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 #define pr_fmt(fmt) "%s: " fmt, __func__
11
12 #include <linux/clk.h>
13 #include <linux/clockchips.h>
14 #include <linux/interrupt.h>
15 #include <linux/kernel.h>
16 #include <linux/of_address.h>
17 #include <linux/of_irq.h>
18 #include <linux/sched_clock.h>
19
20 #include <clocksource/timer-davinci.h>
21
22 #define DAVINCI_TIMER_REG_TIM12 0x10
23 #define DAVINCI_TIMER_REG_TIM34 0x14
24 #define DAVINCI_TIMER_REG_PRD12 0x18
25 #define DAVINCI_TIMER_REG_PRD34 0x1c
26 #define DAVINCI_TIMER_REG_TCR 0x20
27 #define DAVINCI_TIMER_REG_TGCR 0x24
28
29 #define DAVINCI_TIMER_TIMMODE_MASK GENMASK(3, 2)
30 #define DAVINCI_TIMER_RESET_MASK GENMASK(1, 0)
31 #define DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED BIT(2)
32 #define DAVINCI_TIMER_UNRESET GENMASK(1, 0)
33
34 #define DAVINCI_TIMER_ENAMODE_MASK GENMASK(1, 0)
35 #define DAVINCI_TIMER_ENAMODE_DISABLED 0x00
36 #define DAVINCI_TIMER_ENAMODE_ONESHOT BIT(0)
37 #define DAVINCI_TIMER_ENAMODE_PERIODIC BIT(1)
38
39 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM12 6
40 #define DAVINCI_TIMER_ENAMODE_SHIFT_TIM34 22
41
42 #define DAVINCI_TIMER_MIN_DELTA 0x01
43 #define DAVINCI_TIMER_MAX_DELTA 0xfffffffe
44
45 #define DAVINCI_TIMER_CLKSRC_BITS 32
46
47 #define DAVINCI_TIMER_TGCR_DEFAULT \
48 (DAVINCI_TIMER_TIMMODE_32BIT_UNCHAINED | DAVINCI_TIMER_UNRESET)
49
50 struct davinci_clockevent {
51 struct clock_event_device dev;
52 void __iomem *base;
53 unsigned int cmp_off;
54 };
55
56 /*
57 * This must be globally accessible by davinci_timer_read_sched_clock(), so
58 * let's keep it here.
59 */
60 static struct {
61 struct clocksource dev;
62 void __iomem *base;
63 unsigned int tim_off;
64 } davinci_clocksource;
65
66 static struct davinci_clockevent *
to_davinci_clockevent(struct clock_event_device * clockevent)67 to_davinci_clockevent(struct clock_event_device *clockevent)
68 {
69 return container_of(clockevent, struct davinci_clockevent, dev);
70 }
71
72 static unsigned int
davinci_clockevent_read(struct davinci_clockevent * clockevent,unsigned int reg)73 davinci_clockevent_read(struct davinci_clockevent *clockevent,
74 unsigned int reg)
75 {
76 return readl_relaxed(clockevent->base + reg);
77 }
78
davinci_clockevent_write(struct davinci_clockevent * clockevent,unsigned int reg,unsigned int val)79 static void davinci_clockevent_write(struct davinci_clockevent *clockevent,
80 unsigned int reg, unsigned int val)
81 {
82 writel_relaxed(val, clockevent->base + reg);
83 }
84
davinci_tim12_shutdown(void __iomem * base)85 static void davinci_tim12_shutdown(void __iomem *base)
86 {
87 unsigned int tcr;
88
89 tcr = DAVINCI_TIMER_ENAMODE_DISABLED <<
90 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
91 /*
92 * This function is only ever called if we're using both timer
93 * halves. In this case TIM34 runs in periodic mode and we must
94 * not modify it.
