1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  linux/arch/arm/kernel/smp_twd.c
4 *
5 *  Copyright (C) 2002 ARM Ltd.
6 *  All Rights Reserved
7 */
8#include <linux/init.h>
9#include <linux/kernel.h>
10#include <linux/clk.h>
11#include <linux/cpu.h>
12#include <linux/delay.h>
13#include <linux/device.h>
14#include <linux/err.h>
15#include <linux/smp.h>
16#include <linux/jiffies.h>
17#include <linux/clockchips.h>
18#include <linux/interrupt.h>
19#include <linux/io.h>
20#include <linux/of_irq.h>
21#include <linux/of_address.h>
22
23#include <asm/smp_twd.h>
24
25/* set up by the platform code */
26static void __iomem *twd_base;
27
28static struct clk *twd_clk;
29static unsigned long twd_timer_rate;
30static DEFINE_PER_CPU(bool, percpu_setup_called);
31
32static struct clock_event_device __percpu *twd_evt;
33static unsigned int twd_features =
34		CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
35static int twd_ppi;
36
37static int twd_shutdown(struct clock_event_device *clk)
38{
39	writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
40	return 0;
41}
42
43static int twd_set_oneshot(struct clock_event_device *clk)
44{
45	/* period set, and timer enabled in 'next_event' hook */
46	writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT,
47		       twd_base + TWD_TIMER_CONTROL);
48	return 0;
49}
50
51static int twd_set_periodic(struct clock_event_device *clk)
52{
53	unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE |
54			     TWD_TIMER_CONTROL_IT_ENABLE |
55			     TWD_TIMER_CONTROL_PERIODIC;
56
57	writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
58		       twd_base + TWD_TIMER_LOAD);
59	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
60	return 0;
61}
62
63static int twd_set_next_event(unsigned long evt,
64			struct clock_event_device *unused)
65{
66	unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL);
67
68	ctrl |= TWD_TIMER_CONTROL_ENABLE;
69
70	writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER);
71	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
72
73	return 0;
74}
75
76/*
77 * local_timer_ack: checks for a local timer interrupt.
78 *
79 * If a local timer interrupt has occurred, acknowledge and return 1.
80 * Otherwise, return 0.
81 */
82static int twd_timer_ack(void)
83{
84	if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) {
85		writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT);
86		return 1;
87	}
88
89	return 0;
90}
91
92static void twd_timer_stop(void)
93{
94	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
95
96	twd_shutdown(clk);
97	disable_percpu_irq(clk->irq);
98}
99
100/*
101 * Updates clockevent frequency when the cpu frequency changes.
102 * Called on the cpu that is changing frequency with interrupts disabled.
103 */
104static void twd_update_frequency(void *new_rate)
105{
106	twd_timer_rate = *((unsigned long *) new_rate);
107
108	clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
109}
110
111static int twd_rate_change(struct notifier_block *nb,
112	unsigned long flags, void *data)
113{
114	struct clk_notifier_data *cnd = data;
115
116	/*
117	 * The twd clock events must be reprogrammed to account for the new
118	 * frequency.  The timer is local to a cpu, so cross-call to the
119	 * changing cpu.
120	 */
121	if (flags == POST_RATE_CHANGE)
122		on_each_cpu(twd_update_frequency,
123				  (void *)&cnd->new_rate, 1);
124
125	return NOTIFY_OK;
126}
127
128static struct notifier_block twd_clk_nb = {
129	.notifier_call = twd_rate_change,
130};
131
132static int twd_clk_init(void)
133{
134	if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
135		return clk_notifier_register(twd_clk, &twd_clk_nb);
136
137	return 0;
138}
139core_initcall(twd_clk_init);
140
141static void twd_calibrate_rate(void)
142{
143	unsigned long count;
144	u64 waitjiffies;
145
146	/*
147	 * If this is the first time round, we need to work out how fast
148	 * the timer ticks
149	 */
150	if (twd_timer_rate == 0) {
151		pr_info("Calibrating local timer... ");
152
153		/* Wait for a tick to start */
154		waitjiffies = get_jiffies_64() + 1;
155
156		while (get_jiffies_64() < waitjiffies)
157			udelay(10);
158
159		/* OK, now the tick has started, let's get the timer going */
160		waitjiffies += 5;
161
162				 /* enable, no interrupt or reload */
163		writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
164
165				 /* maximum value */
166		writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
167
168		while (get_jiffies_64() < waitjiffies)
169			udelay(10);
170
171		count = readl_relaxed(twd_base + TWD_TIMER_COUNTER);
172
173		twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
174
175		pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
176			(twd_timer_rate / 10000) % 100);
177	}
178}
179
180static irqreturn_t twd_handler(int irq, void *dev_id)
181{
182	struct clock_event_device *evt = dev_id;
183
184	if (twd_timer_ack()) {
185		evt->event_handler(evt);
186		return IRQ_HANDLED;
187	}
188
189	return IRQ_NONE;
190}
191
192static void twd_get_clock(struct device_node *np)
193{
194	int err;
195
196	if (np)
197		twd_clk = of_clk_get(np, 0);
198	else
199		twd_clk = clk_get_sys("smp_twd", NULL);
200
201	if (IS_ERR(twd_clk)) {
202		pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
203		return;
204	}
205
206	err = clk_prepare_enable(twd_clk);
207	if (err) {
208		pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
209		clk_put(twd_clk);
210		return;
211	}
212
213	twd_timer_rate = clk_get_rate(twd_clk);
214}
215
216/*
217 * Setup the local clock events for a CPU.
