summaryrefslogtreecommitdiffstats
path: root/drivers/clocksource/timer-atmel-tcb.c
blob: 27af17c995900477fd3c0037bff9476364c5ecf0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#include <linux/syscore_ops.h>
#include <soc/at91/atmel_tcb.h>


/*
 * We're configured to use a specific TC block, one that's not hooked
 * up to external hardware, to provide a time solution:
 *
 *   - Two channels combine to create a free-running 32 bit counter
 *     with a base rate of 5+ MHz, packaged as a clocksource (with
 *     resolution better than 200 nsec).
 *   - Some chips support 32 bit counter. A single channel is used for
 *     this 32 bit free-running counter. the second channel is not used.
 *
 *   - The third channel may be used to provide a clockevent source, used in
 *   either periodic or oneshot mode. For 16-bit counter its runs at 32 KiHZ,
 *   and can handle delays of up to two seconds. For 32-bit counters, it runs at
 *   the same rate as the clocksource
 *
 * REVISIT behavior during system suspend states... we should disable
 * all clocks and save the power.  Easily done for clockevent devices,
 * but clocksources won't necessarily get the needed notifications.
 * For deeper system sleep states, this will be mandatory...
 */

static void __iomem *tcaddr;
static struct
{
	u32 cmr;
	u32 imr;
	u32 rc;
	bool clken;
} tcb_cache[3];
static u32 bmr_cache;

static const u8 atmel_tcb_divisors[] = { 2, 8, 32, 128 };

static u64 tc_get_cycles(struct clocksource *cs)
{
	unsigned long	flags;
	u32		lower, upper;

	raw_local_irq_save(flags);
	do {
		upper = readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV));
		lower = readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV));
	} while (upper != readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV)));

	raw_local_irq_restore(flags);
	return (upper << 16) | lower;
}

static u64 tc_get_cycles32(struct clocksource *cs)
{
	return readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV));
}

static void tc_clksrc_suspend(struct clocksource *cs)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) {
		tcb_cache[i].cmr = readl(tcaddr + ATMEL_TC_REG(i, CMR));
		tcb_cache[i].imr = readl(tcaddr + ATMEL_TC_REG(i, IMR));
		tcb_cache[i].rc = readl(tcaddr + ATMEL_TC_REG(i, RC));
		tcb_cache[i].clken = !!(readl(tcaddr + ATMEL_TC_REG(i, SR)) &
					ATMEL_TC_CLKSTA);
	}

	bmr_cache = readl(tcaddr + ATMEL_TC_BMR);
}

static void tc_clksrc_resume(struct clocksource *cs)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) {
		/* Restore registers for the channel, RA and RB are not used  */
		writel(tcb_cache[i].cmr, tcaddr + ATMEL_TC_REG(i, CMR));
		writel(tcb_cache[i].rc, tcaddr + ATMEL_TC_REG(i, RC));
		writel(0, tcaddr + ATMEL_TC_REG(i, RA));
		writel(0, tcaddr + ATMEL_TC_REG(i, RB));
		/* Disable all the interrupts */
		writel(0xff, tcaddr + ATMEL_TC_REG(i, IDR));
		/* Reenable interrupts that were enabled before suspending */
		writel(tcb_cache[i].imr, tcaddr + ATMEL_TC_REG(i, IER));
		/* Start the clock if it was used */
		if (tcb_cache[i].clken)
			writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(i, CCR));
	}

	/* Dual channel, chain channels */
	writel(bmr_cache, tcaddr + ATMEL_TC_BMR);
	/* Finally, trigger all the channels*/
	writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
}

static struct clocksource clksrc = {
	.rating         = 200,
	.read           = tc_get_cycles,
	.mask           = CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
	.suspend	= tc_clksrc_suspend,
	.resume		= tc_clksrc_resume,
};

static u64 notrace tc_sched_clock_read(void)
{
	return tc_get_cycles(&clksrc);
}

static u64 notrace tc_sched_clock_read32(void)
{
	return tc_get_cycles32(&clksrc);
}

static struct delay_timer tc_delay_timer;

static unsigned long tc_delay_timer_read(void)
{
	return tc_get_cycles(&clksrc);
}

static unsigned long notrace tc_delay_timer_read32(void)
{
	return tc_get_cycles32(&clksrc);
}

