2 * linux/arch/arm/kernel/smp_twd.c
4 * Copyright (C) 2002 ARM Ltd.
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.
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>
23 #include <linux/of_irq.h>
24 #include <linux/of_address.h>
26 #include <asm/smp_plat.h>
27 #include <asm/smp_twd.h>
29 /* set up by the platform code */
30 static void __iomem *twd_base;
32 static struct clk *twd_clk;
33 static unsigned long twd_timer_rate;
34 static DEFINE_PER_CPU(bool, percpu_setup_called);
36 static struct clock_event_device __percpu *twd_evt;
39 static void twd_set_mode(enum clock_event_mode mode,
40 struct clock_event_device *clk)
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);
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;
55 case CLOCK_EVT_MODE_UNUSED:
56 case CLOCK_EVT_MODE_SHUTDOWN:
61 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
64 static int twd_set_next_event(unsigned long evt,
65 struct clock_event_device *unused)
67 unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL);
69 ctrl |= TWD_TIMER_CONTROL_ENABLE;
71 writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER);
72 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
78 * local_timer_ack: checks for a local timer interrupt.
80 * If a local timer interrupt has occurred, acknowledge and return 1.
81 * Otherwise, return 0.
83 static int twd_timer_ack(void)
85 if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) {
86 writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT);
93 static void twd_timer_stop(void)
95 struct clock_event_device *clk = __this_cpu_ptr(twd_evt);
97 twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
98 disable_percpu_irq(clk->irq);
101 #ifdef CONFIG_COMMON_CLK
104 * Updates clockevent frequency when the cpu frequency changes.
105 * Called on the cpu that is changing frequency with interrupts disabled.
107 static void twd_update_frequency(void *new_rate)
109 twd_timer_rate = *((unsigned long *) new_rate);
111 clockevents_update_freq(__this_cpu_ptr(twd_evt), twd_timer_rate);
114 static int twd_rate_change(struct notifier_block *nb,
115 unsigned long flags, void *data)
117 struct clk_notifier_data *cnd = data;
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
124 if (flags == POST_RATE_CHANGE)
125 on_each_cpu(twd_update_frequency,
126 (void *)&cnd->new_rate, 1);
131 static struct notifier_block twd_clk_nb = {
132 .notifier_call = twd_rate_change,
135 static int twd_clk_init(void)
137 if (twd_evt && __this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
138 return clk_notifier_register(twd_clk, &twd_clk_nb);
142 core_initcall(twd_clk_init);
144 #elif defined (CONFIG_CPU_FREQ)
146 #include <linux/cpufreq.h>
149 * Updates clockevent frequency when the cpu frequency changes.
150 * Called on the cpu that is changing frequency with interrupts disabled.
152 static void twd_update_frequency(void *data)
154 twd_timer_rate = clk_get_rate(twd_clk);
156 clockevents_update_freq(__this_cpu_ptr(twd_evt), twd_timer_rate);
159 static int twd_cpufreq_transition(struct notifier_block *nb,
160 unsigned long state, void *data)
162 struct cpufreq_freqs *freqs = data;
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
169 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
170 smp_call_function_single(freqs->cpu, twd_update_frequency,
176 static struct notifier_block twd_cpufreq_nb = {
177 .notifier_call = twd_cpufreq_transition,
180 static int twd_cpufreq_init(void)
182 if (twd_evt && __this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
183 return cpufreq_register_notifier(&twd_cpufreq_nb,
184 CPUFREQ_TRANSITION_NOTIFIER);
188 core_initcall(twd_cpufreq_init);
192 static void twd_calibrate_rate(void)
198 * If this is the first time round, we need to work out how fast
201 if (twd_timer_rate == 0) {
202 printk(KERN_INFO "Calibrating local timer... ");
204 /* Wait for a tick to start */
205 waitjiffies = get_jiffies_64() + 1;
207 while (get_jiffies_64() < waitjiffies)
210 /* OK, now the tick has started, let's get the timer going */
213 /* enable, no interrupt or reload */
214 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
217 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
219 while (get_jiffies_64() < waitjiffies)
222 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER);
224 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
226 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
227 (twd_timer_rate / 10000) % 100);
231 static irqreturn_t twd_handler(int irq, void *dev_id)
233 struct clock_event_device *evt = dev_id;
235 if (twd_timer_ack()) {
236 evt->event_handler(evt);
243 static void twd_get_clock(struct device_node *np)
248 twd_clk = of_clk_get(np, 0);
250 twd_clk = clk_get_sys("smp_twd", NULL);
252 if (IS_ERR(twd_clk)) {
253 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
257 err = clk_prepare_enable(twd_clk);
259 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
264 twd_timer_rate = clk_get_rate(twd_clk);
268 * Setup the local clock events for a CPU.
270 static void twd_timer_setup(void)
272 struct clock_event_device *clk = __this_cpu_ptr(twd_evt);
273 int cpu = smp_processor_id();
276 * If the basic setup for this CPU has been done before don't
277 * bother with the below.
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);
285 per_cpu(percpu_setup_called, cpu) = true;
287 twd_calibrate_rate();
290 * The following is done once per CPU the first time .setup() is
293 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
295 clk->name = "local_timer";
296 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
297 CLOCK_EVT_FEAT_C3STOP;
299 clk->set_mode = twd_set_mode;
300 clk->set_next_event = twd_set_next_event;
302 clk->cpumask = cpumask_of(cpu);
304 clockevents_config_and_register(clk, twd_timer_rate,
306 enable_percpu_irq(clk->irq, 0);
309 static int twd_timer_cpu_notify(struct notifier_block *self,
310 unsigned long action, void *hcpu)
312 switch (action & ~CPU_TASKS_FROZEN) {
324 static struct notifier_block twd_timer_cpu_nb = {
325 .notifier_call = twd_timer_cpu_notify,
328 static int __init twd_local_timer_common_register(struct device_node *np)
332 twd_evt = alloc_percpu(struct clock_event_device);
338 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
340 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
344 err = register_cpu_notifier(&twd_timer_cpu_nb);
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.
358 late_time_init = twd_timer_setup;
363 free_percpu_irq(twd_ppi, twd_evt);
367 free_percpu(twd_evt);
372 int __init twd_local_timer_register(struct twd_local_timer *tlt)
374 if (twd_base || twd_evt)
377 twd_ppi = tlt->res[1].start;
379 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
383 return twd_local_timer_common_register(NULL);
387 static void __init twd_local_timer_of_register(struct device_node *np)
391 if (!is_smp() || !setup_max_cpus)
394 twd_ppi = irq_of_parse_and_map(np, 0);
400 twd_base = of_iomap(np, 0);
406 err = twd_local_timer_common_register(np);
409 WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
411 CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
412 CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
413 CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);