1 /* 2 * linux/arch/arm/kernel/smp_twd.c 3 * 4 * Copyright (C) 2002 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/clk.h> 14 #include <linux/cpu.h> 15 #include <linux/delay.h> 16 #include <linux/device.h> 17 #include <linux/err.h> 18 #include <linux/smp.h> 19 #include <linux/jiffies.h> 20 #include <linux/clockchips.h> 21 #include <linux/interrupt.h> 22 #include <linux/io.h> 23 #include <linux/of_irq.h> 24 #include <linux/of_address.h> 25 26 #include <asm/smp_twd.h> 27 28 /* set up by the platform code */ 29 static void __iomem *twd_base; 30 31 static struct clk *twd_clk; 32 static unsigned long twd_timer_rate; 33 static DEFINE_PER_CPU(bool, percpu_setup_called); 34 35 static struct clock_event_device __percpu *twd_evt; 36 static unsigned int twd_features = 37 CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; 38 static int twd_ppi; 39 40 static int twd_shutdown(struct clock_event_device *clk) 41 { 42 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 43 return 0; 44 } 45 46 static int twd_set_oneshot(struct clock_event_device *clk) 47 { 48 /* period set, and timer enabled in 'next_event' hook */ 49 writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT, 50 twd_base + TWD_TIMER_CONTROL); 51 return 0; 52 } 53 54 static int twd_set_periodic(struct clock_event_device *clk) 55 { 56 unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE | 57 TWD_TIMER_CONTROL_IT_ENABLE | 58 TWD_TIMER_CONTROL_PERIODIC; 59 60 writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ), 61 twd_base + TWD_TIMER_LOAD); 62 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 63 return 0; 64 } 65 66 static int twd_set_next_event(unsigned long evt, 67 struct clock_event_device *unused) 68 { 69 unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL); 70 71 ctrl |= TWD_TIMER_CONTROL_ENABLE; 72 73 writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER); 74 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 75 76 return 0; 77 } 78 79 /* 80 * local_timer_ack: checks for a local timer interrupt. 81 * 82 * If a local timer interrupt has occurred, acknowledge and return 1. 83 * Otherwise, return 0. 84 */ 85 static int twd_timer_ack(void) 86 { 87 if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) { 88 writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT); 89 return 1; 90 } 91 92 return 0; 93 } 94 95 static void twd_timer_stop(void) 96 { 97 struct clock_event_device *clk = raw_cpu_ptr(twd_evt); 98 99 twd_shutdown(clk); 100 disable_percpu_irq(clk->irq); 101 } 102 103 #ifdef CONFIG_COMMON_CLK 104 105 /* 106 * Updates clockevent frequency when the cpu frequency changes. 107 * Called on the cpu that is changing frequency with interrupts disabled. 108 */ 109 static void twd_update_frequency(void *new_rate) 110 { 111 twd_timer_rate = *((unsigned long *) new_rate); 112 113 clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate); 114 } 115 116 static int twd_rate_change(struct notifier_block *nb, 117 unsigned long flags, void *data) 118 { 119 struct clk_notifier_data *cnd = data; 120 121 /* 122 * The twd clock events must be reprogrammed to account for the new 123 * frequency. The timer is local to a cpu, so cross-call to the 124 * changing cpu. 125 */ 126 if (flags == POST_RATE_CHANGE) 127 on_each_cpu(twd_update_frequency, 128 (void *)&cnd->new_rate, 1); 129 130 return NOTIFY_OK; 131 } 132 133 static struct notifier_block twd_clk_nb = { 134 .notifier_call = twd_rate_change, 135 }; 136 137 static int twd_clk_init(void) 138 { 139 if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 140 return clk_notifier_register(twd_clk, &twd_clk_nb); 141 142 return 0; 143 } 144 core_initcall(twd_clk_init); 145 146 #elif defined (CONFIG_CPU_FREQ) 147 148 #include <linux/cpufreq.h> 149 150 /* 151 * Updates clockevent frequency when the cpu frequency changes. 152 * Called on the cpu that is changing frequency with interrupts disabled. 153 */ 154 static void twd_update_frequency(void *data) 155 { 156 twd_timer_rate = clk_get_rate(twd_clk); 157 158 clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate); 159 } 160 161 static int twd_cpufreq_transition(struct notifier_block *nb, 162 unsigned long state, void *data) 163 { 164 struct cpufreq_freqs *freqs = data; 165 166 /* 167 * The twd clock events must be reprogrammed to account for the new 168 * frequency. The timer is local to a cpu, so cross-call to the 169 * changing cpu. 170 */ 171 if (state == CPUFREQ_POSTCHANGE) 172 smp_call_function_single(freqs->cpu, twd_update_frequency, 173 NULL, 1); 174 175 return NOTIFY_OK; 176 } 177 178 static struct notifier_block twd_cpufreq_nb = { 179 .notifier_call = twd_cpufreq_transition, 180 }; 181 182 static int twd_cpufreq_init(void) 183 { 184 if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 185 return cpufreq_register_notifier(&twd_cpufreq_nb, 186 CPUFREQ_TRANSITION_NOTIFIER); 187 188 return 0; 189 } 190 core_initcall(twd_cpufreq_init); 191 192 #endif 193 194 static void twd_calibrate_rate(void) 195 { 196 unsigned long count; 197 u64 waitjiffies; 198 199 /* 200 * If this is the first time round, we need to work out how fast 201 * the