1/*
2 * Emma Mobile Timer Support - STI
3 *
4 *  Copyright (C) 2012 Magnus Damm
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18 */
19
20#include <linux/init.h>
21#include <linux/platform_device.h>
22#include <linux/spinlock.h>
23#include <linux/interrupt.h>
24#include <linux/ioport.h>
25#include <linux/io.h>
26#include <linux/clk.h>
27#include <linux/irq.h>
28#include <linux/err.h>
29#include <linux/delay.h>
30#include <linux/clocksource.h>
31#include <linux/clockchips.h>
32#include <linux/slab.h>
33#include <linux/module.h>
34
35enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
36
37struct em_sti_priv {
38	void __iomem *base;
39	struct clk *clk;
40	struct platform_device *pdev;
41	unsigned int active[USER_NR];
42	unsigned long rate;
43	raw_spinlock_t lock;
44	struct clock_event_device ced;
45	struct clocksource cs;
46};
47
48#define STI_CONTROL 0x00
49#define STI_COMPA_H 0x10
50#define STI_COMPA_L 0x14
51#define STI_COMPB_H 0x18
52#define STI_COMPB_L 0x1c
53#define STI_COUNT_H 0x20
54#define STI_COUNT_L 0x24
55#define STI_COUNT_RAW_H 0x28
56#define STI_COUNT_RAW_L 0x2c
57#define STI_SET_H 0x30
58#define STI_SET_L 0x34
59#define STI_INTSTATUS 0x40
60#define STI_INTRAWSTATUS 0x44
61#define STI_INTENSET 0x48
62#define STI_INTENCLR 0x4c
63#define STI_INTFFCLR 0x50
64
65static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
66{
67	return ioread32(p->base + offs);
68}
69
70static inline void em_sti_write(struct em_sti_priv *p, int offs,
71				unsigned long value)
72{
73	iowrite32(value, p->base + offs);
74}
75
76static int em_sti_enable(struct em_sti_priv *p)
77{
78	int ret;
79
80	/* enable clock */
81	ret = clk_prepare_enable(p->clk);
82	if (ret) {
83		dev_err(&p->pdev->dev, "cannot enable clock\n");
84		return ret;
85	}
86
87	/* configure channel, periodic mode and maximum timeout */
88	p->rate = clk_get_rate(p->clk);
89
90	/* reset the counter */
91	em_sti_write(p, STI_SET_H, 0x40000000);
92	em_sti_write(p, STI_SET_L, 0x00000000);
93
94	/* mask and clear pending interrupts */
95	em_sti_write(p, STI_INTENCLR, 3);
96	em_sti_write(p, STI_INTFFCLR, 3);
97
98	/* enable updates of counter registers */
99	em_sti_write(p, STI_CONTROL, 1);
100
101	return 0;
102}
103
104static void em_sti_disable(struct em_sti_priv *p)
105{
106	/* mask interrupts */
107	em_sti_write(p, STI_INTENCLR, 3);
108
109	/* stop clock */
110	clk_disable_unprepare(p->clk);
111}
112
113static cycle_t em_sti_count(struct em_sti_priv *p)
114{
115	cycle_t ticks;
116	unsigned long flags;
117
118	/* the STI hardware buffers the 48-bit count, but to
119	 * break it out into two 32-bit access the registers
120	 * must be accessed in a certain order.
121	 * Always read STI_COUNT_H before STI_COUNT_L.
