1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * This file contains driver for the Cadence Triple Timer Counter Rev 06 4 * 5 * Copyright (C) 2011-2013 Xilinx 6 * 7 * based on arch/mips/kernel/time.c timer driver 8 */ 9 10 #include <linux/clk.h> 11 #include <linux/interrupt.h> 12 #include <linux/clockchips.h> 13 #include <linux/clocksource.h> 14 #include <linux/of_address.h> 15 #include <linux/of_irq.h> 16 #include <linux/platform_device.h> 17 #include <linux/slab.h> 18 #include <linux/sched_clock.h> 19 #include <linux/module.h> 20 #include <linux/of_platform.h> 21 22 /* 23 * This driver configures the 2 16/32-bit count-up timers as follows: 24 * 25 * T1: Timer 1, clocksource for generic timekeeping 26 * T2: Timer 2, clockevent source for hrtimers 27 * T3: Timer 3, <unused> 28 * 29 * The input frequency to the timer module for emulation is 2.5MHz which is 30 * common to all the timer channels (T1, T2, and T3). With a pre-scaler of 32, 31 * the timers are clocked at 78.125KHz (12.8 us resolution). 32 33 * The input frequency to the timer module in silicon is configurable and 34 * obtained from device tree. The pre-scaler of 32 is used. 35 */ 36 37 /* 38 * Timer Register Offset Definitions of Timer 1, Increment base address by 4 39 * and use same offsets for Timer 2 40 */ 41 #define TTC_CLK_CNTRL_OFFSET 0x00 /* Clock Control Reg, RW */ 42 #define TTC_CNT_CNTRL_OFFSET 0x0C /* Counter Control Reg, RW */ 43 #define TTC_COUNT_VAL_OFFSET 0x18 /* Counter Value Reg, RO */ 44 #define TTC_INTR_VAL_OFFSET 0x24 /* Interval Count Reg, RW */ 45 #define TTC_ISR_OFFSET 0x54 /* Interrupt Status Reg, RO */ 46 #define TTC_IER_OFFSET 0x60 /* Interrupt Enable Reg, RW */ 47 48 #define TTC_CNT_CNTRL_DISABLE_MASK 0x1 49 50 #define TTC_CLK_CNTRL_CSRC_MASK (1 << 5) /* clock source */ 51 #define TTC_CLK_CNTRL_PSV_MASK 0x1e 52 #define TTC_CLK_CNTRL_PSV_SHIFT 1 53 54 /* 55 * Setup the timers to use pre-scaling, using a fixed value for now that will 56 * work across most input frequency, but it may need to be more dynamic 57 */ 58 #define PRESCALE_EXPONENT 11 /* 2 ^ PRESCALE_EXPONENT = PRESCALE */ 59 #define PRESCALE 2048 /* The exponent must match this */ 60 #define CLK_CNTRL_PRESCALE ((PRESCALE_EXPONENT - 1) << 1) 61 #define CLK_CNTRL_PRESCALE_EN 1 62 #define CNT_CNTRL_RESET (1 << 4) 63 64 #define MAX_F_ERR 50 65 66 /** 67 * struct ttc_timer - This definition defines local timer structure 68 * 69 * @base_addr: Base address of timer 70 * @freq: Timer input clock frequency 71 * @clk: Associated clock source 72 * @clk_rate_change_nb Notifier block for clock rate changes 73 */ 74 struct ttc_timer { 75 void __iomem *base_addr; 76 unsigned long freq; 77 struct clk *clk; 78 struct notifier_block clk_rate_change_nb; 79 }; 80 81 #define to_ttc_timer(x) \ 82 container_of(x, struct ttc_timer, clk_rate_change_nb) 83 84 struct ttc_timer_clocksource { 85 u32 scale_clk_ctrl_reg_old; 86 u32 scale_clk_ctrl_reg_new; 87 struct ttc_timer ttc; 88 struct clocksource cs; 89 }; 90 91 #define to_ttc_timer_clksrc(x) \ 92 container_of(x, struct ttc_timer_clocksource, cs) 93 94 struct ttc_timer_clockevent { 95 struct ttc_timer ttc; 96 struct clock_event_device ce; 97 }; 98 99 #define to_ttc_timer_clkevent(x) \ 100 container_of(x, struct ttc_timer_clockevent, ce) 101 102 static void __iomem *ttc_sched_clock_val_reg; 103 104 /** 105 * ttc_set_interval - Set the timer interval value 106 * 107 * @timer: Pointer to the timer instance 108 * @cycles: Timer interval ticks 109 **/ 110 static void ttc_set_interval(struct ttc_timer *timer, 111 unsigned long cycles) 112 { 113 u32 ctrl_reg; 114 115 /* Disable the counter, set the counter value and re-enable counter */ 116 ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET); 117 ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK; 118 writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET); 119 120 writel_relaxed(cycles, timer->base_addr + TTC_INTR_VAL_OFFSET); 121 122 /* 123 * Reset the counter (0x10) so that it starts from 0, one-shot 124 * mode makes this needed for timing to be right. 125 */ 126 ctrl_reg |= CNT_CNTRL_RESET; 127 ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK; 128 writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET); 129 } 130 131 /** 132 * ttc_clock_event_interrupt - Clock event timer interrupt handler 133 * 134 * @irq: IRQ number of the Timer 135 * @dev_id: void pointer to the ttc_timer instance 136 * 137 * returns: Always IRQ_HANDLED - success 138 **/ 139 static irqreturn_t ttc_clock_event_interrupt(int irq, void *dev_id) 140 { 141 struct ttc_timer_clockevent *ttce = dev_id; 142 struct ttc_timer *timer = &ttce->ttc; 143 144 /* Acknowledge the interrupt and call event handler */ 145 readl_relaxed(timer->base_addr + TTC_ISR_OFFSET); 146 147 ttce->ce.event_handler(&ttce->ce); 148 149 return IRQ_HANDLED; 150 } 151 152 /** 153 * __ttc_clocksource_read - Reads the timer counter register 154 * 155 * returns: Current timer counter register value 156 **/ 157 static u64 __ttc_clocksource_read(struct clocksource *cs) 158 { 159 struct ttc_timer *timer = &to_ttc_timer_clksrc(cs)->ttc; 160 161 return (u64)readl_relaxed(timer->base_addr + 162 TTC_COUNT_VAL_OFFSET); 163 } 164 165 static u64 notrace ttc_sched_clock_read(void) 166 { 167 return readl_relaxed(ttc_sched_clock_val_reg); 168 } 169 170 /** 171 * ttc_set_next_event - Sets the time interval for next event 172 * 173 * @cycles: Timer interval ticks 174 * @evt: Address of clock event instance 175 * 176 * returns: Always 0 - success 177 **/ 178 static int ttc_set_next_event(unsigned long cycles, 179 struct clock_event_device *evt) 180 { 181 struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt); 182 struct ttc_timer *timer = &ttce->ttc; 183 184 ttc_set_interval(timer, cycles); 185 return 0; 186 } 187 188 /** 189 * ttc_set_{shutdown|oneshot|periodic} - Sets the state of timer 190 * 191 * @evt: Address of clock event instance 192 **/ 193 static int ttc_shutdown(struct clock_event_device *evt) 194 { 195 struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt); 196 struct ttc_timer *timer = &ttce->ttc; 197 u32 ctrl_reg; 198 199 ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET); 200 ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK; 201 writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET); 202 return 0; 203 } 204 205 static int ttc_set_periodic(struct clock_event_device *evt) 206 { 207 struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt); 208 struct ttc_timer *timer = &ttce->ttc; 209 210 ttc_set_interval(timer, 211 DIV_ROUND_CLOSEST(ttce->ttc.freq, PRESCALE * HZ)); 212 