1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * TI DaVinci clocksource driver
4  *
5  * Copyright (C) 2019 Texas Instruments
6  * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
7  * (with tiny parts adopted from code by Kevin Hilman <khilman@baylibre.com>)
8  */
9 
10 #include <linux/clk.h>
11 #include <linux/clockchips.h>
12 #include <linux/interrupt.h>
13 #include <linux/kernel.h>
14 #include <linux/of_address.h>
15 #include <linux/of_irq.h>
16 #include <linux/sched_clock.h>
17 
18 #include <clocksource/timer-davinci.h>
19 
20 #undef pr_fmt
21 #define pr_fmt(fmt) "%s: " fmt, __func__
22 
23 #define DAVINCI_TIMER_REG_TIM12			0x10
24 #define DAVINCI_TIMER_REG_TIM34			0x14
25 #define DAVINCI_TIMER_REG_PRD12			0x18
26 #define DAVINCI_TIMER_REG_PRD34			0x1c
27 #define DAVINCI_TIMER_REG_TCR			0x20
28 #define DAVINCI_TIMER_REG_TGCR			0x24
29 
30 #define DAVINCI_TIMER_TIMMODE_MASK		GENMASK(3, 2)
31 #define DAVINCI_TIMER_RESET_MASK		GENMASK(1, 0)
32 #define DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED	BIT(2)
33 #define DAVINCI_TIMER_UNRESET			GENMASK(1, 0)
34 
35 #define DAVINCI_TIMER_ENAMODE_MASK		GENMASK(1, 0)
36 #define DAVINCI_TIMER_ENAMODE_DISABLED		0x00
37 #define DAVINCI_TIMER_ENAMODE_ONESHOT		BIT(0)
38 #define DAVINCI_TIMER_ENAMODE_PERIODIC		BIT(1)
39 
40 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM12	6
41 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM34	22
42 
43 #define DAVINCI_TIMER_MIN_DELTA			0x01
44 #define DAVINCI_TIMER_MAX_DELTA			0xfffffffe
45 
46 #define DAVINCI_TIMER_CLKSRC_BITS		32
47 
48 #define DAVINCI_TIMER_TGCR_DEFAULT \
49 		(DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED | DAVINCI_TIMER_UNRESET)
50 
51 struct davinci_clockevent {
52 	struct clock_event_device dev;
53 	void __iomem *base;
54 	unsigned int cmp_off;
55 };
56 
57 /*
58  * This must be globally accessible by davinci_timer_read_sched_clock(), so
59  * let's keep it here.
60  */
61 static struct {
62 	struct clocksource dev;
63 	void __iomem *base;
64 	unsigned int tim_off;
65 } davinci_clocksource;
66 
67 static struct davinci_clockevent *
68 to_davinci_clockevent(struct clock_event_device *clockevent)
69 {
70 	return container_of(clockevent, struct davinci_clockevent, dev);
71 }
72 
73 static unsigned int
74 davinci_clockevent_read(struct davinci_clockevent *clockevent,
75 			unsigned int reg)
76 {
77 	return readl_relaxed(clockevent->base + reg);
78 }
79 
80 static void davinci_clockevent_write(struct davinci_clockevent *clockevent,
81 				     unsigned int reg, unsigned int val)
82 {
83 	writel_relaxed(val, clockevent->base + reg);
84 }
85 
86 static void davinci_tim12_shutdown(void __iomem *base)
87 {
88 	unsigned int tcr;
89 
90 	tcr = DAVINCI_TIMER_ENAMODE_DISABLED <<
91 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
92 	/*
93 	 * This function is only ever called if we're using both timer
94 	 * halves. In this case TIM34 runs in periodic mode and we must
95 	 * not modify it.
