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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 | |
35 | enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; |
36 | |
37 | struct 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 | |
65 | static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) |
66 | { |
67 | return ioread32(p->base + offs); |
68 | } |
69 | |
70 | static 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 | |
76 | static int em_sti_enable(struct em_sti_priv *p) |
77 | { |
78 | int ret; |
79 | |
80 | /* enable clock */ |
81 | ret = clk_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 | |
104 | static 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(p->clk); |
111 | } |
112 | |
113 | static 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 | |
131 | static 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 | |
155 | static 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 | |
163 | static 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 | |
181 | static 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 | |
196 | static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) |
197 | { |
198 | return container_of(cs, struct em_sti_priv, cs); |
199 | } |
200 | |
201 | static cycle_t em_sti_clocksource_read(struct clocksource *cs) |
202 | { |
203 | return em_sti_count(cs_to_em_sti(cs)); |
204 | } |
205 | |
206 | static 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_updatefreq_hz(cs, p->rate); |
214 | return ret; |
215 | } |
216 | |
217 | static void em_sti_clocksource_disable(struct clocksource *cs) |
218 | { |
219 | em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); |
220 | } |
221 | |
222 | static void em_sti_clocksource_resume(struct clocksource *cs) |
223 | { |
224 | em_sti_clocksource_enable(cs); |
225 | } |
226 | |
227 | static 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 | |
249 | static 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 | |
254 | static 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 | |
283 | static 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 | |
296 | static 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 = cpumask_of(0); |
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 | |
314 | static int em_sti_probe(struct platform_device *pdev) |
315 | { |
316 | struct em_sti_priv *p; |
317 | struct resource *res; |
318 | int irq, ret; |
319 | |
320 | p = kzalloc(sizeof(*p), GFP_KERNEL); |
321 | if (p == NULL) { |
322 | dev_err(&pdev->dev, "failed to allocate driver data\n"); |
323 | ret = -ENOMEM; |
324 | goto err0; |
325 | } |
326 | |
327 | p->pdev = pdev; |
328 | platform_set_drvdata(pdev, p); |
329 | |
330 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
331 | if (!res) { |
332 | dev_err(&pdev->dev, "failed to get I/O memory\n"); |
333 | ret = -EINVAL; |
334 | goto err0; |
335 | } |
336 | |
337 | irq = platform_get_irq(pdev, 0); |
338 | if (irq < 0) { |
339 | dev_err(&pdev->dev, "failed to get irq\n"); |
340 | ret = -EINVAL; |
341 | goto err0; |
342 | } |
343 | |
344 | /* map memory, let base point to the STI instance */ |
345 | p->base = ioremap_nocache(res->start, resource_size(res)); |
346 | if (p->base == NULL) { |
347 | dev_err(&pdev->dev, "failed to remap I/O memory\n"); |
348 | ret = -ENXIO; |
349 | goto err0; |
350 | } |
351 | |
352 | /* get hold of clock */ |
353 | p->clk = clk_get(&pdev->dev, "sclk"); |
354 | if (IS_ERR(p->clk)) { |
355 | dev_err(&pdev->dev, "cannot get clock\n"); |
356 | ret = PTR_ERR(p->clk); |
357 | goto err1; |
358 | } |
359 | |
360 | if (request_irq(irq, em_sti_interrupt, |
361 | IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, |
362 | dev_name(&pdev->dev), p)) { |
363 | dev_err(&pdev->dev, "failed to request low IRQ\n"); |
364 | ret = -ENOENT; |
365 | goto err2; |
366 | } |
367 | |
368 | raw_spin_lock_init(&p->lock); |
369 | em_sti_register_clockevent(p); |
370 | em_sti_register_clocksource(p); |
371 | return 0; |
372 | |
373 | err2: |
374 | clk_put(p->clk); |
375 | err1: |
376 | iounmap(p->base); |
377 | err0: |
378 | kfree(p); |
379 | return ret; |
380 | } |
381 | |
382 | static int em_sti_remove(struct platform_device *pdev) |
383 | { |
384 | return -EBUSY; /* cannot unregister clockevent and clocksource */ |
385 | } |
386 | |
387 | static const struct of_device_id em_sti_dt_ids[] = { |
388 | { .compatible = "renesas,em-sti", }, |
389 | {}, |
390 | }; |
391 | MODULE_DEVICE_TABLE(of, em_sti_dt_ids); |
392 | |
393 | static struct platform_driver em_sti_device_driver = { |
394 | .probe = em_sti_probe, |
395 | .remove = em_sti_remove, |
396 | .driver = { |
397 | .name = "em_sti", |
398 | .of_match_table = em_sti_dt_ids, |
399 | } |
400 | }; |
401 | |
402 | module_platform_driver(em_sti_device_driver); |
403 | |
404 | MODULE_AUTHOR("Magnus Damm"); |
405 | MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); |
406 | MODULE_LICENSE("GPL v2"); |
407 |
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