1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
4 * http://www.samsung.com/
5 *
6 * samsung - Common hr-timer support (s3c and s5p)
7 */
8
9#include <linux/interrupt.h>
10#include <linux/irq.h>
11#include <linux/err.h>
12#include <linux/clk.h>
13#include <linux/clockchips.h>
14#include <linux/list.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/of_address.h>
18#include <linux/of_irq.h>
19#include <linux/platform_device.h>
20#include <linux/slab.h>
21#include <linux/sched_clock.h>
22
23#include <clocksource/samsung_pwm.h>
24
25/*
26 * Clocksource driver
27 */
28
29#define REG_TCFG0 0x00
30#define REG_TCFG1 0x04
31#define REG_TCON 0x08
32#define REG_TINT_CSTAT 0x44
33
34#define REG_TCNTB(chan) (0x0c + 12 * (chan))
35#define REG_TCMPB(chan) (0x10 + 12 * (chan))
36
37#define TCFG0_PRESCALER_MASK 0xff
38#define TCFG0_PRESCALER1_SHIFT 8
39
40#define TCFG1_SHIFT(x) ((x) * 4)
41#define TCFG1_MUX_MASK 0xf
42
43/*
44 * Each channel occupies 4 bits in TCON register, but there is a gap of 4
45 * bits (one channel) after channel 0, so channels have different numbering
46 * when accessing TCON register.
47 *
48 * In addition, the location of autoreload bit for channel 4 (TCON channel 5)
49 * in its set of bits is 2 as opposed to 3 for other channels.
50 */
51#define TCON_START(chan) (1 << (4 * (chan) + 0))
52#define TCON_MANUALUPDATE(chan) (1 << (4 * (chan) + 1))
53#define TCON_INVERT(chan) (1 << (4 * (chan) + 2))
54#define _TCON_AUTORELOAD(chan) (1 << (4 * (chan) + 3))
55#define _TCON_AUTORELOAD4(chan) (1 << (4 * (chan) + 2))
56#define TCON_AUTORELOAD(chan) \
57 ((chan < 5) ? _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan))
58
59DEFINE_SPINLOCK(samsung_pwm_lock);
60EXPORT_SYMBOL(samsung_pwm_lock);
61
62struct samsung_pwm_clocksource {
63 void __iomem *base;
64 const void __iomem *source_reg;
65 unsigned int irq[SAMSUNG_PWM_NUM];
66 struct samsung_pwm_variant variant;
67
68 struct clk *timerclk;
69
70 unsigned int event_id;
71 unsigned int source_id;
72 unsigned int tcnt_max;
73 unsigned int tscaler_div;
74 unsigned int tdiv;
75
76 unsigned long clock_count_per_tick;
77};
78
79static struct samsung_pwm_clocksource pwm;
80
81static void samsung_timer_set_prescale(unsigned int channel, u16 prescale)
82{
83 unsigned long flags;
84 u8 shift = 0;
85 u32 reg;
86
87 if (channel >= 2)
88 shift = TCFG0_PRESCALER1_SHIFT;
89
90 spin_lock_irqsave(&samsung_pwm_lock, flags);
91
92 reg = readl(addr: pwm.base + REG_TCFG0);
93 reg &= ~(TCFG0_PRESCALER_MASK << shift);
94 reg |= (prescale - 1) << shift;
95 writel(val: reg, addr: pwm.base + REG_TCFG0);
96
97 spin_unlock_irqrestore(lock: &samsung_pwm_lock, flags);
98}
99
100static void samsung_timer_set_divisor(unsigned int channel, u8 divisor)
101{
102 u8 shift = TCFG1_SHIFT(channel);
103 unsigned long flags;
104 u32 reg;
105 u8 bits;
106
107 bits = (fls(x: divisor) - 1) - pwm.variant.div_base;
108
109 spin_lock_irqsave(&samsung_pwm_lock, flags);
110
111 reg = readl(addr: pwm.base + REG_TCFG1);
112 reg &= ~(TCFG1_MUX_MASK << shift);
113 reg |= bits << shift;
114 writel(val: reg, addr: pwm.base + REG_TCFG1);
115
116 spin_unlock_irqrestore(lock: &samsung_pwm_lock, flags);
117}
118
119static void samsung_time_stop(unsigned int channel)
120{
121 unsigned long tcon;
122 unsigned long flags;
123
124 if (channel > 0)
125 ++channel;
126
127 spin_lock_irqsave(&samsung_pwm_lock, flags);
128
129 tcon = readl_relaxed(pwm.base + REG_TCON);
130 tcon &= ~TCON_START(channel);
131 writel_relaxed(tcon, pwm.base + REG_TCON);
132
133 spin_unlock_irqrestore(lock: &samsung_pwm_lock, flags);
134}
135
136static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
137{
138 unsigned long tcon;
139 unsigned long flags;