#ifdef CONFIG_GENERIC_CLOCKEVENTS

struct tc_clkevt_device {
	struct clock_event_device	clkevt;
	struct clk			*clk;
	u32				rate;
	void __iomem			*regs;
};

static struct tc_clkevt_device *to_tc_clkevt(struct clock_event_device *clkevt)
{
	return container_of(clkevt, struct tc_clkevt_device, clkevt);
}

static u32 timer_clock;

static int tc_shutdown(struct clock_event_device *d)
{
	struct tc_clkevt_device *tcd = to_tc_clkevt(d);
	void __iomem		*regs = tcd->regs;

	writel(0xff, regs + ATMEL_TC_REG(2, IDR));
	writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR));
	if (!clockevent_state_detached(d))
		clk_disable(tcd->clk);

	return 0;
}

static int tc_set_oneshot(struct clock_event_device *d)
{
	struct tc_clkevt_device *tcd = to_tc_clkevt(d);
	void __iomem		*regs = tcd->regs;

	if (clockevent_state_oneshot(d) || clockevent_state_periodic(d))
		tc_shutdown(d);

	clk_enable(tcd->clk);

	/* count up to RC, then irq and stop */
	writel(timer_clock | ATMEL_TC_CPCSTOP | ATMEL_TC_WAVE |
		     ATMEL_TC_WAVESEL_UP_AUTO, regs + ATMEL_TC_REG(2, CMR));
	writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER));

	/* set_next_event() configures and starts the timer */
	return 0;
}

static int tc_set_periodic(struct clock_event_device *d)
{
	struct tc_clkevt_device *tcd = to_tc_clkevt(d);
	void __iomem		*regs = tcd->regs;

	if (clockevent_state_oneshot(d) || clockevent_state_periodic(d))
		tc_shutdown(d);

	/* By not making the gentime core emulate periodic mode on top
	 * of oneshot, we get lower overhead and improved accuracy.
	 */
	clk_enable(tcd->clk);

	/* count up to RC, then irq and restart */
	writel(timer_clock | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO,
		     regs + ATMEL_TC_REG(2, CMR));
	writel((tcd->rate + HZ / 2) / HZ, tcaddr + ATMEL_TC_REG(2, RC));

	/* Enable clock and interrupts on RC compare */
	writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER));

	/* go go gadget! */
	writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, regs +
		     ATMEL_TC_REG(2, CCR));
	return 0;
}

static int tc_next_event(unsigned long delta, struct clock_event_device *d)
{
	writel_relaxed(delta, tcaddr + ATMEL_TC_REG(2, RC));

	/* go go gadget! */
	writel_relaxed(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
			tcaddr + ATMEL_TC_REG(2, CCR));
	return 0;
}

static struct tc_clkevt_device clkevt = {
	.clkevt	= {
		.features		= CLOCK_EVT_FEAT_PERIODIC |
					  CLOCK_EVT_FEAT_ONESHOT,
		/* Should be lower than at91rm9200's system timer */
		.rating			= 125,
		.set_next_event		= tc_next_event,
		.set_state_shutdown	= tc_shutdown,
		.set_state_periodic	= tc_set_periodic,
		.set_state_oneshot	= tc_set_oneshot,
	},
};

static irqreturn_t ch2_irq(int irq, void *handle)
{
	struct tc_clkevt_device	*dev = handle;
	unsigned int		sr;

	sr = readl_relaxed(dev->regs + ATMEL_TC_REG(2, SR));
	if (sr & ATMEL_TC_CPCS) {
		dev->clkevt.event_handler(&dev->clkevt);
		return IRQ_HANDLED;
	}

	return IRQ_NONE;
}

static int __init setup_clkevents(struct atmel_tc *tc, int divisor_idx)
{
	int ret;
	struct clk *t2_clk = tc->clk[2];
	int irq = tc->irq[2];
	int bits = tc->tcb_config->counter_width;

