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