1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Emma Mobile Timer Support - STI
4  *
5  *  Copyright (C) 2012 Magnus Damm
6  */
7 
8 #include <linux/init.h>
9 #include <linux/platform_device.h>
10 #include <linux/spinlock.h>
11 #include <linux/interrupt.h>
12 #include <linux/ioport.h>
13 #include <linux/io.h>
14 #include <linux/clk.h>
15 #include <linux/irq.h>
16 #include <linux/err.h>
17 #include <linux/delay.h>
18 #include <linux/clocksource.h>
19 #include <linux/clockchips.h>
20 #include <linux/slab.h>
21 #include <linux/module.h>
22 
23 enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
24 
25 struct em_sti_priv {
26 	void __iomem *base;
27 	struct clk *clk;
28 	struct platform_device *pdev;
29 	unsigned int active[USER_NR];
30 	unsigned long rate;
31 	raw_spinlock_t lock;
32 	struct clock_event_device ced;
33 	struct clocksource cs;
34 };
35 
36 #define STI_CONTROL 0x00
37 #define STI_COMPA_H 0x10
38 #define STI_COMPA_L 0x14
39 #define STI_COMPB_H 0x18
40 #define STI_COMPB_L 0x1c
41 #define STI_COUNT_H 0x20
42 #define STI_COUNT_L 0x24
43 #define STI_COUNT_RAW_H 0x28
44 #define STI_COUNT_RAW_L 0x2c
45 #define STI_SET_H 0x30
46 #define STI_SET_L 0x34
47 #define STI_INTSTATUS 0x40
48 #define STI_INTRAWSTATUS 0x44
49 #define STI_INTENSET 0x48
50 #define STI_INTENCLR 0x4c
51 #define STI_INTFFCLR 0x50
52 
em_sti_read(struct em_sti_priv * p,int offs)53 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
54 {
55 	return ioread32(p->base + offs);
56 }
57 
em_sti_write(struct em_sti_priv * p,int offs,unsigned long value)58 static inline void em_sti_write(struct em_sti_priv *p, int offs,
59 				unsigned long value)
60 {
61 	iowrite32(value, p->base + offs);
62 }
63 
em_sti_enable(struct em_sti_priv * p)64 static int em_sti_enable(struct em_sti_priv *p)
65 {
66 	int ret;
67 
68 	/* enable clock */
69 	ret = clk_enable(p->clk);
70 	if (ret) {
71 		dev_err(&p->pdev->dev, "cannot enable clock\n");
72 		return ret;
73 	}
74 
75 	/* reset the counter */
76 	em_sti_write(p, STI_SET_H, 0x40000000);
77 	em_sti_write(p, STI_SET_L, 0x00000000);
78 
79 	/* mask and clear pending interrupts */
80 	em_sti_write(p, STI_INTENCLR, 3);
81 	em_sti_write(p, STI_INTFFCLR, 3);
82 
83 	/* enable updates of counter registers */
84 	em_sti_write(p, STI_CONTROL, 1);
85 
86 	return 0;
87 }
88 
em_sti_disable(struct em_sti_priv * p)89 static void em_sti_disable(struct em_sti_priv *p)
90 {
91 	/* mask interrupts */
92 	em_sti_write(p, STI_INTENCLR, 3);
93 
94 	/* stop clock */
95 	clk_disable(p->clk);
96 }
97 
em_sti_count(struct em_sti_priv * p)98 static u64 em_sti_count(struct em_sti_priv *p)
99 {
100 	u64 ticks;
101 	unsigned long flags;
102 
103 	/* the STI hardware buffers the 48-bit count, but to
104 	 * break it out into two 32-bit access the registers
105 	 * must be accessed in a certain order.
106 	 * Always read STI_COUNT_H before STI_COUNT_L.
