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