xref: /openbmc/linux/arch/nios2/kernel/time.c (revision 5dc4dca4)
1 /*
2  * Copyright (C) 2013-2014 Altera Corporation
3  * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
4  * Copyright (C) 2004 Microtronix Datacom Ltd.
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License. See the file "COPYING" in the main directory of this archive
8  * for more details.
9  */
10 
11 #include <linux/export.h>
12 #include <linux/interrupt.h>
13 #include <linux/clockchips.h>
14 #include <linux/clocksource.h>
15 #include <linux/delay.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/of_irq.h>
19 #include <linux/io.h>
20 #include <linux/slab.h>
21 
22 #define ALTR_TIMER_COMPATIBLE		"altr,timer-1.0"
23 
24 #define ALTERA_TIMER_STATUS_REG	0
25 #define ALTERA_TIMER_CONTROL_REG	4
26 #define ALTERA_TIMER_PERIODL_REG	8
27 #define ALTERA_TIMER_PERIODH_REG	12
28 #define ALTERA_TIMER_SNAPL_REG		16
29 #define ALTERA_TIMER_SNAPH_REG		20
30 
31 #define ALTERA_TIMER_CONTROL_ITO_MSK	(0x1)
32 #define ALTERA_TIMER_CONTROL_CONT_MSK	(0x2)
33 #define ALTERA_TIMER_CONTROL_START_MSK	(0x4)
34 #define ALTERA_TIMER_CONTROL_STOP_MSK	(0x8)
35 
36 struct nios2_timer {
37 	void __iomem *base;
38 	unsigned long freq;
39 };
40 
41 struct nios2_clockevent_dev {
42 	struct nios2_timer timer;
43 	struct clock_event_device ced;
44 };
45 
46 struct nios2_clocksource {
47 	struct nios2_timer timer;
48 	struct clocksource cs;
49 };
50 
51 static inline struct nios2_clockevent_dev *
to_nios2_clkevent(struct clock_event_device * evt)52 	to_nios2_clkevent(struct clock_event_device *evt)
53 {
54 	return container_of(evt, struct nios2_clockevent_dev, ced);
55 }
56 
57 static inline struct nios2_clocksource *
to_nios2_clksource(struct clocksource * cs)58 	to_nios2_clksource(struct clocksource *cs)
59 {
60 	return container_of(cs, struct nios2_clocksource, cs);
61 }
62 
timer_readw(struct nios2_timer * timer,u32 offs)63 static u16 timer_readw(struct nios2_timer *timer, u32 offs)
64 {
65 	return readw(timer->base + offs);
66 }
67 
timer_writew(struct nios2_timer * timer,u16 val,u32 offs)68 static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
69 {
70 	writew(val, timer->base + offs);
71 }
72 
read_timersnapshot(struct nios2_timer * timer)73 static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
74 {
75 	unsigned long count;
76 
77 	timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
78 	count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
79 		timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
80 
81 	return count;
82 }
83 
nios2_timer_read(struct clocksource * cs)84 static u64 nios2_timer_read(struct clocksource *cs)
85 {
86 	struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
87 	unsigned long flags;
88 	u32 count;
89 
90 	local_irq_save(flags);
91 	count = read_timersnapshot(&nios2_cs->timer);
92 	local_irq_restore(flags);
93 
94 	/* Counter is counting down */
95 	return ~count;
96 }
97 
98 static struct nios2_clocksource nios2_cs = {
99 	.cs = {
100 		.name	= "nios2-clksrc",
101 		.rating	= 250,
102 		.read	= nios2_timer_read,
103 		.mask	= CLOCKSOURCE_MASK(32),
104 		.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
105 	},
106 };
107 
get_cycles(void)108 cycles_t get_cycles(void)
109 {
110 	/* Only read timer if it has been initialized */
111 	if (nios2_cs.timer.base)
112 		return nios2_timer_read(&nios2_cs.cs);
113 	return 0;
114 }
115 EXPORT_SYMBOL(get_cycles);
116 
nios2_timer_start(struct nios2_timer * timer)117 static void nios2_timer_start(struct nios2_timer *timer)
118 {
119 	u16 ctrl;
120 
121 	ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
122 	ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
123 	timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
124 }
125 
nios2_timer_stop(struct nios2_timer * timer)126 static void nios2_timer_stop(struct nios2_timer *timer)
127 {
128 	u16 ctrl;
129 
130 	ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
131 	ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
132 	timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
133 }
134 
nios2_timer_config(struct nios2_timer * timer,unsigned long period,bool periodic)135 static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
136 			       bool periodic)
137 {
138 	u16 ctrl;
139 
140 	/* The timer's actual period is one cycle greater than the value
141 	 * stored in the period register. */
142 	 period--;
143 
144 	ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
145 	/* stop counter */
146 	timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
147 		ALTERA_TIMER_CONTROL_REG);
148 
149 	/* write new count */
150 	timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
151 	timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
152 
153 	ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
154 	if (periodic)
155 		ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
156 	else
157 		ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
158 	timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
159 }
160 
nios2_timer_set_next_event(unsigned long delta,struct clock_event_device * evt)161 static int nios2_timer_set_next_event(unsigned long delta,
162 	struct clock_event_device *evt)
163 {
164 	struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
165 
166 	nios2_timer_config(&nios2_ced->timer, delta, false);
167 
168 	return 0;
169 }
170 
nios2_timer_shutdown(struct clock_event_device * evt)171 static int nios2_timer_shutdown(struct clock_event_device *evt)