140 unsigned int tcon_chan = channel;
141
142 if (tcon_chan > 0)
143 ++tcon_chan;
144
145 spin_lock_irqsave(&samsung_pwm_lock, flags);
146
147 tcon = readl_relaxed(pwm.base + REG_TCON);
148
149 tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
150 tcon |= TCON_MANUALUPDATE(tcon_chan);
151
152 writel_relaxed(tcnt, pwm.base + REG_TCNTB(channel));
153 writel_relaxed(tcnt, pwm.base + REG_TCMPB(channel));
154 writel_relaxed(tcon, pwm.base + REG_TCON);
155
156 spin_unlock_irqrestore(lock: &samsung_pwm_lock, flags);
157}
158
159static void samsung_time_start(unsigned int channel, bool periodic)
160{
161 unsigned long tcon;
162 unsigned long flags;
163
164 if (channel > 0)
165 ++channel;
166
167 spin_lock_irqsave(&samsung_pwm_lock, flags);
168
169 tcon = readl_relaxed(pwm.base + REG_TCON);
170
171 tcon &= ~TCON_MANUALUPDATE(channel);
172 tcon |= TCON_START(channel);
173
174 if (periodic)
175 tcon |= TCON_AUTORELOAD(channel);
176 else
177 tcon &= ~TCON_AUTORELOAD(channel);
178
179 writel_relaxed(tcon, pwm.base + REG_TCON);
180
181 spin_unlock_irqrestore(lock: &samsung_pwm_lock, flags);
182}
183
184static int samsung_set_next_event(unsigned long cycles,
185 struct clock_event_device *evt)
186{
187 /*
188 * This check is needed to account for internal rounding
189 * errors inside clockevents core, which might result in
190 * passing cycles = 0, which in turn would not generate any
191 * timer interrupt and hang the system.
192 *
193 * Another solution would be to set up the clockevent device
194 * with min_delta = 2, but this would unnecessarily increase
195 * the minimum sleep period.
196 */
197 if (!cycles)
198 cycles = 1;
199
200 samsung_time_setup(channel: pwm.event_id, tcnt: cycles);
201 samsung_time_start(channel: pwm.event_id, periodic: false);
202
203 return 0;
204}
205
206static int samsung_shutdown(struct clock_event_device *evt)
207{
208 samsung_time_stop(channel: pwm.event_id);
209 return 0;
210}
211
212static int samsung_set_periodic(struct clock_event_device *evt)
213{
214 samsung_time_stop(channel: pwm.event_id);
215 samsung_time_setup(channel: pwm.event_id, tcnt: pwm.clock_count_per_tick - 1);
216 samsung_time_start(channel: pwm.event_id, periodic: true);
217 return 0;
218}
219
220static void samsung_clockevent_resume(struct clock_event_device *cev)
221{
222 samsung_timer_set_prescale(channel: pwm.event_id, prescale: pwm.tscaler_div);
223 samsung_timer_set_divisor(channel: pwm.event_id, divisor: pwm.tdiv);
224
225 if (pwm.variant.has_tint_cstat) {
226 u32 mask = (1 << pwm.event_id);
227
228 writel(val: mask | (mask << 5), addr: pwm.base + REG_TINT_CSTAT);
229 }
230}
231
232static struct clock_event_device time_event_device = {
233 .name = "samsung_event_timer",
234 .features = CLOCK_EVT_FEAT_PERIODIC |
235 CLOCK_EVT_FEAT_ONESHOT,
236 .rating = 200,
237 .set_next_event = samsung_set_next_event,
238 .set_state_shutdown = samsung_shutdown,
239 .set_state_periodic = samsung_set_periodic,
240 .set_state_oneshot = samsung_shutdown,
241 .tick_resume = samsung_shutdown,
242 .resume = samsung_clockevent_resume,
243};
244
245static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
246{
247 struct clock_event_device *evt = dev_id;
248
249 if (pwm.variant.has_tint_cstat) {
250 u32 mask = (1 << pwm.event_id);
251
252 writel(val: mask | (mask << 5), addr: pwm.base + REG_TINT_CSTAT);
253 }
254
255 evt->event_handler(evt);
256
257 return IRQ_HANDLED;
258}
259
260static void __init samsung_clockevent_init(void)
261{
262 unsigned long pclk;
263 unsigned long clock_rate;
264 unsigned int irq_number;
265
266 pclk = clk_get_rate(clk: pwm.timerclk);
267
268 samsung_timer_set_prescale(channel: pwm.event_id, prescale: pwm.tscaler_div);
