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/delay.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/irqreturn.h>
19 #include <linux/reset.h>
20 #include <linux/slab.h>
21 #include <linux/of.h>
22 #include <linux/of_address.h>
23 #include <linux/of_irq.h>
24 
25 #define TIMER_IRQ_EN_REG		0x00
26 #define TIMER_IRQ_EN(val)			BIT(val)
27 #define TIMER_IRQ_ST_REG		0x04
28 #define TIMER_CTL_REG(val)		(0x20 * (val) + 0x10)
29 #define TIMER_CTL_ENABLE			BIT(0)
30 #define TIMER_CTL_RELOAD			BIT(1)
31 #define TIMER_CTL_CLK_PRES(val)			(((val) & 0x7) << 4)
32 #define TIMER_CTL_ONESHOT			BIT(7)
33 #define TIMER_INTVAL_LO_REG(val)	(0x20 * (val) + 0x14)
34 #define TIMER_INTVAL_HI_REG(val)	(0x20 * (val) + 0x18)
35 #define TIMER_CNTVAL_LO_REG(val)	(0x20 * (val) + 0x1c)
36 #define TIMER_CNTVAL_HI_REG(val)	(0x20 * (val) + 0x20)
37 
38 #define TIMER_SYNC_TICKS	3
39 
40 struct sun5i_timer {
41 	void __iomem		*base;
42 	struct clk		*clk;
43 	struct notifier_block	clk_rate_cb;
44 	u32			ticks_per_jiffy;
45 };
46 
47 #define to_sun5i_timer(x) \
48 	container_of(x, struct sun5i_timer, clk_rate_cb)
49 
50 struct sun5i_timer_clksrc {
51 	struct sun5i_timer	timer;
52 	struct clocksource	clksrc;
53 };
54 
55 #define to_sun5i_timer_clksrc(x) \
56 	container_of(x, struct sun5i_timer_clksrc, clksrc)
57 
58 struct sun5i_timer_clkevt {
59 	struct sun5i_timer		timer;
60 	struct clock_event_device	clkevt;
61 };
62 
63 #define to_sun5i_timer_clkevt(x) \
64 	container_of(x, struct sun5i_timer_clkevt, clkevt)
65 
66 /*
67  * When we disable a timer, we need to wait at least for 2 cycles of
68  * the timer source clock. We will use for that the clocksource timer
69  * that is already setup and runs at the same frequency than the other
70  * timers, and we never will be disabled.
71  */
72 static void sun5i_clkevt_sync(struct sun5i_timer_clkevt *ce)
73 {
74 	u32 old = readl(ce->timer.base + TIMER_CNTVAL_LO_REG(1));
75 
76 	while ((old - readl(ce->timer.base + TIMER_CNTVAL_LO_REG(1))) < TIMER_SYNC_TICKS)
77 		cpu_relax();
78 }
79 
80 static void sun5i_clkevt_time_stop(struct sun5i_timer_clkevt *ce, u8 timer)
81 {
82 	u32 val = readl(ce->timer.base + TIMER_CTL_REG(timer));
83 	writel(val & ~TIMER_CTL_ENABLE, ce->timer.base + TIMER_CTL_REG(timer));
84 
85 	sun5i_clkevt_sync(ce);
86 }
87 
88 static void sun5i_clkevt_time_setup(struct sun5i_timer_clkevt *ce, u8 timer, u32 delay)
89 {
90 	writel(delay, ce->timer.base + TIMER_INTVAL_LO_REG(timer));
91 }
92 
93 static void sun5i_clkevt_time_start(struct sun5i_timer_clkevt *ce, u8 timer, bool periodic)
94 {
95 	u32 val = readl(ce->timer.base + TIMER_CTL_REG(timer));
96 
97 	if (periodic)
98 		val &= ~TIMER_CTL_ONESHOT;
99 	else
100 		val |= TIMER_CTL_ONESHOT;
101 
102 	writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
103 	       ce->timer.base + TIMER_CTL_REG(timer));
104 }
105 
106 static int sun5i_clkevt_shutdown(struct clock_event_device *clkevt)
107 {
108 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
109 
110 	sun5i_clkevt_time_stop(ce, 0);
111 	return 0;
112 }
113 
114 static int sun5i_clkevt_set_oneshot(struct clock_event_device *clkevt)
115 {
116 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
117 
118 	sun5i_clkevt_time_stop(ce, 0);
119 	sun5i_clkevt_time_start(ce, 0, false);
120 	return 0;
