Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 8e12b11e81b096b77c8bcc6c9eca0cc0a3c5c240 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Emma Mobile Timer Support - STI
 *
 *  Copyright (C) 2012 Magnus Damm
 */

#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/slab.h>
#include <linux/module.h>

enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };

struct em_sti_priv {
	void __iomem *base;
	struct clk *clk;
	struct platform_device *pdev;
	unsigned int active[USER_NR];
	unsigned long rate;
	raw_spinlock_t lock;
	struct clock_event_device ced;
	struct clocksource cs;
};

#define STI_CONTROL 0x00
#define STI_COMPA_H 0x10
#define STI_COMPA_L 0x14
#define STI_COMPB_H 0x18
#define STI_COMPB_L 0x1c
#define STI_COUNT_H 0x20
#define STI_COUNT_L 0x24
#define STI_COUNT_RAW_H 0x28
#define STI_COUNT_RAW_L 0x2c
#define STI_SET_H 0x30
#define STI_SET_L 0x34
#define STI_INTSTATUS 0x40
#define STI_INTRAWSTATUS 0x44
#define STI_INTENSET 0x48
#define STI_INTENCLR 0x4c
#define STI_INTFFCLR 0x50

static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
{
	return ioread32(p->base + offs);
}

static inline void em_sti_write(struct em_sti_priv *p, int offs,
				unsigned long value)
{
	iowrite32(value, p->base + offs);
}

static int em_sti_enable(struct em_sti_priv *p)
{
	int ret;

	/* enable clock */
	ret = clk_enable(p->clk);
	if (ret) {
		dev_err(&p->pdev->dev, "cannot enable clock\n");
		return ret;
	}

	/* reset the counter */
	em_sti_write(p, STI_SET_H, 0x40000000);
	em_sti_write(p, STI_SET_L, 0x00000000);

	/* mask and clear pending interrupts */
	em_sti_write(p, STI_INTENCLR, 3);
	em_sti_write(p, STI_INTFFCLR, 3);

	/* enable updates of counter registers */
	em_sti_write(p, STI_CONTROL, 1);

	return 0;
}

static void em_sti_disable(struct em_sti_priv *p)
{
	/* mask interrupts */
	em_sti_write(p, STI_INTENCLR, 3);

	/* stop clock */
	clk_disable(p->clk);
}

static u64 em_sti_count(struct em_sti_priv *p)
{
	u64 ticks;
	unsigned long flags;

	/* the STI hardware buffers the 48-bit count, but to
	 * break it out into two 32-bit access the registers
	 * must be accessed in a certain order.
	 * Always read STI_COUNT_H before STI_COUNT_L.
	 */
	raw_spin_lock_irqsave(&p->lock, flags);
	ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
	ticks |= em_sti_read(p, STI_COUNT_L);
	raw_spin_unlock_irqrestore(&p->lock, flags);

	return ticks;
}

static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
{
	unsigned long flags;

	raw_spin_lock_irqsave(&p->lock, flags);

	/* mask compare A interrupt */
	em_sti_write(p, STI_INTENCLR, 1);

	/* update compare A value */
	em_sti_write(p, STI_COMPA_H, next >> 32);
	em_sti_write(p, STI_COMPA_L, next & 0xffffffff);

	/* clear compare A interrupt source */
	em_sti_write(p, STI_INTFFCLR, 1);

	/* unmask compare A interrupt */
	em_sti_write(p, STI_INTENSET, 1);

	raw_spin_unlock_irqrestore(&p->lock, flags);

	return next;
}

static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
{
	struct em_sti_priv *p = dev_id;

	p->ced.event_handler(&p->ced);
	return IRQ_HANDLED;
}

static int em_sti_start(struct em_sti_priv *p, unsigned int user)
{
	unsigned long flags;
	int used_before;
	int ret = 0;

	raw_spin_lock_irqsave(&p->lock, flags);
	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
	if (!used_before)
		ret = em_sti_enable(p);

	if (!ret)
		p->active[user] = 1;
	raw_spin_unlock_irqrestore(&p->lock, flags);

	return ret;
}

static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
{
	unsigned long flags;
	int used_before, used_after;

	raw_spin_lock_irqsave(&p->lock, flags);
	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
	p->active[user] = 0;
	used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];

	if (used_before && !used_after)
		em_sti_disable(p);
	raw_spin_unlock_irqrestore(&p->lock, flags);
}

static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
{
	return container_of(cs, struct em_sti_priv, cs);
}

static u64 em_sti_clocksource_read(struct clocksource *cs)
{
	return em_sti_count(cs_to_em_sti(cs));
}

static int em_sti_clocksource_enable(struct clocksource *cs)
{
	struct em_sti_priv *p = cs_to_em_sti(cs);

