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/delay.h>
  15#include <linux/device.h>
  16#include <linux/err.h>
  17#include <linux/smp.h>
  18#include <linux/jiffies.h>
  19#include <linux/clockchips.h>
  20#include <linux/interrupt.h>
  21#include <linux/io.h>
  22#include <linux/of_irq.h>
  23#include <linux/of_address.h>
  24
  25#include <asm/smp_plat.h>
  26#include <asm/smp_twd.h>
  27#include <asm/localtimer.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                __raw_writel(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        __raw_writel(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 = __raw_readl(twd_base + TWD_TIMER_CONTROL);
  68
  69        ctrl |= TWD_TIMER_CONTROL_ENABLE;
  70
  71        __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
  72        __raw_writel(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 (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
  86                __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
  87                return 1;
  88        }
  89
  90        return 0;
  91}
  92
  93static void twd_timer_stop(struct clock_event_device *clk)
  94{
  95        twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
  96        disable_percpu_irq(clk->irq);
  97}
  98
  99#ifdef CONFIG_COMMON_CLK
 100
 101/*
 102 * Updates clockevent frequency when the cpu frequency changes.
 103 * Called on the cpu that is changing frequency with interrupts disabled.
 104 */
 105static void twd_update_frequency(void *new_rate)
 106{
 107        twd_timer_rate = *((unsigned long *) new_rate);
 108
 109        clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
 110}
 111
 112static int twd_rate_change(struct notifier_block *nb,
 113        unsigned long flags, void *data)
 114{
 115        struct clk_notifier_data *cnd = data;
 116
 117        /*
 118         * The twd clock events must be reprogrammed to account for the new
 119         * frequency.  The timer is local to a cpu, so cross-call to the
 120         * changing cpu.
 121         */
 122        if (flags == POST_RATE_CHANGE)
 123                smp_call_function(twd_update_frequency,
 124                                  (void *)&cnd->new_rate, 1);
 125
 126        return NOTIFY_OK;
 127}
 128
 129static struct notifier_block twd_clk_nb = {
 130        .notifier_call = twd_rate_change,
 131};
 132
 133static int twd_clk_init(void)
 134{
 135        if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
 136                return clk_notifier_register(twd_clk, &twd_clk_nb);
 137
 138        return 0;
 139}
 140core_initcall(twd_clk_init);
 141
 142#elif defined (CONFIG_CPU_FREQ)
 143
 144#include <linux/cpufreq.h>
 145
 146/*
 147 * Updates clockevent frequency when the cpu frequency changes.
 148 * Called on the cpu that is changing frequency with interrupts disabled.
 149 */
 150static void twd_update_frequency(void *data)
 151{
 152        twd_timer_rate = clk_get_rate(twd_clk);
 153
 154        clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
 155}
 156
 157static int twd_cpufreq_transition(struct notifier_block *nb,
 158        unsigned long state, void *data)
 159{
 160        struct cpufreq_freqs *freqs = data;
 161
 162        /*
 163         * The twd clock events must be reprogrammed to account for the new
 164         * frequency.  The timer is local to a cpu, so cross-call to the
 165         * changing cpu.
 166         */
 167        if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
 168                smp_call_function_single(freqs->cpu, twd_update_frequency,
 169                        NULL, 1);
 170
 171        return NOTIFY_OK;
 172}
 173
 174static struct notifier_block twd_cpufreq_nb = {
 175        .notifier_call = twd_cpufreq_transition,
 176};
 177
 178static int twd_cpufreq_init(void)
 179{
 180        if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
 181                return cpufreq_register_notifier(&twd_cpufreq_nb,
 182                        CPUFREQ_TRANSITION_NOTIFIER);
 183
 184        return 0;
 185}
 186core_initcall(twd_cpufreq_init);
 187
 188#endif
 189
 190static void __cpuinit twd_calibrate_rate(void)
 191{
 192        unsigned long count;
 193        u64 waitjiffies;
 194
 195        /*
 196         * If this is the first time round, we need to work out how fast
 197         * the timer ticks
 198         */
 199        if (twd_timer_rate == 0) {
 200                printk(KERN_INFO "Calibrating local timer... ");
 201
 202                /* Wait for a tick to start */
 203                waitjiffies = get_jiffies_64() + 1;
 204
 205                while (get_jiffies_64() < waitjiffies)
 206                        udelay(10);
 207
 208                /* OK, now the tick has started, let's get the timer going */
 209                waitjiffies += 5;
 210
 211                                 /* enable, no interrupt or reload */
 212                __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
 213
 214                                 /* maximum value */
 215                __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
 216
 217                while (get_jiffies_64() < waitjiffies)
 218                        udelay(10);
 219
 220                count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
 221
 222                twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
 223
 224                printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
 225                        (twd_timer_rate / 10000) % 100);
 226        }
 227}
 228
 229static irqreturn_t twd_handler(int irq, void *dev_id)
 230{
 231        struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
 232
 233        if (twd_timer_ack()) {
 234                evt->event_handler(evt);
 235                return IRQ_HANDLED;
 236        }
 237
 238        return IRQ_NONE;
 239}
 240
 241static void twd_get_clock(struct device_node *np)
 242{
 243        int err;
 244
 245        if (np)
 246                twd_clk = of_clk_get(np, 0);
 247        else
 248                twd_clk = clk_get_sys("smp_twd", NULL);
 249
 250        if (IS_ERR(twd_clk)) {
 251                pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk));
 252                return;
 253        }
 254
 255        err = clk_prepare_enable(twd_clk);
 256        if (err) {
 257                pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
 258                clk_put(twd_clk);
 259                return;
 260        }
 261
 262        twd_timer_rate = clk_get_rate(twd_clk);
 263}
 264
 265/*
 266 * Setup the local clock events for a CPU.
