drivers/clocksource/arm_arch_timer.c

   1 /*
   2  *  linux/drivers/clocksource/arm_arch_timer.c
   3  *
   4  *  Copyright (C) 2011 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/device.h>
  14 #include <linux/smp.h>
  15 #include <linux/cpu.h>
  16 #include <linux/clockchips.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/io.h>
  20
  21 #include <asm/arch_timer.h>
  22 #include <asm/virt.h>
  23
  24 #include <clocksource/arm_arch_timer.h>
  25
  26 static u32 arch_timer_rate;
  27
  28 enum ppi_nr {
  29         PHYS_SECURE_PPI,
  30         PHYS_NONSECURE_PPI,
  31         VIRT_PPI,
  32         HYP_PPI,
  33         MAX_TIMER_PPI
  34 };
  35
  36 static int arch_timer_ppi[MAX_TIMER_PPI];
  37
  38 static struct clock_event_device __percpu *arch_timer_evt;
  39
  40 static bool arch_timer_use_virtual = true;
  41
  42 /*
  43  * Architected system timer support.
  44  */
  45
  46 static inline irqreturn_t timer_handler(const int access,
  47                                         struct clock_event_device *evt)
  48 {
  49         unsigned long ctrl;
  50         ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
  51         if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
  52                 ctrl |= ARCH_TIMER_CTRL_IT_MASK;
  53                 arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
  54                 evt->event_handler(evt);
  55                 return IRQ_HANDLED;
  56         }
  57
  58         return IRQ_NONE;
  59 }
  60
  61 static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
  62 {
  63         struct clock_event_device *evt = dev_id;
  64
  65         return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
  66 }
  67
  68 static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
  69 {
  70         struct clock_event_device *evt = dev_id;
  71
  72         return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
  73 }
  74
  75 static inline void timer_set_mode(const int access, int mode)
  76 {
  77         unsigned long ctrl;
  78         switch (mode) {
  79         case CLOCK_EVT_MODE_UNUSED:
  80         case CLOCK_EVT_MODE_SHUTDOWN:
  81                 ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
  82                 ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
  83                 arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
  84                 break;
  85         default:
  86                 break;
  87         }
  88 }
  89
  90 static void arch_timer_set_mode_virt(enum clock_event_mode mode,
  91                                      struct clock_event_device *clk)
  92 {
  93         timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
  94 }
  95
  96 static void arch_timer_set_mode_phys(enum clock_event_mode mode,
  97                                      struct clock_event_device *clk)
  98 {
  99         timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
 100 }
 101
 102 static inline void set_next_event(const int access, unsigned long evt)
 103 {
 104         unsigned long ctrl;
 105         ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 106         ctrl |= ARCH_TIMER_CTRL_ENABLE;
 107         ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 108         arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
 109         arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 110 }
 111
 112 static int arch_timer_set_next_event_virt(unsigned long evt,
 113                                           struct clock_event_device *unused)
 114 {
 115         set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
 116         return 0;
 117 }
 118
 119 static int arch_timer_set_next_event_phys(unsigned long evt,
 120                                           struct clock_event_device *unused)
 121 {
 122         set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
 123         return 0;
 124 }
 125
 126 static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
 127 {
 128         clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
 129         clk->name = "arch_sys_timer";
 130         clk->rating = 450;
 131         if (arch_timer_use_virtual) {
 132                 clk->irq = arch_timer_ppi[VIRT_PPI];
 133                 clk->set_mode = arch_timer_set_mode_virt;
 134                 clk->set_next_event = arch_timer_set_next_event_virt;
 135         } else {
 136                 clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
 137                 clk->set_mode = arch_timer_set_mode_phys;
 138                 clk->set_next_event = arch_timer_set_next_event_phys;
 139         }
 140
 141         clk->cpumask = cpumask_of(smp_processor_id());
 142
 143         clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);
 144
 145         clockevents_config_and_register(clk, arch_timer_rate,
 146                                         0xf, 0x7fffffff);
 147
 148         if (arch_timer_use_virtual)
 149                 enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
 150         else {
 151                 enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
 152                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 153                         enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
 154         }
 155
 156         arch_counter_set_user_access();
 157
 158         return 0;
 159 }
 160
 161 static int arch_timer_available(void)
 162 {
 163         u32 freq;
 164
 165         if (arch_timer_rate == 0) {
 166                 freq = arch_timer_get_cntfrq();
 167
 168                 /* Check the timer frequency. */
 169                 if (freq == 0) {
 170                         pr_warn("Architected timer frequency not available\n");
 171                         return -EINVAL;
 172                 }
 173
 174                 arch_timer_rate = freq;
 175         }
 176
 177         pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
 178                      (unsigned long)arch_timer_rate / 1000000,
 179                      (unsigned long)(arch_timer_rate / 10000) % 100,
 180                      arch_timer_use_virtual ? "virt" : "phys");
 181         return 0;
 182 }
 183
 184 u32 arch_timer_get_rate(void)
 185 {
 186         return arch_timer_rate;
 187 }
 188
 189 /*
 190  * Some external users of arch_timer_read_counter (e.g. sched_clock) may try to
 191  * call it before it has been initialised. Rather than incur a performance
 192  * penalty checking for initialisation, provide a default implementation that
 193  * won't lead to time appearing to jump backwards.
