drivers/clocksource/timer-ti-dm-systimer.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 #include <linux/clk.h>
   3 #include <linux/clocksource.h>
   4 #include <linux/clockchips.h>
   5 #include <linux/interrupt.h>
   6 #include <linux/io.h>
   7 #include <linux/iopoll.h>
   8 #include <linux/err.h>
   9 #include <linux/of.h>
  10 #include <linux/of_address.h>
  11 #include <linux/of_irq.h>
  12 #include <linux/sched_clock.h>
  13
  14 #include <linux/clk/clk-conf.h>
  15
  16 #include <clocksource/timer-ti-dm.h>
  17 #include <dt-bindings/bus/ti-sysc.h>
  18
  19 /* For type1, set SYSC_OMAP2_CLOCKACTIVITY for fck off on idle, l4 clock on */
  20 #define DMTIMER_TYPE1_ENABLE    ((1 << 9) | (SYSC_IDLE_SMART << 3) | \
  21                                  SYSC_OMAP2_ENAWAKEUP | SYSC_OMAP2_AUTOIDLE)
  22 #define DMTIMER_TYPE1_DISABLE   (SYSC_OMAP2_SOFTRESET | SYSC_OMAP2_AUTOIDLE)
  23 #define DMTIMER_TYPE2_ENABLE    (SYSC_IDLE_SMART_WKUP << 2)
  24 #define DMTIMER_RESET_WAIT      100000
  25
  26 #define DMTIMER_INST_DONT_CARE  ~0U
  27
  28 static int counter_32k;
  29 static u32 clocksource;
  30 static u32 clockevent;
  31
  32 /*
  33  * Subset of the timer registers we use. Note that the register offsets
  34  * depend on the timer revision detected.
  35  */
  36 struct dmtimer_systimer {
  37         void __iomem *base;
  38         u8 sysc;
  39         u8 irq_stat;
  40         u8 irq_ena;
  41         u8 pend;
  42         u8 load;
  43         u8 counter;
  44         u8 ctrl;
  45         u8 wakeup;
  46         u8 ifctrl;
  47         struct clk *fck;
  48         struct clk *ick;
  49         unsigned long rate;
  50 };
  51
  52 struct dmtimer_clockevent {
  53         struct clock_event_device dev;
  54         struct dmtimer_systimer t;
  55         u32 period;
  56 };
  57
  58 struct dmtimer_clocksource {
  59         struct clocksource dev;
  60         struct dmtimer_systimer t;
  61         unsigned int loadval;
  62 };
  63
  64 /* Assumes v1 ip if bits [31:16] are zero */
  65 static bool dmtimer_systimer_revision1(struct dmtimer_systimer *t)
  66 {
  67         u32 tidr = readl_relaxed(t->base);
  68
  69         return !(tidr >> 16);
  70 }
  71
  72 static void dmtimer_systimer_enable(struct dmtimer_systimer *t)
  73 {
  74         u32 val;
  75
  76         if (dmtimer_systimer_revision1(t))
  77                 val = DMTIMER_TYPE1_ENABLE;
  78         else
  79                 val = DMTIMER_TYPE2_ENABLE;
  80
  81         writel_relaxed(val, t->base + t->sysc);
  82 }
  83
  84 static void dmtimer_systimer_disable(struct dmtimer_systimer *t)
  85 {
  86         if (!dmtimer_systimer_revision1(t))
  87                 return;
  88
  89         writel_relaxed(DMTIMER_TYPE1_DISABLE, t->base + t->sysc);
  90 }
  91
  92 static int __init dmtimer_systimer_type1_reset(struct dmtimer_systimer *t)
  93 {
  94         void __iomem *syss = t->base + OMAP_TIMER_V1_SYS_STAT_OFFSET;
  95         int ret;
  96         u32 l;
  97
  98         dmtimer_systimer_enable(t);
  99         writel_relaxed(BIT(1) | BIT(2), t->base + t->ifctrl);
 100         ret = readl_poll_timeout_atomic(syss, l, l & BIT(0), 100,
 101                                         DMTIMER_RESET_WAIT);
 102
 103         return ret;
 104 }
 105
 106 /* Note we must use io_base instead of func_base for type2 OCP regs */
 107 static int __init dmtimer_systimer_type2_reset(struct dmtimer_systimer *t)
 108 {
 109         void __iomem *sysc = t->base + t->sysc;
 110         u32 l;
 111
 112         dmtimer_systimer_enable(t);
 113         l = readl_relaxed(sysc);
 114         l |= BIT(0);
 115         writel_relaxed(l, sysc);
 116
 117         return readl_poll_timeout_atomic(sysc, l, !(l & BIT(0)), 100,