122	 */
123	raw_spin_lock_irqsave(&p->lock, flags);
124	ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
125	ticks |= em_sti_read(p, STI_COUNT_L);
126	raw_spin_unlock_irqrestore(&p->lock, flags);
127
128	return ticks;
129}
130
131static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next)
132{
133	unsigned long flags;
134
135	raw_spin_lock_irqsave(&p->lock, flags);
136
137	/* mask compare A interrupt */
138	em_sti_write(p, STI_INTENCLR, 1);
139
140	/* update compare A value */
141	em_sti_write(p, STI_COMPA_H, next >> 32);
142	em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
143
144	/* clear compare A interrupt source */
145	em_sti_write(p, STI_INTFFCLR, 1);
146
147	/* unmask compare A interrupt */
148	em_sti_write(p, STI_INTENSET, 1);
149
150	raw_spin_unlock_irqrestore(&p->lock, flags);
151
152	return next;
153}
154
155static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
156{
157	struct em_sti_priv *p = dev_id;
158
159	p->ced.event_handler(&p->ced);
160	return IRQ_HANDLED;
161}
162
163static int em_sti_start(struct em_sti_priv *p, unsigned int user)
164{
165	unsigned long flags;
166	int used_before;
167	int ret = 0;
168
169	raw_spin_lock_irqsave(&p->lock, flags);
170	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
171	if (!used_before)
172		ret = em_sti_enable(p);
173
174	if (!ret)
175		p->active[user] = 1;
176	raw_spin_unlock_irqrestore(&p->lock, flags);
177
178	return ret;
179}
180
181static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
182{
183	unsigned long flags;
184	int used_before, used_after;
185
186	raw_spin_lock_irqsave(&p->lock, flags);
187	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
188	p->active[user] = 0;
189	used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
190
191	if (used_before && !used_after)
192		em_sti_disable(p);
193	raw_spin_unlock_irqrestore(&p->lock, flags);
194}
195
196static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
197{
198	return container_of(cs, struct em_sti_priv, cs);
199}
200
201static cycle_t em_sti_clocksource_read(struct clocksource *cs)
202{
203	return em_sti_count(cs_to_em_sti(cs));
204}
205
206static int em_sti_clocksource_enable(struct clocksource *cs)
207{
208	int ret;
209	struct em_sti_priv *p = cs_to_em_sti(cs);
210
211	ret = em_sti_start(p, USER_CLOCKSOURCE);
212	if (!ret)
213		__clocksource_update_freq_hz(cs, p->rate);
214	return ret;
215}
216
217static void em_sti_clocksource_disable(struct clocksource *cs)
218{
219	em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
220}
221
222static void em_sti_clocksource_resume(struct clocksource *cs)
223{
224	em_sti_clocksource_enable(cs);
225}
226
227static int em_sti_register_clocksource(struct em_sti_priv *p)
228{
229	struct clocksource *cs = &p->cs;
230
231	memset(cs, 0, sizeof(*cs));
232	cs->name = dev_name(&p->pdev->dev);
233	cs->rating = 200;
234	cs->read = em_sti_clocksource_read;
235	cs->enable = em_sti_clocksource_enable;
236	cs->disable = em_sti_clocksource_disable;
237	cs->suspend = em_sti_clocksource_disable;
238	cs->resume = em_sti_clocksource_resume;
239	cs->mask = CLOCKSOURCE_MASK(48);
240	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
241
242	dev_info(&p->pdev->dev, "used as clock source\n");
243
244	/* Register with dummy 1 Hz value, gets updated in ->enable() */
245	clocksource_register_hz(cs, 1);
246	return 0;
247}
248
249static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
250{
251	return container_of(ced, struct em_sti_priv, ced);
252}
253
254static void em_sti_clock_event_mode(enum clock_event_mode mode,
255				    struct clock_event_device *ced)
256{
257	struct em_sti_priv *p = ced_to_em_sti(ced);
