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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/interrupt.h> | |
12 | #include <linux/clockchips.h> | |
13 | #include <linux/clocksource.h> | |
14 | #include <linux/delay.h> | |
15 | #include <linux/of.h> | |
16 | #include <linux/of_address.h> | |
17 | #include <linux/of_irq.h> | |
18 | #include <linux/io.h> | |
19 | #include <linux/slab.h> | |
20 | ||
21 | #define ALTERA_TIMER_STATUS_REG 0 | |
22 | #define ALTERA_TIMER_CONTROL_REG 4 | |
23 | #define ALTERA_TIMER_PERIODL_REG 8 | |
24 | #define ALTERA_TIMER_PERIODH_REG 12 | |
25 | #define ALTERA_TIMER_SNAPL_REG 16 | |
26 | #define ALTERA_TIMER_SNAPH_REG 20 | |
27 | ||
28 | #define ALTERA_TIMER_CONTROL_ITO_MSK (0x1) | |
29 | #define ALTERA_TIMER_CONTROL_CONT_MSK (0x2) | |
30 | #define ALTERA_TIMER_CONTROL_START_MSK (0x4) | |
31 | #define ALTERA_TIMER_CONTROL_STOP_MSK (0x8) | |
32 | ||
33 | struct nios2_timer { | |
34 | void __iomem *base; | |
35 | unsigned long freq; | |
4182de9e LFT |
36 | }; |
37 | ||
38 | struct nios2_clockevent_dev { | |
39 | struct nios2_timer timer; | |
40 | struct clock_event_device ced; | |
41 | }; | |
42 | ||
43 | struct nios2_clocksource { | |
44 | struct nios2_timer timer; | |
45 | struct clocksource cs; | |
46 | }; | |
47 | ||
48 | static inline struct nios2_clockevent_dev * | |
49 | to_nios2_clkevent(struct clock_event_device *evt) | |
50 | { | |
51 | return container_of(evt, struct nios2_clockevent_dev, ced); | |
52 | } | |
53 | ||
54 | static inline struct nios2_clocksource * | |
55 | to_nios2_clksource(struct clocksource *cs) | |
56 | { | |
57 | return container_of(cs, struct nios2_clocksource, cs); | |
58 | } | |
59 | ||
60 | static u16 timer_readw(struct nios2_timer *timer, u32 offs) | |
61 | { | |
62 | return readw(timer->base + offs); | |
63 | } | |
64 | ||
65 | static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs) | |
66 | { | |
67 | writew(val, timer->base + offs); | |
68 | } | |
69 | ||
70 | static inline unsigned long read_timersnapshot(struct nios2_timer *timer) | |
71 | { | |
72 | unsigned long count; | |
73 | ||
74 | timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG); | |
75 | count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 | | |
76 | timer_readw(timer, ALTERA_TIMER_SNAPL_REG); | |
77 | ||
78 | return count; | |
79 | } | |
80 | ||
81 | static cycle_t nios2_timer_read(struct clocksource *cs) | |
82 | { | |
83 | struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs); | |
84 | unsigned long flags; | |
85 | u32 count; | |
86 | ||
87 | local_irq_save(flags); | |
88 | count = read_timersnapshot(&nios2_cs->timer); | |
89 | local_irq_restore(flags); | |
90 | ||
91 | /* Counter is counting down */ | |
92 | return ~count; | |
93 | } | |
94 | ||
95 | static struct nios2_clocksource nios2_cs = { | |
96 | .cs = { | |
97 | .name = "nios2-clksrc", | |
98 | .rating = 250, | |
99 | .read = nios2_timer_read, | |
100 | .mask = CLOCKSOURCE_MASK(32), | |
101 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
102 | }, | |
103 | }; | |
104 | ||
105 | cycles_t get_cycles(void) | |
106 | { | |
107 | return nios2_timer_read(&nios2_cs.cs); | |
108 | } | |
109 | ||
110 | static void nios2_timer_start(struct nios2_timer *timer) | |
111 | { | |
112 | u16 ctrl; | |
113 | ||
114 | ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); | |
115 | ctrl |= ALTERA_TIMER_CONTROL_START_MSK; | |
116 | timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); | |
117 | } | |
118 | ||
119 | static void nios2_timer_stop(struct nios2_timer *timer) | |
120 | { | |
121 | u16 ctrl; | |
122 | ||
123 | ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); | |
124 | ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK; | |
125 | timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); | |
126 | } | |
127 | ||
128 | static void nios2_timer_config(struct nios2_timer *timer, unsigned long period, | |
129 | enum clock_event_mode mode) | |
130 | { | |
131 | u16 ctrl; | |
132 | ||
133 | /* The timer's actual period is one cycle greater than the value | |
134 | * stored in the period register. */ | |
135 | period--; | |
136 | ||
137 | ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); | |
138 | /* stop counter */ | |
139 | timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK, | |
140 | ALTERA_TIMER_CONTROL_REG); | |
141 | ||
142 | /* write new count */ | |
143 | timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG); | |
144 | timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG); | |
145 | ||
146 | ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK; | |
147 | if (mode == CLOCK_EVT_MODE_PERIODIC) | |
148 | ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK; | |
149 | else | |
150 | ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK; | |
151 | timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); | |
152 | } | |
153 | ||
154 | static int nios2_timer_set_next_event(unsigned long delta, | |
155 | struct clock_event_device *evt) | |
156 | { | |
157 | struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); | |
