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Linux/arch/arm/kernel/smp_twd.c

  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_twd.h>
 27 
 28 /* set up by the platform code */
 29 static void __iomem *twd_base;
 30 
 31 static struct clk *twd_clk;
 32 static unsigned long twd_timer_rate;
 33 static DEFINE_PER_CPU(bool, percpu_setup_called);
 34 
 35 static struct clock_event_device __percpu *twd_evt;
 36 static unsigned int twd_features =
 37                 CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 38 static int twd_ppi;
 39 
 40 static int twd_shutdown(struct clock_event_device *clk)
 41 {
 42         writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
 43         return 0;
 44 }
 45 
 46 static int twd_set_oneshot(struct clock_event_device *clk)
 47 {
 48         /* period set, and timer enabled in 'next_event' hook */
 49         writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT,
 50                        twd_base + TWD_TIMER_CONTROL);
 51         return 0;
 52 }
 53 
 54 static int twd_set_periodic(struct clock_event_device *clk)
 55 {
 56         unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE |
 57                              TWD_TIMER_CONTROL_IT_ENABLE |
 58                              TWD_TIMER_CONTROL_PERIODIC;
 59 
 60         writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
 61                        twd_base + TWD_TIMER_LOAD);
 62         writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
 63         return 0;
 64 }
 65 
 66 static int twd_set_next_event(unsigned long evt,
 67                         struct clock_event_device *unused)
 68 {
 69         unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL);
 70 
 71         ctrl |= TWD_TIMER_CONTROL_ENABLE;
 72 
 73         writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER);
 74         writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL);
 75 
 76         return 0;
 77 }
 78 
 79 /*
 80  * local_timer_ack: checks for a local timer interrupt.
 81  *
 82  * If a local timer interrupt has occurred, acknowledge and return 1.
 83  * Otherwise, return 0.
 84  */
 85 static int twd_timer_ack(void)
 86 {
 87         if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) {
 88                 writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT);
 89                 return 1;
 90         }
 91 
 92         return 0;
 93 }
 94 
 95 static void twd_timer_stop(void)
 96 {
 97         struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
 98 
 99         twd_shutdown(clk);
100         disable_percpu_irq(clk->irq);
101 }
102 
103 #ifdef CONFIG_COMMON_CLK
104 
105 /*
106  * Updates clockevent frequency when the cpu frequency changes.
107  * Called on the cpu that is changing frequency with interrupts disabled.
108  */
109 static void twd_update_frequency(void *new_rate)
110 {
111         twd_timer_rate = *((unsigned long *) new_rate);
112 
113         clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
114 }
115 
116 static int twd_rate_change(struct notifier_block *nb,
117         unsigned long flags, void *data)
118 {
119         struct clk_notifier_data *cnd = data;
120 
121         /*
122          * The twd clock events must be reprogrammed to account for the new
123          * frequency.  The timer is local to a cpu, so cross-call to the
124          * changing cpu.
125          */
126         if (flags == POST_RATE_CHANGE)
127                 on_each_cpu(twd_update_frequency,
128                                   (void *)&cnd->new_rate, 1);
129 
130         return NOTIFY_OK;
131 }
132 
133 static struct notifier_block twd_clk_nb = {
134         .notifier_call = twd_rate_change,
135 };
136 
137 static int twd_clk_init(void)
138 {
139         if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
140                 return clk_notifier_register(twd_clk, &twd_clk_nb);
141 
142         return 0;
143 }
144 core_initcall(twd_clk_init);
145 
146 #elif defined (CONFIG_CPU_FREQ)
147 
148 #include <linux/cpufreq.h>
149 
150 /*
151  * Updates clockevent frequency when the cpu frequency changes.
152  * Called on the cpu that is changing frequency with interrupts disabled.
153  */
154 static void twd_update_frequency(void *data)
155 {
156         twd_timer_rate = clk_get_rate(twd_clk);
157 
158         clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate);
159 }
160 
161 static int twd_cpufreq_transition(struct notifier_block *nb,
162         unsigned long state, void *data)
163 {
164         struct cpufreq_freqs *freqs = data;
165 
166         /*
167          * The twd clock events must be reprogrammed to account for the new
168          * frequency.  The timer is local to a cpu, so cross-call to the
169          * changing cpu.