 118                                          DMTIMER_RESET_WAIT);
 119 }
 120
 121 static int __init dmtimer_systimer_reset(struct dmtimer_systimer *t)
 122 {
 123         int ret;
 124
 125         if (dmtimer_systimer_revision1(t))
 126                 ret = dmtimer_systimer_type1_reset(t);
 127         else
 128                 ret = dmtimer_systimer_type2_reset(t);
 129         if (ret < 0) {
 130                 pr_err("%s failed with %i\n", __func__, ret);
 131
 132                 return ret;
 133         }
 134
 135         return 0;
 136 }
 137
 138 static const struct of_device_id counter_match_table[] = {
 139         { .compatible = "ti,omap-counter32k" },
 140         { /* Sentinel */ },
 141 };
 142
 143 /*
 144  * Check if the SoC als has a usable working 32 KiHz counter. The 32 KiHz
 145  * counter is handled by timer-ti-32k, but we need to detect it as it
 146  * affects the preferred dmtimer system timer configuration. There is
 147  * typically no use for a dmtimer clocksource if the 32 KiHz counter is
 148  * present, except on am437x as described below.
 149  */
 150 static void __init dmtimer_systimer_check_counter32k(void)
 151 {
 152         struct device_node *np;
 153
 154         if (counter_32k)
 155                 return;
 156
 157         np = of_find_matching_node(NULL, counter_match_table);
 158         if (!np) {
 159                 counter_32k = -ENODEV;
 160
 161                 return;
 162         }
 163
 164         if (of_device_is_available(np))
 165                 counter_32k = 1;
 166         else
 167                 counter_32k = -ENODEV;
 168
 169         of_node_put(np);
 170 }
 171
 172 static const struct of_device_id dmtimer_match_table[] = {
 173         { .compatible = "ti,omap2420-timer", },
 174         { .compatible = "ti,omap3430-timer", },
 175         { .compatible = "ti,omap4430-timer", },
 176         { .compatible = "ti,omap5430-timer", },
 177         { .compatible = "ti,am335x-timer", },
 178         { .compatible = "ti,am335x-timer-1ms", },
 179         { .compatible = "ti,dm814-timer", },
 180         { .compatible = "ti,dm816-timer", },
 181         { /* Sentinel */ },
 182 };
 183
 184 /*
 185  * Checks that system timers are configured to not reset and idle during
 186  * the generic timer-ti-dm device driver probe. And that the system timer
 187  * source clocks are properly configured. Also, let's not hog any DSP and
 188  * PWM capable timers unnecessarily as system timers.
 189  */
 190 static bool __init dmtimer_is_preferred(struct device_node *np)
 191 {
 192         if (!of_device_is_available(np))
 193                 return false;
 194
 195         if (!of_property_read_bool(np->parent,
 196                                    "ti,no-reset-on-init"))
 197                 return false;
 198
 199         if (!of_property_read_bool(np->parent, "ti,no-idle"))
 200                 return false;
 201
 202         /* Secure gptimer12 is always clocked with a fixed source */
 203         if (!of_property_read_bool(np, "ti,timer-secure")) {
 204                 if (!of_property_read_bool(np, "assigned-clocks"))
 205                         return false;
 206
 207                 if (!of_property_read_bool(np, "assigned-clock-parents"))
 208                         return false;
 209         }
 210
 211         if (of_property_read_bool(np, "ti,timer-dsp"))
 212                 return false;
 213
 214         if (of_property_read_bool(np, "ti,timer-pwm"))
 215                 return false;
 216
 217         return true;
 218 }
 219
 220 /*
 221  * Finds the first available usable always-on timer, and assigns it to either
 222  * clockevent or clocksource depending if the counter_32k is available on the
 223  * SoC or not.
