1/*
2 *  linux/arch/arm/kernel/smp_twd.c
3 *
4 *  Copyright (C) 2002 ARM Ltd.
5 *  All Rights Reserved
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/clk.h>
14#include <linux/cpu.h>
15#include <linux/delay.h>
16#include <linux/device.h>
17#include <linux/err.h>
18#include <linux/smp.h>
19#include <linux/jiffies.h>
20#include <linux/clockchips.h>
21#include <linux/interrupt.h>
22#include <linux/io.h>
23#include <linux/of_irq.h>
24#include <linux/of_address.h>
25
26#include <asm/smp_plat.h>
27#include <asm/smp_twd.h>
28
29/* set up by the platform code */
30static void __iomem *twd_base;
31
32static struct clk *twd_clk;
33static unsigned long twd_timer_rate;
34static DEFINE_PER_CPU(bool, percpu_setup_called);
35
36static struct clock_event_device __percpu *twd_evt;
37static int twd_ppi;
38
39static void twd_set_mode(enum clock_event_mode mode,
40			struct clock_event_device *clk)
41{
42	unsigned long ctrl;
43
44	switch (mode) {
45	case CLOCK_EVT_MODE_PERIODIC:
46		ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
47			| TWD_TIMER_CONTROL_PERIODIC;
48		writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
49			twd_base + TWD_TIMER_LOAD);
50		break;
51	case CLOCK_EVT_MODE_ONESHOT:
52		/* period set, and timer enabled in 'next_event' hook */
53		ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
54		break;
55	case CLOCK_EVT_MODE_UNUSED:
56	case CLOCK_EVT_MODE_SHUTDOWN:
57	default:
58		ctrl = 0;
59	}
60
61	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
62}
63
64static int twd_set_next_event(unsigned long evt,
65			struct clock_event_device *unused)
66{
67	unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL);
68
69	ctrl |= TWD_TIMER_CONTROL_ENABLE;
70
71	writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER);
72	writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
73
74	return 0;
75}
76
77/*
78 * local_timer_ack: checks for a local timer interrupt.
79 *
80 * If a local timer interrupt has occurred, acknowledge and return 1.
81 * Otherwise, return 0.
82 */
83static int twd_timer_ack(void)
84{
85	if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) {
86		writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT);
87		return 1;
88	}
89
90	return 0;
91}
92
93static void twd_timer_stop(void)
94{
95	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
96
97	twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
98	disable_percpu_irq(clk->irq);
99}
100
101#ifdef CONFIG_COMMON_CLK
102
103/*
104 * Updates clockevent frequency when the cpu frequency changes.
105 * Called on the cpu that is changing frequency with interrupts disabled.
106 */
107static void twd_update_frequency(void *new_rate)
108{
109	twd_timer_rate = *((unsigned long *) new_rate);
110
111	clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
112}
113
114static int twd_rate_change(struct notifier_block *nb,
115	unsigned long flags, void *data)
116{
117	struct clk_notifier_data *cnd = data;
118
119	/*
120	 * The twd clock events must be reprogrammed to account for the new
121	 * frequency.  The timer is local to a cpu, so cross-call to the
122	 * changing cpu.
123	 */
124	if (flags == POST_RATE_CHANGE)
125		on_each_cpu(twd_update_frequency,
126				  (void *)&cnd->new_rate, 1);
127
128	return NOTIFY_OK;
129}
130
131static struct notifier_block twd_clk_nb = {
132	.notifier_call = twd_rate_change,
133};
134
135static int twd_clk_init(void)
136{
137	if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
138		return clk_notifier_register(twd_clk, &twd_clk_nb);
139
140	return 0;
141}
142core_initcall(twd_clk_init);
143
144#elif defined (CONFIG_CPU_FREQ)
145
146#include <linux/cpufreq.h>
147
148/*
149 * Updates clockevent frequency when the cpu frequency changes.
150 * Called on the cpu that is changing frequency with interrupts disabled.
151 */
152static void twd_update_frequency(void *data)
153{
154	twd_timer_rate = clk_get_rate(twd_clk);
155
156	clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
157}
158
159static int twd_cpufreq_transition(struct notifier_block *nb,
160	unsigned long state, void *data)
161{
162	struct cpufreq_freqs *freqs = data;
163
164	/*
165	 * The twd clock events must be reprogrammed to account for the new
166	 * frequency.  The timer is local to a cpu, so cross-call to the
167	 * changing cpu.
