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1/*
2 * Copyright (C) 2013-2014 Altera Corporation
3 * Copyright (C) 2010 Tobias Klauser <[email protected]>
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
36struct nios2_timer {
37 void __iomem *base;
38 unsigned long freq;
39};
40
41struct nios2_clockevent_dev {
42 struct nios2_timer timer;
43 struct clock_event_device ced;
44};
45
46struct nios2_clocksource {
47 struct nios2_timer timer;
48 struct clocksource cs;
49};
50
51static inline struct nios2_clockevent_dev *
52 to_nios2_clkevent(struct clock_event_device *evt)
53{
54 return container_of(evt, struct nios2_clockevent_dev, ced);
55}
56
57static inline struct nios2_clocksource *
58 to_nios2_clksource(struct clocksource *cs)
59{
60 return container_of(cs, struct nios2_clocksource, cs);
61}
62
63static u16 timer_readw(struct nios2_timer *timer, u32 offs)
64{
65 return readw(timer->base + offs);
66}
67
68static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
69{
70 writew(val, timer->base + offs);
71}
72
73static 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
84static 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
98static 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
108cycles_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}
115EXPORT_SYMBOL(get_cycles);
116
117static 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
126static 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
135static 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
161static 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
171static 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
180static 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
191static 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
200irqreturn_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
212static 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
229static 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
243static __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
281static __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*/
317static 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
339void 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
345void __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
359TIMER_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init);