return 0; 213 } 214 215 static int ttc_resume(struct clock_event_device *evt) 216 { 217 struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt); 218 struct ttc_timer *timer = &ttce->ttc; 219 u32 ctrl_reg; 220 221 ctrl_reg = readl_relaxed(timer->base_addr + TTC_CNT_CNTRL_OFFSET); 222 ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK; 223 writel_relaxed(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET); 224 return 0; 225 } 226 227 static int ttc_rate_change_clocksource_cb(struct notifier_block *nb, 228 unsigned long event, void *data) 229 { 230 struct clk_notifier_data *ndata = data; 231 struct ttc_timer *ttc = to_ttc_timer(nb); 232 struct ttc_timer_clocksource *ttccs = container_of(ttc, 233 struct ttc_timer_clocksource, ttc); 234 235 switch (event) { 236 case PRE_RATE_CHANGE: 237 { 238 u32 psv; 239 unsigned long factor, rate_low, rate_high; 240 241 if (ndata->new_rate > ndata->old_rate) { 242 factor = DIV_ROUND_CLOSEST(ndata->new_rate, 243 ndata->old_rate); 244 rate_low = ndata->old_rate; 245 rate_high = ndata->new_rate; 246 } else { 247 factor = DIV_ROUND_CLOSEST(ndata->old_rate, 248 ndata->new_rate); 249 rate_low = ndata->new_rate; 250 rate_high = ndata->old_rate; 251 } 252 253 if (!is_power_of_2(factor)) 254 return NOTIFY_BAD; 255 256 if (abs(rate_high - (factor * rate_low)) > MAX_F_ERR) 257 return NOTIFY_BAD; 258 259 factor = __ilog2_u32(factor); 260 261 /* 262 * store timer clock ctrl register so we can restore it in case 263 * of an abort. 264 */ 265 ttccs->scale_clk_ctrl_reg_old = 266 readl_relaxed(ttccs->ttc.base_addr + 267 TTC_CLK_CNTRL_OFFSET); 268 269 psv = (ttccs->scale_clk_ctrl_reg_old & 270 TTC_CLK_CNTRL_PSV_MASK) >> 271 TTC_CLK_CNTRL_PSV_SHIFT; 272 if (ndata->new_rate < ndata->old_rate) 273 psv -= factor; 274 else 275 psv += factor; 276 277 /* prescaler within legal range? */ 278 if (psv & ~(TTC_CLK_CNTRL_PSV_MASK >> TTC_CLK_CNTRL_PSV_SHIFT)) 279 return NOTIFY_BAD; 280 281 ttccs->scale_clk_ctrl_reg_new = ttccs->scale_clk_ctrl_reg_old & 282 ~TTC_CLK_CNTRL_PSV_MASK; 283 ttccs->scale_clk_ctrl_reg_new |= psv << TTC_CLK_CNTRL_PSV_SHIFT; 284 285 286 /* scale down: adjust divider in post-change notification */ 287 if (ndata->new_rate < ndata->old_rate) 288 return NOTIFY_DONE; 289 290 /* scale up: adjust divider now - before frequency change */ 291 writel_relaxed(ttccs->scale_clk_ctrl_reg_new, 292 ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET); 293 break; 294 } 295 case POST_RATE_CHANGE: 296 /* scale up: pre-change notification did the adjustment */ 297 if (ndata->new_rate > ndata->old_rate) 298 return NOTIFY_OK; 299 300 /* scale down: adjust divider now - after frequency change */ 301 writel_relaxed(ttccs->scale_clk_ctrl_reg_new, 302 ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET); 303 break; 304 305 case ABORT_RATE_CHANGE: 306 /* we have to undo the adjustment in case we scale up */ 307 if (ndata->new_rate < ndata->old_rate) 308 return NOTIFY_OK; 309 310 /* restore original register value */ 311 writel_relaxed(ttccs->scale_clk_ctrl_reg_old, 312 ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET); 313 fallthrough; 314 default: 315 return NOTIFY_DONE; 316 } 317 318 return NOTIFY_DONE; 319 } 320 321 static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base, 322 u32 timer_width) 323 { 324 