	return em_sti_start(p, USER_CLOCKSOURCE);
}

static void em_sti_clocksource_disable(struct clocksource *cs)
{
	em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
}

static void em_sti_clocksource_resume(struct clocksource *cs)
{
	em_sti_clocksource_enable(cs);
}

static int em_sti_register_clocksource(struct em_sti_priv *p)
{
	struct clocksource *cs = &p->cs;

	cs->name = dev_name(&p->pdev->dev);
	cs->rating = 200;
	cs->read = em_sti_clocksource_read;
	cs->enable = em_sti_clocksource_enable;
	cs->disable = em_sti_clocksource_disable;
	cs->suspend = em_sti_clocksource_disable;
	cs->resume = em_sti_clocksource_resume;
	cs->mask = CLOCKSOURCE_MASK(48);
	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;

	dev_info(&p->pdev->dev, "used as clock source\n");

	clocksource_register_hz(cs, p->rate);
	return 0;
}

static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
{
	return container_of(ced, struct em_sti_priv, ced);
}

static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
{
	struct em_sti_priv *p = ced_to_em_sti(ced);
	em_sti_stop(p, USER_CLOCKEVENT);
	return 0;
}

static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
{
	struct em_sti_priv *p = ced_to_em_sti(ced);

	dev_info(&p->pdev->dev, "used for oneshot clock events\n");
	em_sti_start(p, USER_CLOCKEVENT);
	return 0;
}

static int em_sti_clock_event_next(unsigned long delta,
				   struct clock_event_device *ced)
{
	struct em_sti_priv *p = ced_to_em_sti(ced);
	u64 next;
	int safe;

	next = em_sti_set_next(p, em_sti_count(p) + delta);
	safe = em_sti_count(p) < (next - 1);

	return !safe;
}

static void em_sti_register_clockevent(struct em_sti_priv *p)
{
	struct clock_event_device *ced = &p->ced;

	ced->name = dev_name(&p->pdev->dev);
	ced->features = CLOCK_EVT_FEAT_ONESHOT;
	ced->rating = 200;
	ced->cpumask = cpu_possible_mask;
	ced->set_next_event = em_sti_clock_event_next;
	ced->set_state_shutdown = em_sti_clock_event_shutdown;
	ced->set_state_oneshot = em_sti_clock_event_set_oneshot;

	dev_info(&p->pdev->dev, "used for clock events\n");

	clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
}

static int em_sti_probe(struct platform_device *pdev)
{
	struct em_sti_priv *p;
	struct resource *res;
	int irq;
	int ret;

	p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
	if (p == NULL)
		return -ENOMEM;

	p->pdev = pdev;
	platform_set_drvdata(pdev, p);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(&pdev->dev, "failed to get irq\n");
		return irq;
	}

	/* map memory, let base point to the STI instance */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	p->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(p->base))
		return PTR_ERR(p->base);

	ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
			       IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
			       dev_name(&pdev->dev), p);
	if (ret) {
		dev_err(&pdev->dev, "failed to request low IRQ\n");
		return ret;
	}

	/* get hold of clock */
	p->clk = devm_clk_get(&pdev->dev, "sclk");
	if (IS_ERR(p->clk)) {
		dev_err(&pdev->dev, "cannot get clock\n");
		return PTR_ERR(p->clk);
	}

	ret = clk_prepare(p->clk);
	if (ret < 0) {
		dev_err(&pdev->dev, "cannot prepare clock\n");
		return ret;
	}

	ret = clk_enable(p->clk);
	if (ret < 0) {
		dev_err(&p->pdev->dev, "cannot enable clock\n");
		clk_unprepare(p->clk);
		return ret;
	}
	p->rate = clk_get_rate(p->clk);
	clk_disable(p->clk);

	raw_spin_lock_init(&p->lock);
	em_sti_register_clockevent(p);
	em_sti_register_clocksource(p);
	return 0;
}

static int em_sti_remove(struct platform_device *pdev)
{
	return -EBUSY; /* cannot unregister clockevent and clocksource */
}

static const struct of_device_id em_sti_dt_ids[] = {
	{ .compatible = "renesas,em-sti", },
	{},
};
MODULE_DEVICE_TABLE(of, em_sti_dt_ids);

static struct platform_driver em_sti_device_driver = {
	.probe		= em_sti_probe,
	.remove		= em_sti_remove,
	.driver		= {
		.name	= "em_sti",
		.of_match_table = em_sti_dt_ids,
	}
};

static int __init em_sti_init(void)
{
	return platform_driver_register(&em_sti_device_driver);
}

static void __exit em_sti_exit(void)
{
	platform_driver_unregister(&em_sti_device_driver);
}

subsys_initcall(em_sti_init);
module_exit(em_sti_exit);

MODULE_AUTHOR("Magnus Damm");
MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
MODULE_LICENSE("GPL v2");