 224  *
 225  * Some omap3 boards with unreliable oscillator must not use the counter_32k
 226  * or dmtimer1 with 32 KiHz source. Additionally, the boards with unreliable
 227  * oscillator should really set counter_32k as disabled, and delete dmtimer1
 228  * ti,always-on property, but let's not count on it. For these quirky cases,
 229  * we prefer using the always-on secure dmtimer12 with the internal 32 KiHz
 230  * clock as the clocksource, and any available dmtimer as clockevent.
 231  *
 232  * For am437x, we are using am335x style dmtimer clocksource. It is unclear
 233  * if this quirk handling is really needed, but let's change it separately
 234  * based on testing as it might cause side effects.
 235  */
 236 static void __init dmtimer_systimer_assign_alwon(void)
 237 {
 238         struct device_node *np;
 239         u32 pa = 0;
 240         bool quirk_unreliable_oscillator = false;
 241
 242         /* Quirk unreliable 32 KiHz oscillator with incomplete dts */
 243         if (of_machine_is_compatible("ti,omap3-beagle") ||
 244             of_machine_is_compatible("timll,omap3-devkit8000")) {
 245                 quirk_unreliable_oscillator = true;
 246                 counter_32k = -ENODEV;
 247         }
 248
 249         /* Quirk am437x using am335x style dmtimer clocksource */
 250         if (of_machine_is_compatible("ti,am43"))
 251                 counter_32k = -ENODEV;
 252
 253         for_each_matching_node(np, dmtimer_match_table) {
 254                 if (!dmtimer_is_preferred(np))
 255                         continue;
 256
 257                 if (of_property_read_bool(np, "ti,timer-alwon")) {
 258                         const __be32 *addr;
 259
 260                         addr = of_get_address(np, 0, NULL, NULL);
 261                         pa = of_translate_address(np, addr);
 262                         if (pa) {
 263                                 /* Quirky omap3 boards must use dmtimer12 */
 264                                 if (quirk_unreliable_oscillator &&
 265                                     pa == 0x48318000)
 266                                         continue;
 267
 268                                 of_node_put(np);
 269                                 break;
 270                         }
 271                 }
 272         }
 273
 274         /* Usually no need for dmtimer clocksource if we have counter32 */
 275         if (counter_32k >= 0) {
 276                 clockevent = pa;
 277                 clocksource = 0;
 278         } else {
 279                 clocksource = pa;
 280                 clockevent = DMTIMER_INST_DONT_CARE;
 281         }
 282 }
 283
 284 /* Finds the first usable dmtimer, used for the don't care case */
 285 static u32 __init dmtimer_systimer_find_first_available(void)
 286 {
 287         struct device_node *np;
 288         const __be32 *addr;
 289         u32 pa = 0;
 290
 291         for_each_matching_node(np, dmtimer_match_table) {
 292                 if (!dmtimer_is_preferred(np))
 293                         continue;
 294
 295                 addr = of_get_address(np, 0, NULL, NULL);
 296                 pa = of_translate_address(np, addr);
 297                 if (pa) {
 298                         if (pa == clocksource || pa == clockevent) {
 299                                 pa = 0;
 300                                 continue;
 301                         }
 302
 303                         of_node_put(np);
 304                         break;
 305                 }
 306         }
 307
 308         return pa;
 309 }
 310
 311 /* Selects the best clocksource and clockevent to use */
 312 static void __init dmtimer_systimer_select_best(void)
 313 {
 314         dmtimer_systimer_check_counter32k();
 315         dmtimer_systimer_assign_alwon();
 316
 317         if (clockevent == DMTIMER_INST_DONT_CARE)
 318                 clockevent = dmtimer_systimer_find_first_available();
 319
 320         pr_debug("%s: counter_32k: %i clocksource: %08x clockevent: %08x\n",
 321                  __func__, counter_32k, clocksource, clockevent);
 322 }
 323
