1 /*
2  * Allwinner SoCs hstimer driver.
3  *
4  * Copyright (C) 2013 Maxime Ripard
5  *
6  * Maxime Ripard <maxime.ripard@free-electrons.com>
7  *
8  * This file is licensed under the terms of the GNU General Public
9  * License version 2.  This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  */
12 
13 #include <linux/clk.h>
14 #include <linux/clockchips.h>
15 #include <linux/clocksource.h>
16 #include <linux/delay.h>
17 #include <linux/interrupt.h>
18 #include <linux/irq.h>
19 #include <linux/irqreturn.h>
20 #include <linux/reset.h>
21 #include <linux/slab.h>
22 #include <linux/of.h>
23 #include <linux/of_address.h>
24 #include <linux/of_irq.h>
25 
26 #define TIMER_IRQ_EN_REG		0x00
27 #define TIMER_IRQ_EN(val)			BIT(val)
28 #define TIMER_IRQ_ST_REG		0x04
29 #define TIMER_CTL_REG(val)		(0x20 * (val) + 0x10)
30 #define TIMER_CTL_ENABLE			BIT(0)
31 #define TIMER_CTL_RELOAD			BIT(1)
32 #define TIMER_CTL_CLK_PRES(val)			(((val) & 0x7) << 4)
33 #define TIMER_CTL_ONESHOT			BIT(7)
34 #define TIMER_INTVAL_LO_REG(val)	(0x20 * (val) + 0x14)
35 #define TIMER_INTVAL_HI_REG(val)	(0x20 * (val) + 0x18)
36 #define TIMER_CNTVAL_LO_REG(val)	(0x20 * (val) + 0x1c)
37 #define TIMER_CNTVAL_HI_REG(val)	(0x20 * (val) + 0x20)
38 
39 #define TIMER_SYNC_TICKS	3
40 
41 struct sun5i_timer {
42 	void __iomem		*base;
43 	struct clk		*clk;
44 	struct notifier_block	clk_rate_cb;
45 	u32			ticks_per_jiffy;
46 };
47 
48 #define to_sun5i_timer(x) \
49 	container_of(x, struct sun5i_timer, clk_rate_cb)
50 
51 struct sun5i_timer_clksrc {
52 	struct sun5i_timer	timer;
53 	struct clocksource	clksrc;
54 };
55 
56 #define to_sun5i_timer_clksrc(x) \
57 	container_of(x, struct sun5i_timer_clksrc, clksrc)
58 
59 struct sun5i_timer_clkevt {
60 	struct sun5i_timer		timer;
61 	struct clock_event_device	clkevt;
62 };
63 
64 #define to_sun5i_timer_clkevt(x) \
65 	container_of(x, struct sun5i_timer_clkevt, clkevt)
66 
67 /*
68  * When we disable a timer, we need to wait at least for 2 cycles of
69  * the timer source clock. We will use for that the clocksource timer
70  * that is already setup and runs at the same frequency than the other
71  * timers, and we never will be disabled.
72  */
73 static void sun5i_clkevt_sync(struct sun5i_timer_clkevt *ce)
74 {
75 	u32 old = readl(ce->timer.base + TIMER_CNTVAL_LO_REG(1));
76 
77 	while ((old - readl(ce->timer.base + TIMER_CNTVAL_LO_REG(1))) < TIMER_SYNC_TICKS)
78 		cpu_relax();
79 }
80 
81 static void sun5i_clkevt_time_stop(struct sun5i_timer_clkevt *ce, u8 timer)
82 {
83 	u32 val = readl(ce->timer.base + TIMER_CTL_REG(timer));
84 	writel(val & ~TIMER_CTL_ENABLE, ce->timer.base + TIMER_CTL_REG(timer));
85 
86 	sun5i_clkevt_sync(ce);
87 }
88 
89 static void sun5i_clkevt_time_setup(struct sun5i_timer_clkevt *ce, u8 timer, u32 delay)
90 {
91 	writel(delay, ce->timer.base + TIMER_INTVAL_LO_REG(timer));
92 }
93 
94 static void sun5i_clkevt_time_start(struct sun5i_timer_clkevt *ce, u8 timer, bool periodic)
95 {
96 	u32 val = readl(ce->timer.base + TIMER_CTL_REG(timer));
97 
98 	if (periodic)
99 		val &= ~TIMER_CTL_ONESHOT;
100 	else
101 		val |= TIMER_CTL_ONESHOT;
102 
103 	writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
104 	       ce->timer.base + TIMER_CTL_REG(timer));
105 }
106 
107 static int sun5i_clkevt_shutdown(struct clock_event_device *clkevt)
108 {
109 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
110 
111 	sun5i_clkevt_time_stop(ce, 0);
112 	return 0;
113 }
114 
115 static int sun5i_clkevt_set_oneshot(struct clock_event_device *clkevt)
116 {
117 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
118 
119 	sun5i_clkevt_time_stop(ce, 0);
120 	sun5i_clkevt_time_start(ce, 0, false);
