1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2012-2013 Freescale Semiconductor, Inc.
4 * Copyright 2018,2021-2025 NXP
5 */
6#include <linux/interrupt.h>
7#include <linux/clockchips.h>
8#include <linux/cpuhotplug.h>
9#include <linux/clk.h>
10#include <linux/of_address.h>
11#include <linux/of_irq.h>
12#include <linux/sched_clock.h>
13#include <linux/platform_device.h>
14
15/*
16 * Each pit takes 0x10 Bytes register space
17 */
18#define PIT0_OFFSET 0x100
19#define PIT_CH(n) (PIT0_OFFSET + 0x10 * (n))
20
21#define PITMCR(__base) (__base)
22
23#define PITMCR_FRZ BIT(0)
24#define PITMCR_MDIS BIT(1)
25
26#define PITLDVAL(__base) (__base)
27#define PITTCTRL(__base) ((__base) + 0x08)
28
29#define PITCVAL_OFFSET 0x04
30#define PITCVAL(__base) ((__base) + 0x04)
31
32#define PITTCTRL_TEN BIT(0)
33#define PITTCTRL_TIE BIT(1)
34
35#define PITTFLG(__base) ((__base) + 0x0c)
36
37#define PITTFLG_TIF BIT(0)
38
39struct pit_timer {
40 void __iomem *clksrc_base;
41 void __iomem *clkevt_base;
42 struct clock_event_device ced;
43 struct clocksource cs;
44 int rate;
45};
46
47struct pit_timer_data {
48 int max_pit_instances;
49};
50
51static DEFINE_PER_CPU(struct pit_timer *, pit_timers);
52
53/*
54 * Global structure for multiple PITs initialization
55 */
56static int pit_instances;
57static int max_pit_instances = 1;
58
59static void __iomem *sched_clock_base;
60
61static inline struct pit_timer *ced_to_pit(struct clock_event_device *ced)
62{
63 return container_of(ced, struct pit_timer, ced);
64}
65
66static inline struct pit_timer *cs_to_pit(struct clocksource *cs)
67{
68 return container_of(cs, struct pit_timer, cs);
69}
70
71static inline void pit_module_enable(void __iomem *base)
72{
73 writel(val: 0, PITMCR(base));
74}
75
76static inline void pit_module_disable(void __iomem *base)
77{
78 writel(PITMCR_MDIS, PITMCR(base));
79}
80
81static inline void pit_timer_enable(void __iomem *base, bool tie)
82{
83 u32 val = PITTCTRL_TEN | (tie ? PITTCTRL_TIE : 0);
84
85 writel(val, PITTCTRL(base));
86}
87
88static inline void pit_timer_disable(void __iomem *base)
89{
90 writel(val: 0, PITTCTRL(base));
91}
92
93static inline void pit_timer_set_counter(void __iomem *base, unsigned int cnt)
94{
95 writel(val: cnt, PITLDVAL(base));
96}
97
98static inline void pit_timer_irqack(struct pit_timer *pit)
99{
100 writel(PITTFLG_TIF, PITTFLG(pit->clkevt_base));
101}
102
103static u64 notrace pit_read_sched_clock(void)
104{
105 return ~readl(addr: sched_clock_base);
106}
107
108static u64 pit_timer_clocksource_read(struct clocksource *cs)
109{
110 struct pit_timer *pit = cs_to_pit(cs);
111
112 return (u64)~readl(PITCVAL(pit->clksrc_base));
113}
114
115static int pit_clocksource_init(struct pit_timer *pit, const char *name,
116 void __iomem *base, unsigned long rate)
117{
118 /*
119 * The channels 0 and 1 can be chained to build a 64-bit
120 * timer. Let's use the channel 2 as a clocksource and leave
121 * the channels 0 and 1 unused for anyone else who needs them
122 */
123 pit->clksrc_base = base + PIT_CH(2);
124 pit->cs.name = name;
125 pit->cs.rating = 300;
126 pit->cs.read = pit_timer_clocksource_read;
127 pit->cs.mask = CLOCKSOURCE_MASK(32);
128 pit->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
129
130 /* set the max load value and start the clock source counter */
131 pit_timer_disable(base: pit->clksrc_base);
132 pit_timer_set_counter(base: pit->clksrc_base, cnt: ~0);
133 pit_timer_enable(base: pit->clksrc_base, tie: 0);
134
135 sched_clock_base = pit->clksrc_base + PITCVAL_OFFSET;
136 sched_clock_register(read: pit_read_sched_clock, bits: 32, rate);
137
138 return clocksource_register_hz(cs: &pit->cs, hz: rate);
139}
140
141static int pit_set_next_event(unsigned long delta, struct clock_event_device *ced)
142{
143 struct pit_timer *pit = ced_to_pit(ced);
144
145 /*
146 * set a new value to PITLDVAL register will not restart the timer,
147 * to abort the current cycle and start a timer period with the new
148 * value, the timer must be disabled and enabled again.