 324 /* Interface clocks are only available on some SoCs variants */
 325 static int __init dmtimer_systimer_init_clock(struct dmtimer_systimer *t,
 326                                               struct device_node *np,
 327                                               const char *name,
 328                                               unsigned long *rate)
 329 {
 330         struct clk *clock;
 331         unsigned long r;
 332         bool is_ick = false;
 333         int error;
 334
 335         is_ick = !strncmp(name, "ick", 3);
 336
 337         clock = of_clk_get_by_name(np, name);
 338         if ((PTR_ERR(clock) == -EINVAL) && is_ick)
 339                 return 0;
 340         else if (IS_ERR(clock))
 341                 return PTR_ERR(clock);
 342
 343         error = clk_prepare_enable(clock);
 344         if (error)
 345                 return error;
 346
 347         r = clk_get_rate(clock);
 348         if (!r)
 349                 return -ENODEV;
 350
 351         if (is_ick)
 352                 t->ick = clock;
 353         else
 354                 t->fck = clock;
 355
 356         *rate = r;
 357
 358         return 0;
 359 }
 360
 361 static int __init dmtimer_systimer_setup(struct device_node *np,
 362                                          struct dmtimer_systimer *t)
 363 {
 364         unsigned long rate;
 365         u8 regbase;
 366         int error;
 367
 368         if (!of_device_is_compatible(np->parent, "ti,sysc"))
 369                 return -EINVAL;
 370
 371         t->base = of_iomap(np, 0);
 372         if (!t->base)
 373                 return -ENXIO;
 374
 375         /*
 376          * Enable optional assigned-clock-parents configured at the timer
 377          * node level. For regular device drivers, this is done automatically
 378          * by bus related code such as platform_drv_probe().
 379          */
 380         error = of_clk_set_defaults(np, false);
 381         if (error < 0)
 382                 pr_err("%s: clock source init failed: %i\n", __func__, error);
 383
 384         /* For ti-sysc, we have timer clocks at the parent module level */
 385         error = dmtimer_systimer_init_clock(t, np->parent, "fck", &rate);
 386         if (error)
 387                 goto err_unmap;
 388
 389         t->rate = rate;
 390
 391         error = dmtimer_systimer_init_clock(t, np->parent, "ick", &rate);
 392         if (error)
 393                 goto err_unmap;
 394
 395         if (dmtimer_systimer_revision1(t)) {
 396                 t->irq_stat = OMAP_TIMER_V1_STAT_OFFSET;
 397                 t->irq_ena = OMAP_TIMER_V1_INT_EN_OFFSET;
 398                 t->pend = _OMAP_TIMER_WRITE_PEND_OFFSET;
 399                 regbase = 0;
 400         } else {
 401                 t->irq_stat = OMAP_TIMER_V2_IRQSTATUS;
 402                 t->irq_ena = OMAP_TIMER_V2_IRQENABLE_SET;
 403                 regbase = OMAP_TIMER_V2_FUNC_OFFSET;
 404                 t->pend = regbase + _OMAP_TIMER_WRITE_PEND_OFFSET;
 405         }
 406
 407         t->sysc = OMAP_TIMER_OCP_CFG_OFFSET;
 408         t->load = regbase + _OMAP_TIMER_LOAD_OFFSET;
 409         t->counter = regbase + _OMAP_TIMER_COUNTER_OFFSET;
 410         t->ctrl = regbase + _OMAP_TIMER_CTRL_OFFSET;
 411         t->wakeup = regbase + _OMAP_TIMER_WAKEUP_EN_OFFSET;
 412         t->ifctrl = regbase + _OMAP_TIMER_IF_CTRL_OFFSET;
 413
 414         dmtimer_systimer_reset(t);
 415         dmtimer_systimer_enable(t);
 416         pr_debug("dmtimer rev %08x sysc %08x\n", readl_relaxed(t->base),
 417                  readl_relaxed(t->base + t->sysc));
 418
 419         return 0;
 420
 421 err_unmap:
 422         iounmap(t->base);
 423
 424         return error;
 425 }
 426
 427 /* Clockevent */
 428 static struct dmtimer_clockevent *
 429 to_dmtimer_clockevent(struct clock_event_device *clockevent)
 430 {
 431         return container_of(clockevent, struct dmtimer_clockevent, dev);
 432 }
 433
 434 static irqreturn_t dmtimer_clockevent_interrupt(int irq, void *data)
 435 {
 436         struct dmtimer_clockevent *clkevt = data;
 437         struct dmtimer_systimer *t = &clkevt->t;
