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/delay.h>
15 #include <linux/device.h>
16 #include <linux/err.h>
17 #include <linux/smp.h>
18 #include <linux/jiffies.h>
19 #include <linux/clockchips.h>
20 #include <linux/interrupt.h>
22 #include <linux/of_irq.h>
23 #include <linux/of_address.h>
25 #include <asm/smp_twd.h>
26 #include <asm/localtimer.h>
28 /* set up by the platform code */
29 static void __iomem *twd_base;
31 static struct clk *twd_clk;
32 static unsigned long twd_timer_rate;
33 static DEFINE_PER_CPU(bool, percpu_setup_called);
35 static struct clock_event_device __percpu **twd_evt;
38 static void twd_set_mode(enum clock_event_mode mode,
39 struct clock_event_device *clk)
44 case CLOCK_EVT_MODE_PERIODIC:
45 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
46 | TWD_TIMER_CONTROL_PERIODIC;
47 __raw_writel(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
48 twd_base + TWD_TIMER_LOAD);
50 case CLOCK_EVT_MODE_ONESHOT:
51 /* period set, and timer enabled in 'next_event' hook */
52 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
54 case CLOCK_EVT_MODE_UNUSED:
55 case CLOCK_EVT_MODE_SHUTDOWN:
60 __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
63 static int twd_set_next_event(unsigned long evt,
64 struct clock_event_device *unused)
66 unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
68 ctrl |= TWD_TIMER_CONTROL_ENABLE;
70 __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
71 __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
77 * local_timer_ack: checks for a local timer interrupt.
79 * If a local timer interrupt has occurred, acknowledge and return 1.
80 * Otherwise, return 0.
82 static int twd_timer_ack(void)
84 if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
85 __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
92 static void twd_timer_stop(struct clock_event_device *clk)
94 twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
95 disable_percpu_irq(clk->irq);
98 #ifdef CONFIG_COMMON_CLK
101 * Updates clockevent frequency when the cpu frequency changes.
102 * Called on the cpu that is changing frequency with interrupts disabled.
104 static void twd_update_frequency(void *new_rate)
106 twd_timer_rate = *((unsigned long *) new_rate);
108 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
111 static int twd_rate_change(struct notifier_block *nb,
112 unsigned long flags, void *data)
114 struct clk_notifier_data *cnd = data;
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
121 if (flags == POST_RATE_CHANGE)
122 smp_call_function(twd_update_frequency,
123 (void *)&cnd->new_rate, 1);
128 static struct notifier_block twd_clk_nb = {
129 .notifier_call = twd_rate_change,
132 static int twd_clk_init(void)
134 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
135 return clk_notifier_register(twd_clk, &twd_clk_nb);
139 core_initcall(twd_clk_init);
141 #elif defined (CONFIG_CPU_FREQ)
143 #include <linux/cpufreq.h>
146 * Updates clockevent frequency when the cpu frequency changes.
147 * Called on the cpu that is changing frequency with interrupts disabled.
149 static void twd_update_frequency(void *data)
151 twd_timer_rate = clk_get_rate(twd_clk);
153 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
156 static int twd_cpufreq_transition(struct notifier_block *nb,
157 unsigned long state, void *data)
159 struct cpufreq_freqs *freqs = data;
162 * The twd clock events must be reprogrammed to account for the new
163 * frequency. The timer is local to a cpu, so cross-call to the
166 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
167 smp_call_function_single(freqs->cpu, twd_update_frequency,
173 static struct notifier_block twd_cpufreq_nb = {
174 .notifier_call = twd_cpufreq_transition,
177 static int twd_cpufreq_init(void)
179 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
180 return cpufreq_register_notifier(&twd_cpufreq_nb,
181 CPUFREQ_TRANSITION_NOTIFIER);
185 core_initcall(twd_cpufreq_init);
189 static void __cpuinit twd_calibrate_rate(void)
195 * If this is the first time round, we need to work out how fast
198 if (twd_timer_rate == 0) {
199 printk(KERN_INFO "Calibrating local timer... ");
201 /* Wait for a tick to start */
202 waitjiffies = get_jiffies_64() + 1;
204 while (get_jiffies_64() < waitjiffies)
207 /* OK, now the tick has started, let's get the timer going */
210 /* enable, no interrupt or reload */
211 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
214 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
216 while (get_jiffies_64() < waitjiffies)
219 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
221 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
223 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
224 (twd_timer_rate / 10000) % 100);
228 static irqreturn_t twd_handler(int irq, void *dev_id)
230 struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
232 if (twd_timer_ack()) {
233 evt->event_handler(evt);
240 static void twd_get_clock(struct device_node *np)
245 twd_clk = of_clk_get(np, 0);
247 twd_clk = clk_get_sys("smp_twd", NULL);
249 if (IS_ERR(twd_clk)) {
250 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
254 err = clk_prepare_enable(twd_clk);
256 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
261 twd_timer_rate = clk_get_rate(twd_clk);
265 * Setup the local clock events for a CPU.
267 static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
269 struct clock_event_device **this_cpu_clk;
270 int cpu = smp_processor_id();
273 * If the basic setup for this CPU has been done before don't
274 * bother with the below.
276 if (per_cpu(percpu_setup_called, cpu)) {
277 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
278 clockevents_register_device(*__this_cpu_ptr(twd_evt));
279 enable_percpu_irq(clk->irq, 0);
282 per_cpu(percpu_setup_called, cpu) = true;
284 twd_calibrate_rate();
287 * The following is done once per CPU the first time .setup() is
290 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
292 clk->name = "local_timer";
293 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
294 CLOCK_EVT_FEAT_C3STOP;
296 clk->set_mode = twd_set_mode;
297 clk->set_next_event = twd_set_next_event;
300 this_cpu_clk = __this_cpu_ptr(twd_evt);
303 clockevents_config_and_register(clk, twd_timer_rate,
305 enable_percpu_irq(clk->irq, 0);
310 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
311 .setup = twd_timer_setup,
312 .stop = twd_timer_stop,
315 static int __init twd_local_timer_common_register(struct device_node *np)
319 twd_evt = alloc_percpu(struct clock_event_device *);
325 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
327 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
331 err = local_timer_register(&twd_lt_ops);
340 free_percpu_irq(twd_ppi, twd_evt);
344 free_percpu(twd_evt);
349 int __init twd_local_timer_register(struct twd_local_timer *tlt)
351 if (twd_base || twd_evt)
354 twd_ppi = tlt->res[1].start;
356 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
360 return twd_local_timer_common_register(NULL);
364 const static struct of_device_id twd_of_match[] __initconst = {
365 { .compatible = "arm,cortex-a9-twd-timer", },
366 { .compatible = "arm,cortex-a5-twd-timer", },
367 { .compatible = "arm,arm11mp-twd-timer", },
371 void __init twd_local_timer_of_register(void)
373 struct device_node *np;
376 np = of_find_matching_node(NULL, twd_of_match);
380 twd_ppi = irq_of_parse_and_map(np, 0);
386 twd_base = of_iomap(np, 0);
392 err = twd_local_timer_common_register(np);
395 WARN(err, "twd_local_timer_of_register failed (%d)\n", err);