linux/arch/arm/kernel/smp_twd.c
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   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 */
  29static void __iomem *twd_base;
  30
  31static struct clk *twd_clk;
  32static unsigned long twd_timer_rate;
  33static DEFINE_PER_CPU(bool, percpu_setup_called);
  34
  35static struct clock_event_device __percpu *twd_evt;
  36static unsigned int twd_features =
  37                CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
  38static int twd_ppi;
  39
  40static int twd_shutdown(struct clock_event_device *clk)
  41{
  42        writel_relaxed(0, twd_base + TWD_TIMER_CONTROL);
  43        return 0;
  44}
  45
  46static 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
  54static 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
  66static 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 */
  85static 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
  95static 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 */
 109static 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
 116static 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
 133static struct notifier_block twd_clk_nb = {
 134        .notifier_call = twd_rate_change,
 135};
 136
 137static 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}
 144core_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 */
 154static 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
 161static 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
 178static struct notifier_block twd_cpufreq_nb = {
 179        .notifier_call = twd_cpufreq_transition,
 180};
 181
 182static 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}
 190core_initcall(twd_cpufreq_init);
 191
 192#endif
 193
 194static 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
 233static 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
 245static 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 */
 272static 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
 313static 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
 328static struct notifier_block twd_timer_cpu_nb = {
 329        .notifier_call = twd_timer_cpu_notify,
 330};
 331
 332static 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
 368out_irq:
 369        free_percpu_irq(twd_ppi, twd_evt);
 370out_free:
 371        iounmap(twd_base);
 372        twd_base = NULL;
 373        free_percpu(twd_evt);
 374
 375        return err;
 376}
 377
 378int __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
 393static 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
 411out:
 412        WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
 413}
 414CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
 415CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
 416CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
 417#endif
 418
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