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

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