269 samsung_timer_set_divisor(channel: pwm.event_id, divisor: pwm.tdiv);
270
271 clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
272 pwm.clock_count_per_tick = clock_rate / HZ;
273
274 time_event_device.cpumask = cpumask_of(0);
275 clockevents_config_and_register(dev: &time_event_device,
276 freq: clock_rate, min_delta: 1, max_delta: pwm.tcnt_max);
277
278 irq_number = pwm.irq[pwm.event_id];
279 if (request_irq(irq: irq_number, handler: samsung_clock_event_isr,
280 IRQF_TIMER | IRQF_IRQPOLL, name: "samsung_time_irq",
281 dev: &time_event_device))
282 pr_err("%s: request_irq() failed\n", "samsung_time_irq");
283
284 if (pwm.variant.has_tint_cstat) {
285 u32 mask = (1 << pwm.event_id);
286
287 writel(val: mask | (mask << 5), addr: pwm.base + REG_TINT_CSTAT);
288 }
289}
290
291static void samsung_clocksource_suspend(struct clocksource *cs)
292{
293 samsung_time_stop(channel: pwm.source_id);
294}
295
296static void samsung_clocksource_resume(struct clocksource *cs)
297{
298 samsung_timer_set_prescale(channel: pwm.source_id, prescale: pwm.tscaler_div);
299 samsung_timer_set_divisor(channel: pwm.source_id, divisor: pwm.tdiv);
300
301 samsung_time_setup(channel: pwm.source_id, tcnt: pwm.tcnt_max);
302 samsung_time_start(channel: pwm.source_id, periodic: true);
303}
304
305static u64 notrace samsung_clocksource_read(struct clocksource *c)
306{
307 return ~readl_relaxed(pwm.source_reg);
308}
309
310static struct clocksource samsung_clocksource = {
311 .name = "samsung_clocksource_timer",
312 .rating = 250,
313 .read = samsung_clocksource_read,
314 .suspend = samsung_clocksource_suspend,
315 .resume = samsung_clocksource_resume,
316 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
317};
318
319/*
320 * Override the global weak sched_clock symbol with this
321 * local implementation which uses the clocksource to get some
322 * better resolution when scheduling the kernel. We accept that
323 * this wraps around for now, since it is just a relative time
324 * stamp. (Inspired by U300 implementation.)
325 */
326static u64 notrace samsung_read_sched_clock(void)
327{
328 return samsung_clocksource_read(NULL);
329}
330
331static int __init samsung_clocksource_init(void)
332{
333 unsigned long pclk;
334 unsigned long clock_rate;
335
336 pclk = clk_get_rate(clk: pwm.timerclk);
337
338 samsung_timer_set_prescale(channel: pwm.source_id, prescale: pwm.tscaler_div);
339 samsung_timer_set_divisor(channel: pwm.source_id, divisor: pwm.tdiv);
340
341 clock_rate = pclk / (pwm.tscaler_div * pwm.tdiv);
342
343 samsung_time_setup(channel: pwm.source_id, tcnt: pwm.tcnt_max);
344 samsung_time_start(channel: pwm.source_id, periodic: true);
345
346 if (pwm.source_id == 4)
347 pwm.source_reg = pwm.base + 0x40;
348 else
349 pwm.source_reg = pwm.base + pwm.source_id * 0x0c + 0x14;
350
351 sched_clock_register(read: samsung_read_sched_clock,
352 bits: pwm.variant.bits, rate: clock_rate);
353
354 samsung_clocksource.mask = CLOCKSOURCE_MASK(pwm.variant.bits);
355 return clocksource_register_hz(cs: &samsung_clocksource, hz: clock_rate);
356}
357
358static void __init samsung_timer_resources(void)
359{
360 clk_prepare_enable(clk: pwm.timerclk);
361
362 pwm.tcnt_max = (1UL << pwm.variant.bits) - 1;
363 if (pwm.variant.bits == 16) {
364 pwm.tscaler_div = 25;
365 pwm.tdiv = 2;
366 } else {
367 pwm.tscaler_div = 2;
368 pwm.tdiv = 1;
369 }
370}
371
372/*
373 * PWM master driver
374 */
375static int __init _samsung_pwm_clocksource_init(void)
376{
377 u8 mask;
378 int channel;
379
380 mask = ~pwm.variant.output_mask & ((1 << SAMSUNG_PWM_NUM) - 1);
381 channel = fls(x: mask) - 1;
382 if (channel < 0) {
383 pr_crit("failed to find PWM channel for clocksource\n");
384 return -EINVAL;
385 }