timer ticks 202 */ 203 if (twd_timer_rate == 0) { 204 pr_info("Calibrating local timer... "); 205 206 /* Wait for a tick to start */ 207 waitjiffies = get_jiffies_64() + 1; 208 209 while (get_jiffies_64() < waitjiffies) 210 udelay(10); 211 212 /* OK, now the tick has started, let's get the timer going */ 213 waitjiffies += 5; 214 215 /* enable, no interrupt or reload */ 216 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); 217 218 /* maximum value */ 219 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); 220 221 while (get_jiffies_64() < waitjiffies) 222 udelay(10); 223 224 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER); 225 226 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); 227 228 pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000, 229 (twd_timer_rate / 10000) % 100); 230 } 231 } 232 233 static irqreturn_t twd_handler(int irq, void *dev_id) 234 { 235 struct clock_event_device *evt = dev_id; 236 237 if (twd_timer_ack()) { 238 evt->event_handler(evt); 239 return IRQ_HANDLED; 240 } 241 242 return IRQ_NONE; 243 } 244 245 static void twd_get_clock(struct device_node *np) 246 { 247 int err; 248 249 if (np) 250 twd_clk = of_clk_get(np, 0); 251 else 252 twd_clk = clk_get_sys("smp_twd", NULL); 253 254 if (IS_ERR(twd_clk)) { 255 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); 256 return; 257 } 258 259 err = clk_prepare_enable(twd_clk); 260 if (err) { 261 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); 262 clk_put(twd_clk); 263 return; 264 } 265 266 twd_timer_rate = clk_get_rate(twd_clk); 267 } 268 269 /* 270 * Setup the local clock events for a CPU. 271 */ 272 static void twd_timer_setup(void) 273 { 274 struct clock_event_device *clk = raw_cpu_ptr(twd_evt); 275 int cpu = smp_processor_id(); 276 277 /* 278 * If the basic setup for this CPU has been done before don't 279 * bother with the below. 280 */ 281 if (per_cpu(percpu_setup_called, cpu)) { 282 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 283 clockevents_register_device(clk); 284 enable_percpu_irq(clk->irq, 0); 285 return; 286 } 287 per_cpu(percpu_setup_called, cpu) = true; 288 289 twd_calibrate_rate(); 290 291 /* 292 * The following is done once per CPU the first time .setup() is 293 * called. 294 */ 295 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 296 297 clk->name = "local_timer"; 298 clk->features = twd_features; 299 clk->rating = 350; 300 clk->set_state_shutdown = twd_shutdown; 301 clk->set_state_periodic = twd_set_periodic; 302 clk->set_state_oneshot = twd_set_oneshot; 303 clk->tick_resume = twd_shutdown; 304 clk->set_next_event = twd_set_next_event; 305 clk->irq = twd_ppi; 306 clk->cpumask = cpumask_of(cpu); 307 308 clockevents_config_and_register(clk, twd_timer_rate, 309 0xf, 0xffffffff); 310 enable_percpu_irq(clk->irq, 0); 311 } 312 313 static int twd_timer_starting_cpu(unsigned int cpu) 314 { 315 twd_timer_setup(); 316 return 0; 317 } 318 319 static int twd_timer_dying_cpu(unsigned int cpu) 320 { 321 twd_timer_stop(); 322 return 0; 323 } 324 325 static int __init twd_local_timer_common_register(struct device_node *np) 326 { 327 int err; 328 329 twd_evt = alloc_percpu(struct clock_event_device); 330 if (!twd_evt) { 331 err = -ENOMEM; 332 goto out_free; 333 } 334 335 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt); 336 if (err) { 337 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err); 338 goto out_free; 339 } 340 341 cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING, 342 "arm/timer/twd:starting", 343 twd_timer_starting_cpu, twd_timer_dying_cpu); 344 345 twd_get_clock(np); 346 if (!of_property_read_bool(np, "always-on")) 347 twd_features |= CLOCK_EVT_FEAT_C3STOP; 348 349 /* 350 * Immediately configure the timer on the boot CPU, unless we need 351 * jiffies to be incrementing to calibrate the rate in which case 352 * setup the timer in late_time_init. 353 */ 354 if (twd_timer_rate) 355 twd_timer_setup(); 356 else 357 late_time_init = twd_timer_setup; 358 359 return 0; 360 361 out_free: 362 iounmap(twd_base); 363 twd_base = NULL; 364 free_percpu(twd_evt); 365 366 return err; 367 } 368 369 int __init twd_local_timer_register(struct twd_local_timer *tlt) 370 { 371 if (twd_base || twd_evt) 372 return -EBUSY; 373 374 twd_ppi = tlt->res[1].start; 375 376 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0])); 377 if (!twd_base) 378 return -ENOMEM; 379 380 return twd_local_timer_common_register(NULL); 381 } 382 383 #ifdef CONFIG_OF 384 static int __init twd_local_timer_of_register(struct device_node *np) 385 { 386 int err; 387 388 twd_ppi = irq_of_parse_and_map(np, 0); 389 if (!twd_ppi) { 390 err = -EINVAL; 391 goto out; 392 } 393 394 twd_base = of_iomap(np, 0); 395 if (!twd_base) { 396 err = -ENOMEM; 397 goto out; 398 } 399 400 err = twd_local_timer_common_register(np); 401 402 out: 403 WARN(err, "twd_local_timer_of_register failed (%d)\n", err); 404 return err; 405 } 406 TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); 407 TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); 408 TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register); 409 #endif 410