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_plat.h> 27 #include <asm/smp_twd.h> 28 29 /* set up by the platform code */ 30 static void __iomem *twd_base; 31 32 static struct clk *twd_clk; 33 static unsigned long twd_timer_rate; 34 static DEFINE_PER_CPU(bool, percpu_setup_called); 35 36 static struct clock_event_device __percpu *twd_evt; 37 static int twd_ppi; 38 39 static void twd_set_mode(enum clock_event_mode mode, 40 struct clock_event_device *clk) 41 { 42 unsigned long ctrl; 43 44 switch (mode) { 45 case CLOCK_EVT_MODE_PERIODIC: 46 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE 47 | TWD_TIMER_CONTROL_PERIODIC; 48 writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ), 49 twd_base + TWD_TIMER_LOAD); 50 break; 51 case CLOCK_EVT_MODE_ONESHOT: 52 /* period set, and timer enabled in 'next_event' hook */ 53 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT; 54 break; 55 case CLOCK_EVT_MODE_UNUSED: 56 case CLOCK_EVT_MODE_SHUTDOWN: 57 default: 58 ctrl = 0; 59 } 60 61 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 62 } 63 64 static int twd_set_next_event(unsigned long evt, 65 struct clock_event_device *unused) 66 { 67 unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL); 68 69 ctrl |= TWD_TIMER_CONTROL_ENABLE; 70 71 writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER); 72 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 73 74 return 0; 75 } 76 77 /* 78 * local_timer_ack: checks for a local timer interrupt. 79 * 80 * If a local timer interrupt has occurred, acknowledge and return 1. 81 * Otherwise, return 0. 82 */ 83 static int twd_timer_ack(void) 84 { 85 if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) { 86 writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT); 87 return 1; 88 } 89 90 return 0; 91 } 92 93 static void twd_timer_stop(void) 94 { 95 struct clock_event_device *clk = __this_cpu_ptr(twd_evt); 96 97 twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk); 98 disable_percpu_irq(clk->irq); 99 } 100 101 #ifdef CONFIG_COMMON_CLK 102 103 /* 104 * Updates clockevent frequency when the cpu frequency changes. 105 * Called on the cpu that is changing frequency with interrupts disabled. 106 */ 107 static void twd_update_frequency(void *new_rate) 108 { 109 twd_timer_rate = *((unsigned long *) new_rate); 110 111 clockevents_update_freq(__this_cpu_ptr(twd_evt), twd_timer_rate); 112 } 113 114 static int twd_rate_change(struct notifier_block *nb, 115 unsigned long flags, void *data) 116 { 117 struct clk_notifier_data *cnd = data; 118 119 /* 120 * The twd clock events must be reprogrammed to account for the new 121 * frequency. The timer is local to a cpu, so cross-call to the 122 * changing cpu. 123 */ 124 if (flags == POST_RATE_CHANGE) 125 on_each_cpu(twd_update_frequency, 126 (void *)&cnd->new_rate, 1); 127 128 return NOTIFY_OK; 129 } 130 131 static struct notifier_block twd_clk_nb = { 132 .notifier_call = twd_rate_change, 133 }; 134 135 static int twd_clk_init(void) 136 { 137 if (twd_evt && __this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 138 return clk_notifier_register(twd_clk, &twd_clk_nb); 139 140 return 0; 141 } 142 core_initcall(twd_clk_init); 143 144 #elif defined (CONFIG_CPU_FREQ) 145 146 #include <linux/cpufreq.h> 147 148 /* 149 * Updates clockevent frequency when the cpu frequency changes. 150 * Called on the cpu that is changing frequency with interrupts disabled. 151 */ 152 static void twd_update_frequency(void *data) 153 { 154 twd_timer_rate = clk_get_rate(twd_clk); 155 156 clockevents_update_freq(__this_cpu_ptr(twd_evt), twd_timer_rate); 157 } 158 159 static int twd_cpufreq_transition(struct notifier_block *nb, 160 unsigned long state, void *data) 161 { 162 struct cpufreq_freqs *freqs = data; 163 164 /* 165 * The twd clock events must be reprogrammed to account for the new 166 * frequency. The timer is local to a cpu, so cross-call to the 167 * changing cpu. 168 */ 169 if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) 170 smp_call_function_single(freqs->cpu, twd_update_frequency, 171 NULL, 1); 172 173 return NOTIFY_OK; 174 } 175 176 static struct notifier_block twd_cpufreq_nb = { 177 .notifier_call = twd_cpufreq_transition, 178 }; 179 180 static int twd_cpufreq_init(void) 181 { 182 if (twd_evt && __this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 183 return cpufreq_register_notifier(&twd_cpufreq_nb, 184 CPUFREQ_TRANSITION_NOTIFIER); 185 186 return 0; 187 } 188 core_initcall(twd_cpufreq_init); 189 190 #endif 191 192 static void twd_calibrate_rate(void) 193 { 194 unsigned long count; 195 u64 waitjiffies; 196 197 /* 198 * If this is the first time round, we need to work out how fast 199 * the timer ticks 200 */ 201 if (twd_timer_rate == 0) { 202 printk(KERN_INFO "Calibrating local timer... "); 203 204 /* Wait for a tick to start */ 205 waitjiffies = get_jiffies_64() + 1; 206 207 while (get_jiffies_64() < waitjiffies) 208 udelay(10); 