struct ttc_timer_clocksource *ttccs; 325 int err; 326 327 ttccs = kzalloc(sizeof(*ttccs), GFP_KERNEL); 328 if (!ttccs) 329 return -ENOMEM; 330 331 ttccs->ttc.clk = clk; 332 333 err = clk_prepare_enable(ttccs->ttc.clk); 334 if (err) { 335 kfree(ttccs); 336 return err; 337 } 338 339 ttccs->ttc.freq = clk_get_rate(ttccs->ttc.clk); 340 341 ttccs->ttc.clk_rate_change_nb.notifier_call = 342 ttc_rate_change_clocksource_cb; 343 ttccs->ttc.clk_rate_change_nb.next = NULL; 344 345 err = clk_notifier_register(ttccs->ttc.clk, 346 &ttccs->ttc.clk_rate_change_nb); 347 if (err) 348 pr_warn("Unable to register clock notifier.\n"); 349 350 ttccs->ttc.base_addr = base; 351 ttccs->cs.name = "ttc_clocksource"; 352 ttccs->cs.rating = 200; 353 ttccs->cs.read = __ttc_clocksource_read; 354 ttccs->cs.mask = CLOCKSOURCE_MASK(timer_width); 355 ttccs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS; 356 357 /* 358 * Setup the clock source counter to be an incrementing counter 359 * with no interrupt and it rolls over at 0xFFFF. Pre-scale 360 * it by 32 also. Let it start running now. 361 */ 362 writel_relaxed(0x0, ttccs->ttc.base_addr + TTC_IER_OFFSET); 363 writel_relaxed(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN, 364 ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET); 365 writel_relaxed(CNT_CNTRL_RESET, 366 ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET); 367 368 err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE); 369 if (err) { 370 kfree(ttccs); 371 return err; 372 } 373 374 ttc_sched_clock_val_reg = base + TTC_COUNT_VAL_OFFSET; 375 sched_clock_register(ttc_sched_clock_read, timer_width, 376 ttccs->ttc.freq / PRESCALE); 377 378 return 0; 379 } 380 381 static int ttc_rate_change_clockevent_cb(struct notifier_block *nb, 382 unsigned long event, void *data) 383 { 384 struct clk_notifier_data *ndata = data; 385 struct ttc_timer *ttc = to_ttc_timer(nb); 386 struct ttc_timer_clockevent *ttcce = container_of(ttc, 387 struct ttc_timer_clockevent, ttc); 388 389 switch (event) { 390 case POST_RATE_CHANGE: 391 /* update cached frequency */ 392 ttc->freq = ndata->new_rate; 393 394 clockevents_update_freq(&ttcce->ce, ndata->new_rate / PRESCALE); 395 396 fallthrough; 397 case PRE_RATE_CHANGE: 398 case ABORT_RATE_CHANGE: 399 default: 400 return NOTIFY_DONE; 401 } 402 } 403 404 static int __init ttc_setup_clockevent(struct clk *clk, 405 void __iomem *base, u32 irq) 406 { 407 struct ttc_timer_clockevent *ttcce; 408 int err; 409 410 ttcce = kzalloc(sizeof(*ttcce), GFP_KERNEL); 411 if (!ttcce) 412 return -ENOMEM; 413 414 ttcce->ttc.clk = clk; 415 416 err = clk_prepare_enable(ttcce->ttc.clk); 417 if (err) 418 goto out_kfree; 419 420 ttcce->ttc.clk_rate_change_nb.notifier_call = 421 ttc_rate_change_clockevent_cb; 422 ttcce->ttc.clk_rate_change_nb.next = NULL; 423 424 err = clk_notifier_register(ttcce->ttc.clk, 425 &ttcce->ttc.clk_rate_change_nb); 426 if (err) { 427 pr_warn("Unable to register clock notifier.\n"); 428 goto out_kfree; 429 } 430 431 ttcce->ttc.freq = clk_get_rate(ttcce->ttc.clk); 432 433 ttcce->ttc.base_addr = base; 434 ttcce->ce.name = "ttc_clockevent"; 435 ttcce->ce.