arch/arm/kernel/arch_timer.c

   1 /*
   2  *  linux/arch/arm/kernel/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/delay.h>
  14 #include <linux/device.h>
  15 #include <linux/smp.h>
  16 #include <linux/cpu.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/of_irq.h>
  21 #include <linux/io.h>
  22
  23 #include <asm/cputype.h>
  24 #include <asm/localtimer.h>
  25 #include <asm/arch_timer.h>
  26 #include <asm/system_info.h>
  27 #include <asm/sched_clock.h>
  28
  29 static unsigned long arch_timer_rate;
  30 static int arch_timer_ppi;
  31 static int arch_timer_ppi2;
  32
  33 static struct clock_event_device __percpu **arch_timer_evt;
  34
  35 /*
  36  * Architected system timer support.
  37  */
  38
  39 #define ARCH_TIMER_CTRL_ENABLE          (1 << 0)
  40 #define ARCH_TIMER_CTRL_IT_MASK         (1 << 1)
  41 #define ARCH_TIMER_CTRL_IT_STAT         (1 << 2)
  42
  43 #define ARCH_TIMER_REG_CTRL             0
  44 #define ARCH_TIMER_REG_FREQ             1
  45 #define ARCH_TIMER_REG_TVAL             2
  46
  47 static void arch_timer_reg_write(int reg, u32 val)
  48 {
  49         switch (reg) {
  50         case ARCH_TIMER_REG_CTRL:
  51                 asm volatile("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
  52                 break;
  53         case ARCH_TIMER_REG_TVAL:
  54                 asm volatile("mcr p15, 0, %0, c14, c2, 0" : : "r" (val));
  55                 break;
  56         }
  57
  58         isb();
  59 }
  60
  61 static u32 arch_timer_reg_read(int reg)
  62 {
  63         u32 val;
  64
  65         switch (reg) {
  66         case ARCH_TIMER_REG_CTRL:
  67                 asm volatile("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
  68                 break;
  69         case ARCH_TIMER_REG_FREQ:
  70                 asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (val));
  71                 break;
  72         case ARCH_TIMER_REG_TVAL:
  73                 asm volatile("mrc p15, 0, %0, c14, c2, 0" : "=r" (val));
  74                 break;
  75         default:
  76                 BUG();
  77         }
  78
  79         return val;
  80 }
  81
  82 static irqreturn_t arch_timer_handler(int irq, void *dev_id)
  83 {
  84         struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
  85         unsigned long ctrl;
  86
  87         ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
  88         if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
  89                 ctrl |= ARCH_TIMER_CTRL_IT_MASK;
  90                 arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
  91                 evt->event_handler(evt);
  92                 return IRQ_HANDLED;
  93         }
  94
  95         return IRQ_NONE;
  96 }
  97
  98 static void arch_timer_disable(void)
  99 {
 100         unsigned long ctrl;
 101
 102         ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
 103         ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
 104         arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
 105 }
 106
 107 static void arch_timer_set_mode(enum clock_event_mode mode,
 108                                 struct clock_event_device *clk)
 109 {
 110         switch (mode) {
 111         case CLOCK_EVT_MODE_UNUSED:
 112         case CLOCK_EVT_MODE_SHUTDOWN:
 113                 arch_timer_disable();
 114                 break;
 115         default:
 116                 break;
 117         }
 118 }
 119
 120 static int arch_timer_set_next_event(unsigned long evt,
 121                                      struct clock_event_device *unused)
 122 {
 123         unsigned long ctrl;
 124
 125         ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
 126         ctrl |= ARCH_TIMER_CTRL_ENABLE;
 127         ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 128
 129         arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt);
 130         arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
 131
 132         return 0;
 133 }
 134
 135 static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
 136 {
 137         /* Be safe... */
 138         arch_timer_disable();
 139
 140         clk->features = CLOCK_EVT_FEAT_ONESHOT;
 141         clk->name = "arch_sys_timer";
 142         clk->rating = 450;
 143         clk->set_mode = arch_timer_set_mode;
 144         clk->set_next_event = arch_timer_set_next_event;
 145         clk->irq = arch_timer_ppi;
 146
 147         clockevents_config_and_register(clk, arch_timer_rate,
 148                                         0xf, 0x7fffffff);
 149
 150         *__this_cpu_ptr(arch_timer_evt) = clk;
 151
 152         enable_percpu_irq(clk->irq, 0);
 153         if (arch_timer_ppi2)
 154                 enable_percpu_irq(arch_timer_ppi2, 0);
 155
 156         return 0;
 157 }
 158
 159 /* Is the optional system timer available? */
 160 static int local_timer_is_architected(void)
 161 {
 162         return (cpu_architecture() >= CPU_ARCH_ARMv7) &&
 163                ((read_cpuid_ext(CPUID_EXT_PFR1) >> 16) & 0xf) == 1;
 164 }
 165
 166 static int arch_timer_available(void)
 167 {
 168         unsigned long freq;
 169
 170         if (!local_timer_is_architected())
 171                 return -ENXIO;
 172
 173         if (arch_timer_rate == 0) {
 174                 arch_timer_reg_write(ARCH_TIMER_REG_CTRL, 0);
 175                 freq = arch_timer_reg_read(ARCH_TIMER_REG_FREQ);
 176
 177                 /* Check the timer frequency. */
 178                 if (freq == 0) {
 179                         pr_warn("Architected timer frequency not available\n");
 180                         return -EINVAL;
 181                 }
 182
 183                 arch_timer_rate = freq;
 184         }
 185
 186         pr_info_once("Architected local timer running at %lu.%02luMHz.\n",
 187                      arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100);
 188         return 0;
 189 }
 190
 191 static inline cycle_t arch_counter_get_cntpct(void)
 192 {
 193         u32 cvall, cvalh;
 194
 195         asm volatile("mrrc p15, 0, %0, %1, c14" : "=r" (cvall), "=r" (cvalh));
 196
 197         return ((cycle_t) cvalh << 32) | cvall;
 198 }
 199
 200 static inline cycle_t arch_counter_get_cntvct(void)
 201 {
 202         u32 cvall, cvalh;
 203
 204         asm volatile("mrrc p15, 1, %0, %1, c14" : "=r" (cvall), "=r" (cvalh));
 205
 206         return ((cycle_t) cvalh << 32) | cvall;
 207 }
 208
 209 static u32 notrace arch_counter_get_cntvct32(void)
 210 {
 211         cycle_t cntvct = arch_counter_get_cntvct();
 212
 213         /*
 214          * The sched_clock infrastructure only knows about counters
 215          * with at most 32bits. Forget about the upper 24 bits for the
 216          * time being...