168	 */
169	if (state == CPUFREQ_POSTCHANGE)
170		smp_call_function_single(freqs->cpu, twd_update_frequency,
171			NULL, 1);
172
173	return NOTIFY_OK;
174}
175
176static struct notifier_block twd_cpufreq_nb = {
177	.notifier_call = twd_cpufreq_transition,
178};
179
180static int twd_cpufreq_init(void)
181{
182	if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
183		return cpufreq_register_notifier(&twd_cpufreq_nb,
184			CPUFREQ_TRANSITION_NOTIFIER);
185
186	return 0;
187}
188core_initcall(twd_cpufreq_init);
189
190#endif
191
192static void twd_calibrate_rate(void)
193{
194	unsigned long count;
195	u64 waitjiffies;
196
197	/*
198	 * If this is the first time round, we need to work out how fast
199	 * the timer ticks
200	 */
201	if (twd_timer_rate == 0) {
202		pr_info("Calibrating local timer... ");
203
204		/* Wait for a tick to start */
205		waitjiffies = get_jiffies_64() + 1;
206
207		while (get_jiffies_64() < waitjiffies)
208			udelay(10);
209
210		/* OK, now the tick has started, let's get the timer going */
211		waitjiffies += 5;
212
213				 /* enable, no interrupt or reload */
214		writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
215
216				 /* maximum value */
217		writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
218
219		while (get_jiffies_64() < waitjiffies)
220			udelay(10);
221
222		count = readl_relaxed(twd_base + TWD_TIMER_COUNTER);
223
224		twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
225
226		pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
227			(twd_timer_rate / 10000) % 100);
228	}
229}
230
231static irqreturn_t twd_handler(int irq, void *dev_id)
232{
233	struct clock_event_device *evt = dev_id;
234
235	if (twd_timer_ack()) {
236		evt->event_handler(evt);
237		return IRQ_HANDLED;
238	}
239
240	return IRQ_NONE;
241}
242
243static void twd_get_clock(struct device_node *np)
244{
245	int err;
246
247	if (np)
248		twd_clk = of_clk_get(np, 0);
249	else
250		twd_clk = clk_get_sys("smp_twd", NULL);
251
252	if (IS_ERR(twd_clk)) {
253		pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
254		return;
255	}
256
257	err = clk_prepare_enable(twd_clk);
258	if (err) {
259		pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
260		clk_put(twd_clk);
261		return;
262	}
263
264	twd_timer_rate = clk_get_rate(twd_clk);
265}
266
267/*
268 * Setup the local clock events for a CPU.
269 */
270static void twd_timer_setup(void)
271{
272	struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
273	int cpu = smp_processor_id();
274
275	/*
276	 * If the basic setup for this CPU has been done before don't
277	 * bother with the below.
278	 */
279	if (per_cpu(percpu_setup_called, cpu)) {
280		writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
281		clockevents_register_device(clk);
282		enable_percpu_irq(clk->irq, 0);
283		return;
284	}
285	per_cpu(percpu_setup_called, cpu) = true;
286
287	twd_calibrate_rate();
288
289	/*
290	 * The following is done once per CPU the first time .setup() is
291	 * called.
292	 */
293	writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
294
295	clk->name = "local_timer";
296	clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
297			CLOCK_EVT_FEAT_C3STOP;
298	clk->rating = 350;
299	clk->set_mode = twd_set_mode;
300	clk->set_next_event = twd_set_next_event;
301	clk->irq = twd_ppi;
302	clk->cpumask = cpumask_of(cpu);
303
304	clockevents_config_and_register(clk, twd_timer_rate,
305					0xf, 0xffffffff);
306	enable_percpu_irq(clk->irq, 0);
307}
308
309static int twd_timer_cpu_notify(struct notifier_block *self,
310				unsigned long action, void *hcpu)
311{
312	switch (action & ~CPU_TASKS_FROZEN) {
313	case CPU_STARTING:
314		twd_timer_setup();
315		break;
316	case CPU_DYING:
317		twd_timer_stop();
318		break;
319	}
320
321	return NOTIFY_OK;
322}
323
324static struct notifier_block twd_timer_cpu_nb = {
325	.notifier_call = twd_timer_cpu_notify,
326};
327
328static int __init twd_local_timer_common_register(struct device_node *np)
329{
330	int err;
331
332	twd_evt = alloc_percpu(struct clock_event_device);
333	if (!twd_evt) {
334		err = -ENOMEM;
335		goto out_free;
336	}
337
338	err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
339	if (err) {
340		pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
341		goto out_free;
342	}
343
344	err = register_cpu_notifier(&twd_timer_cpu_nb);
345	if (err)
346		goto out_irq;
347
348	twd_get_clock(np);
349
350	/*
351	 * Immediately configure the timer on the boot CPU, unless we need
352	 * jiffies to be incrementing to calibrate the rate in which case
353	 * setup the timer in late_time_init.
354	 */
355	if (twd_timer_rate)
356		twd_timer_setup();
357	else
358		late_time_init = twd_timer_setup;
359
360	return 0;
361
362out_irq:
363	free_percpu_irq(twd_ppi, twd_evt);
364out_free:
365	iounmap(twd_base);
366	twd_base = NULL;
367	free_percpu(twd_evt);
368
369	return err;
370}
371
372int __init twd_local_timer_register(struct twd_local_timer *tlt)
373{
374	if (twd_base || twd_evt)
375		return -EBUSY;
376
377	twd_ppi	= tlt->res[1].start;
378
379	twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
380	if (!twd_base)
381		return -ENOMEM;
382
383	return twd_local_timer_common_register(NULL);
384}
385
386#ifdef CONFIG_OF
387static void __init twd_local_timer_of_register(struct device_node *np)
388{
389	int err;
390
391	if (!is_smp() || !setup_max_cpus)
392		return;
393
394	twd_ppi = irq_of_parse_and_map(np, 0);
395	if (!twd_ppi) {
396		err = -EINVAL;
397		goto out;
398	}
399
400	twd_base = of_iomap(np, 0);
401	if (!twd_base) {
402		err = -ENOMEM;
403		goto out;
404	}
405
406	err = twd_local_timer_common_register(np);
407
408out:
409	WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
410}
411CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
412CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
413CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
414#endif
415