121 	return 0;
122 }
123 
124 static int sun5i_clkevt_set_periodic(struct clock_event_device *clkevt)
125 {
126 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
127 
128 	sun5i_clkevt_time_stop(ce, 0);
129 	sun5i_clkevt_time_setup(ce, 0, ce->timer.ticks_per_jiffy);
130 	sun5i_clkevt_time_start(ce, 0, true);
131 	return 0;
132 }
133 
134 static int sun5i_clkevt_next_event(unsigned long evt,
135 				   struct clock_event_device *clkevt)
136 {
137 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
138 
139 	sun5i_clkevt_time_stop(ce, 0);
140 	sun5i_clkevt_time_setup(ce, 0, evt - TIMER_SYNC_TICKS);
141 	sun5i_clkevt_time_start(ce, 0, false);
142 
143 	return 0;
144 }
145 
146 static irqreturn_t sun5i_timer_interrupt(int irq, void *dev_id)
147 {
148 	struct sun5i_timer_clkevt *ce = (struct sun5i_timer_clkevt *)dev_id;
149 
150 	writel(0x1, ce->timer.base + TIMER_IRQ_ST_REG);
151 	ce->clkevt.event_handler(&ce->clkevt);
152 
153 	return IRQ_HANDLED;
154 }
155 
156 static u64 sun5i_clksrc_read(struct clocksource *clksrc)
157 {
158 	struct sun5i_timer_clksrc *cs = to_sun5i_timer_clksrc(clksrc);
159 
160 	return ~readl(cs->timer.base + TIMER_CNTVAL_LO_REG(1));
161 }
162 
163 static int sun5i_rate_cb_clksrc(struct notifier_block *nb,
164 				unsigned long event, void *data)
165 {
166 	struct clk_notifier_data *ndata = data;
167 	struct sun5i_timer *timer = to_sun5i_timer(nb);
168 	struct sun5i_timer_clksrc *cs = container_of(timer, struct sun5i_timer_clksrc, timer);
169 
170 	switch (event) {
171 	case PRE_RATE_CHANGE:
172 		clocksource_unregister(&cs->clksrc);
173 		break;
174 
175 	case POST_RATE_CHANGE:
176 		clocksource_register_hz(&cs->clksrc, ndata->new_rate);
177 		break;
178 
179 	default:
180 		break;
181 	}
182 
183 	return NOTIFY_DONE;
184 }
185 
186 static int __init sun5i_setup_clocksource(struct device_node *node,
187 					  void __iomem *base,
188 					  struct clk *clk, int irq)
189 {
190 	struct sun5i_timer_clksrc *cs;
191 	unsigned long rate;
192 	int ret;
193 
194 	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
195 	if (!cs)
196 		return -ENOMEM;
197 
198 	ret = clk_prepare_enable(clk);
199 	if (ret) {
200 		pr_err("Couldn't enable parent clock\n");
201 		goto err_free;
202 	}
203 
204 	rate = clk_get_rate(clk);
205 	if (!rate) {
206 		pr_err("Couldn't get parent clock rate\n");
207 		ret = -EINVAL;
208 		goto err_disable_clk;
209 	}
210 
211 	cs->timer.base = base;
212 	cs->timer.clk = clk;
213 	cs->timer.clk_rate_cb.notifier_call = sun5i_rate_cb_clksrc;
214 	cs->timer.clk_rate_cb.next = NULL;
215 
216 	ret = clk_notifier_register(clk, &cs->timer.clk_rate_cb);
217 	if (ret) {
218 		pr_err("Unable to register clock notifier.\n");
219 		goto err_disable_clk;
220 	}
221 
222 	writel(~0, base + TIMER_INTVAL_LO_REG(1));
223 	writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
224 	       base + TIMER_CTL_REG(1));
225 
226 	cs->clksrc.name = node->name;
227 	cs->clksrc.rating = 340;
228 	cs->clksrc.read = sun5i_clksrc_read;
229 	cs->clksrc.mask = CLOCKSOURCE_MASK(32);
230 	cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
231 
232 	ret = clocksource_register_hz(&cs->clksrc, rate);
233 	if (ret) {
234 		pr_err("Couldn't register clock source.\n");
235 		goto err_remove_notifier;
236 	}
237 
238 	return 0;
239 
240 err_remove_notifier:
241 	clk_notifier_unregister(clk, &cs->timer.clk_rate_cb);
242 err_disable_clk:
243 	clk_disable_unprepare(clk);
244 err_free:
245 	kfree(cs);
246 	return ret;
247 }
248 
249 static int sun5i_rate_cb_clkevt(struct notifier_block *nb,
250 				unsigned long event, void *data)
251 {
252 	struct clk_notifier_data *ndata = data;
