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 bool common_setup_called;
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 __raw_writel(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 __raw_writel(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 = __raw_readl(twd_base + TWD_TIMER_CONTROL);
69 ctrl |= TWD_TIMER_CONTROL_ENABLE;
71 __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
72 __raw_writel(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 (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
86 __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
93 static void twd_timer_stop(struct clock_event_device *clk)
95 twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
96 disable_percpu_irq(clk->irq);
99 #ifdef CONFIG_COMMON_CLK
102 * Updates clockevent frequency when the cpu frequency changes.
103 * Called on the cpu that is changing frequency with interrupts disabled.
105 static void twd_update_frequency(void *new_rate)
107 twd_timer_rate = *((unsigned long *) new_rate);
109 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
112 static int twd_rate_change(struct notifier_block *nb,
113 unsigned long flags, void *data)
115 struct clk_notifier_data *cnd = data;
118 * The twd clock events must be reprogrammed to account for the new
119 * frequency. The timer is local to a cpu, so cross-call to the
122 if (flags == POST_RATE_CHANGE)
123 smp_call_function(twd_update_frequency,
124 (void *)&cnd->new_rate, 1);
129 static struct notifier_block twd_clk_nb = {
130 .notifier_call = twd_rate_change,
133 static int twd_clk_init(void)
135 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
136 return clk_notifier_register(twd_clk, &twd_clk_nb);
140 core_initcall(twd_clk_init);
142 #elif defined (CONFIG_CPU_FREQ)
144 #include <linux/cpufreq.h>
147 * Updates clockevent frequency when the cpu frequency changes.
148 * Called on the cpu that is changing frequency with interrupts disabled.
150 static void twd_update_frequency(void *data)
152 twd_timer_rate = clk_get_rate(twd_clk);
154 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
157 static int twd_cpufreq_transition(struct notifier_block *nb,
158 unsigned long state, void *data)
160 struct cpufreq_freqs *freqs = data;
163 * The twd clock events must be reprogrammed to account for the new
164 * frequency. The timer is local to a cpu, so cross-call to the
167 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
168 smp_call_function_single(freqs->cpu, twd_update_frequency,
174 static struct notifier_block twd_cpufreq_nb = {
175 .notifier_call = twd_cpufreq_transition,
178 static int twd_cpufreq_init(void)
180 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
181 return cpufreq_register_notifier(&twd_cpufreq_nb,
182 CPUFREQ_TRANSITION_NOTIFIER);
186 core_initcall(twd_cpufreq_init);
190 static void __cpuinit twd_calibrate_rate(void)
196 * If this is the first time round, we need to work out how fast
199 if (twd_timer_rate == 0) {
200 printk(KERN_INFO "Calibrating local timer... ");
202 /* Wait for a tick to start */
203 waitjiffies = get_jiffies_64() + 1;
205 while (get_jiffies_64() < waitjiffies)
208 /* OK, now the tick has started, let's get the timer going */
211 /* enable, no interrupt or reload */
212 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
215 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
217 while (get_jiffies_64() < waitjiffies)
220 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
222 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
224 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
225 (twd_timer_rate / 10000) % 100);
229 static irqreturn_t twd_handler(int irq, void *dev_id)
231 struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
233 if (twd_timer_ack()) {
234 evt->event_handler(evt);
241 static struct clk *twd_get_clock(void)
246 clk = clk_get_sys("smp_twd", NULL);
248 pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
252 err = clk_prepare_enable(clk);
254 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
263 * Setup the local clock events for a CPU.
265 static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
267 struct clock_event_device **this_cpu_clk;
268 int cpu = smp_processor_id();
271 * If the basic setup for this CPU has been done before don't
272 * bother with the below.
274 if (per_cpu(percpu_setup_called, cpu)) {
275 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
276 clockevents_register_device(*__this_cpu_ptr(twd_evt));
277 enable_percpu_irq(clk->irq, 0);
280 per_cpu(percpu_setup_called, cpu) = true;
283 * This stuff only need to be done once for the entire TWD cluster
284 * during the runtime of the system.
286 if (!common_setup_called) {
287 twd_clk = twd_get_clock();
290 * We use IS_ERR_OR_NULL() here, because if the clock stubs
291 * are active we will get a valid clk reference which is
292 * however NULL and will return the rate 0. In that case we
293 * need to calibrate the rate instead.
295 if (!IS_ERR_OR_NULL(twd_clk))
296 twd_timer_rate = clk_get_rate(twd_clk);
298 twd_calibrate_rate();
300 common_setup_called = true;
304 * The following is done once per CPU the first time .setup() is
307 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
309 clk->name = "local_timer";
310 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
311 CLOCK_EVT_FEAT_C3STOP;
313 clk->set_mode = twd_set_mode;
314 clk->set_next_event = twd_set_next_event;
317 this_cpu_clk = __this_cpu_ptr(twd_evt);
320 clockevents_config_and_register(clk, twd_timer_rate,
322 enable_percpu_irq(clk->irq, 0);
327 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
328 .setup = twd_timer_setup,
329 .stop = twd_timer_stop,
332 static int __init twd_local_timer_common_register(void)
336 twd_evt = alloc_percpu(struct clock_event_device *);
342 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
344 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
348 err = local_timer_register(&twd_lt_ops);
355 free_percpu_irq(twd_ppi, twd_evt);
359 free_percpu(twd_evt);
364 int __init twd_local_timer_register(struct twd_local_timer *tlt)
366 if (twd_base || twd_evt)
369 twd_ppi = tlt->res[1].start;
371 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
375 return twd_local_timer_common_register();
379 const static struct of_device_id twd_of_match[] __initconst = {
380 { .compatible = "arm,cortex-a9-twd-timer", },
381 { .compatible = "arm,cortex-a5-twd-timer", },
382 { .compatible = "arm,arm11mp-twd-timer", },
386 void __init twd_local_timer_of_register(void)
388 struct device_node *np;
391 np = of_find_matching_node(NULL, twd_of_match);
395 twd_ppi = irq_of_parse_and_map(np, 0);
401 twd_base = of_iomap(np, 0);
407 err = twd_local_timer_common_register();
410 WARN(err, "twd_local_timer_of_register failed (%d)\n", err);