 217          */
 218         return (u32)(cntvct & (u32)~0);
 219 }
 220
 221 static cycle_t arch_counter_read(struct clocksource *cs)
 222 {
 223         return arch_counter_get_cntpct();
 224 }
 225
 226 static struct clocksource clocksource_counter = {
 227         .name   = "arch_sys_counter",
 228         .rating = 400,
 229         .read   = arch_counter_read,
 230         .mask   = CLOCKSOURCE_MASK(56),
 231         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 232 };
 233
 234 static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
 235 {
 236         pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
 237                  clk->irq, smp_processor_id());
 238         disable_percpu_irq(clk->irq);
 239         if (arch_timer_ppi2)
 240                 disable_percpu_irq(arch_timer_ppi2);
 241         arch_timer_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
 242 }
 243
 244 static struct local_timer_ops arch_timer_ops __cpuinitdata = {
 245         .setup  = arch_timer_setup,
 246         .stop   = arch_timer_stop,
 247 };
 248
 249 static struct clock_event_device arch_timer_global_evt;
 250
 251 static int __init arch_timer_register(void)
 252 {
 253         int err;
 254
 255         err = arch_timer_available();
 256         if (err)
 257                 return err;
 258
 259         arch_timer_evt = alloc_percpu(struct clock_event_device *);
 260         if (!arch_timer_evt)
 261                 return -ENOMEM;
 262
 263         clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 264
 265         err = request_percpu_irq(arch_timer_ppi, arch_timer_handler,
 266                                  "arch_timer", arch_timer_evt);
 267         if (err) {
 268                 pr_err("arch_timer: can't register interrupt %d (%d)\n",
 269                        arch_timer_ppi, err);
 270                 goto out_free;
 271         }
 272
 273         if (arch_timer_ppi2) {
 274                 err = request_percpu_irq(arch_timer_ppi2, arch_timer_handler,
 275                                          "arch_timer", arch_timer_evt);
 276                 if (err) {
 277                         pr_err("arch_timer: can't register interrupt %d (%d)\n",
 278                                arch_timer_ppi2, err);
 279                         arch_timer_ppi2 = 0;
 280                         goto out_free_irq;
 281                 }
 282         }
 283
 284         err = local_timer_register(&arch_timer_ops);
 285         if (err) {
 286                 /*
 287                  * We couldn't register as a local timer (could be
 288                  * because we're on a UP platform, or because some
 289                  * other local timer is already present...). Try as a
 290                  * global timer instead.
 291                  */
 292                 arch_timer_global_evt.cpumask = cpumask_of(0);
 293                 err = arch_timer_setup(&arch_timer_global_evt);
 294         }
 295
 296         if (err)
 297                 goto out_free_irq;
 298
 299         return 0;
 300
 301 out_free_irq:
 302         free_percpu_irq(arch_timer_ppi, arch_timer_evt);
 303         if (arch_timer_ppi2)
 304                 free_percpu_irq(arch_timer_ppi2, arch_timer_evt);
 305
 306 out_free:
 307         free_percpu(arch_timer_evt);
 308
 309         return err;
 310 }
 311
 312 static const struct of_device_id arch_timer_of_match[] __initconst = {
 313         { .compatible   = "arm,armv7-timer",    },
 314         {},
 315 };
 316
 317 int __init arch_timer_of_register(void)
 318 {
 319         struct device_node *np;
 320         u32 freq;
 321
 322         np = of_find_matching_node(NULL, arch_timer_of_match);
 323         if (!np) {
 324                 pr_err("arch_timer: can't find DT node\n");
 325                 return -ENODEV;
 326         }
 327
 328         /* Try to determine the frequency from the device tree or CNTFRQ */
 329         if (!of_property_read_u32(np, "clock-frequency", &freq))
 330                 arch_timer_rate = freq;
 331
 332         arch_timer_ppi = irq_of_parse_and_map(np, 0);
 333         arch_timer_ppi2 = irq_of_parse_and_map(np, 1);
 334         pr_info("arch_timer: found %s irqs %d %d\n",
 335                 np->name, arch_timer_ppi, arch_timer_ppi2);
 336
 337         return arch_timer_register();
 338 }
 339
 340 int __init arch_timer_sched_clock_init(void)
 341 {
 342         int err;
 343
 344         err = arch_timer_available();
 345         if (err)
 346                 return err;
 347
 348         setup_sched_clock(arch_counter_get_cntvct32, 32, arch_timer_rate);
 349         return 0;
 350 }