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/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 */
  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(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  */
 105 static 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
 112 static 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                 on_each_cpu(twd_update_frequency,
 124                                   (void *)&cnd->new_rate, 1);
 125
 126         return NOTIFY_OK;
 127 }
 128
 129 static struct notifier_block twd_clk_nb = {
 130         .notifier_call = twd_rate_change,
 131 };
 132
 133 static 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 }
 140 core_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  */
 150 static 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
 157 static 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
 174 static struct notifier_block twd_cpufreq_nb = {
 175         .notifier_call = twd_cpufreq_transition,
 176 };
 177
 178 static 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 }
 186 core_initcall(twd_cpufreq_init);
 187
 188 #endif
 189
 190 static 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                 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL);
 213
 214                                  /* maximum value */
 215                 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
 216
 217                 while (get_jiffies_64() < waitjiffies)
 218                         udelay(10);
 219
 220                 count = readl_relaxed(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
 229 static 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
 241 static 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  */
 268 static 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                 writel_relaxed(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         writel_relaxed(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
 311 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
 312         .setup  = twd_timer_setup,
 313         .stop   = twd_timer_stop,
 314 };
 315
 316 static 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
 340 out_irq:
 341         free_percpu_irq(twd_ppi, twd_evt);
 342 out_free:
 343         iounmap(twd_base);
 344         twd_base = NULL;
 345         free_percpu(twd_evt);
 346
 347         return err;
 348 }
 349
 350 int __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
 365 static void __init twd_local_timer_of_register(struct device_node *np)
 366 {
 367         int err;
 368
 369         if (!is_smp() || !setup_max_cpus)
 370                 return;
 371
 372         twd_ppi = irq_of_parse_and_map(np, 0);
 373         if (!twd_ppi) {
 374                 err = -EINVAL;
 375                 goto out;
 376         }
 377
 378         twd_base = of_iomap(np, 0);
 379         if (!twd_base) {
 380                 err = -ENOMEM;
 381                 goto out;
 382         }
 383
 384         err = twd_local_timer_common_register(np);
 385
 386 out:
 387         WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
 388 }
 389 CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register);
 390 CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register);
 391 CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register);
 392 #endif