149 * and the PITLAVAL should be set to delta minus one according to pit
150 * hardware requirement.
151 */
152 pit_timer_disable(base: pit->clkevt_base);
153 pit_timer_set_counter(base: pit->clkevt_base, cnt: delta - 1);
154 pit_timer_enable(base: pit->clkevt_base, tie: true);
155
156 return 0;
157}
158
159static int pit_shutdown(struct clock_event_device *ced)
160{
161 struct pit_timer *pit = ced_to_pit(ced);
162
163 pit_timer_disable(base: pit->clkevt_base);
164
165 return 0;
166}
167
168static int pit_set_periodic(struct clock_event_device *ced)
169{
170 struct pit_timer *pit = ced_to_pit(ced);
171
172 pit_set_next_event(delta: pit->rate / HZ, ced);
173
174 return 0;
175}
176
177static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
178{
179 struct clock_event_device *ced = dev_id;
180 struct pit_timer *pit = ced_to_pit(ced);
181
182 pit_timer_irqack(pit);
183
184 /*
185 * pit hardware doesn't support oneshot, it will generate an interrupt
186 * and reload the counter value from PITLDVAL when PITCVAL reach zero,
187 * and start the counter again. So software need to disable the timer
188 * to stop the counter loop in ONESHOT mode.
189 */
190 if (likely(clockevent_state_oneshot(ced)))
191 pit_timer_disable(base: pit->clkevt_base);
192
193 ced->event_handler(ced);
194
195 return IRQ_HANDLED;
196}
197
198static int pit_clockevent_per_cpu_init(struct pit_timer *pit, const char *name,
199 void __iomem *base, unsigned long rate,
200 int irq, unsigned int cpu)
201{
202 int ret;
203
204 /*
205 * The channels 0 and 1 can be chained to build a 64-bit
206 * timer. Let's use the channel 3 as a clockevent and leave
207 * the channels 0 and 1 unused for anyone else who needs them
208 */
209 pit->clkevt_base = base + PIT_CH(3);
210 pit->rate = rate;
211
212 pit_timer_disable(base: pit->clkevt_base);
213
214 pit_timer_irqack(pit);
215
216 ret = request_irq(irq, handler: pit_timer_interrupt, IRQF_TIMER | IRQF_NOBALANCING,
217 name, dev: &pit->ced);
218 if (ret)
219 return ret;
220
221 pit->ced.cpumask = cpumask_of(cpu);
222 pit->ced.irq = irq;
223
224 pit->ced.name = name;
225 pit->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
226 pit->ced.set_state_shutdown = pit_shutdown;
227 pit->ced.set_state_periodic = pit_set_periodic;
228 pit->ced.set_next_event = pit_set_next_event;
229 pit->ced.rating = 300;
230
231 per_cpu(pit_timers, cpu) = pit;
232
233 return 0;
234}
235
236static void pit_clockevent_per_cpu_exit(struct pit_timer *pit, unsigned int cpu)
237{
238 pit_timer_disable(base: pit->clkevt_base);
239 free_irq(pit->ced.irq, &pit->ced);
240 per_cpu(pit_timers, cpu) = NULL;
241}
242
243static int pit_clockevent_starting_cpu(unsigned int cpu)
244{
245 struct pit_timer *pit = per_cpu(pit_timers, cpu);
246 int ret;
247
248 if (!pit)
249 return 0;
250
251 ret = irq_force_affinity(irq: pit->ced.irq, cpumask_of(cpu));
252 if (ret) {
253 pit_clockevent_per_cpu_exit(pit, cpu);
254 return ret;
255 }
256
257 /*
258 * The value for the LDVAL register trigger is calculated as:
259 * LDVAL trigger = (period / clock period) - 1
260 * The pit is a 32-bit down count timer, when the counter value
261 * reaches 0, it will generate an interrupt, thus the minimal
262 * LDVAL trigger value is 1. And then the min_delta is
263 * minimal LDVAL trigger value + 1, and the max_delta is full 32-bit.