	/* try to enable t2 clk to avoid future errors in mode change */
	ret = clk_prepare_enable(t2_clk);
	if (ret)
		return ret;

	clkevt.regs = tc->regs;
	clkevt.clk = t2_clk;

	if (bits == 32) {
		timer_clock = divisor_idx;
		clkevt.rate = clk_get_rate(t2_clk) / atmel_tcb_divisors[divisor_idx];
	} else {
		ret = clk_prepare_enable(tc->slow_clk);
		if (ret) {
			clk_disable_unprepare(t2_clk);
			return ret;
		}

		clkevt.rate = clk_get_rate(tc->slow_clk);
		timer_clock = ATMEL_TC_TIMER_CLOCK5;
	}

	clk_disable(t2_clk);

	clkevt.clkevt.cpumask = cpumask_of(0);

	ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt);
	if (ret) {
		clk_unprepare(t2_clk);
		if (bits != 32)
			clk_disable_unprepare(tc->slow_clk);
		return ret;
	}

	clockevents_config_and_register(&clkevt.clkevt, clkevt.rate, 1, BIT(bits) - 1);

	return ret;
}

#else /* !CONFIG_GENERIC_CLOCKEVENTS */

static int __init setup_clkevents(struct atmel_tc *tc, int divisor_idx)
{
	/* NOTHING */
	return 0;
}

#endif

static void __init tcb_setup_dual_chan(struct atmel_tc *tc, int mck_divisor_idx)
{
	/* channel 0:  waveform mode, input mclk/8, clock TIOA0 on overflow */
	writel(mck_divisor_idx			/* likely divide-by-8 */
			| ATMEL_TC_WAVE
			| ATMEL_TC_WAVESEL_UP		/* free-run */
			| ATMEL_TC_ACPA_SET		/* TIOA0 rises at 0 */
			| ATMEL_TC_ACPC_CLEAR,		/* (duty cycle 50%) */
			tcaddr + ATMEL_TC_REG(0, CMR));
	writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA));
	writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC));
	writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR));	/* no irqs */
	writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

	/* channel 1:  waveform mode, input TIOA0 */
	writel(ATMEL_TC_XC1			/* input: TIOA0 */
			| ATMEL_TC_WAVE
			| ATMEL_TC_WAVESEL_UP,		/* free-run */
			tcaddr + ATMEL_TC_REG(1, CMR));
	writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR));	/* no irqs */
	writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR));

	/* chain channel 0 to channel 1*/
	writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR);
	/* then reset all the timers */
	writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
}

static void __init tcb_setup_single_chan(struct atmel_tc *tc, int mck_divisor_idx)
{
	/* channel 0:  waveform mode, input mclk/8 */
	writel(mck_divisor_idx			/* likely divide-by-8 */
			| ATMEL_TC_WAVE
			| ATMEL_TC_WAVESEL_UP,		/* free-run */
			tcaddr + ATMEL_TC_REG(0, CMR));
	writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR));	/* no irqs */
	writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

	/* then reset all the timers */
	writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
}

static struct atmel_tcb_config tcb_rm9200_config = {
	.counter_width = 16,
};

static struct atmel_tcb_config tcb_sam9x5_config = {
	.counter_width = 32,
};

static struct atmel_tcb_config tcb_sama5d2_config = {
	.counter_width = 32,
	.has_gclk = 1,
};

static const struct of_device_id atmel_tcb_of_match[] = {
	{ .compatible = "atmel,at91rm9200-tcb", .data = &tcb_rm9200_config, },
	{ .compatible = "atmel,at91sam9x5-tcb", .data = &tcb_sam9x5_config, },
	{ .compatible = "atmel,sama5d2-tcb", .data = &tcb_sama5d2_config, },
	{ /* sentinel */ }
};

static int __init tcb_clksrc_init(struct device_node *node)
{
	struct atmel_tc tc;
	struct clk *t0_clk;
	const struct of_device_id *match;
	u64 (*tc_sched_clock)(void);
	u32 rate, divided_rate = 0;
	int best_divisor_idx = -1;
	int bits;
	int i;
	int ret;

