drivers/clocksource/timer-tegra.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2010 Google, Inc.
   4  *
   5  * Author:
   6  *      Colin Cross <ccross@google.com>
   7  */
   8
   9 #define pr_fmt(fmt)     "tegra-timer: " fmt
  10
  11 #include <linux/clk.h>
  12 #include <linux/clockchips.h>
  13 #include <linux/cpu.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/delay.h>
  16 #include <linux/err.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_irq.h>
  20 #include <linux/percpu.h>
  21 #include <linux/sched_clock.h>
  22 #include <linux/time.h>
  23
  24 #include "timer-of.h"
  25
  26 #define RTC_SECONDS             0x08
  27 #define RTC_SHADOW_SECONDS      0x0c
  28 #define RTC_MILLISECONDS        0x10
  29
  30 #define TIMERUS_CNTR_1US        0x10
  31 #define TIMERUS_USEC_CFG        0x14
  32 #define TIMERUS_CNTR_FREEZE     0x4c
  33
  34 #define TIMER_PTV               0x0
  35 #define TIMER_PTV_EN            BIT(31)
  36 #define TIMER_PTV_PER           BIT(30)
  37 #define TIMER_PCR               0x4
  38 #define TIMER_PCR_INTR_CLR      BIT(30)
  39
  40 #define TIMER1_BASE             0x00
  41 #define TIMER2_BASE             0x08
  42 #define TIMER3_BASE             0x50
  43 #define TIMER4_BASE             0x58
  44 #define TIMER10_BASE            0x90
  45
  46 #define TIMER1_IRQ_IDX          0
  47 #define TIMER10_IRQ_IDX         10
  48
  49 #define TIMER_1MHz              1000000
  50
  51 static u32 usec_config;
  52 static void __iomem *timer_reg_base;
  53
  54 static int tegra_timer_set_next_event(unsigned long cycles,
  55                                       struct clock_event_device *evt)
  56 {
  57         void __iomem *reg_base = timer_of_base(to_timer_of(evt));
  58
  59         /*
  60          * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
  61          * fire after one tick if 0 is loaded.
  62          *
  63          * The minimum and maximum numbers of oneshot ticks are defined
  64          * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation
  65          * below in the code. Hence the cycles (ticks) can't be outside of
  66          * a range supportable by hardware.
  67          */
  68         writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV);
  69
  70         return 0;
  71 }
  72
  73 static int tegra_timer_shutdown(struct clock_event_device *evt)
  74 {
  75         void __iomem *reg_base = timer_of_base(to_timer_of(evt));
  76
  77         writel_relaxed(0, reg_base + TIMER_PTV);
  78
  79         return 0;
  80 }
  81
  82 static int tegra_timer_set_periodic(struct clock_event_device *evt)
  83 {
  84         void __iomem *reg_base = timer_of_base(to_timer_of(evt));
  85         unsigned long period = timer_of_period(to_timer_of(evt));
  86
  87         writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
  88                        reg_base + TIMER_PTV);
  89
  90         return 0;
  91 }
  92
  93 static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
  94 {
  95         struct clock_event_device *evt = dev_id;
  96         void __iomem *reg_base = timer_of_base(to_timer_of(evt));
  97
  98         writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
  99         evt->event_handler(evt);
 100
 101         return IRQ_HANDLED;
 102 }
 103
 104 static void tegra_timer_suspend(struct clock_event_device *evt)
 105 {
 106         void __iomem *reg_base = timer_of_base(to_timer_of(evt));
 107
 108         writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
 109 }
 110
 111 static void tegra_timer_resume(struct clock_event_device *evt)
 112 {
 113         writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
 114 }
 115
 116 static DEFINE_PER_CPU(struct timer_of, tegra_to) = {
 117         .flags = TIMER_OF_CLOCK | TIMER_OF_BASE,
 118
 119         .clkevt = {
 120                 .name = "tegra_timer",
 121                 .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 122                 .set_next_event = tegra_timer_set_next_event,
 123                 .set_state_shutdown = tegra_timer_shutdown,
 124                 .set_state_periodic = tegra_timer_set_periodic,
 125                 .set_state_oneshot = tegra_timer_shutdown,
 126                 .tick_resume = tegra_timer_shutdown,
 127                 .suspend = tegra_timer_suspend,
 128                 .resume = tegra_timer_resume,
 129         },
 130 };
 131
 132 static int tegra_timer_setup(unsigned int cpu)
 133 {
 134         struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);
 135
 136         writel_relaxed(0, timer_of_base(to) + TIMER_PTV);
 137         writel_relaxed(TIMER_PCR_INTR_CLR, timer_of_base(to) + TIMER_PCR);
 138
 139         irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
 140         enable_irq(to->clkevt.irq);
 141
 142         /*
 143          * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
 144          * fire after one tick if 0 is loaded and thus minimum number of
 145          * ticks is 1. In result both of the clocksource's tick limits are
 146          * higher than a minimum and maximum that hardware register can
 147          * take by 1, this is then taken into account by set_next_event
 148          * callback.