96 	 */
97 	tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
98 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
99 
100 	writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
101 }
102 
103 static void davinci_tim12_set_oneshot(void __iomem *base)
104 {
105 	unsigned int tcr;
106 
107 	tcr = DAVINCI_TIMER_ENAMODE_ONESHOT <<
108 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
109 	/* Same as above. */
110 	tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
111 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
112 
113 	writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
114 }
115 
116 static int davinci_clockevent_shutdown(struct clock_event_device *dev)
117 {
118 	struct davinci_clockevent *clockevent;
119 
120 	clockevent = to_davinci_clockevent(dev);
121 
122 	davinci_tim12_shutdown(clockevent->base);
123 
124 	return 0;
125 }
126 
127 static int davinci_clockevent_set_oneshot(struct clock_event_device *dev)
128 {
129 	struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
130 
131 	davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
132 
133 	davinci_tim12_set_oneshot(clockevent->base);
134 
135 	return 0;
136 }
137 
138 static int
139 davinci_clockevent_set_next_event_std(unsigned long cycles,
140 				      struct clock_event_device *dev)
141 {
142 	struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
143 
144 	davinci_clockevent_shutdown(dev);
145 
146 	davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
147 	davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_PRD12, cycles);
148 
149 	davinci_clockevent_set_oneshot(dev);
150 
151 	return 0;
152 }
153 
154 static int
155 davinci_clockevent_set_next_event_cmp(unsigned long cycles,
156 				      struct clock_event_device *dev)
157 {
158 	struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
159 	unsigned int curr_time;
160 
161 	curr_time = davinci_clockevent_read(clockevent,
162 					    DAVINCI_TIMER_REG_TIM12);
163 	davinci_clockevent_write(clockevent,
164 				 clockevent->cmp_off, curr_time + cycles);
165 
166 	return 0;
167 }
168 
169 static irqreturn_t davinci_timer_irq_timer(int irq, void *data)
170 {
171 	struct davinci_clockevent *clockevent = data;
172 
173 	if (!clockevent_state_oneshot(&clockevent->dev))
174 		davinci_tim12_shutdown(clockevent->base);
175 
176 	clockevent->dev.event_handler(&clockevent->dev);
177 
178 	return IRQ_HANDLED;
179 }
180 
181 static u64 notrace davinci_timer_read_sched_clock(void)
182 {
183 	return readl_relaxed(davinci_clocksource.base +
184 			     davinci_clocksource.tim_off);
185 }
186 
187 static u64 davinci_clocksource_read(struct clocksource *dev)
188 {
189 	return davinci_timer_read_sched_clock();
190 }
191 
192 /*
193  * Standard use-case: we're using tim12 for clockevent and tim34 for
194  * clocksource. The default is making the former run in oneshot mode
195  * and the latter in periodic mode.
196  */
197 static void davinci_clocksource_init_tim34(void __iomem *base)
198 {
199 	int tcr;
200 
201 	tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
202 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
203 	tcr |= DAVINCI_TIMER_ENAMODE_ONESHOT <<
204 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
205 
206 	writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
207 	writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD34);
208 	writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
209 }
210 
211 /*
212  * Special use-case on da830: the DSP may use tim34. We're using tim12 for
213  * both clocksource and clockevent. We set tim12 to periodic and don't touch
214  * tim34.
215  */
216 static void davinci_clocksource_init_tim12(void __iomem *base)
217 {
218 	unsigned int tcr;
219 
220 	tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
221 		DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
222 
223 	writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
224 	writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD12);
225 	writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
226 }
227 
228 static void davinci_timer_init(void __iomem *base)
229 {
230 	/* Set clock to internal mode and disable it. */
231 	writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TCR);
232 	/*
233 	 * Reset both 32-bit timers, set no prescaler for timer 34, set the
234 	 * timer to dual 32-bit unchained mode, unreset both 32-bit timers.