107 	 */
108 	raw_spin_lock_irqsave(&p->lock, flags);
109 	ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
110 	ticks |= em_sti_read(p, STI_COUNT_L);
111 	raw_spin_unlock_irqrestore(&p->lock, flags);
112 
113 	return ticks;
114 }
115 
em_sti_set_next(struct em_sti_priv * p,u64 next)116 static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
117 {
118 	unsigned long flags;
119 
120 	raw_spin_lock_irqsave(&p->lock, flags);
121 
122 	/* mask compare A interrupt */
123 	em_sti_write(p, STI_INTENCLR, 1);
124 
125 	/* update compare A value */
126 	em_sti_write(p, STI_COMPA_H, next >> 32);
127 	em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
128 
129 	/* clear compare A interrupt source */
130 	em_sti_write(p, STI_INTFFCLR, 1);
131 
132 	/* unmask compare A interrupt */
133 	em_sti_write(p, STI_INTENSET, 1);
134 
135 	raw_spin_unlock_irqrestore(&p->lock, flags);
136 
137 	return next;
138 }
139 
em_sti_interrupt(int irq,void * dev_id)140 static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
141 {
142 	struct em_sti_priv *p = dev_id;
143 
144 	p->ced.event_handler(&p->ced);
145 	return IRQ_HANDLED;
146 }
147 
em_sti_start(struct em_sti_priv * p,unsigned int user)148 static int em_sti_start(struct em_sti_priv *p, unsigned int user)
149 {
150 	unsigned long flags;
151 	int used_before;
152 	int ret = 0;
153 
154 	raw_spin_lock_irqsave(&p->lock, flags);
155 	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
156 	if (!used_before)
157 		ret = em_sti_enable(p);
158 
159 	if (!ret)
160 		p->active[user] = 1;
161 	raw_spin_unlock_irqrestore(&p->lock, flags);
162 
163 	return ret;
164 }
165 
em_sti_stop(struct em_sti_priv * p,unsigned int user)166 static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
167 {
168 	unsigned long flags;
169 	int used_before, used_after;
170 
171 	raw_spin_lock_irqsave(&p->lock, flags);
172 	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
173 	p->active[user] = 0;
174 	used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
175 
176 	if (used_before && !used_after)
177 		em_sti_disable(p);
178 	raw_spin_unlock_irqrestore(&p->lock, flags);
179 }
180 
cs_to_em_sti(struct clocksource * cs)181 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
182 {
183 	return container_of(cs, struct em_sti_priv, cs);
184 }
185 
em_sti_clocksource_read(struct clocksource * cs)186 static u64 em_sti_clocksource_read(struct clocksource *cs)
187 {
188 	return em_sti_count(cs_to_em_sti(cs));
189 }
190 
em_sti_clocksource_enable(struct clocksource * cs)191 static int em_sti_clocksource_enable(struct clocksource *cs)
192 {
193 	struct em_sti_priv *p = cs_to_em_sti(cs);
194 
195 	return em_sti_start(p, USER_CLOCKSOURCE);
196 }
197 
em_sti_clocksource_disable(struct clocksource * cs)198 static void em_sti_clocksource_disable(struct clocksource *cs)
199 {
200 	em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
201 }
202 
em_sti_clocksource_resume(struct clocksource * cs)203 static void em_sti_clocksource_resume(struct clocksource *cs)
204 {
205 	em_sti_clocksource_enable(cs);
206 }
207 
em_sti_register_clocksource(struct em_sti_priv * p)208 static int em_sti_register_clocksource(struct em_sti_priv *p)
209 {
210 	struct clocksource *cs = &p->cs;
211 
212 	cs->name = dev_name(&p->pdev->dev);
213 	cs->rating = 200;
214 	cs->read = em_sti_clocksource_read;
215 	cs->enable = em_sti_clocksource_enable;
216 	cs->disable = em_sti_clocksource_disable;
217 	cs->suspend = em_sti_clocksource_disable;
218 	cs->resume = em_sti_clocksource_resume;
219 	cs->mask = CLOCKSOURCE_MASK(48);
220 	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
221 
222 	dev_info(&p->pdev->dev, "used as clock source\n");
223 
224 	clocksource_register_hz(cs, p->rate);
225 	return 0;
226 }
227 
ced_to_em_sti(struct clock_event_device * ced)228 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
229 {
230 	return container_of(ced, struct em_sti_priv, ced);
231 }
232 
em_sti_clock_event_shutdown(struct clock_event_device * ced)233 static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
