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 = raw_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(raw_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 && raw_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(raw_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 && raw_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                 pr_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                 pr_cont("%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 = raw_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