235 	 */
236 	writel_relaxed(DAVINCI_TIMER_TGCR_DEFAULT,
237 		       base + DAVINCI_TIMER_REG_TGCR);
238 	/* Init both counters to zero. */
239 	writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
240 	writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
241 }
242 
243 int __init davinci_timer_register(struct clk *clk,
244 				  const struct davinci_timer_cfg *timer_cfg)
245 {
246 	struct davinci_clockevent *clockevent;
247 	unsigned int tick_rate;
248 	void __iomem *base;
249 	int rv;
250 
251 	rv = clk_prepare_enable(clk);
252 	if (rv) {
253 		pr_err("Unable to prepare and enable the timer clock\n");
254 		return rv;
255 	}
256 
257 	if (!request_mem_region(timer_cfg->reg.start,
258 				resource_size(&timer_cfg->reg),
259 				"davinci-timer")) {
260 		pr_err("Unable to request memory region\n");
261 		return -EBUSY;
262 	}
263 
264 	base = ioremap(timer_cfg->reg.start, resource_size(&timer_cfg->reg));
265 	if (!base) {
266 		pr_err("Unable to map the register range\n");
267 		return -ENOMEM;
268 	}
269 
270 	davinci_timer_init(base);
271 	tick_rate = clk_get_rate(clk);
272 
273 	clockevent = kzalloc(sizeof(*clockevent), GFP_KERNEL);
274 	if (!clockevent)
275 		return -ENOMEM;
276 
277 	clockevent->dev.name = "tim12";
278 	clockevent->dev.features = CLOCK_EVT_FEAT_ONESHOT;
279 	clockevent->dev.cpumask = cpumask_of(0);
280 	clockevent->base = base;
281 
282 	if (timer_cfg->cmp_off) {
283 		clockevent->cmp_off = timer_cfg->cmp_off;
284 		clockevent->dev.set_next_event =
285 				davinci_clockevent_set_next_event_cmp;
286 	} else {
287 		clockevent->dev.set_next_event =
288 				davinci_clockevent_set_next_event_std;
289 		clockevent->dev.set_state_oneshot =
290 				davinci_clockevent_set_oneshot;
291 		clockevent->dev.set_state_shutdown =
292 				davinci_clockevent_shutdown;
293 	}
294 
295 	rv = request_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
296 			 davinci_timer_irq_timer, IRQF_TIMER,
297 			 "clockevent/tim12", clockevent);
298 	if (rv) {
299 		pr_err("Unable to request the clockevent interrupt\n");
300 		return rv;
301 	}
302 
303 	davinci_clocksource.dev.rating = 300;
304 	davinci_clocksource.dev.read = davinci_clocksource_read;
305 	davinci_clocksource.dev.mask =
306 			CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
307 	davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
308 	davinci_clocksource.base = base;
309 
310 	if (timer_cfg->cmp_off) {
311 		davinci_clocksource.dev.name = "tim12";
312 		davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
313 		davinci_clocksource_init_tim12(base);
314 	} else {
315 		davinci_clocksource.dev.name = "tim34";
316 		davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
317 		davinci_clocksource_init_tim34(base);
318 	}
319 
320 	clockevents_config_and_register(&clockevent->dev, tick_rate,
321 					DAVINCI_TIMER_MIN_DELTA,
322 					DAVINCI_TIMER_MAX_DELTA);
323 
324 	rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
325 	if (rv) {
326 		pr_err("Unable to register clocksource\n");
327 		return rv;
328 	}
329 
330 	sched_clock_register(davinci_timer_read_sched_clock,
331 			     DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
332 
333 	return 0;
334 }
335 
336 static int __init of_davinci_timer_register(struct device_node *np)
337 {
338 	struct davinci_timer_cfg timer_cfg = { };
339 	struct clk *clk;
340 	int rv;
341 
342 	rv = of_address_to_resource(np, 0, &timer_cfg.reg);
343 	if (rv) {
344 		pr_err("Unable to get the register range for timer\n");
345 		return rv;
346 	}
347 
348 	rv = of_irq_to_resource_table(np, timer_cfg.irq,
349 				      DAVINCI_TIMER_NUM_IRQS);
350 	if (rv != DAVINCI_TIMER_NUM_IRQS) {
351 		pr_err("Unable to get the interrupts for timer\n");
352 		return rv;
353 	}
354 
355 	clk = of_clk_get(np, 0);
356 	if (IS_ERR(clk)) {
357 		pr_err("Unable to get the timer clock\n");
358 		return PTR_ERR(clk);
359 	}
360 
361 	rv = davinci_timer_register(clk, &timer_cfg);
362 	if (rv)
363 		clk_put(clk);
364 
365 	return rv;
366 }
367 TIMER_OF_DECLARE(davinci_timer, "ti,da830-timer", of_davinci_timer_register);
368