234 {
235 	struct em_sti_priv *p = ced_to_em_sti(ced);
236 	em_sti_stop(p, USER_CLOCKEVENT);
237 	return 0;
238 }
239 
em_sti_clock_event_set_oneshot(struct clock_event_device * ced)240 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
241 {
242 	struct em_sti_priv *p = ced_to_em_sti(ced);
243 
244 	dev_info(&p->pdev->dev, "used for oneshot clock events\n");
245 	em_sti_start(p, USER_CLOCKEVENT);
246 	return 0;
247 }
248 
em_sti_clock_event_next(unsigned long delta,struct clock_event_device * ced)249 static int em_sti_clock_event_next(unsigned long delta,
250 				   struct clock_event_device *ced)
251 {
252 	struct em_sti_priv *p = ced_to_em_sti(ced);
253 	u64 next;
254 	int safe;
255 
256 	next = em_sti_set_next(p, em_sti_count(p) + delta);
257 	safe = em_sti_count(p) < (next - 1);
258 
259 	return !safe;
260 }
261 
em_sti_register_clockevent(struct em_sti_priv * p)262 static void em_sti_register_clockevent(struct em_sti_priv *p)
263 {
264 	struct clock_event_device *ced = &p->ced;
265 
266 	ced->name = dev_name(&p->pdev->dev);
267 	ced->features = CLOCK_EVT_FEAT_ONESHOT;
268 	ced->rating = 200;
269 	ced->cpumask = cpu_possible_mask;
270 	ced->set_next_event = em_sti_clock_event_next;
271 	ced->set_state_shutdown = em_sti_clock_event_shutdown;
272 	ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
273 
274 	dev_info(&p->pdev->dev, "used for clock events\n");
275 
276 	clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
277 }
278 
em_sti_probe(struct platform_device * pdev)279 static int em_sti_probe(struct platform_device *pdev)
280 {
281 	struct em_sti_priv *p;
282 	int irq, ret;
283 
284 	p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
285 	if (p == NULL)
286 		return -ENOMEM;
287 
288 	p->pdev = pdev;
289 	platform_set_drvdata(pdev, p);
290 
291 	irq = platform_get_irq(pdev, 0);
292 	if (irq < 0)
293 		return irq;
294 
295 	/* map memory, let base point to the STI instance */
296 	p->base = devm_platform_ioremap_resource(pdev, 0);
297 	if (IS_ERR(p->base))
298 		return PTR_ERR(p->base);
299 
300 	ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
301 			       IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
302 			       dev_name(&pdev->dev), p);
303 	if (ret) {
304 		dev_err(&pdev->dev, "failed to request low IRQ\n");
305 		return ret;
306 	}
307 
308 	/* get hold of clock */
309 	p->clk = devm_clk_get(&pdev->dev, "sclk");
310 	if (IS_ERR(p->clk)) {
311 		dev_err(&pdev->dev, "cannot get clock\n");
312 		return PTR_ERR(p->clk);
313 	}
314 
315 	ret = clk_prepare(p->clk);
316 	if (ret < 0) {
317 		dev_err(&pdev->dev, "cannot prepare clock\n");
318 		return ret;
319 	}
320 
321 	ret = clk_enable(p->clk);
322 	if (ret < 0) {
323 		dev_err(&p->pdev->dev, "cannot enable clock\n");
324 		clk_unprepare(p->clk);
325 		return ret;
326 	}
327 	p->rate = clk_get_rate(p->clk);
328 	clk_disable(p->clk);
329 
330 	raw_spin_lock_init(&p->lock);
331 	em_sti_register_clockevent(p);
332 	em_sti_register_clocksource(p);
333 	return 0;
334 }
335 
em_sti_remove(struct platform_device * pdev)336 static int em_sti_remove(struct platform_device *pdev)
337 {
338 	return -EBUSY; /* cannot unregister clockevent and clocksource */
339 }
340 
341 static const struct of_device_id em_sti_dt_ids[] = {
342 	{ .compatible = "renesas,em-sti", },
343 	{},
344 };
345 MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
346 
347 static struct platform_driver em_sti_device_driver = {
348 	.probe		= em_sti_probe,
349 	.remove		= em_sti_remove,
350 	.driver		= {
351 		.name	= "em_sti",
352 		.of_match_table = em_sti_dt_ids,
353 	}
354 };
355 
em_sti_init(void)356 static int __init em_sti_init(void)
357 {
358 	return platform_driver_register(&em_sti_device_driver);
359 }
360 
em_sti_exit(void)361 static void __exit em_sti_exit(void)
362 {
363 	platform_driver_unregister(&em_sti_device_driver);
364 }
365 
366 subsys_initcall(em_sti_init);
367 module_exit(em_sti_exit);
368 
369 MODULE_AUTHOR("Magnus Damm");
370 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
371 MODULE_LICENSE("GPL v2");
372