172 {
173 	struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
174 	struct nios2_timer *timer = &nios2_ced->timer;
175 
176 	nios2_timer_stop(timer);
177 	return 0;
178 }
179 
nios2_timer_set_periodic(struct clock_event_device * evt)180 static int nios2_timer_set_periodic(struct clock_event_device *evt)
181 {
182 	unsigned long period;
183 	struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
184 	struct nios2_timer *timer = &nios2_ced->timer;
185 
186 	period = DIV_ROUND_UP(timer->freq, HZ);
187 	nios2_timer_config(timer, period, true);
188 	return 0;
189 }
190 
nios2_timer_resume(struct clock_event_device * evt)191 static int nios2_timer_resume(struct clock_event_device *evt)
192 {
193 	struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
194 	struct nios2_timer *timer = &nios2_ced->timer;
195 
196 	nios2_timer_start(timer);
197 	return 0;
198 }
199 
timer_interrupt(int irq,void * dev_id)200 irqreturn_t timer_interrupt(int irq, void *dev_id)
201 {
202 	struct clock_event_device *evt = (struct clock_event_device *) dev_id;
203 	struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
204 
205 	/* Clear the interrupt condition */
206 	timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
207 	evt->event_handler(evt);
208 
209 	return IRQ_HANDLED;
210 }
211 
nios2_timer_get_base_and_freq(struct device_node * np,void __iomem ** base,u32 * freq)212 static int __init nios2_timer_get_base_and_freq(struct device_node *np,
213 				void __iomem **base, u32 *freq)
214 {
215 	*base = of_iomap(np, 0);
216 	if (!*base) {
217 		pr_crit("Unable to map reg for %pOFn\n", np);
218 		return -ENXIO;
219 	}
220 
221 	if (of_property_read_u32(np, "clock-frequency", freq)) {
222 		pr_crit("Unable to get %pOFn clock frequency\n", np);
223 		return -EINVAL;
224 	}
225 
226 	return 0;
227 }
228 
229 static struct nios2_clockevent_dev nios2_ce = {
230 	.ced = {
231 		.name = "nios2-clkevent",
232 		.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
233 		.rating = 250,
234 		.shift = 32,
235 		.set_next_event = nios2_timer_set_next_event,
236 		.set_state_shutdown = nios2_timer_shutdown,
237 		.set_state_periodic = nios2_timer_set_periodic,
238 		.set_state_oneshot = nios2_timer_shutdown,
239 		.tick_resume = nios2_timer_resume,
240 	},
241 };
242 
nios2_clockevent_init(struct device_node * timer)243 static __init int nios2_clockevent_init(struct device_node *timer)
244 {
245 	void __iomem *iobase;
246 	u32 freq;
247 	int irq, ret;
248 
249 	ret = nios2_timer_get_base_and_freq(timer, &iobase, &freq);
250 	if (ret)
251 		return ret;
252 
253 	irq = irq_of_parse_and_map(timer, 0);
254 	if (!irq) {
255 		pr_crit("Unable to parse timer irq\n");
256 		return -EINVAL;
257 	}
258 
259 	nios2_ce.timer.base = iobase;
260 	nios2_ce.timer.freq = freq;
261 
262 	nios2_ce.ced.cpumask = cpumask_of(0);
263 	nios2_ce.ced.irq = irq;
264 
265 	nios2_timer_stop(&nios2_ce.timer);
266 	/* clear pending interrupt */
267 	timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
268 
269 	ret = request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
270 			  &nios2_ce.ced);
271 	if (ret) {
272 		pr_crit("Unable to setup timer irq\n");
273 		return ret;
274 	}
275 
276 	clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
277 
278 	return 0;
279 }
280 
nios2_clocksource_init(struct device_node * timer)281 static __init int nios2_clocksource_init(struct device_node *timer)
282 {
283 	unsigned int ctrl;
284 	void __iomem *iobase;
285 	u32 freq;
286 	int ret;
287 
288 	ret = nios2_timer_get_base_and_freq(timer, &iobase, &freq);
289 	if (ret)
290 		return ret;
291 
292 	nios2_cs.timer.base = iobase;
293 	nios2_cs.timer.freq = freq;
294 
295 	ret = clocksource_register_hz(&nios2_cs.cs, freq);
296 	if (ret)
297 		return ret;
298 
299 	timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
300 	timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
301 
302 	/* interrupt disable + continuous + start */
303 	ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
304 	timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
305 
306 	/* Calibrate the delay loop directly */
307 	lpj_fine = freq / HZ;
308 
309 	return 0;
310 }
311 
312 /*
313  * The first timer instance will use as a clockevent. If there are two or
314  * more instances, the second one gets used as clocksource and all
315  * others are unused.
316 */
nios2_time_init(struct device_node * timer)317 static int __init nios2_time_init(struct device_node *timer)
318 {
319 	static int num_called;
320 	int ret;
321 
322 	switch (num_called) {
323 	case 0:
324 		ret = nios2_clockevent_init(timer);
325 		break;
326 	case 1:
327 		ret = nios2_clocksource_init(timer);
328 		break;
329 	default:
330 		ret = 0;
331 		break;
332 	}
333 
334 	num_called++;
335 
336 	return ret;
337 }
338 
read_persistent_clock64(struct timespec64 * ts)339 void read_persistent_clock64(struct timespec64 *ts)
340 {
341 	ts->tv_sec = mktime64(2007, 1, 1, 0, 0, 0);
342 	ts->tv_nsec = 0;
343 }
344 
time_init(void)345 void __init time_init(void)
346 {
347 	struct device_node *np;
348 	int count = 0;
349 
350 	for_each_compatible_node(np, NULL,  ALTR_TIMER_COMPATIBLE)
351 		count++;
352 
353 	if (count < 2)
354 		panic("%d timer is found, it needs 2 timers in system\n", count);
355 
356 	timer_probe();
357 }
358 
359 TIMER_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init);
360