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_plat.h>
  27#include <asm/smp_twd.h>
  28
  29/* set up by the platform code */
  30static void __iomem *twd_base;
  31
  32static struct clk *twd_clk;
  33static unsigned long twd_timer_rate;
  34static DEFINE_PER_CPU(bool, percpu_setup_called);
  35
  36static struct clock_event_device __percpu *twd_evt;
  37static int twd_ppi;
  38
  39static 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
  64static 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 */
  83static 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
  93static 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 */
 107static 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
 114static 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
 131static struct notifier_block twd_clk_nb = {
 132        .notifier_call = twd_rate_change,
 133};
 134
 135static 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}
 142core_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 */
 152static 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
 159static 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 || state == CPUFREQ_RESUMECHANGE)
 170                smp_call_function_single(freqs->cpu, twd_update_frequency,
 171                        NULL, 1);
 172
 173        return NOTIFY_OK;
 174}
 175
 176static struct notifier_block twd_cpufreq_nb = {
 177        .notifier_call = twd_cpufreq_transition,
 178};
 179
 180static 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}
 188core_initcall(twd_cpufreq_init);
 189
 190#endif
 191
 192static 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
 231static 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
 243static 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 */
 270static 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
 309static 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
 324static struct notifier_block twd_timer_cpu_nb = {
 325        .notifier_call = twd_timer_cpu_notify,
 326};
 327
 328static 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
 362out_irq:
 363        free_percpu_irq(twd_ppi, twd_evt);
 364out_free:
 365        iounmap(twd_base);
 366        twd_base = NULL;
 367        free_percpu(twd_evt);
 368
 369        return err;
 370}
 371
 372int __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
 387static 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
 408out:
 409        WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
 410}
 411CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
 412CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
 413CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
 414#endif
 415
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