95 */
96 tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
97 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
98
99 writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
100 }
101
davinci_tim12_set_oneshot(void __iomem * base)102 static void davinci_tim12_set_oneshot(void __iomem *base)
103 {
104 unsigned int tcr;
105
106 tcr = DAVINCI_TIMER_ENAMODE_ONESHOT <<
107 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
108 /* Same as above. */
109 tcr |= DAVINCI_TIMER_ENAMODE_PERIODIC <<
110 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
111
112 writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
113 }
114
davinci_clockevent_shutdown(struct clock_event_device * dev)115 static int davinci_clockevent_shutdown(struct clock_event_device *dev)
116 {
117 struct davinci_clockevent *clockevent;
118
119 clockevent = to_davinci_clockevent(dev);
120
121 davinci_tim12_shutdown(clockevent->base);
122
123 return 0;
124 }
125
davinci_clockevent_set_oneshot(struct clock_event_device * dev)126 static int davinci_clockevent_set_oneshot(struct clock_event_device *dev)
127 {
128 struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
129
130 davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
131
132 davinci_tim12_set_oneshot(clockevent->base);
133
134 return 0;
135 }
136
137 static int
davinci_clockevent_set_next_event_std(unsigned long cycles,struct clock_event_device * dev)138 davinci_clockevent_set_next_event_std(unsigned long cycles,
139 struct clock_event_device *dev)
140 {
141 struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
142
143 davinci_clockevent_shutdown(dev);
144
145 davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_TIM12, 0x0);
146 davinci_clockevent_write(clockevent, DAVINCI_TIMER_REG_PRD12, cycles);
147
148 davinci_clockevent_set_oneshot(dev);
149
150 return 0;
151 }
152
153 static int
davinci_clockevent_set_next_event_cmp(unsigned long cycles,struct clock_event_device * dev)154 davinci_clockevent_set_next_event_cmp(unsigned long cycles,
155 struct clock_event_device *dev)
156 {
157 struct davinci_clockevent *clockevent = to_davinci_clockevent(dev);
158 unsigned int curr_time;
159
160 curr_time = davinci_clockevent_read(clockevent,
161 DAVINCI_TIMER_REG_TIM12);
162 davinci_clockevent_write(clockevent,
163 clockevent->cmp_off, curr_time + cycles);
164
165 return 0;
166 }
167
davinci_timer_irq_timer(int irq,void * data)168 static irqreturn_t davinci_timer_irq_timer(int irq, void *data)
169 {
170 struct davinci_clockevent *clockevent = data;
171
172 if (!clockevent_state_oneshot(&clockevent->dev))
173 davinci_tim12_shutdown(clockevent->base);
174
175 clockevent->dev.event_handler(&clockevent->dev);
176
177 return IRQ_HANDLED;
178 }
179
davinci_timer_read_sched_clock(void)180 static u64 notrace davinci_timer_read_sched_clock(void)
181 {
182 return readl_relaxed(davinci_clocksource.base +
183 davinci_clocksource.tim_off);
184 }
185
davinci_clocksource_read(struct clocksource * dev)186 static u64 davinci_clocksource_read(struct clocksource *dev)
187 {
188 return davinci_timer_read_sched_clock();
189 }
190
191 /*
192 * Standard use-case: we're using tim12 for clockevent and tim34 for
193 * clocksource. The default is making the former run in oneshot mode
194 * and the latter in periodic mode.
195 */
davinci_clocksource_init_tim34(void __iomem * base)196 static void davinci_clocksource_init_tim34(void __iomem *base)
197 {
198 int tcr;
199
200 tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
201 DAVINCI_TIMER_ENAMODE_SHIFT_TIM34;
202 tcr |= DAVINCI_TIMER_ENAMODE_ONESHOT <<
203 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
204
205 writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
206 writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD34);
207 writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
208 }
209
210 /*
211 * Special use-case on da830: the DSP may use tim34. We're using tim12 for
212 * both clocksource and clockevent. We set tim12 to periodic and don't touch
213 * tim34.
214 */
davinci_clocksource_init_tim12(void __iomem * base)215 static void davinci_clocksource_init_tim12(void __iomem *base)
216 {
217 unsigned int tcr;
218
219 tcr = DAVINCI_TIMER_ENAMODE_PERIODIC <<
220 DAVINCI_TIMER_ENAMODE_SHIFT_TIM12;
221
222 writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
223 writel_relaxed(UINT_MAX, base + DAVINCI_TIMER_REG_PRD12);
224 writel_relaxed(tcr, base + DAVINCI_TIMER_REG_TCR);
225 }
226
davinci_timer_init(void __iomem * base)227 static void davinci_timer_init(void __iomem *base)
228 {
229 /* Set clock to internal mode and disable it. */
230 writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TCR);
231 /*
232 * Reset both 32-bit timers, set no prescaler for timer 34, set the
233 * timer to dual 32-bit unchained mode, unreset both 32-bit timers.
