2 * Copyright (C) 2013-2014 Altera Corporation
3 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
4 * Copyright (C) 2004 Microtronix Datacom Ltd.
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
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>
17 #include <linux/of_address.h>
18 #include <linux/of_irq.h>
20 #include <linux/slab.h>
22 #define ALTERA_TIMER_STATUS_REG 0
23 #define ALTERA_TIMER_CONTROL_REG 4
24 #define ALTERA_TIMER_PERIODL_REG 8
25 #define ALTERA_TIMER_PERIODH_REG 12
26 #define ALTERA_TIMER_SNAPL_REG 16
27 #define ALTERA_TIMER_SNAPH_REG 20
29 #define ALTERA_TIMER_CONTROL_ITO_MSK (0x1)
30 #define ALTERA_TIMER_CONTROL_CONT_MSK (0x2)
31 #define ALTERA_TIMER_CONTROL_START_MSK (0x4)
32 #define ALTERA_TIMER_CONTROL_STOP_MSK (0x8)
39 struct nios2_clockevent_dev {
40 struct nios2_timer timer;
41 struct clock_event_device ced;
44 struct nios2_clocksource {
45 struct nios2_timer timer;
46 struct clocksource cs;
49 static inline struct nios2_clockevent_dev *
50 to_nios2_clkevent(struct clock_event_device *evt)
52 return container_of(evt, struct nios2_clockevent_dev, ced);
55 static inline struct nios2_clocksource *
56 to_nios2_clksource(struct clocksource *cs)
58 return container_of(cs, struct nios2_clocksource, cs);
61 static u16 timer_readw(struct nios2_timer *timer, u32 offs)
63 return readw(timer->base + offs);
66 static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs)
68 writew(val, timer->base + offs);
71 static inline unsigned long read_timersnapshot(struct nios2_timer *timer)
75 timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG);
76 count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 |
77 timer_readw(timer, ALTERA_TIMER_SNAPL_REG);
82 static cycle_t nios2_timer_read(struct clocksource *cs)
84 struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs);
88 local_irq_save(flags);
89 count = read_timersnapshot(&nios2_cs->timer);
90 local_irq_restore(flags);
92 /* Counter is counting down */
96 static struct nios2_clocksource nios2_cs = {
98 .name = "nios2-clksrc",
100 .read = nios2_timer_read,
101 .mask = CLOCKSOURCE_MASK(32),
102 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
106 cycles_t get_cycles(void)
108 return nios2_timer_read(&nios2_cs.cs);
110 EXPORT_SYMBOL(get_cycles);
112 static void nios2_timer_start(struct nios2_timer *timer)
116 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
117 ctrl |= ALTERA_TIMER_CONTROL_START_MSK;
118 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
121 static void nios2_timer_stop(struct nios2_timer *timer)
125 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
126 ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK;
127 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
130 static void nios2_timer_config(struct nios2_timer *timer, unsigned long period,
131 enum clock_event_mode mode)
135 /* The timer's actual period is one cycle greater than the value
136 * stored in the period register. */
139 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG);
141 timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK,
142 ALTERA_TIMER_CONTROL_REG);
144 /* write new count */
145 timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG);
146 timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG);
148 ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK;
149 if (mode == CLOCK_EVT_MODE_PERIODIC)
150 ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK;
152 ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK;
153 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG);
156 static int nios2_timer_set_next_event(unsigned long delta,
157 struct clock_event_device *evt)
159 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
161 nios2_timer_config(&nios2_ced->timer, delta, evt->mode);
166 static void nios2_timer_set_mode(enum clock_event_mode mode,
167 struct clock_event_device *evt)
169 unsigned long period;
170 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
171 struct nios2_timer *timer = &nios2_ced->timer;
174 case CLOCK_EVT_MODE_PERIODIC:
175 period = DIV_ROUND_UP(timer->freq, HZ);
176 nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC);
178 case CLOCK_EVT_MODE_ONESHOT:
179 case CLOCK_EVT_MODE_UNUSED:
180 case CLOCK_EVT_MODE_SHUTDOWN:
181 nios2_timer_stop(timer);
183 case CLOCK_EVT_MODE_RESUME:
184 nios2_timer_start(timer);
189 irqreturn_t timer_interrupt(int irq, void *dev_id)
191 struct clock_event_device *evt = (struct clock_event_device *) dev_id;
192 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt);
194 /* Clear the interrupt condition */
195 timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG);
196 evt->event_handler(evt);
201 static void __init nios2_timer_get_base_and_freq(struct device_node *np,
202 void __iomem **base, u32 *freq)
204 *base = of_iomap(np, 0);
206 panic("Unable to map reg for %s\n", np->name);
208 if (of_property_read_u32(np, "clock-frequency", freq))
209 panic("Unable to get %s clock frequency\n", np->name);
212 static struct nios2_clockevent_dev nios2_ce = {
214 .name = "nios2-clkevent",
215 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
218 .set_next_event = nios2_timer_set_next_event,
219 .set_mode = nios2_timer_set_mode,
223 static __init void nios2_clockevent_init(struct device_node *timer)
225 void __iomem *iobase;
229 nios2_timer_get_base_and_freq(timer, &iobase, &freq);
231 irq = irq_of_parse_and_map(timer, 0);
233 panic("Unable to parse timer irq\n");
235 nios2_ce.timer.base = iobase;
236 nios2_ce.timer.freq = freq;
238 nios2_ce.ced.cpumask = cpumask_of(0);
239 nios2_ce.ced.irq = irq;
241 nios2_timer_stop(&nios2_ce.timer);
242 /* clear pending interrupt */
243 timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG);
245 if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name,
247 panic("Unable to setup timer irq\n");
249 clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX);
252 static __init void nios2_clocksource_init(struct device_node *timer)
255 void __iomem *iobase;
258 nios2_timer_get_base_and_freq(timer, &iobase, &freq);
260 nios2_cs.timer.base = iobase;
261 nios2_cs.timer.freq = freq;
263 clocksource_register_hz(&nios2_cs.cs, freq);
265 timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG);
266 timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG);
268 /* interrupt disable + continuous + start */
269 ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK;
270 timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG);
272 /* Calibrate the delay loop directly */
273 lpj_fine = freq / HZ;
277 * The first timer instance will use as a clockevent. If there are two or
278 * more instances, the second one gets used as clocksource and all
281 static void __init nios2_time_init(struct device_node *timer)
283 static int num_called;
285 switch (num_called) {
287 nios2_clockevent_init(timer);
290 nios2_clocksource_init(timer);
299 void read_persistent_clock(struct timespec *ts)
301 ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
305 void __init time_init(void)
307 clocksource_of_init();
310 CLOCKSOURCE_OF_DECLARE(nios2_timer, "altr,timer-1.0", nios2_time_init);