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/cpufreq.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_twd.h>
27 #include <asm/localtimer.h>
28 #include <asm/hardware/gic.h>
30 /* set up by the platform code */
31 static void __iomem *twd_base;
33 static struct clk *twd_clk;
34 static unsigned long twd_timer_rate;
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 /* timer load already set up */
47 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
48 | TWD_TIMER_CONTROL_PERIODIC;
49 __raw_writel(twd_timer_rate / HZ, 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_CPU_FREQ
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 *data)
107 twd_timer_rate = clk_get_rate(twd_clk);
109 clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
112 static int twd_cpufreq_transition(struct notifier_block *nb,
113 unsigned long state, void *data)
115 struct cpufreq_freqs *freqs = 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 * Only wait for it to finish, if the cpu is active to avoid
123 * deadlock when cpu1 is spinning on while(!cpu_active(cpu1)) during
124 * booting of that cpu.
126 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
127 smp_call_function_single(freqs->cpu, twd_update_frequency,
128 NULL, cpu_active(freqs->cpu));
133 static struct notifier_block twd_cpufreq_nb = {
134 .notifier_call = twd_cpufreq_transition,
137 static int twd_cpufreq_init(void)
139 if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
140 return cpufreq_register_notifier(&twd_cpufreq_nb,
141 CPUFREQ_TRANSITION_NOTIFIER);
145 core_initcall(twd_cpufreq_init);
149 static void __cpuinit twd_calibrate_rate(void)
155 * If this is the first time round, we need to work out how fast
158 if (twd_timer_rate == 0) {
159 printk(KERN_INFO "Calibrating local timer... ");
161 /* Wait for a tick to start */
162 waitjiffies = get_jiffies_64() + 1;
164 while (get_jiffies_64() < waitjiffies)
167 /* OK, now the tick has started, let's get the timer going */
170 /* enable, no interrupt or reload */
171 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
174 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
176 while (get_jiffies_64() < waitjiffies)
179 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
181 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
183 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
184 (twd_timer_rate / 10000) % 100);
188 static irqreturn_t twd_handler(int irq, void *dev_id)
190 struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
192 if (twd_timer_ack()) {
193 evt->event_handler(evt);
200 static struct clk *twd_get_clock(void)
205 clk = clk_get_sys("smp_twd", NULL);
207 pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
211 err = clk_prepare(clk);
213 pr_err("smp_twd: clock failed to prepare: %d\n", err);
218 err = clk_enable(clk);
220 pr_err("smp_twd: clock failed to enable: %d\n", err);
230 * Setup the local clock events for a CPU.
232 static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
234 struct clock_event_device **this_cpu_clk;
237 twd_clk = twd_get_clock();
239 if (!IS_ERR_OR_NULL(twd_clk))
240 twd_timer_rate = clk_get_rate(twd_clk);
242 twd_calibrate_rate();
244 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
246 clk->name = "local_timer";
247 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
248 CLOCK_EVT_FEAT_C3STOP;
250 clk->set_mode = twd_set_mode;
251 clk->set_next_event = twd_set_next_event;
254 this_cpu_clk = __this_cpu_ptr(twd_evt);
257 clockevents_config_and_register(clk, twd_timer_rate,
259 enable_percpu_irq(clk->irq, 0);
264 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
265 .setup = twd_timer_setup,
266 .stop = twd_timer_stop,
269 static int __init twd_local_timer_common_register(void)
273 twd_evt = alloc_percpu(struct clock_event_device *);
279 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
281 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
285 err = local_timer_register(&twd_lt_ops);
292 free_percpu_irq(twd_ppi, twd_evt);
296 free_percpu(twd_evt);
301 int __init twd_local_timer_register(struct twd_local_timer *tlt)
303 if (twd_base || twd_evt)
306 twd_ppi = tlt->res[1].start;
308 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
312 return twd_local_timer_common_register();
316 const static struct of_device_id twd_of_match[] __initconst = {
317 { .compatible = "arm,cortex-a9-twd-timer", },
318 { .compatible = "arm,cortex-a5-twd-timer", },
319 { .compatible = "arm,arm11mp-twd-timer", },
323 void __init twd_local_timer_of_register(void)
325 struct device_node *np;
328 np = of_find_matching_node(NULL, twd_of_match);
334 twd_ppi = irq_of_parse_and_map(np, 0);
340 twd_base = of_iomap(np, 0);
346 err = twd_local_timer_common_register();
349 WARN(err, "twd_local_timer_of_register failed (%d)\n", err);