170          */
171         if (state == CPUFREQ_POSTCHANGE)
172                 smp_call_function_single(freqs->cpu, twd_update_frequency,
173                         NULL, 1);
174 
175         return NOTIFY_OK;
176 }
177 
178 static struct notifier_block twd_cpufreq_nb = {
179         .notifier_call = twd_cpufreq_transition,
180 };
181 
182 static int twd_cpufreq_init(void)
183 {
184         if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
185                 return cpufreq_register_notifier(&twd_cpufreq_nb,
186                         CPUFREQ_TRANSITION_NOTIFIER);
187 
188         return 0;
189 }
190 core_initcall(twd_cpufreq_init);
191 
192 #endif
193 
194 static void twd_calibrate_rate(void)
195 {
196         unsigned long count;
197         u64 waitjiffies;
198 
199         /*
200          * If this is the first time round, we need to work out how fast
201          * the timer ticks
202          */
203         if (twd_timer_rate == 0) {
204                 pr_info("Calibrating local timer... ");
205 
206                 /* Wait for a tick to start */
207                 waitjiffies = get_jiffies_64() + 1;
208 
209                 while (get_jiffies_64() < waitjiffies)
210                         udelay(10);
211 
212                 /* OK, now the tick has started, let's get the timer going */
213                 waitjiffies += 5;
214 
215                                  /* enable, no interrupt or reload */
216                 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
217 
218                                  /* maximum value */
219                 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
220 
221                 while (get_jiffies_64() < waitjiffies)
222                         udelay(10);
223 
224                 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER);
225 
226                 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
227 
228                 pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
229                         (twd_timer_rate / 10000) % 100);
230         }
231 }
232 
233 static irqreturn_t twd_handler(int irq, void *dev_id)
234 {
235         struct clock_event_device *evt = dev_id;
236 
237         if (twd_timer_ack()) {
238                 evt->event_handler(evt);
239                 return IRQ_HANDLED;
240         }
241 
242         return IRQ_NONE;
243 }
244 
245 static void twd_get_clock(struct device_node *np)
246 {
247         int err;
248 
249         if (np)
250                 twd_clk = of_clk_get(np, 0);
251         else
252                 twd_clk = clk_get_sys("smp_twd", NULL);
253 
254         if (IS_ERR(twd_clk)) {
255                 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
256                 return;
257         }
258 
259         err = clk_prepare_enable(twd_clk);
260         if (err) {
261                 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
262                 clk_put(twd_clk);
263                 return;
264         }
265 
266         twd_timer_rate = clk_get_rate(twd_clk);
267 }
268 
269 /*
270  * Setup the local clock events for a CPU.
271  */
272 static void twd_timer_setup(void)
273 {
274         struct clock_event_device *clk = raw_cpu_ptr(twd_evt);
275         int cpu = smp_processor_id();
276 
277         /*
278          * If the basic setup for this CPU has been done before don't
279          * bother with the below.
280          */
281         if (per_cpu(percpu_setup_called, cpu)) {
282                 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
283                 clockevents_register_device(clk);
284                 enable_percpu_irq(clk->irq, 0);
285                 return;
286         }
287         per_cpu(percpu_setup_called, cpu) = true;
288 
289         twd_calibrate_rate();
290 
291         /*
292          * The following is done once per CPU the first time .setup() is
293          * called.
294          */
295         writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
296 
297         clk->name = "local_timer";
298         clk->features = twd_features;
299         clk->rating = 350;
300         clk->set_state_shutdown = twd_shutdown;
301         clk->set_state_periodic = twd_set_periodic;
302         clk->set_state_oneshot = twd_set_oneshot;
303         clk->tick_resume = twd_shutdown;
304         clk->set_next_event = twd_set_next_event;
305         clk->irq = twd_ppi;
306         clk->cpumask = cpumask_of(cpu);
307 
308         clockevents_config_and_register(clk, twd_timer_rate,
309                                         0xf, 0xffffffff);
310         enable_percpu_irq(clk->irq, 0);
311 }
312 
313 static int twd_timer_cpu_notify(struct notifier_block *self,
314                                 unsigned long action, void *hcpu)
315 {
316         switch (action & ~CPU_TASKS_FROZEN) {
317         case CPU_STARTING:
318                 twd_timer_setup();
319                 break;
320         case CPU_DYING:
321                 twd_timer_stop();
322                 break;
323         }
324 
325         return NOTIFY_OK;
326 }
327 
328 static struct notifier_block twd_timer_cpu_nb = {
329         .notifier_call = twd_timer_cpu_notify,
330 };
331 
332 static int __init twd_local_timer_common_register(struct device_node *np)
333 {
334         int err;
335 
336         twd_evt = alloc_percpu(struct clock_event_device);
337         if (!twd_evt) {
338                 err = -ENOMEM;
339                 goto out_free;
340         }
341 
342         err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
343         if (err) {
344                 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
345                 goto out_free;
346         }
347 
348         err = register_cpu_notifier(&twd_timer_cpu_nb);
349         if (err)
350                 goto out_irq;
351 
352         twd_get_clock(np);
353         if (!of_property_read_bool(np, "always-on"))
354                 twd_features |= CLOCK_EVT_FEAT_C3STOP;
355 
356         /*
357          * Immediately configure the timer on the boot CPU, unless we need
358          * jiffies to be incrementing to calibrate the rate in which case
359          * setup the timer in late_time_init.
360          */
361         if (twd_timer_rate)
362                 twd_timer_setup();
363         else
364                 late_time_init = twd_timer_setup;
365 
366         return 0;
367 
368 out_irq:
369         free_percpu_irq(twd_ppi, twd_evt);
370 out_free:
371         iounmap(twd_base);
372         twd_base = NULL;
373         free_percpu(twd_evt);
374 
375         return err;
376 }
377 
378 int __init twd_local_timer_register(struct twd_local_timer *tlt)
379 {
380         if (twd_base || twd_evt)
381                 return -EBUSY;
382 
383         twd_ppi = tlt->res[1].start;
384 
385         twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
386         if (!twd_base)
387                 return -ENOMEM;
388 
389         return twd_local_timer_common_register(NULL);
390 }
391 
392 #ifdef CONFIG_OF
393 static void __init twd_local_timer_of_register(struct device_node *np)
394 {
395         int err;
396 
397         twd_ppi = irq_of_parse_and_map(np, 0);
398         if (!twd_ppi) {
399                 err = -EINVAL;
400                 goto out;
401         }
402 
403         twd_base = of_iomap(np, 0);
404         if (!twd_base) {
405                 err = -ENOMEM;
406                 goto out;
407         }
408 
409         err = twd_local_timer_common_register(np);
410 
411 out:
412         WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
413 }
414 CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
415 CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
416 CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
417 #endif
418 

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