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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
50struct 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 */
60static struct {
61 struct clocksource dev;
62 void __iomem *base;
63 unsigned int tim_off;
64} davinci_clocksource;
65
66static struct davinci_clockevent *
67to_davinci_clockevent(struct clock_event_device *clockevent)
68{
69 return container_of(clockevent, struct davinci_clockevent, dev);
70}
71
72static unsigned int
73davinci_clockevent_read(struct davinci_clockevent *clockevent,
74 unsigned int reg)
75{
76 return readl_relaxed(clockevent->base + reg);
77}
78
79static 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
85static 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
102static 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
115static 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
126static 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
137static int
138davinci_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
153static int
154davinci_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
168static 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
180static u64 notrace davinci_timer_read_sched_clock(void)
181{
182 return readl_relaxed(davinci_clocksource.base +
183 davinci_clocksource.tim_off);
184}
185
186static 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 */
196static 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 */
215static 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
227static 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
242int __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 return -EBUSY;
261 }
262
263 base = ioremap(timer_cfg->reg.start, resource_size(&timer_cfg->reg));
264 if (!base) {
265 pr_err("Unable to map the register range\n");
266 return -ENOMEM;
267 }
268
269 davinci_timer_init(base);
270 tick_rate = clk_get_rate(clk);
271
272 clockevent = kzalloc(sizeof(*clockevent), GFP_KERNEL);
273 if (!clockevent)
274 return -ENOMEM;
275
276 clockevent->dev.name = "tim12";
277 clockevent->dev.features = CLOCK_EVT_FEAT_ONESHOT;
278 clockevent->dev.cpumask = cpumask_of(0);
279 clockevent->base = base;
280
281 if (timer_cfg->cmp_off) {
282 clockevent->cmp_off = timer_cfg->cmp_off;
283 clockevent->dev.set_next_event =
284 davinci_clockevent_set_next_event_cmp;
285 } else {
286 clockevent->dev.set_next_event =
287 davinci_clockevent_set_next_event_std;
288 clockevent->dev.set_state_oneshot =
289 davinci_clockevent_set_oneshot;
290 clockevent->dev.set_state_shutdown =
291 davinci_clockevent_shutdown;
292 }
293
294 rv = request_irq(timer_cfg->irq[DAVINCI_TIMER_CLOCKEVENT_IRQ].start,
295 davinci_timer_irq_timer, IRQF_TIMER,
296 "clockevent/tim12", clockevent);
297 if (rv) {
298 pr_err("Unable to request the clockevent interrupt\n");
299 return rv;
300 }
301
302 davinci_clocksource.dev.rating = 300;
303 davinci_clocksource.dev.read = davinci_clocksource_read;
304 davinci_clocksource.dev.mask =
305 CLOCKSOURCE_MASK(DAVINCI_TIMER_CLKSRC_BITS);
306 davinci_clocksource.dev.flags = CLOCK_SOURCE_IS_CONTINUOUS;
307 davinci_clocksource.base = base;
308
309 if (timer_cfg->cmp_off) {
310 davinci_clocksource.dev.name = "tim12";
311 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM12;
312 davinci_clocksource_init_tim12(base);
313 } else {
314 davinci_clocksource.dev.name = "tim34";
315 davinci_clocksource.tim_off = DAVINCI_TIMER_REG_TIM34;
316 davinci_clocksource_init_tim34(base);
317 }
318
319 clockevents_config_and_register(&clockevent->dev, tick_rate,
320 DAVINCI_TIMER_MIN_DELTA,
321 DAVINCI_TIMER_MAX_DELTA);
322
323 rv = clocksource_register_hz(&davinci_clocksource.dev, tick_rate);
324 if (rv) {
325 pr_err("Unable to register clocksource\n");
326 return rv;
327 }
328
329 sched_clock_register(davinci_timer_read_sched_clock,
330 DAVINCI_TIMER_CLKSRC_BITS, tick_rate);
331
332 return 0;
333}
334
335static int __init of_davinci_timer_register(struct device_node *np)
336{
337 struct davinci_timer_cfg timer_cfg = { };
338 struct clk *clk;
339 int rv;
340
341 rv = of_address_to_resource(np, 0, &timer_cfg.reg);
342 if (rv) {
343 pr_err("Unable to get the register range for timer\n");
344 return rv;
345 }
346
347 rv = of_irq_to_resource_table(np, timer_cfg.irq,
348 DAVINCI_TIMER_NUM_IRQS);
349 if (rv != DAVINCI_TIMER_NUM_IRQS) {
350 pr_err("Unable to get the interrupts for timer\n");
351 return rv;
352 }
353
354 clk = of_clk_get(np, 0);
355 if (IS_ERR(clk)) {
356 pr_err("Unable to get the timer clock\n");
357 return PTR_ERR(clk);
358 }
359
360 rv = davinci_timer_register(clk, &timer_cfg);
361 if (rv)
362 clk_put(clk);
363
364 return rv;
365}
366TIMER_OF_DECLARE(davinci_timer, "ti,da830-timer", of_davinci_timer_register);