32bit (-/W) */
150 #define U300_TIMER_APP_DGPT2					(0x00c8)
151 #define U300_TIMER_APP_DGPT2_TIMER_DISABLE			(0x00000000)
152 /* GP2 Timer Mode Register 32bit (-/W) */
153 #define U300_TIMER_APP_SGPT2M					(0x00cc)
154 #define U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS			(0x00000000)
155 #define U300_TIMER_APP_SGPT2M_MODE_ONE_SHOT			(0x00000001)
156 /* GP2 Timer Status Register 32bit (R/-) */
157 #define U300_TIMER_APP_GPT2S					(0x00d0)
158 #define U300_TIMER_APP_GPT2S_TIMER_STATE_MASK			(0x0000000F)
159 #define U300_TIMER_APP_GPT2S_TIMER_STATE_IDLE			(0x00000001)
160 #define U300_TIMER_APP_GPT2S_TIMER_STATE_ACTIVE			(0x00000002)
161 #define U300_TIMER_APP_GPT2S_ENABLE_IND				(0x00000010)
162 #define U300_TIMER_APP_GPT2S_MODE_MASK				(0x00000020)
163 #define U300_TIMER_APP_GPT2S_MODE_CONTINUOUS			(0x00000000)
164 #define U300_TIMER_APP_GPT2S_MODE_ONE_SHOT			(0x00000020)
165 #define U300_TIMER_APP_GPT2S_IRQ_ENABLED_IND			(0x00000040)
166 #define U300_TIMER_APP_GPT2S_IRQ_PENDING_IND			(0x00000080)
167 /* GP2 Timer Current Count Register 32bit (R/-) */
168 #define U300_TIMER_APP_GPT2CC					(0x00d4)
169 /* GP2 Timer Terminal Count Register 32bit (R/W) */
170 #define U300_TIMER_APP_GPT2TC					(0x00d8)
171 /* GP2 Timer Interrupt Enable Register 32bit (-/W) */
172 #define U300_TIMER_APP_GPT2IE					(0x00dc)
173 #define U300_TIMER_APP_GPT2IE_IRQ_DISABLE			(0x00000000)
174 #define U300_TIMER_APP_GPT2IE_IRQ_ENABLE			(0x00000001)
175 /* GP2 Timer Interrupt Acknowledge Register 32bit (-/W) */
176 #define U300_TIMER_APP_GPT2IA					(0x00e0)
177 #define U300_TIMER_APP_GPT2IA_IRQ_ACK				(0x00000080)
178 
179 /* Clock request control register - all four timers */
180 #define U300_TIMER_APP_CRC					(0x100)
181 #define U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE			(0x00000001)
182 
183 static void __iomem *u300_timer_base;
184 
185 struct u300_clockevent_data {
186 	struct clock_event_device cevd;
187 	unsigned ticks_per_jiffy;
188 };
189 
u300_shutdown(struct clock_event_device * evt)190 static int u300_shutdown(struct clock_event_device *evt)
191 {
192 	/* Disable interrupts on GP1 */
193 	writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
194 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
195 	/* Disable GP1 */
196 	writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
197 	       u300_timer_base + U300_TIMER_APP_DGPT1);
198 	return 0;
199 }
200 
201 /*
202  * If we have oneshot timer active, the oneshot scheduling function
203  * u300_set_next_event() is called immediately after.
204  */
u300_set_oneshot(struct clock_event_device * evt)205 static int u300_set_oneshot(struct clock_event_device *evt)
206 {
207 	/* Just return; here? */
208 	/*
209 	 * The actual event will be programmed by the next event hook,
210 	 * so we just set a dummy value somewhere at the end of the
211 	 * universe here.
212 	 */
213 	/* Disable interrupts on GPT1 */
214 	writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
215 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
216 	/* Disable GP1 while we're reprogramming it. */
217 	writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
218 	       u300_timer_base + U300_TIMER_APP_DGPT1);
219 	/*
220 	 * Expire far in the future, u300_set_next_event() will be
221 	 * called soon...
222 	 */
223 	writel(0xFFFFFFFF, u300_timer_base + U300_TIMER_APP_GPT1TC);
224 	/* We run one shot per tick here! */
225 	writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
226 	       u300_timer_base + U300_TIMER_APP_SGPT1M);
227 	/* Enable interrupts for this timer */
228 	writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
229 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
230 	/* Enable timer */
231 	writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
232 	       u300_timer_base + U300_TIMER_APP_EGPT1);
233 	return 0;
234 }
235 
u300_set_periodic(struct clock_event_device * evt)236 static int u300_set_periodic(struct clock_event_device *evt)
237 {
238 	struct u300_clockevent_data *cevdata =
239 		container_of(evt, struct u300_clockevent_data, cevd);
240 
241 	/* Disable interrupts on GPT1 */
242 	writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
243 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
244 	/* Disable GP1 while we're reprogramming it. */
245 	writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
246 	       u300_timer_base + U300_TIMER_APP_DGPT1);
247 	/*
248 	 * Set the periodic mode to a certain number of ticks per
249 	 * jiffy.