	/* Protect against multiple calls */
	if (tcaddr)
		return 0;

	tc.regs = of_iomap(node->parent, 0);
	if (!tc.regs)
		return -ENXIO;

	t0_clk = of_clk_get_by_name(node->parent, "t0_clk");
	if (IS_ERR(t0_clk))
		return PTR_ERR(t0_clk);

	tc.slow_clk = of_clk_get_by_name(node->parent, "slow_clk");
	if (IS_ERR(tc.slow_clk))
		return PTR_ERR(tc.slow_clk);

	tc.clk[0] = t0_clk;
	tc.clk[1] = of_clk_get_by_name(node->parent, "t1_clk");
	if (IS_ERR(tc.clk[1]))
		tc.clk[1] = t0_clk;
	tc.clk[2] = of_clk_get_by_name(node->parent, "t2_clk");
	if (IS_ERR(tc.clk[2]))
		tc.clk[2] = t0_clk;

	tc.irq[2] = of_irq_get(node->parent, 2);
	if (tc.irq[2] <= 0) {
		tc.irq[2] = of_irq_get(node->parent, 0);
		if (tc.irq[2] <= 0)
			return -EINVAL;
	}

	match = of_match_node(atmel_tcb_of_match, node->parent);
	if (!match)
		return -ENODEV;

	tc.tcb_config = match->data;
	bits = tc.tcb_config->counter_width;

	for (i = 0; i < ARRAY_SIZE(tc.irq); i++)
		writel(ATMEL_TC_ALL_IRQ, tc.regs + ATMEL_TC_REG(i, IDR));

	ret = clk_prepare_enable(t0_clk);
	if (ret) {
		pr_debug("can't enable T0 clk\n");
		return ret;
	}

	/* How fast will we be counting?  Pick something over 5 MHz.  */
	rate = (u32) clk_get_rate(t0_clk);
	i = 0;
	if (tc.tcb_config->has_gclk)
		i = 1;
	for (; i < ARRAY_SIZE(atmel_tcb_divisors); i++) {
		unsigned divisor = atmel_tcb_divisors[i];
		unsigned tmp;

		tmp = rate / divisor;
		pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp);
		if ((best_divisor_idx >= 0) && (tmp < 5 * 1000 * 1000))
			break;
		divided_rate = tmp;
		best_divisor_idx = i;
	}

	clksrc.name = kbasename(node->parent->full_name);
	clkevt.clkevt.name = kbasename(node->parent->full_name);
	pr_debug("%s at %d.%03d MHz\n", clksrc.name, divided_rate / 1000000,
			((divided_rate % 1000000) + 500) / 1000);

	tcaddr = tc.regs;

	if (bits == 32) {
		/* use appropriate function to read 32 bit counter */
		clksrc.read = tc_get_cycles32;
		/* setup only channel 0 */
		tcb_setup_single_chan(&tc, best_divisor_idx);
		tc_sched_clock = tc_sched_clock_read32;
		tc_delay_timer.read_current_timer = tc_delay_timer_read32;
	} else {
		/* we have three clocks no matter what the
		 * underlying platform supports.
		 */
		ret = clk_prepare_enable(tc.clk[1]);
		if (ret) {
			pr_debug("can't enable T1 clk\n");
			goto err_disable_t0;
		}
		/* setup both channel 0 & 1 */
		tcb_setup_dual_chan(&tc, best_divisor_idx);
		tc_sched_clock = tc_sched_clock_read;
		tc_delay_timer.read_current_timer = tc_delay_timer_read;
	}

	/* and away we go! */
	ret = clocksource_register_hz(&clksrc, divided_rate);
	if (ret)
		goto err_disable_t1;

	/* channel 2:  periodic and oneshot timer support */
	ret = setup_clkevents(&tc, best_divisor_idx);
	if (ret)
		goto err_unregister_clksrc;

	sched_clock_register(tc_sched_clock, 32, divided_rate);

	tc_delay_timer.freq = divided_rate;
	register_current_timer_delay(&tc_delay_timer);

	return 0;

err_unregister_clksrc:
	clocksource_unregister(&clksrc);

err_disable_t1:
	if (bits != 32)
		clk_disable_unprepare(tc.clk[1]);

err_disable_t0:
	clk_disable_unprepare(t0_clk);

	tcaddr = NULL;

	return ret;
}
TIMER_OF_DECLARE(atmel_tcb_clksrc, "atmel,tcb-timer", tcb_clksrc_init);