218 */
219static void twd_timer_setup(void)
220{
221	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
222	int cpu = smp_processor_id();
223
224	/*
225	 * If the basic setup for this CPU has been done before don't
226	 * bother with the below.
227	 */
228	if (per_cpu(percpu_setup_called, cpu)) {
229		writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
230		clockevents_register_device(clk);
231		enable_percpu_irq(clk->irq, 0);
232		return;
233	}
234	per_cpu(percpu_setup_called, cpu) = true;
235
236	twd_calibrate_rate();
237
238	/*
239	 * The following is done once per CPU the first time .setup() is
240	 * called.
241	 */
242	writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
243
244	clk->name = "local_timer";
245	clk->features = twd_features;
246	clk->rating = 350;
247	clk->set_state_shutdown = twd_shutdown;
248	clk->set_state_periodic = twd_set_periodic;
249	clk->set_state_oneshot = twd_set_oneshot;
250	clk->tick_resume = twd_shutdown;
251	clk->set_next_event = twd_set_next_event;
252	clk->irq = twd_ppi;
253	clk->cpumask = cpumask_of(cpu);
254
255	clockevents_config_and_register(clk, twd_timer_rate,
256					0xf, 0xffffffff);
257	enable_percpu_irq(clk->irq, 0);
258}
259
260static int twd_timer_starting_cpu(unsigned int cpu)
261{
262	twd_timer_setup();
263	return 0;
264}
265
266static int twd_timer_dying_cpu(unsigned int cpu)
267{
268	twd_timer_stop();
269	return 0;
270}
271
272static int __init twd_local_timer_common_register(struct device_node *np)
273{
274	int err;
275
276	twd_evt = alloc_percpu(struct clock_event_device);
277	if (!twd_evt) {
278		err = -ENOMEM;
279		goto out_free;
280	}
281
282	err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
283	if (err) {
284		pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
285		goto out_free;
286	}
287
288	cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING,
289				  "arm/timer/twd:starting",
290				  twd_timer_starting_cpu, twd_timer_dying_cpu);
291
292	twd_get_clock(np);
293	if (!of_property_read_bool(np, "always-on"))
294		twd_features |= CLOCK_EVT_FEAT_C3STOP;
295
296	/*
297	 * Immediately configure the timer on the boot CPU, unless we need
298	 * jiffies to be incrementing to calibrate the rate in which case
299	 * setup the timer in late_time_init.
300	 */
301	if (twd_timer_rate)
302		twd_timer_setup();
303	else
304		late_time_init = twd_timer_setup;
305
306	return 0;
307
308out_free:
309	iounmap(twd_base);
310	twd_base = NULL;
311	free_percpu(twd_evt);
312
313	return err;
314}
315
316static int __init twd_local_timer_of_register(struct device_node *np)
317{
318	int err;
319
320	twd_ppi = irq_of_parse_and_map(np, 0);
321	if (!twd_ppi) {
322		err = -EINVAL;
323		goto out;
324	}
325
326	twd_base = of_iomap(np, 0);
327	if (!twd_base) {
328		err = -ENOMEM;
329		goto out;
330	}
331
332	err = twd_local_timer_common_register(np);
333
334out:
335	WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
336	return err;
337}
338TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
339TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
340TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
341