250 	 */
251 	writel(cevdata->ticks_per_jiffy,
252 	       u300_timer_base + U300_TIMER_APP_GPT1TC);
253 	/*
254 	 * Set continuous mode, so the timer keeps triggering
255 	 * interrupts.
256 	 */
257 	writel(U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS,
258 	       u300_timer_base + U300_TIMER_APP_SGPT1M);
259 	/* Enable timer interrupts */
260 	writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
261 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
262 	/* Then enable the OS timer again */
263 	writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
264 	       u300_timer_base + U300_TIMER_APP_EGPT1);
265 	return 0;
266 }
267 
268 /*
269  * The app timer in one shot mode obviously has to be reprogrammed
270  * in EXACTLY this sequence to work properly. Do NOT try to e.g. replace
271  * the interrupt disable + timer disable commands with a reset command,
272  * it will fail miserably. Apparently (and I found this the hard way)
273  * the timer is very sensitive to the instruction order, though you don't
274  * get that impression from the data sheet.
275  */
u300_set_next_event(unsigned long cycles,struct clock_event_device * evt)276 static int u300_set_next_event(unsigned long cycles,
277 			       struct clock_event_device *evt)
278 
279 {
280 	/* Disable interrupts on GPT1 */
281 	writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
282 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
283 	/* Disable GP1 while we're reprogramming it. */
284 	writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
285 	       u300_timer_base + U300_TIMER_APP_DGPT1);
286 	/* Reset the General Purpose timer 1. */
287 	writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
288 	       u300_timer_base + U300_TIMER_APP_RGPT1);
289 	/* IRQ in n * cycles */
290 	writel(cycles, u300_timer_base + U300_TIMER_APP_GPT1TC);
291 	/*
292 	 * We run one shot per tick here! (This is necessary to reconfigure,
293 	 * the timer will tilt if you don't!)
294 	 */
295 	writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
296 	       u300_timer_base + U300_TIMER_APP_SGPT1M);
297 	/* Enable timer interrupts */
298 	writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
299 	       u300_timer_base + U300_TIMER_APP_GPT1IE);
300 	/* Then enable the OS timer again */
301 	writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
302 	       u300_timer_base + U300_TIMER_APP_EGPT1);
303 	return 0;
304 }
305 
306 static struct u300_clockevent_data u300_clockevent_data = {
307 	/* Use general purpose timer 1 as clock event */
308 	.cevd = {
309 		.name			= "GPT1",
310 		/* Reasonably fast and accurate clock event */
311 		.rating			= 300,
312 		.features		= CLOCK_EVT_FEAT_PERIODIC |
313 					  CLOCK_EVT_FEAT_ONESHOT,
314 		.set_next_event		= u300_set_next_event,
315 		.set_state_shutdown	= u300_shutdown,
316 		.set_state_periodic	= u300_set_periodic,
317 		.set_state_oneshot	= u300_set_oneshot,
318 	},
319 };
320 
321 /* Clock event timer interrupt handler */
u300_timer_interrupt(int irq,void * dev_id)322 static irqreturn_t u300_timer_interrupt(int irq, void *dev_id)
323 {
324 	struct clock_event_device *evt = &u300_clockevent_data.cevd;
325 	/* ACK/Clear timer IRQ for the APP GPT1 Timer */
326 
327 	writel(U300_TIMER_APP_GPT1IA_IRQ_ACK,
328 		u300_timer_base + U300_TIMER_APP_GPT1IA);
329 	evt->event_handler(evt);
330 	return IRQ_HANDLED;
331 }
332 
333 static struct irqaction u300_timer_irq = {
334 	.name		= "U300 Timer Tick",
335 	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
336 	.handler	= u300_timer_interrupt,
337 };
338 
339 /*
340  * Override the global weak sched_clock symbol with this
341  * local implementation which uses the clocksource to get some
342  * better resolution when scheduling the kernel. We accept that
343  * this wraps around for now, since it is just a relative time
344  * stamp. (Inspired by OMAP implementation.)
345  */
346 
u300_read_sched_clock(void)347 static u64 notrace u300_read_sched_clock(void)
348 {
349 	return readl(u300_timer_base + U300_TIMER_APP_GPT2CC);
350 }
351 
u300_read_current_timer(void)352 static unsigned long u300_read_current_timer(void)
353 {
354 	return readl(u300_timer_base + U300_TIMER_APP_GPT2CC);
355 }
356 
357 static struct delay_timer u300_delay_timer;
358 
359 /*
360  * This sets up the system timers, clock source and clock event.