 438
 439         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_stat);
 440         clkevt->dev.event_handler(&clkevt->dev);
 441
 442         return IRQ_HANDLED;
 443 }
 444
 445 static int dmtimer_set_next_event(unsigned long cycles,
 446                                   struct clock_event_device *evt)
 447 {
 448         struct dmtimer_clockevent *clkevt = to_dmtimer_clockevent(evt);
 449         struct dmtimer_systimer *t = &clkevt->t;
 450         void __iomem *pend = t->base + t->pend;
 451
 452         writel_relaxed(0xffffffff - cycles, t->base + t->counter);
 453         while (readl_relaxed(pend) & WP_TCRR)
 454                 cpu_relax();
 455
 456         writel_relaxed(OMAP_TIMER_CTRL_ST, t->base + t->ctrl);
 457         while (readl_relaxed(pend) & WP_TCLR)
 458                 cpu_relax();
 459
 460         return 0;
 461 }
 462
 463 static int dmtimer_clockevent_shutdown(struct clock_event_device *evt)
 464 {
 465         struct dmtimer_clockevent *clkevt = to_dmtimer_clockevent(evt);
 466         struct dmtimer_systimer *t = &clkevt->t;
 467         void __iomem *ctrl = t->base + t->ctrl;
 468         u32 l;
 469
 470         l = readl_relaxed(ctrl);
 471         if (l & OMAP_TIMER_CTRL_ST) {
 472                 l &= ~BIT(0);
 473                 writel_relaxed(l, ctrl);
 474                 /* Flush posted write */
 475                 l = readl_relaxed(ctrl);
 476                 /*  Wait for functional clock period x 3.5 */
 477                 udelay(3500000 / t->rate + 1);
 478         }
 479         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_stat);
 480
 481         return 0;
 482 }
 483
 484 static int dmtimer_set_periodic(struct clock_event_device *evt)
 485 {
 486         struct dmtimer_clockevent *clkevt = to_dmtimer_clockevent(evt);
 487         struct dmtimer_systimer *t = &clkevt->t;
 488         void __iomem *pend = t->base + t->pend;
 489
 490         dmtimer_clockevent_shutdown(evt);
 491
 492         /* Looks like we need to first set the load value separately */
 493         writel_relaxed(clkevt->period, t->base + t->load);
 494         while (readl_relaxed(pend) & WP_TLDR)
 495                 cpu_relax();
 496
 497         writel_relaxed(clkevt->period, t->base + t->counter);
 498         while (readl_relaxed(pend) & WP_TCRR)
 499                 cpu_relax();
 500
 501         writel_relaxed(OMAP_TIMER_CTRL_AR | OMAP_TIMER_CTRL_ST,
 502                        t->base + t->ctrl);
 503         while (readl_relaxed(pend) & WP_TCLR)
 504                 cpu_relax();
 505
 506         return 0;
 507 }
 508
 509 static void omap_clockevent_idle(struct clock_event_device *evt)
 510 {
 511         struct dmtimer_clockevent *clkevt = to_dmtimer_clockevent(evt);
 512         struct dmtimer_systimer *t = &clkevt->t;
 513
 514         dmtimer_systimer_disable(t);
 515         clk_disable(t->fck);
 516 }
 517
 518 static void omap_clockevent_unidle(struct clock_event_device *evt)
 519 {
 520         struct dmtimer_clockevent *clkevt = to_dmtimer_clockevent(evt);
 521         struct dmtimer_systimer *t = &clkevt->t;
 522         int error;
 523
 524         error = clk_enable(t->fck);
 525         if (error)
 526                 pr_err("could not enable timer fck on resume: %i\n", error);
 527
 528         dmtimer_systimer_enable(t);
 529         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_ena);
 530         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup);
 531 }
 532
 533 static int __init dmtimer_clockevent_init(struct device_node *np)
 534 {
 535         struct dmtimer_clockevent *clkevt;
 536         struct clock_event_device *dev;
 537         struct dmtimer_systimer *t;
 538         int error;
 539
 540         clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
 541         if (!clkevt)
 542                 return -ENOMEM;
 543
 544         t = &clkevt->t;
 545         dev = &clkevt->dev;
 546
 547         /*
 548          * We mostly use cpuidle_coupled with ARM local timers for runtime,
 549          * so there's probably no use for CLOCK_EVT_FEAT_DYNIRQ here.