 149          */
 150         clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
 151                                         1, /* min */
 152                                         0x1fffffff + 1); /* max 29 bits + 1 */
 153
 154         return 0;
 155 }
 156
 157 static int tegra_timer_stop(unsigned int cpu)
 158 {
 159         struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);
 160
 161         to->clkevt.set_state_shutdown(&to->clkevt);
 162         disable_irq_nosync(to->clkevt.irq);
 163
 164         return 0;
 165 }
 166
 167 static u64 notrace tegra_read_sched_clock(void)
 168 {
 169         return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
 170 }
 171
 172 #ifdef CONFIG_ARM
 173 static unsigned long tegra_delay_timer_read_counter_long(void)
 174 {
 175         return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
 176 }
 177
 178 static struct delay_timer tegra_delay_timer = {
 179         .read_current_timer = tegra_delay_timer_read_counter_long,
 180         .freq = TIMER_1MHz,
 181 };
 182 #endif
 183
 184 static struct timer_of suspend_rtc_to = {
 185         .flags = TIMER_OF_BASE | TIMER_OF_CLOCK,
 186 };
 187
 188 /*
 189  * tegra_rtc_read - Reads the Tegra RTC registers
 190  * Care must be taken that this function is not called while the
 191  * tegra_rtc driver could be executing to avoid race conditions
 192  * on the RTC shadow register
 193  */
 194 static u64 tegra_rtc_read_ms(struct clocksource *cs)
 195 {
 196         void __iomem *reg_base = timer_of_base(&suspend_rtc_to);
 197
 198         u32 ms = readl_relaxed(reg_base + RTC_MILLISECONDS);
 199         u32 s = readl_relaxed(reg_base + RTC_SHADOW_SECONDS);
 200
 201         return (u64)s * MSEC_PER_SEC + ms;
 202 }
 203
 204 static struct clocksource suspend_rtc_clocksource = {
 205         .name   = "tegra_suspend_timer",
 206         .rating = 200,
 207         .read   = tegra_rtc_read_ms,
 208         .mask   = CLOCKSOURCE_MASK(32),
 209         .flags  = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,
 210 };
 211
 212 static inline unsigned int tegra_base_for_cpu(int cpu, bool tegra20)
 213 {
 214         if (tegra20) {
 215                 switch (cpu) {
 216                 case 0:
 217                         return TIMER1_BASE;
 218                 case 1:
 219                         return TIMER2_BASE;
 220                 case 2:
 221                         return TIMER3_BASE;
 222                 default:
 223                         return TIMER4_BASE;
 224                 }
 225         }
 226
 227         return TIMER10_BASE + cpu * 8;
 228 }
 229
 230 static inline unsigned int tegra_irq_idx_for_cpu(int cpu, bool tegra20)
 231 {
 232         if (tegra20)
 233                 return TIMER1_IRQ_IDX + cpu;
 234
 235         return TIMER10_IRQ_IDX + cpu;
 236 }
 237
 238 static inline unsigned long tegra_rate_for_timer(struct timer_of *to,
 239                                                  bool tegra20)
 240 {
 241         /*
 242          * TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the
 243          * parent clock.
 244          */
 245         if (tegra20)
 246                 return TIMER_1MHz;
 247
 248         return timer_of_rate(to);
 249 }
 250
 251 static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 252                                    int rating)
 253 {
 254         struct timer_of *to;
 255         int cpu, ret;
 256
 257         to = this_cpu_ptr(&tegra_to);
 258         ret = timer_of_init(np, to);
 259         if (ret)
 260                 goto out;
 261
 262         timer_reg_base = timer_of_base(to);
 263
 264         /*
 265          * Configure microsecond timers to have 1MHz clock
 266          * Config register is 0xqqww, where qq is "dividend", ww is "divisor"
 267          * Uses n+1 scheme
 268          */
 269         switch (timer_of_rate(to)) {
 270         case 12000000:
 271                 usec_config = 0x000b; /* (11+1)/(0+1) */
 272                 break;
 273         case 12800000:
 274                 usec_config = 0x043f; /* (63+1)/(4+1) */
 275                 break;
 276         case 13000000:
 277                 usec_config = 0x000c; /* (12+1)/(0+1) */
 278                 break;
 279         case 16800000:
 280                 usec_config = 0x0453; /* (83+1)/(4+1) */
 281                 break;
 282         case 19200000:
 283                 usec_config = 0x045f; /* (95+1)/(4+1) */
 284                 break;
 285         case 26000000:
 286                 usec_config = 0x0019; /* (25+1)/(0+1) */
 287                 break;
 288         case 38400000:
 289                 usec_config = 0x04bf; /* (191+1)/(4+1) */
 290                 break;
 291         case 48000000:
 292                 usec_config = 0x002f; /* (47+1)/(0+1) */
 293                 break;
 294         default:
 295                 ret = -EINVAL;