 194  */
 195 static u64 arch_timer_read_zero(void)
 196 {
 197         return 0;
 198 }
 199
 200 u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero;
 201
 202 static cycle_t arch_counter_read(struct clocksource *cs)
 203 {
 204         return arch_timer_read_counter();
 205 }
 206
 207 static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
 208 {
 209         return arch_timer_read_counter();
 210 }
 211
 212 static struct clocksource clocksource_counter = {
 213         .name   = "arch_sys_counter",
 214         .rating = 400,
 215         .read   = arch_counter_read,
 216         .mask   = CLOCKSOURCE_MASK(56),
 217         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 218 };
 219
 220 static struct cyclecounter cyclecounter = {
 221         .read   = arch_counter_read_cc,
 222         .mask   = CLOCKSOURCE_MASK(56),
 223 };
 224
 225 static struct timecounter timecounter;
 226
 227 struct timecounter *arch_timer_get_timecounter(void)
 228 {
 229         return &timecounter;
 230 }
 231
 232 static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
 233 {
 234         pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
 235                  clk->irq, smp_processor_id());
 236
 237         if (arch_timer_use_virtual)
 238                 disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
 239         else {
 240                 disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
 241                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 242                         disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
 243         }
 244
 245         clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
 246 }
 247
 248 static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
 249                                            unsigned long action, void *hcpu)
 250 {
 251         /*
 252          * Grab cpu pointer in each case to avoid spurious
 253          * preemptible warnings
 254          */
 255         switch (action & ~CPU_TASKS_FROZEN) {
 256         case CPU_STARTING:
 257                 arch_timer_setup(this_cpu_ptr(arch_timer_evt));
 258                 break;
 259         case CPU_DYING:
 260                 arch_timer_stop(this_cpu_ptr(arch_timer_evt));
 261                 break;
 262         }
 263
 264         return NOTIFY_OK;
 265 }
 266
 267 static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
 268         .notifier_call = arch_timer_cpu_notify,
 269 };
 270
 271 static int __init arch_timer_register(void)
 272 {
 273         int err;
 274         int ppi;
 275
 276         err = arch_timer_available();
 277         if (err)
 278                 goto out;
 279
 280         arch_timer_evt = alloc_percpu(struct clock_event_device);
 281         if (!arch_timer_evt) {
 282                 err = -ENOMEM;
 283                 goto out;
 284         }
 285
 286         clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 287         cyclecounter.mult = clocksource_counter.mult;
 288         cyclecounter.shift = clocksource_counter.shift;
 289         timecounter_init(&timecounter, &cyclecounter,
 290                          arch_counter_get_cntpct());
 291
 292         if (arch_timer_use_virtual) {
 293                 ppi = arch_timer_ppi[VIRT_PPI];
 294                 err = request_percpu_irq(ppi, arch_timer_handler_virt,
 295                                          "arch_timer", arch_timer_evt);
 296         } else {
 297                 ppi = arch_timer_ppi[PHYS_SECURE_PPI];
 298                 err = request_percpu_irq(ppi, arch_timer_handler_phys,
 299                                          "arch_timer", arch_timer_evt);
 300                 if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 301                         ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
 302                         err = request_percpu_irq(ppi, arch_timer_handler_phys,
 303                                                  "arch_timer", arch_timer_evt);
 304                         if (err)
 305                                 free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 306                                                 arch_timer_evt);
 307                 }
 308         }
 309
 310         if (err) {
 311                 pr_err("arch_timer: can't register interrupt %d (%d)\n",
 312                        ppi, err);
 313                 goto out_free;
 314         }
 315
 316         err = register_cpu_notifier(&arch_timer_cpu_nb);
 317         if (err)
 318                 goto out_free_irq;
 319
 320         /* Immediately configure the timer on the boot CPU */
 321         arch_timer_setup(this_cpu_ptr(arch_timer_evt));
 322
 323         return 0;
 324
 325 out_free_irq:
 326         if (arch_timer_use_virtual)
 327                 free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
 328         else {
 329                 free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 330                                 arch_timer_evt);
 331                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 332                         free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
 333                                         arch_timer_evt);
 334         }
 335
 336 out_free:
 337         free_percpu(arch_timer_evt);
 338 out:
 339         return err;
 340 }
 341
 342 static void __init arch_timer_init(struct device_node *np)
 343 {
 344         u32 freq;
 345         int i;
 346
 347         if (arch_timer_get_rate()) {
 348                 pr_warn("arch_timer: multiple nodes in dt, skipping\n");
 349                 return;
 350         }
 351
 352         /* Try to determine the frequency from the device tree or CNTFRQ */
 353         if (!of_property_read_u32(np, "clock-frequency", &freq))
 354                 arch_timer_rate = freq;
 355
 356         for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
 357                 arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
 358
 359         of_node_put(np);
 360
 361         /*
 362          * If HYP mode is available, we know that the physical timer
 363          * has been configured to be accessible from PL1. Use it, so
 364          * that a guest can use the virtual timer instead.
 365          *
 366          * If no interrupt provided for virtual timer, we'll have to
 367          * stick to the physical timer. It'd better be accessible...
 368          */
 369         if (is_hyp_mode_available() || !arch_timer_ppi[VIRT_PPI]) {
 370                 arch_timer_use_virtual = false;
 371
 372                 if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
 373                     !arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 374                         pr_warn("arch_timer: No interrupt available, giving up\n");
 375                         return;
 376                 }
 377         }
 378
 379         if (arch_timer_use_virtual)
 380                 arch_timer_read_counter = arch_counter_get_cntvct;
 381         else
 382                 arch_timer_read_counter = arch_counter_get_cntpct;
 383
 384         arch_timer_register();
 385         arch_timer_arch_init();
 386 }
 387 CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_init);
 388 CLOCKSOURCE_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_init);