 267 */
 268static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
 269{
 270        struct clock_event_device **this_cpu_clk;
 271        int cpu = smp_processor_id();
 272
 273        /*
 274         * If the basic setup for this CPU has been done before don't
 275         * bother with the below.
 276         */
 277        if (per_cpu(percpu_setup_called, cpu)) {
 278                __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
 279                clockevents_register_device(*__this_cpu_ptr(twd_evt));
 280                enable_percpu_irq(clk->irq, 0);
 281                return 0;
 282        }
 283        per_cpu(percpu_setup_called, cpu) = true;
 284
 285        twd_calibrate_rate();
 286
 287        /*
 288         * The following is done once per CPU the first time .setup() is
 289         * called.
 290         */
 291        __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
 292
 293        clk->name = "local_timer";
 294        clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
 295                        CLOCK_EVT_FEAT_C3STOP;
 296        clk->rating = 350;
 297        clk->set_mode = twd_set_mode;
 298        clk->set_next_event = twd_set_next_event;
 299        clk->irq = twd_ppi;
 300
 301        this_cpu_clk = __this_cpu_ptr(twd_evt);
 302        *this_cpu_clk = clk;
 303
 304        clockevents_config_and_register(clk, twd_timer_rate,
 305                                        0xf, 0xffffffff);
 306        enable_percpu_irq(clk->irq, 0);
 307
 308        return 0;
 309}
 310
 311static struct local_timer_ops twd_lt_ops __cpuinitdata = {
 312        .setup  = twd_timer_setup,
 313        .stop   = twd_timer_stop,
 314};
 315
 316static int __init twd_local_timer_common_register(struct device_node *np)
 317{
 318        int err;
 319
 320        twd_evt = alloc_percpu(struct clock_event_device *);
 321        if (!twd_evt) {
 322                err = -ENOMEM;
 323                goto out_free;
 324        }
 325
 326        err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
 327        if (err) {
 328                pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
 329                goto out_free;
 330        }
 331
 332        err = local_timer_register(&twd_lt_ops);
 333        if (err)
 334                goto out_irq;
 335
 336        twd_get_clock(np);
 337
 338        return 0;
 339
 340out_irq:
 341        free_percpu_irq(twd_ppi, twd_evt);
 342out_free:
 343        iounmap(twd_base);
 344        twd_base = NULL;
 345        free_percpu(twd_evt);
 346
 347        return err;
 348}
 349
 350int __init twd_local_timer_register(struct twd_local_timer *tlt)
 351{
 352        if (twd_base || twd_evt)
 353                return -EBUSY;
 354
 355        twd_ppi = tlt->res[1].start;
 356
 357        twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
 358        if (!twd_base)
 359                return -ENOMEM;
 360
 361        return twd_local_timer_common_register(NULL);
 362}
 363
 364#ifdef CONFIG_OF
 365const static struct of_device_id twd_of_match[] __initconst = {
 366        { .compatible = "arm,cortex-a9-twd-timer",      },
 367        { .compatible = "arm,cortex-a5-twd-timer",      },
 368        { .compatible = "arm,arm11mp-twd-timer",        },
 369        { },
 370};
 371
 372void __init twd_local_timer_of_register(void)
 373{
 374        struct device_node *np;
 375        int err;
 376
 377        if (!is_smp() || !setup_max_cpus)
 378                return;
 379
 380        np = of_find_matching_node(NULL, twd_of_match);
 381        if (!np)
 382                return;
 383
 384        twd_ppi = irq_of_parse_and_map(np, 0);
 385        if (!twd_ppi) {
 386                err = -EINVAL;
 387                goto out;
 388        }
 389
 390        twd_base = of_iomap(np, 0);
 391        if (!twd_base) {
 392                err = -ENOMEM;
 393                goto out;
 394        }
 395
 396        err = twd_local_timer_common_register(np);
 397
 398out:
 399        WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
 400}
 401#endif
 402