264 */
265 clockevents_config_and_register(dev: &pit->ced, freq: pit->rate, min_delta: 2, max_delta: 0xffffffff);
266
267 return 0;
268}
269
270static int pit_timer_init(struct device_node *np)
271{
272 struct pit_timer *pit;
273 struct clk *pit_clk;
274 void __iomem *timer_base;
275 const char *name = of_node_full_name(np);
276 unsigned long clk_rate;
277 int irq, ret;
278
279 pit = kzalloc(sizeof(*pit), GFP_KERNEL);
280 if (!pit)
281 return -ENOMEM;
282
283 ret = -ENXIO;
284 timer_base = of_iomap(node: np, index: 0);
285 if (!timer_base) {
286 pr_err("Failed to iomap\n");
287 goto out_kfree;
288 }
289
290 ret = -EINVAL;
291 irq = irq_of_parse_and_map(node: np, index: 0);
292 if (irq <= 0) {
293 pr_err("Failed to irq_of_parse_and_map\n");
294 goto out_iounmap;
295 }
296
297 pit_clk = of_clk_get(np, index: 0);
298 if (IS_ERR(ptr: pit_clk)) {
299 ret = PTR_ERR(ptr: pit_clk);
300 goto out_irq_dispose_mapping;
301 }
302
303 ret = clk_prepare_enable(clk: pit_clk);
304 if (ret)
305 goto out_clk_put;
306
307 clk_rate = clk_get_rate(clk: pit_clk);
308
309 pit_module_disable(base: timer_base);
310
311 ret = pit_clocksource_init(pit, name, base: timer_base, rate: clk_rate);
312 if (ret) {
313 pr_err("Failed to initialize clocksource '%pOF'\n", np);
314 goto out_pit_module_disable;
315 }
316
317 ret = pit_clockevent_per_cpu_init(pit, name, base: timer_base, rate: clk_rate, irq, cpu: pit_instances);
318 if (ret) {
319 pr_err("Failed to initialize clockevent '%pOF'\n", np);
320 goto out_pit_clocksource_unregister;
321 }
322
323 /* enable the pit module */
324 pit_module_enable(base: timer_base);
325
326 pit_instances++;
327
328 if (pit_instances == max_pit_instances) {
329 ret = cpuhp_setup_state(state: CPUHP_AP_ONLINE_DYN, name: "PIT timer:starting",
330 startup: pit_clockevent_starting_cpu, NULL);
331 if (ret < 0)
332 goto out_pit_clocksource_unregister;
333 }
334
335 return 0;
336
337out_pit_clocksource_unregister:
338 clocksource_unregister(&pit->cs);
339out_pit_module_disable:
340 pit_module_disable(base: timer_base);
341 clk_disable_unprepare(clk: pit_clk);
342out_clk_put:
343 clk_put(clk: pit_clk);
344out_irq_dispose_mapping:
345 irq_dispose_mapping(virq: irq);
346out_iounmap:
347 iounmap(addr: timer_base);
348out_kfree:
349 kfree(objp: pit);
350
351 return ret;
352}
353
354static int pit_timer_probe(struct platform_device *pdev)
355{
356 const struct pit_timer_data *pit_timer_data;
357
358 pit_timer_data = of_device_get_match_data(dev: &pdev->dev);
359 if (pit_timer_data)
360 max_pit_instances = pit_timer_data->max_pit_instances;
361
362 return pit_timer_init(np: pdev->dev.of_node);
363}
364
365static struct pit_timer_data s32g2_data = { .max_pit_instances = 2 };
366
367static const struct of_device_id pit_timer_of_match[] = {
368 { .compatible = "nxp,s32g2-pit", .data = &s32g2_data },
369 { }
370};
371MODULE_DEVICE_TABLE(of, pit_timer_of_match);
372
373static struct platform_driver nxp_pit_driver = {
374 .driver = {
375 .name = "nxp-pit",
376 .of_match_table = pit_timer_of_match,
377 .suppress_bind_attrs = true,
378 },
379 .probe = pit_timer_probe,
380};
381builtin_platform_driver(nxp_pit_driver);
382
383TIMER_OF_DECLARE(vf610, "fsl,vf610-pit", pit_timer_init);
384

source code of linux/drivers/clocksource/timer-nxp-pit.c