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