 296                 goto out;
 297         }
 298
 299         writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
 300
 301         for_each_possible_cpu(cpu) {
 302                 struct timer_of *cpu_to = per_cpu_ptr(&tegra_to, cpu);
 303                 unsigned long flags = IRQF_TIMER | IRQF_NOBALANCING;
 304                 unsigned long rate = tegra_rate_for_timer(to, tegra20);
 305                 unsigned int base = tegra_base_for_cpu(cpu, tegra20);
 306                 unsigned int idx = tegra_irq_idx_for_cpu(cpu, tegra20);
 307                 unsigned int irq = irq_of_parse_and_map(np, idx);
 308
 309                 if (!irq) {
 310                         pr_err("failed to map irq for cpu%d\n", cpu);
 311                         ret = -EINVAL;
 312                         goto out_irq;
 313                 }
 314
 315                 cpu_to->clkevt.irq = irq;
 316                 cpu_to->clkevt.rating = rating;
 317                 cpu_to->clkevt.cpumask = cpumask_of(cpu);
 318                 cpu_to->of_base.base = timer_reg_base + base;
 319                 cpu_to->of_clk.period = rate / HZ;
 320                 cpu_to->of_clk.rate = rate;
 321
 322                 irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
 323
 324                 ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr, flags,
 325                                   cpu_to->clkevt.name, &cpu_to->clkevt);
 326                 if (ret) {
 327                         pr_err("failed to set up irq for cpu%d: %d\n",
 328                                cpu, ret);
 329                         irq_dispose_mapping(cpu_to->clkevt.irq);
 330                         cpu_to->clkevt.irq = 0;
 331                         goto out_irq;
 332                 }
 333         }
 334
 335         sched_clock_register(tegra_read_sched_clock, 32, TIMER_1MHz);
 336
 337         ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
 338                                     "timer_us", TIMER_1MHz, 300, 32,
 339                                     clocksource_mmio_readl_up);
 340         if (ret)
 341                 pr_err("failed to register clocksource: %d\n", ret);
 342
 343 #ifdef CONFIG_ARM
 344         register_current_timer_delay(&tegra_delay_timer);
 345 #endif
 346
 347         ret = cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING,
 348                                 "AP_TEGRA_TIMER_STARTING", tegra_timer_setup,
 349                                 tegra_timer_stop);
 350         if (ret)
 351                 pr_err("failed to set up cpu hp state: %d\n", ret);
 352
 353         return ret;
 354
 355 out_irq:
 356         for_each_possible_cpu(cpu) {
 357                 struct timer_of *cpu_to;
 358
 359                 cpu_to = per_cpu_ptr(&tegra_to, cpu);
 360                 if (cpu_to->clkevt.irq) {
 361                         free_irq(cpu_to->clkevt.irq, &cpu_to->clkevt);
 362                         irq_dispose_mapping(cpu_to->clkevt.irq);
 363                 }
 364         }
 365
 366         to->of_base.base = timer_reg_base;
 367 out:
 368         timer_of_cleanup(to);
 369
 370         return ret;
 371 }
 372
 373 static int __init tegra210_init_timer(struct device_node *np)
 374 {
 375         /*
 376          * Arch-timer can't survive across power cycle of CPU core and
 377          * after CPUPORESET signal due to a system design shortcoming,
 378          * hence tegra-timer is more preferable on Tegra210.
 379          */
 380         return tegra_init_timer(np, false, 460);
 381 }
 382 TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_init_timer);
 383
 384 static int __init tegra20_init_timer(struct device_node *np)
 385 {
 386         int rating;
 387
 388         /*
 389          * Tegra20 and Tegra30 have Cortex A9 CPU that has a TWD timer,
 390          * that timer runs off the CPU clock and hence is subjected to
 391          * a jitter caused by DVFS clock rate changes. Tegra-timer is
 392          * more preferable for older Tegra's, while later SoC generations
 393          * have arch-timer as a main per-CPU timer and it is not affected
 394          * by DVFS changes.
 395          */
 396         if (of_machine_is_compatible("nvidia,tegra20") ||
 397             of_machine_is_compatible("nvidia,tegra30"))
 398                 rating = 460;
 399         else
 400                 rating = 330;
 401
 402         return tegra_init_timer(np, true, rating);
 403 }
 404 TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", tegra20_init_timer);
 405
 406 static int __init tegra20_init_rtc(struct device_node *np)
 407 {
 408         int ret;
 409
 410         ret = timer_of_init(np, &suspend_rtc_to);
 411         if (ret)
 412                 return ret;
 413
 414         return clocksource_register_hz(&suspend_rtc_clocksource, 1000);
 415 }
 416 TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);