121 }
122 
123 static int sun5i_clkevt_set_periodic(struct clock_event_device *clkevt)
124 {
125 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
126 
127 	sun5i_clkevt_time_stop(ce, 0);
128 	sun5i_clkevt_time_setup(ce, 0, ce->timer.ticks_per_jiffy);
129 	sun5i_clkevt_time_start(ce, 0, true);
130 	return 0;
131 }
132 
133 static int sun5i_clkevt_next_event(unsigned long evt,
134 				   struct clock_event_device *clkevt)
135 {
136 	struct sun5i_timer_clkevt *ce = to_sun5i_timer_clkevt(clkevt);
137 
138 	sun5i_clkevt_time_stop(ce, 0);
139 	sun5i_clkevt_time_setup(ce, 0, evt - TIMER_SYNC_TICKS);
140 	sun5i_clkevt_time_start(ce, 0, false);
141 
142 	return 0;
143 }
144 
145 static irqreturn_t sun5i_timer_interrupt(int irq, void *dev_id)
146 {
147 	struct sun5i_timer_clkevt *ce = (struct sun5i_timer_clkevt *)dev_id;
148 
149 	writel(0x1, ce->timer.base + TIMER_IRQ_ST_REG);
150 	ce->clkevt.event_handler(&ce->clkevt);
151 
152 	return IRQ_HANDLED;
153 }
154 
155 static int sun5i_rate_cb_clksrc(struct notifier_block *nb,
156 				unsigned long event, void *data)
157 {
158 	struct clk_notifier_data *ndata = data;
159 	struct sun5i_timer *timer = to_sun5i_timer(nb);
160 	struct sun5i_timer_clksrc *cs = container_of(timer, struct sun5i_timer_clksrc, timer);
161 
162 	switch (event) {
163 	case PRE_RATE_CHANGE:
164 		clocksource_unregister(&cs->clksrc);
165 		break;
166 
167 	case POST_RATE_CHANGE:
168 		clocksource_register_hz(&cs->clksrc, ndata->new_rate);
169 		break;
170 
171 	default:
172 		break;
173 	}
174 
175 	return NOTIFY_DONE;
176 }
177 
178 static int __init sun5i_setup_clocksource(struct device_node *node,
179 					  void __iomem *base,
180 					  struct clk *clk, int irq)
181 {
182 	struct sun5i_timer_clksrc *cs;
183 	unsigned long rate;
184 	int ret;
185 
186 	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
187 	if (!cs)
188 		return -ENOMEM;
189 
190 	ret = clk_prepare_enable(clk);
191 	if (ret) {
192 		pr_err("Couldn't enable parent clock\n");
193 		goto err_free;
194 	}
195 
196 	rate = clk_get_rate(clk);
197 
198 	cs->timer.base = base;
199 	cs->timer.clk = clk;
200 	cs->timer.clk_rate_cb.notifier_call = sun5i_rate_cb_clksrc;
201 	cs->timer.clk_rate_cb.next = NULL;
202 
203 	ret = clk_notifier_register(clk, &cs->timer.clk_rate_cb);
204 	if (ret) {
205 		pr_err("Unable to register clock notifier.\n");
206 		goto err_disable_clk;
207 	}
208 
209 	writel(~0, base + TIMER_INTVAL_LO_REG(1));
210 	writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
211 	       base + TIMER_CTL_REG(1));
212 
213 	ret = clocksource_mmio_init(base + TIMER_CNTVAL_LO_REG(1), node->name,
214 				    rate, 340, 32, clocksource_mmio_readl_down);
215 	if (ret) {
216 		pr_err("Couldn't register clock source.\n");
217 		goto err_remove_notifier;
218 	}
219 
220 	return 0;
221 
222 err_remove_notifier:
223 	clk_notifier_unregister(clk, &cs->timer.clk_rate_cb);
224 err_disable_clk:
225 	clk_disable_unprepare(clk);
226 err_free:
227 	kfree(cs);
228 	return ret;
229 }
230 
231 static int sun5i_rate_cb_clkevt(struct notifier_block *nb,
232 				unsigned long event, void *data)
233 {
234 	struct clk_notifier_data *ndata = data;
235 	struct sun5i_timer *timer = to_sun5i_timer(nb);
236 	struct sun5i_timer_clkevt *ce = container_of(timer, struct sun5i_timer_clkevt, timer);