253 	struct sun5i_timer *timer = to_sun5i_timer(nb);
254 	struct sun5i_timer_clkevt *ce = container_of(timer, struct sun5i_timer_clkevt, timer);
255 
256 	if (event == POST_RATE_CHANGE) {
257 		clockevents_update_freq(&ce->clkevt, ndata->new_rate);
258 		ce->timer.ticks_per_jiffy = DIV_ROUND_UP(ndata->new_rate, HZ);
259 	}
260 
261 	return NOTIFY_DONE;
262 }
263 
264 static int __init sun5i_setup_clockevent(struct device_node *node, void __iomem *base,
265 					 struct clk *clk, int irq)
266 {
267 	struct sun5i_timer_clkevt *ce;
268 	unsigned long rate;
269 	int ret;
270 	u32 val;
271 
272 	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
273 	if (!ce)
274 		return -ENOMEM;
275 
276 	ret = clk_prepare_enable(clk);
277 	if (ret) {
278 		pr_err("Couldn't enable parent clock\n");
279 		goto err_free;
280 	}
281 
282 	rate = clk_get_rate(clk);
283 	if (!rate) {
284 		pr_err("Couldn't get parent clock rate\n");
285 		ret = -EINVAL;
286 		goto err_disable_clk;
287 	}
288 
289 	ce->timer.base = base;
290 	ce->timer.ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
291 	ce->timer.clk = clk;
292 	ce->timer.clk_rate_cb.notifier_call = sun5i_rate_cb_clkevt;
293 	ce->timer.clk_rate_cb.next = NULL;
294 
295 	ret = clk_notifier_register(clk, &ce->timer.clk_rate_cb);
296 	if (ret) {
297 		pr_err("Unable to register clock notifier.\n");
298 		goto err_disable_clk;
299 	}
300 
301 	ce->clkevt.name = node->name;
302 	ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
303 	ce->clkevt.set_next_event = sun5i_clkevt_next_event;
304 	ce->clkevt.set_state_shutdown = sun5i_clkevt_shutdown;
305 	ce->clkevt.set_state_periodic = sun5i_clkevt_set_periodic;
306 	ce->clkevt.set_state_oneshot = sun5i_clkevt_set_oneshot;
307 	ce->clkevt.tick_resume = sun5i_clkevt_shutdown;
308 	ce->clkevt.rating = 340;
309 	ce->clkevt.irq = irq;
310 	ce->clkevt.cpumask = cpu_possible_mask;
311 
312 	/* Enable timer0 interrupt */
313 	val = readl(base + TIMER_IRQ_EN_REG);
314 	writel(val | TIMER_IRQ_EN(0), base + TIMER_IRQ_EN_REG);
315 
316 	clockevents_config_and_register(&ce->clkevt, rate,
317 					TIMER_SYNC_TICKS, 0xffffffff);
318 
319 	ret = request_irq(irq, sun5i_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
320 			  "sun5i_timer0", ce);
321 	if (ret) {
322 		pr_err("Unable to register interrupt\n");
323 		goto err_remove_notifier;
324 	}
325 
326 	return 0;
327 
328 err_remove_notifier:
329 	clk_notifier_unregister(clk, &ce->timer.clk_rate_cb);
330 err_disable_clk:
331 	clk_disable_unprepare(clk);
332 err_free:
333 	kfree(ce);
334 	return ret;
335 }
336 
337 static int __init sun5i_timer_init(struct device_node *node)
338 {
339 	struct reset_control *rstc;
340 	void __iomem *timer_base;
341 	struct clk *clk;
342 	int irq, ret;
343 
344 	timer_base = of_io_request_and_map(node, 0, of_node_full_name(node));
345 	if (IS_ERR(timer_base)) {
346 		pr_err("Can't map registers\n");
347 		return PTR_ERR(timer_base);
348 	}
349 
350 	irq = irq_of_parse_and_map(node, 0);
351 	if (irq <= 0) {
352 		pr_err("Can't parse IRQ\n");
353 		return -EINVAL;
354 	}
355 
356 	clk = of_clk_get(node, 0);
357 	if (IS_ERR(clk)) {
358 		pr_err("Can't get timer clock\n");
359 		return PTR_ERR(clk);
360 	}
361 
362 	rstc = of_reset_control_get(node, NULL);
363 	if (!IS_ERR(rstc))
364 		reset_control_deassert(rstc);
365 
366 	ret = sun5i_setup_clocksource(node, timer_base, clk, irq);
367 	if (ret)
368 		return ret;
369 
370 	return sun5i_setup_clockevent(node, timer_base, clk, irq);
371 }
372 TIMER_OF_DECLARE(sun5i_a13, "allwinner,sun5i-a13-hstimer",
373 			   sun5i_timer_init);
374 TIMER_OF_DECLARE(sun7i_a20, "allwinner,sun7i-a20-hstimer",
375 			   sun5i_timer_init);
376