 550          */
 551         dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 552         dev->rating = 300;
 553         dev->set_next_event = dmtimer_set_next_event;
 554         dev->set_state_shutdown = dmtimer_clockevent_shutdown;
 555         dev->set_state_periodic = dmtimer_set_periodic;
 556         dev->set_state_oneshot = dmtimer_clockevent_shutdown;
 557         dev->tick_resume = dmtimer_clockevent_shutdown;
 558         dev->cpumask = cpu_possible_mask;
 559
 560         dev->irq = irq_of_parse_and_map(np, 0);
 561         if (!dev->irq) {
 562                 error = -ENXIO;
 563                 goto err_out_free;
 564         }
 565
 566         error = dmtimer_systimer_setup(np, &clkevt->t);
 567         if (error)
 568                 goto err_out_free;
 569
 570         clkevt->period = 0xffffffff - DIV_ROUND_CLOSEST(t->rate, HZ);
 571
 572         /*
 573          * For clock-event timers we never read the timer counter and
 574          * so we are not impacted by errata i103 and i767. Therefore,
 575          * we can safely ignore this errata for clock-event timers.
 576          */
 577         writel_relaxed(OMAP_TIMER_CTRL_POSTED, t->base + t->ifctrl);
 578
 579         error = request_irq(dev->irq, dmtimer_clockevent_interrupt,
 580                             IRQF_TIMER, "clockevent", clkevt);
 581         if (error)
 582                 goto err_out_unmap;
 583
 584         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_ena);
 585         writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup);
 586
 587         pr_info("TI gptimer clockevent: %s%lu Hz at %pOF\n",
 588                 of_find_property(np, "ti,timer-alwon", NULL) ?
 589                 "always-on " : "", t->rate, np->parent);
 590
 591         clockevents_config_and_register(dev, t->rate,
 592                                         3, /* Timer internal resynch latency */
 593                                         0xffffffff);
 594
 595         if (of_machine_is_compatible("ti,am33xx") ||
 596             of_machine_is_compatible("ti,am43")) {
 597                 dev->suspend = omap_clockevent_idle;
 598                 dev->resume = omap_clockevent_unidle;
 599         }
 600
 601         return 0;
 602
 603 err_out_unmap:
 604         iounmap(t->base);
 605
 606 err_out_free:
 607         kfree(clkevt);
 608
 609         return error;
 610 }
 611
 612 /* Clocksource */
 613 static struct dmtimer_clocksource *
 614 to_dmtimer_clocksource(struct clocksource *cs)
 615 {
 616         return container_of(cs, struct dmtimer_clocksource, dev);
 617 }
 618
 619 static u64 dmtimer_clocksource_read_cycles(struct clocksource *cs)
 620 {
 621         struct dmtimer_clocksource *clksrc = to_dmtimer_clocksource(cs);
 622         struct dmtimer_systimer *t = &clksrc->t;
 623
 624         return (u64)readl_relaxed(t->base + t->counter);
 625 }
 626
 627 static void __iomem *dmtimer_sched_clock_counter;
 628
 629 static u64 notrace dmtimer_read_sched_clock(void)
 630 {
 631         return readl_relaxed(dmtimer_sched_clock_counter);
 632 }
 633
 634 static void dmtimer_clocksource_suspend(struct clocksource *cs)
 635 {
 636         struct dmtimer_clocksource *clksrc = to_dmtimer_clocksource(cs);
 637         struct dmtimer_systimer *t = &clksrc->t;
 638
 639         clksrc->loadval = readl_relaxed(t->base + t->counter);
 640         dmtimer_systimer_disable(t);
 641         clk_disable(t->fck);
 642 }
 643
 644 static void dmtimer_clocksource_resume(struct clocksource *cs)
 645 {
 646         struct dmtimer_clocksource *clksrc = to_dmtimer_clocksource(cs);
 647         struct dmtimer_systimer *t = &clksrc->t;
 648         int error;
 649
 650         error = clk_enable(t->fck);
 651         if (error)
 652                 pr_err("could not enable timer fck on resume: %i\n", error);
 653
 654         dmtimer_systimer_enable(t);