258
259	/* deal with old setting first */
260	switch (ced->mode) {
261	case CLOCK_EVT_MODE_ONESHOT:
262		em_sti_stop(p, USER_CLOCKEVENT);
263		break;
264	default:
265		break;
266	}
267
268	switch (mode) {
269	case CLOCK_EVT_MODE_ONESHOT:
270		dev_info(&p->pdev->dev, "used for oneshot clock events\n");
271		em_sti_start(p, USER_CLOCKEVENT);
272		clockevents_config(&p->ced, p->rate);
273		break;
274	case CLOCK_EVT_MODE_SHUTDOWN:
275	case CLOCK_EVT_MODE_UNUSED:
276		em_sti_stop(p, USER_CLOCKEVENT);
277		break;
278	default:
279		break;
280	}
281}
282
283static int em_sti_clock_event_next(unsigned long delta,
284				   struct clock_event_device *ced)
285{
286	struct em_sti_priv *p = ced_to_em_sti(ced);
287	cycle_t next;
288	int safe;
289
290	next = em_sti_set_next(p, em_sti_count(p) + delta);
291	safe = em_sti_count(p) < (next - 1);
292
293	return !safe;
294}
295
296static void em_sti_register_clockevent(struct em_sti_priv *p)
297{
298	struct clock_event_device *ced = &p->ced;
299
300	memset(ced, 0, sizeof(*ced));
301	ced->name = dev_name(&p->pdev->dev);
302	ced->features = CLOCK_EVT_FEAT_ONESHOT;
303	ced->rating = 200;
304	ced->cpumask = cpu_possible_mask;
305	ced->set_next_event = em_sti_clock_event_next;
306	ced->set_mode = em_sti_clock_event_mode;
307
308	dev_info(&p->pdev->dev, "used for clock events\n");
309
310	/* Register with dummy 1 Hz value, gets updated in ->set_mode() */
311	clockevents_config_and_register(ced, 1, 2, 0xffffffff);
312}
313
314static int em_sti_probe(struct platform_device *pdev)
315{
316	struct em_sti_priv *p;
317	struct resource *res;
318	int irq;
319
320	p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
321	if (p == NULL)
322		return -ENOMEM;
323
324	p->pdev = pdev;
325	platform_set_drvdata(pdev, p);
326
327	irq = platform_get_irq(pdev, 0);
328	if (irq < 0) {
329		dev_err(&pdev->dev, "failed to get irq\n");
330		return -EINVAL;
331	}
332
333	/* map memory, let base point to the STI instance */
334	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
335	p->base = devm_ioremap_resource(&pdev->dev, res);
336	if (IS_ERR(p->base))
337		return PTR_ERR(p->base);
338
339	/* get hold of clock */
340	p->clk = devm_clk_get(&pdev->dev, "sclk");
341	if (IS_ERR(p->clk)) {
342		dev_err(&pdev->dev, "cannot get clock\n");
343		return PTR_ERR(p->clk);
344	}
345
346	if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
347			     IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
348			     dev_name(&pdev->dev), p)) {
349		dev_err(&pdev->dev, "failed to request low IRQ\n");
350		return -ENOENT;
351	}
352
353	raw_spin_lock_init(&p->lock);
354	em_sti_register_clockevent(p);
355	em_sti_register_clocksource(p);
356	return 0;
357}
358
359static int em_sti_remove(struct platform_device *pdev)
360{
361	return -EBUSY; /* cannot unregister clockevent and clocksource */
362}
363
364static const struct of_device_id em_sti_dt_ids[] = {
365	{ .compatible = "renesas,em-sti", },
366	{},
367};
368MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
369
370static struct platform_driver em_sti_device_driver = {
371	.probe		= em_sti_probe,
372	.remove		= em_sti_remove,
373	.driver		= {
374		.name	= "em_sti",
375		.of_match_table = em_sti_dt_ids,
376	}
377};
378
379static int __init em_sti_init(void)
380{
381	return platform_driver_register(&em_sti_device_driver);
382}
383
384static void __exit em_sti_exit(void)
385{
386	platform_driver_unregister(&em_sti_device_driver);
387}
388
389subsys_initcall(em_sti_init);
390module_exit(em_sti_exit);
391
392MODULE_AUTHOR("Magnus Damm");
393MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
394MODULE_LICENSE("GPL v2");
395