234 */
235 writel_relaxed(DAVINCI_TIMER_TGCR_DEFAULT,
236 base + DAVINCI_TIMER_REG_TGCR);
237 /* Init both counters to zero. */
238 writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM12);
239 writel_relaxed(0x0, base + DAVINCI_TIMER_REG_TIM34);
240 }
241
davinci_timer_register(struct clk * clk,const struct davinci_timer_cfg * timer_cfg)242 int __init davinci_timer_register(struct clk *clk,
243 const struct davinci_timer_cfg *timer_cfg)
244 {
245 struct davinci_clockevent *clockevent;
246 unsigned int tick_rate;
247 void __iomem *base;
248 int rv;
249
250 rv = clk_prepare_enable(clk);
251 if (rv) {
252 pr_err("Unable to prepare and enable the timer clock\n");
253 return rv;
254 }
255
256 if (!request_mem_region(timer_cfg->reg.start,
257 resource_size(&timer_cfg->reg),
258 "davinci-timer")) {
259 pr_err("Unable to request memory region\n");
260 rv = -EBUSY;
261 goto exit_clk_disable;
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 rv = -ENOMEM;
268 goto exit_mem_region;
269 }
270
271 davinci_timer_init(base);
272 tick_rate = clk_get_rate(clk);
273
274 clockevent = kzalloc(sizeof(*clockevent), GFP_KERNEL);
275 if (!clockevent) {
276 rv = -ENOMEM;
277 goto exit_iounmap_base;
278 }
279
280 clockevent->dev.name = "tim12";
281 clockevent->dev.features = CLOCK_EVT_FEAT_ONESHOT;
282 clockevent->dev.cpumask = cpumask_of(0);
283 clockevent->base = base;
284
285 if (timer_cfg->cmp_off) {
286 clockevent->cmp_off = timer_cfg->cmp_off;
287 clockevent->dev.set_next_event =
288 davinci_clockevent_set_next_event_cmp;
289 } else {
290 clockevent->dev.set_next_event =
291 davinci_clockevent_set_next_event_std;
292 clockevent->dev.set_state_oneshot =
293 davinci_clockevent_set_oneshot;
294 clockevent->dev.set_state_shutdown =
295 davinci_clockevent_shutdown;
296 }
297
298 rv = request_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
299 davinci_timer_irq_timer, IRQF_TIMER,
300 "clockevent/tim12", clockevent);
301 if (rv) {
302 pr_err("Unable to request the clockevent interrupt\n");
303 goto exit_free_clockevent;
304 }
305
306 davinci_clocksource.dev.rating = 300;
307 davinci_clocksource.dev.read = davinci_clocksource_read;
308 davinci_clocksource.dev.mask =
309 CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
310 davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
311 davinci_clocksource.base = base;
312
313 if (timer_cfg->cmp_off) {
314 davinci_clocksource.dev.name = "tim12";
315 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
316 davinci_clocksource_init_tim12(base);
317 } else {
318 davinci_clocksource.dev.name = "tim34";
319 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
320 davinci_clocksource_init_tim34(base);
321 }
322
323 clockevents_config_and_register(&clockevent->dev, tick_rate,
324 DAVINCI_TIMER_MIN_DELTA,
325 DAVINCI_TIMER_MAX_DELTA);
326
327 rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
328 if (rv) {
329 pr_err("Unable to register clocksource\n");
330 goto exit_free_irq;
331 }
332
333 sched_clock_register(davinci_timer_read_sched_clock,
334 DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
335
336 return 0;
337
338 exit_free_irq:
339 free_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
340 clockevent);
341 exit_free_clockevent:
342 kfree(clockevent);
343 exit_iounmap_base:
344 iounmap(base);
345 exit_mem_region:
346 release_mem_region(timer_cfg->reg.start,
347 resource_size(&timer_cfg->reg));
348 exit_clk_disable:
349 clk_disable_unprepare(clk);
350 return rv;
351 }
352
of_davinci_timer_register(struct device_node * np)353 static int __init of_davinci_timer_register(struct device_node *np)
354 {
355 struct davinci_timer_cfg timer_cfg = { };
356 struct clk *clk;
357 int rv;
358
359 rv = of_address_to_resource(np, 0, &timer_cfg.reg);
360 if (rv) {
361 pr_err("Unable to get the register range for timer\n");
362 return rv;
363 }
364
365 rv = of_irq_to_resource_table(np, timer_cfg.irq,
366 DAVINCI_TIMER_NUM_IRQS);
367 if (rv != DAVINCI_TIMER_NUM_IRQS) {
368 pr_err("Unable to get the interrupts for timer\n");
369 return rv;
370 }
371
372 clk = of_clk_get(np, 0);
373 if (IS_ERR(clk)) {
374 pr_err("Unable to get the timer clock\n");
375 return PTR_ERR(clk);
376 }
377
378 rv = davinci_timer_register(clk, &timer_cfg);
379 if (rv)
380 clk_put(clk);
381
382 return rv;
383 }
384 TIMER_OF_DECLARE(davinci_timer, "ti,da830-timer", of_davinci_timer_register);
385