 655         writel_relaxed(clksrc->loadval, t->base + t->counter);
 656         writel_relaxed(OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR,
 657                        t->base + t->ctrl);
 658 }
 659
 660 static int __init dmtimer_clocksource_init(struct device_node *np)
 661 {
 662         struct dmtimer_clocksource *clksrc;
 663         struct dmtimer_systimer *t;
 664         struct clocksource *dev;
 665         int error;
 666
 667         clksrc = kzalloc(sizeof(*clksrc), GFP_KERNEL);
 668         if (!clksrc)
 669                 return -ENOMEM;
 670
 671         dev = &clksrc->dev;
 672         t = &clksrc->t;
 673
 674         error = dmtimer_systimer_setup(np, t);
 675         if (error)
 676                 goto err_out_free;
 677
 678         dev->name = "dmtimer";
 679         dev->rating = 300;
 680         dev->read = dmtimer_clocksource_read_cycles;
 681         dev->mask = CLOCKSOURCE_MASK(32);
 682         dev->flags = CLOCK_SOURCE_IS_CONTINUOUS;
 683
 684         /* Unlike for clockevent, legacy code sets suspend only for am4 */
 685         if (of_machine_is_compatible("ti,am43")) {
 686                 dev->suspend = dmtimer_clocksource_suspend;
 687                 dev->resume = dmtimer_clocksource_resume;
 688         }
 689
 690         writel_relaxed(0, t->base + t->counter);
 691         writel_relaxed(OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR,
 692                        t->base + t->ctrl);
 693
 694         pr_info("TI gptimer clocksource: %s%pOF\n",
 695                 of_find_property(np, "ti,timer-alwon", NULL) ?
 696                 "always-on " : "", np->parent);
 697
 698         if (!dmtimer_sched_clock_counter) {
 699                 dmtimer_sched_clock_counter = t->base + t->counter;
 700                 sched_clock_register(dmtimer_read_sched_clock, 32, t->rate);
 701         }
 702
 703         if (clocksource_register_hz(dev, t->rate))
 704                 pr_err("Could not register clocksource %pOF\n", np);
 705
 706         return 0;
 707
 708 err_out_free:
 709         kfree(clksrc);
 710
 711         return -ENODEV;
 712 }
 713
 714 /*
 715  * To detect between a clocksource and clockevent, we assume the device tree
 716  * has no interrupts configured for a clocksource timer.
 717  */
 718 static int __init dmtimer_systimer_init(struct device_node *np)
 719 {
 720         const __be32 *addr;
 721         u32 pa;
 722
 723         /* One time init for the preferred timer configuration */
 724         if (!clocksource && !clockevent)
 725                 dmtimer_systimer_select_best();
 726
 727         if (!clocksource && !clockevent) {
 728                 pr_err("%s: unable to detect system timers, update dtb?\n",
 729                        __func__);
 730
 731                 return -EINVAL;
 732         }
 733
 734         addr = of_get_address(np, 0, NULL, NULL);
 735         pa = of_translate_address(np, addr);
 736         if (!pa)
 737                 return -EINVAL;
 738
 739         if (counter_32k <= 0 && clocksource == pa)
 740                 return dmtimer_clocksource_init(np);
 741
 742         if (clockevent == pa)
 743                 return dmtimer_clockevent_init(np);
 744
 745         return 0;
 746 }
 747
 748 TIMER_OF_DECLARE(systimer_omap2, "ti,omap2420-timer", dmtimer_systimer_init);
 749 TIMER_OF_DECLARE(systimer_omap3, "ti,omap3430-timer", dmtimer_systimer_init);
 750 TIMER_OF_DECLARE(systimer_omap4, "ti,omap4430-timer", dmtimer_systimer_init);
 751 TIMER_OF_DECLARE(systimer_omap5, "ti,omap5430-timer", dmtimer_systimer_init);
 752 TIMER_OF_DECLARE(systimer_am33x, "ti,am335x-timer", dmtimer_systimer_init);
 753 TIMER_OF_DECLARE(systimer_am3ms, "ti,am335x-timer-1ms", dmtimer_systimer_init);
 754 TIMER_OF_DECLARE(systimer_dm814, "ti,dm814-timer", dmtimer_systimer_init);
 755 TIMER_OF_DECLARE(systimer_dm816, "ti,dm816-timer", dmtimer_systimer_init);