386 pwm.source_id = channel;
387
388 mask &= ~(1 << channel);
389 channel = fls(x: mask) - 1;
390 if (channel < 0) {
391 pr_crit("failed to find PWM channel for clock event\n");
392 return -EINVAL;
393 }
394 pwm.event_id = channel;
395
396 samsung_timer_resources();
397 samsung_clockevent_init();
398
399 return samsung_clocksource_init();
400}
401
402void __init samsung_pwm_clocksource_init(void __iomem *base,
403 unsigned int *irqs,
404 const struct samsung_pwm_variant *variant)
405{
406 pwm.base = base;
407 memcpy(&pwm.variant, variant, sizeof(pwm.variant));
408 memcpy(pwm.irq, irqs, SAMSUNG_PWM_NUM * sizeof(*irqs));
409
410 pwm.timerclk = clk_get(NULL, id: "timers");
411 if (IS_ERR(ptr: pwm.timerclk))
412 panic(fmt: "failed to get timers clock for timer");
413
414 _samsung_pwm_clocksource_init();
415}
416
417#ifdef CONFIG_TIMER_OF
418static int __init samsung_pwm_alloc(struct device_node *np,
419 const struct samsung_pwm_variant *variant)
420{
421 u32 val;
422 int i, ret;
423
424 memcpy(&pwm.variant, variant, sizeof(pwm.variant));
425 for (i = 0; i < SAMSUNG_PWM_NUM; ++i)
426 pwm.irq[i] = irq_of_parse_and_map(node: np, index: i);
427
428 of_property_for_each_u32(np, "samsung,pwm-outputs", val) {
429 if (val >= SAMSUNG_PWM_NUM) {
430 pr_warn("%s: invalid channel index in samsung,pwm-outputs property\n", __func__);
431 continue;
432 }
433 pwm.variant.output_mask |= 1 << val;
434 }
435
436 pwm.base = of_iomap(node: np, index: 0);
437 if (!pwm.base) {
438 pr_err("%s: failed to map PWM registers\n", __func__);
439 return -ENXIO;
440 }
441
442 pwm.timerclk = of_clk_get_by_name(np, name: "timers");
443 if (IS_ERR(ptr: pwm.timerclk)) {
444 pr_crit("failed to get timers clock for timer\n");
445 ret = PTR_ERR(ptr: pwm.timerclk);
446 goto err_clk;
447 }
448
449 ret = _samsung_pwm_clocksource_init();
450 if (ret)
451 goto err_clocksource;
452
453 return 0;
454
455err_clocksource:
456 clk_put(clk: pwm.timerclk);
457 pwm.timerclk = NULL;
458err_clk:
459 iounmap(addr: pwm.base);
460 pwm.base = NULL;
461
462 return ret;
463}
464
465static const struct samsung_pwm_variant s3c24xx_variant = {
466 .bits = 16,
467 .div_base = 1,
468 .has_tint_cstat = false,
469 .tclk_mask = (1 << 4),
470};
471
472static int __init s3c2410_pwm_clocksource_init(struct device_node *np)
473{
474 return samsung_pwm_alloc(np, variant: &s3c24xx_variant);
475}
476TIMER_OF_DECLARE(s3c2410_pwm, "samsung,s3c2410-pwm", s3c2410_pwm_clocksource_init);
477
478static const struct samsung_pwm_variant s3c64xx_variant = {
479 .bits = 32,
480 .div_base = 0,
481 .has_tint_cstat = true,
482 .tclk_mask = (1 << 7) | (1 << 6) | (1 << 5),
483};
484
485static int __init s3c64xx_pwm_clocksource_init(struct device_node *np)
486{
487 return samsung_pwm_alloc(np, variant: &s3c64xx_variant);
488}
489TIMER_OF_DECLARE(s3c6400_pwm, "samsung,s3c6400-pwm", s3c64xx_pwm_clocksource_init);
490
491static const struct samsung_pwm_variant s5p64x0_variant = {
492 .bits = 32,
493 .div_base = 0,
494 .has_tint_cstat = true,
495 .tclk_mask = 0,
496};
497
498static int __init s5p64x0_pwm_clocksource_init(struct device_node *np)
499{
500 return samsung_pwm_alloc(np, variant: &s5p64x0_variant);
501}
502TIMER_OF_DECLARE(s5p6440_pwm, "samsung,s5p6440-pwm", s5p64x0_pwm_clocksource_init);
503
504static const struct samsung_pwm_variant s5p_variant = {
505 .bits = 32,
506 .div_base = 0,
507 .has_tint_cstat = true,
508 .tclk_mask = (1 << 5),
509};
510
511static int __init s5p_pwm_clocksource_init(struct device_node *np)
512{
513 return samsung_pwm_alloc(np, variant: &s5p_variant);
514}
515TIMER_OF_DECLARE(s5pc100_pwm, "samsung,s5pc100-pwm", s5p_pwm_clocksource_init);
516#endif
517

source code of linux/drivers/clocksource/samsung_pwm_timer.c