237 
238 	if (event == POST_RATE_CHANGE) {
239 		clockevents_update_freq(&ce->clkevt, ndata->new_rate);
240 		ce->timer.ticks_per_jiffy = DIV_ROUND_UP(ndata->new_rate, HZ);
241 	}
242 
243 	return NOTIFY_DONE;
244 }
245 
246 static int __init sun5i_setup_clockevent(struct device_node *node, void __iomem *base,
247 					 struct clk *clk, int irq)
248 {
249 	struct sun5i_timer_clkevt *ce;
250 	unsigned long rate;
251 	int ret;
252 	u32 val;
253 
254 	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
255 	if (!ce)
256 		return -ENOMEM;
257 
258 	ret = clk_prepare_enable(clk);
259 	if (ret) {
260 		pr_err("Couldn't enable parent clock\n");
261 		goto err_free;
262 	}
263 
264 	rate = clk_get_rate(clk);
265 
266 	ce->timer.base = base;
267 	ce->timer.ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
268 	ce->timer.clk = clk;
269 	ce->timer.clk_rate_cb.notifier_call = sun5i_rate_cb_clkevt;
270 	ce->timer.clk_rate_cb.next = NULL;
271 
272 	ret = clk_notifier_register(clk, &ce->timer.clk_rate_cb);
273 	if (ret) {
274 		pr_err("Unable to register clock notifier.\n");
275 		goto err_disable_clk;
276 	}
277 
278 	ce->clkevt.name = node->name;
279 	ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
280 	ce->clkevt.set_next_event = sun5i_clkevt_next_event;
281 	ce->clkevt.set_state_shutdown = sun5i_clkevt_shutdown;
282 	ce->clkevt.set_state_periodic = sun5i_clkevt_set_periodic;
283 	ce->clkevt.set_state_oneshot = sun5i_clkevt_set_oneshot;
284 	ce->clkevt.tick_resume = sun5i_clkevt_shutdown;
285 	ce->clkevt.rating = 340;
286 	ce->clkevt.irq = irq;
287 	ce->clkevt.cpumask = cpu_possible_mask;
288 
289 	/* Enable timer0 interrupt */
290 	val = readl(base + TIMER_IRQ_EN_REG);
291 	writel(val | TIMER_IRQ_EN(0), base + TIMER_IRQ_EN_REG);
292 
293 	clockevents_config_and_register(&ce->clkevt, rate,
294 					TIMER_SYNC_TICKS, 0xffffffff);
295 
296 	ret = request_irq(irq, sun5i_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
297 			  "sun5i_timer0", ce);
298 	if (ret) {
299 		pr_err("Unable to register interrupt\n");
300 		goto err_remove_notifier;
301 	}
302 
303 	return 0;
304 
305 err_remove_notifier:
306 	clk_notifier_unregister(clk, &ce->timer.clk_rate_cb);
307 err_disable_clk:
308 	clk_disable_unprepare(clk);
309 err_free:
310 	kfree(ce);
311 	return ret;
312 }
313 
314 static void __init sun5i_timer_init(struct device_node *node)
315 {
316 	struct reset_control *rstc;
317 	void __iomem *timer_base;
318 	struct clk *clk;
319 	int irq;
320 
321 	timer_base = of_io_request_and_map(node, 0, of_node_full_name(node));
322 	if (IS_ERR(timer_base))
323 		panic("Can't map registers");
324 
325 	irq = irq_of_parse_and_map(node, 0);
326 	if (irq <= 0)
327 		panic("Can't parse IRQ");
328 
329 	clk = of_clk_get(node, 0);
330 	if (IS_ERR(clk))
331 		panic("Can't get timer clock");
332 
333 	rstc = of_reset_control_get(node, NULL);
334 	if (!IS_ERR(rstc))
335 		reset_control_deassert(rstc);
336 
337 	sun5i_setup_clocksource(node, timer_base, clk, irq);
338 	sun5i_setup_clockevent(node, timer_base, clk, irq);
339 }
340 CLOCKSOURCE_OF_DECLARE(sun5i_a13, "allwinner,sun5i-a13-hstimer",
341 		       sun5i_timer_init);
342 CLOCKSOURCE_OF_DECLARE(sun7i_a20, "allwinner,sun7i-a20-hstimer",
343 		       sun5i_timer_init);
344