158 | ||
159 | nios2_timer_config(&nios2_ced->timer, delta, evt->mode); | |
160 | ||
161 | return 0; | |
162 | } | |
163 | ||
164 | static void nios2_timer_set_mode(enum clock_event_mode mode, | |
165 | struct clock_event_device *evt) | |
166 | { | |
167 | unsigned long period; | |
168 | struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); | |
169 | struct nios2_timer *timer = &nios2_ced->timer; | |
170 | ||
171 | switch (mode) { | |
172 | case CLOCK_EVT_MODE_PERIODIC: | |
173 | period = DIV_ROUND_UP(timer->freq, HZ); | |
174 | nios2_timer_config(timer, period, CLOCK_EVT_MODE_PERIODIC); | |
175 | break; | |
176 | case CLOCK_EVT_MODE_ONESHOT: | |
177 | case CLOCK_EVT_MODE_UNUSED: | |
178 | case CLOCK_EVT_MODE_SHUTDOWN: | |
179 | nios2_timer_stop(timer); | |
180 | break; | |
181 | case CLOCK_EVT_MODE_RESUME: | |
182 | nios2_timer_start(timer); | |
183 | break; | |
184 | } | |
185 | } | |
186 | ||
187 | irqreturn_t timer_interrupt(int irq, void *dev_id) | |
188 | { | |
189 | struct clock_event_device *evt = (struct clock_event_device *) dev_id; | |
190 | struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); | |
191 | ||
192 | /* Clear the interrupt condition */ | |
193 | timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG); | |
194 | evt->event_handler(evt); | |
195 | ||
196 | return IRQ_HANDLED; | |
197 | } | |
198 | ||
199 | static void __init nios2_timer_get_base_and_freq(struct device_node *np, | |
200 | void __iomem **base, u32 *freq) | |
201 | { | |
202 | *base = of_iomap(np, 0); | |
203 | if (!*base) | |
204 | panic("Unable to map reg for %s\n", np->name); | |
205 | ||
206 | if (of_property_read_u32(np, "clock-frequency", freq)) | |
207 | panic("Unable to get %s clock frequency\n", np->name); | |
208 | } | |
209 | ||
210 | static struct nios2_clockevent_dev nios2_ce = { | |
211 | .ced = { | |
212 | .name = "nios2-clkevent", | |
213 | .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, | |
214 | .rating = 250, | |
215 | .shift = 32, | |
216 | .set_next_event = nios2_timer_set_next_event, | |
217 | .set_mode = nios2_timer_set_mode, | |
218 | }, | |
219 | }; | |
220 | ||
221 | static __init void nios2_clockevent_init(struct device_node *timer) | |
222 | { | |
223 | void __iomem *iobase; | |
224 | u32 freq; | |
225 | int irq; | |
226 | ||
227 | nios2_timer_get_base_and_freq(timer, &iobase, &freq); | |
228 | ||
229 | irq = irq_of_parse_and_map(timer, 0); | |
b29438f2 | 230 | if (!irq) |
4182de9e LFT |
231 | panic("Unable to parse timer irq\n"); |
232 | ||
233 | nios2_ce.timer.base = iobase; | |
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234 | nios2_ce.timer.freq = freq; |
235 | ||
236 | nios2_ce.ced.cpumask = cpumask_of(0); | |
237 | nios2_ce.ced.irq = irq; | |
238 | ||
239 | nios2_timer_stop(&nios2_ce.timer); | |
240 | /* clear pending interrupt */ | |
241 | timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG); | |
242 | ||
243 | if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name, | |
244 | &nios2_ce.ced)) | |
245 | panic("Unable to setup timer irq\n"); | |
246 | ||
247 | clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX); | |
248 | } | |
249 | ||
250 | static __init void nios2_clocksource_init(struct device_node *timer) | |
251 | { | |
252 | unsigned int ctrl; | |
253 | void __iomem *iobase; | |
254 | u32 freq; | |
255 | ||
256 | nios2_timer_get_base_and_freq(timer, &iobase, &freq); | |
257 | ||
258 | nios2_cs.timer.base = iobase; | |
259 | nios2_cs.timer.freq = freq; | |
260 | ||
261 | clocksource_register_hz(&nios2_cs.cs, freq); | |
262 | ||
263 | timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG); | |
264 | timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG); | |
265 | ||
266 | /* interrupt disable + continuous + start */ | |
267 | ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK; | |
268 | timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG); | |
269 | ||
270 | /* Calibrate the delay loop directly */ | |
271 | lpj_fine = freq / HZ; | |
272 | } | |
273 | ||
274 | /* | |
275 | * The first timer instance will use as a clockevent. If there are two or | |
276 | * more instances, the second one gets used as clocksource and all | |
277 | * others are unused. | |
278 | */ | |
279 | static void __init nios2_time_init(struct device_node *timer) | |
280 | { | |
281 | static int num_called; | |
282 | ||
283 | switch (num_called) { | |
284 | case 0: | |
285 | nios2_clockevent_init(timer); | |
286 | break; | |
287 | case 1: | |
288 | nios2_clocksource_init(timer); | |
289 | break; | |
290 | default: | |
291 | break; | |
292 | } | |
293 | ||
294 | num_called++; | |
295 | } | |
296 | ||
297 | void read_persistent_clock(struct timespec *ts) | |
298 | { | |
299 | ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0); | |
300 | ts->tv_nsec = 0; | |
301 | } | |
302 | ||
303 | void __init time_init(void) | |
304 | { | |
305 | clocksource_of_init(); | |
306 | } | |
307 | ||
308 | CLOCKSOURCE_OF_DECLARE(nios2_timer, "altr,timer-1.0", nios2_time_init); |