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; 436 ttcce->ce.set_next_event = ttc_set_next_event; 437 ttcce->ce.set_state_shutdown = ttc_shutdown; 438 ttcce->ce.set_state_periodic = ttc_set_periodic; 439 ttcce->ce.set_state_oneshot = ttc_shutdown; 440 ttcce->ce.tick_resume = ttc_resume; 441 ttcce->ce.rating = 200; 442 ttcce->ce.irq = irq; 443 ttcce->ce.cpumask = cpu_possible_mask; 444 445 /* 446 * Setup the clock event timer to be an interval timer which 447 * is prescaled by 32 using the interval interrupt. Leave it 448 * disabled for now. 449 */ 450 writel_relaxed(0x23, ttcce->ttc.base_addr + TTC_CNT_CNTRL_OFFSET); 451 writel_relaxed(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN, 452 ttcce->ttc.base_addr + TTC_CLK_CNTRL_OFFSET); 453 writel_relaxed(0x1, ttcce->ttc.base_addr + TTC_IER_OFFSET); 454 455 err = request_irq(irq, ttc_clock_event_interrupt, 456 IRQF_TIMER, ttcce->ce.name, ttcce); 457 if (err) 458 goto out_kfree; 459 460 clockevents_config_and_register(&ttcce->ce, 461 ttcce->ttc.freq / PRESCALE, 1, 0xfffe); 462 463 return 0; 464 465 out_kfree: 466 kfree(ttcce); 467 return err; 468 } 469 470 static int __init ttc_timer_probe(struct platform_device *pdev) 471 { 472 unsigned int irq; 473 void __iomem *timer_baseaddr; 474 struct clk *clk_cs, *clk_ce; 475 static int initialized; 476 int clksel, ret; 477 u32 timer_width = 16; 478 struct device_node *timer = pdev->dev.of_node; 479 480 if (initialized) 481 return 0; 482 483 initialized = 1; 484 485 /* 486 * Get the 1st Triple Timer Counter (TTC) block from the device tree 487 * and use it. Note that the event timer uses the interrupt and it's the 488 * 2nd TTC hence the irq_of_parse_and_map(,1) 489 */ 490 timer_baseaddr = devm_of_iomap(&pdev->dev, timer, 0, NULL); 491 if (IS_ERR(timer_baseaddr)) { 492 pr_err("ERROR: invalid timer base address\n"); 493 return PTR_ERR(timer_baseaddr); 494 } 495 496 irq = irq_of_parse_and_map(timer, 1); 497 if (irq <= 0) { 498 pr_err("ERROR: invalid interrupt number\n"); 499 return -EINVAL; 500 } 501 502 of_property_read_u32(timer, "timer-width", &timer_width); 503 504 clksel = readl_relaxed(timer_baseaddr + TTC_CLK_CNTRL_OFFSET); 505 clksel = !!(clksel & TTC_CLK_CNTRL_CSRC_MASK); 506 clk_cs = of_clk_get(timer, clksel); 507 if (IS_ERR(clk_cs)) { 508 pr_err("ERROR: timer input clock not found\n"); 509 return PTR_ERR(clk_cs); 510 } 511 512 clksel = readl_relaxed(timer_baseaddr + 4 + TTC_CLK_CNTRL_OFFSET); 513 clksel = !!(clksel & TTC_CLK_CNTRL_CSRC_MASK); 514 clk_ce = of_clk_get(timer, clksel); 515 if (IS_ERR(clk_ce)) { 516 pr_err("ERROR: timer input clock not found\n"); 517 ret = PTR_ERR(clk_ce); 518 goto put_clk_cs; 519 } 520 521 ret = ttc_setup_clocksource(clk_cs, timer_baseaddr, timer_width); 522 if (ret) 523 goto put_clk_ce; 524 525 ret = ttc_setup_clockevent(clk_ce, timer_baseaddr + 4, irq); 526 if (ret) 527 goto put_clk_ce; 528 529 pr_info("%pOFn #0 at %p, irq=%d\n", timer, timer_baseaddr, irq); 530 531 return 0; 532 533 put_clk_ce: 534 clk_put(clk_ce); 535 put_clk_cs: 536 clk_put(clk_cs); 537 return ret; 538 } 539 540 static const struct of_device_id ttc_timer_of_match[] = { 541 {.compatible = "cdns,ttc"}, 542 {}, 543 }; 544 545 MODULE_DEVICE_TABLE(of, ttc_timer_of_match); 546 547 static struct platform_driver ttc_timer_driver = { 548 .driver = { 549 .name = "cdns_ttc_timer", 550 .of_match_table = ttc_timer_of_match, 551 }, 552 }; 553 builtin_platform_driver_probe(ttc_timer_driver, ttc_timer_probe); 554