209 210 /* OK, now the tick has started, let's get the timer going */ 211 waitjiffies += 5; 212 213 /* enable, no interrupt or reload */ 214 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); 215 216 /* maximum value */ 217 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); 218 219 while (get_jiffies_64() < waitjiffies) 220 udelay(10); 221 222 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER); 223 224 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); 225 226 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000, 227 (twd_timer_rate / 10000) % 100); 228 } 229 } 230 231 static irqreturn_t twd_handler(int irq, void *dev_id) 232 { 233 struct clock_event_device *evt = dev_id; 234 235 if (twd_timer_ack()) { 236 evt->event_handler(evt); 237 return IRQ_HANDLED; 238 } 239 240 return IRQ_NONE; 241 } 242 243 static void twd_get_clock(struct device_node *np) 244 { 245 int err; 246 247 if (np) 248 twd_clk = of_clk_get(np, 0); 249 else 250 twd_clk = clk_get_sys("smp_twd", NULL); 251 252 if (IS_ERR(twd_clk)) { 253 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); 254 return; 255 } 256 257 err = clk_prepare_enable(twd_clk); 258 if (err) { 259 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); 260 clk_put(twd_clk); 261 return; 262 } 263 264 twd_timer_rate = clk_get_rate(twd_clk); 265 } 266 267 /* 268 * Setup the local clock events for a CPU. 269 */ 270 static void twd_timer_setup(void) 271 { 272 struct clock_event_device *clk = __this_cpu_ptr(twd_evt); 273 int cpu = smp_processor_id(); 274 275 /* 276 * If the basic setup for this CPU has been done before don't 277 * bother with the below. 278 */ 279 if (per_cpu(percpu_setup_called, cpu)) { 280 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 281 clockevents_register_device(clk); 282 enable_percpu_irq(clk->irq, 0); 283 return; 284 } 285 per_cpu(percpu_setup_called, cpu) = true; 286 287 twd_calibrate_rate(); 288 289 /* 290 * The following is done once per CPU the first time .setup() is 291 * called. 292 */ 293 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 294 295 clk->name = "local_timer"; 296 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | 297 CLOCK_EVT_FEAT_C3STOP; 298 clk->rating = 350; 299 clk->set_mode = twd_set_mode; 300 clk->set_next_event = twd_set_next_event; 301 clk->irq = twd_ppi; 302 clk->cpumask = cpumask_of(cpu); 303 304 clockevents_config_and_register(clk, twd_timer_rate, 305 0xf, 0xffffffff); 306 enable_percpu_irq(clk->irq, 0); 307 } 308 309 static int twd_timer_cpu_notify(struct notifier_block *self, 310 unsigned long action, void *hcpu) 311 { 312 switch (action & ~CPU_TASKS_FROZEN) { 313 case CPU_STARTING: 314 twd_timer_setup(); 315 break; 316 case CPU_DYING: 317 twd_timer_stop(); 318 break; 319 } 320 321 return NOTIFY_OK; 322 } 323 324 static struct notifier_block twd_timer_cpu_nb = { 325 .notifier_call = twd_timer_cpu_notify, 326 }; 327 328 static int __init twd_local_timer_common_register(struct device_node *np) 329 { 330 int err; 331 332 twd_evt = alloc_percpu(struct clock_event_device); 333 if (!twd_evt) { 334 err = -ENOMEM; 335 goto out_free; 336 } 337 338 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt); 339 if (err) { 340 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err); 341 goto out_free; 342 } 343 344 err = register_cpu_notifier(&twd_timer_cpu_nb); 345 if (err) 346 goto out_irq; 347 348 twd_get_clock(np); 349 350 /* 351 * Immediately configure the timer on the boot CPU, unless we need 352 * jiffies to be incrementing to calibrate the rate in which case 353 * setup the timer in late_time_init. 354 */ 355 if (twd_timer_rate) 356 twd_timer_setup(); 357 else 358 late_time_init = twd_timer_setup; 359 360 return 0; 361 362 out_irq: 363 free_percpu_irq(twd_ppi, twd_evt); 364 out_free: 365 iounmap(twd_base); 366 twd_base = NULL; 367 free_percpu(twd_evt); 368 369 return err; 370 } 371 372 int __init twd_local_timer_register(struct twd_local_timer *tlt) 373 { 374 if (twd_base || twd_evt) 375 return -EBUSY; 376 377 twd_ppi = tlt->res[1].start; 378 379 twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0])); 380 if (!twd_base) 381 return -ENOMEM; 382 383 return twd_local_timer_common_register(NULL); 384 } 385 386 #ifdef CONFIG_OF 387 static void __init twd_local_timer_of_register(struct device_node *np) 388 { 389 int err; 390 391 if (!is_smp() || !setup_max_cpus) 392 return; 393 394 twd_ppi = irq_of_parse_and_map(np, 0); 395 if (!twd_ppi) { 396 err = -EINVAL; 397 goto out; 398 } 399 400 twd_base = of_iomap(np, 0); 401 if (!twd_base) { 402 err = -ENOMEM; 403 goto out; 404 } 405 406 err = twd_local_timer_common_register(np); 407 408 out: 409 WARN(err, "twd_local_timer_of_register failed (%d)\n", err); 410 } 411 CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); 412 CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); 413 CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register); 414 #endif 415