361  */
u300_timer_init_of(struct device_node * np)362 static int __init u300_timer_init_of(struct device_node *np)
363 {
364 	unsigned int irq;
365 	struct clk *clk;
366 	unsigned long rate;
367 	int ret;
368 
369 	u300_timer_base = of_iomap(np, 0);
370 	if (!u300_timer_base) {
371 		pr_err("could not ioremap system timer\n");
372 		return -ENXIO;
373 	}
374 
375 	/* Get the IRQ for the GP1 timer */
376 	irq = irq_of_parse_and_map(np, 2);
377 	if (!irq) {
378 		pr_err("no IRQ for system timer\n");
379 		return -EINVAL;
380 	}
381 
382 	pr_info("U300 GP1 timer @ base: %p, IRQ: %u\n", u300_timer_base, irq);
383 
384 	/* Clock the interrupt controller */
385 	clk = of_clk_get(np, 0);
386 	if (IS_ERR(clk))
387 		return PTR_ERR(clk);
388 
389 	ret = clk_prepare_enable(clk);
390 	if (ret)
391 		return ret;
392 
393 	rate = clk_get_rate(clk);
394 
395 	u300_clockevent_data.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
396 
397 	sched_clock_register(u300_read_sched_clock, 32, rate);
398 
399 	u300_delay_timer.read_current_timer = &u300_read_current_timer;
400 	u300_delay_timer.freq = rate;
401 	register_current_timer_delay(&u300_delay_timer);
402 
403 	/*
404 	 * Disable the "OS" and "DD" timers - these are designed for Symbian!
405 	 * Example usage in cnh1601578 cpu subsystem pd_timer_app.c
406 	 */
407 	writel(U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE,
408 		u300_timer_base + U300_TIMER_APP_CRC);
409 	writel(U300_TIMER_APP_ROST_TIMER_RESET,
410 		u300_timer_base + U300_TIMER_APP_ROST);
411 	writel(U300_TIMER_APP_DOST_TIMER_DISABLE,
412 		u300_timer_base + U300_TIMER_APP_DOST);
413 	writel(U300_TIMER_APP_RDDT_TIMER_RESET,
414 		u300_timer_base + U300_TIMER_APP_RDDT);
415 	writel(U300_TIMER_APP_DDDT_TIMER_DISABLE,
416 		u300_timer_base + U300_TIMER_APP_DDDT);
417 
418 	/* Reset the General Purpose timer 1. */
419 	writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
420 		u300_timer_base + U300_TIMER_APP_RGPT1);
421 
422 	/* Set up the IRQ handler */
423 	ret = setup_irq(irq, &u300_timer_irq);
424 	if (ret)
425 		return ret;
426 
427 	/* Reset the General Purpose timer 2 */
428 	writel(U300_TIMER_APP_RGPT2_TIMER_RESET,
429 		u300_timer_base + U300_TIMER_APP_RGPT2);
430 	/* Set this timer to run around forever */
431 	writel(0xFFFFFFFFU, u300_timer_base + U300_TIMER_APP_GPT2TC);
432 	/* Set continuous mode so it wraps around */
433 	writel(U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS,
434 	       u300_timer_base + U300_TIMER_APP_SGPT2M);
435 	/* Disable timer interrupts */
436 	writel(U300_TIMER_APP_GPT2IE_IRQ_DISABLE,
437 		u300_timer_base + U300_TIMER_APP_GPT2IE);
438 	/* Then enable the GP2 timer to use as a free running us counter */
439 	writel(U300_TIMER_APP_EGPT2_TIMER_ENABLE,
440 		u300_timer_base + U300_TIMER_APP_EGPT2);
441 
442 	/* Use general purpose timer 2 as clock source */
443 	ret = clocksource_mmio_init(u300_timer_base + U300_TIMER_APP_GPT2CC,
444 				    "GPT2", rate, 300, 32, clocksource_mmio_readl_up);
445 	if (ret) {
446 		pr_err("timer: failed to initialize U300 clock source\n");
447 		return ret;
448 	}
449 
450 	/* Configure and register the clockevent */
451 	clockevents_config_and_register(&u300_clockevent_data.cevd, rate,
452 					1, 0xffffffff);
453 
454 	/*
455 	 * TODO: init and register the rest of the timers too, they can be
456 	 * used by hrtimers!
457 	 */
458 	return 0;
459 }
460 
461 TIMER_OF_DECLARE(u300_timer, "stericsson,u300-apptimer",
462 		       u300_timer_init_of);
463