1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/kernel/smp_twd.c 4 * 5 * Copyright (C) 2002 ARM Ltd. 6 * All Rights Reserved 7 */ 8 #include <linux/init.h> 9 #include <linux/kernel.h> 10 #include <linux/clk.h> 11 #include <linux/cpu.h> 12 #include <linux/delay.h> 13 #include <linux/device.h> 14 #include <linux/err.h> 15 #include <linux/smp.h> 16 #include <linux/jiffies.h> 17 #include <linux/clockchips.h> 18 #include <linux/interrupt.h> 19 #include <linux/io.h> 20 #include <linux/of_irq.h> 21 #include <linux/of_address.h> 22 23 #include <asm/smp_twd.h> 24 25 /* set up by the platform code */ 26 static void __iomem *twd_base; 27 28 static struct clk *twd_clk; 29 static unsigned long twd_timer_rate; 30 static DEFINE_PER_CPU(bool, percpu_setup_called); 31 32 static struct clock_event_device __percpu *twd_evt; 33 static unsigned int twd_features = 34 CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; 35 static int twd_ppi; 36 37 static int twd_shutdown(struct clock_event_device *clk) 38 { 39 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 40 return 0; 41 } 42 43 static int twd_set_oneshot(struct clock_event_device *clk) 44 { 45 /* period set, and timer enabled in 'next_event' hook */ 46 writel_relaxed(TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT, 47 twd_base + TWD_TIMER_CONTROL); 48 return 0; 49 } 50 51 static int twd_set_periodic(struct clock_event_device *clk) 52 { 53 unsigned long ctrl = TWD_TIMER_CONTROL_ENABLE | 54 TWD_TIMER_CONTROL_IT_ENABLE | 55 TWD_TIMER_CONTROL_PERIODIC; 56 57 writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ), 58 twd_base + TWD_TIMER_LOAD); 59 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 60 return 0; 61 } 62 63 static int twd_set_next_event(unsigned long evt, 64 struct clock_event_device *unused) 65 { 66 unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL); 67 68 ctrl |= TWD_TIMER_CONTROL_ENABLE; 69 70 writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER); 71 writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); 72 73 return 0; 74 } 75 76 /* 77 * local_timer_ack: checks for a local timer interrupt. 78 * 79 * If a local timer interrupt has occurred, acknowledge and return 1. 80 * Otherwise, return 0. 81 */ 82 static int twd_timer_ack(void) 83 { 84 if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) { 85 writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT); 86 return 1; 87 } 88 89 return 0; 90 } 91 92 static void twd_timer_stop(void) 93 { 94 struct clock_event_device *clk = raw_cpu_ptr(twd_evt); 95 96 twd_shutdown(clk); 97 disable_percpu_irq(clk->irq); 98 } 99 100 /* 101 * Updates clockevent frequency when the cpu frequency changes. 102 * Called on the cpu that is changing frequency with interrupts disabled. 103 */ 104 static void twd_update_frequency(void *new_rate) 105 { 106 twd_timer_rate = *((unsigned long *) new_rate); 107 108 clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate); 109 } 110 111 static int twd_rate_change(struct notifier_block *nb, 112 unsigned long flags, void *data) 113 { 114 struct clk_notifier_data *cnd = data; 115 116 /* 117 * The twd clock events must be reprogrammed to account for the new 118 * frequency. The timer is local to a cpu, so cross-call to the 119 * changing cpu. 120 */ 121 if (flags == POST_RATE_CHANGE) 122 on_each_cpu(twd_update_frequency, 123 (void *)&cnd->new_rate, 1); 124 125 return NOTIFY_OK; 126 } 127 128 static struct notifier_block twd_clk_nb = { 129 .notifier_call = twd_rate_change, 130 }; 131 132 static int twd_clk_init(void) 133 { 134 if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 135 return clk_notifier_register(twd_clk, &twd_clk_nb); 136 137 return 0; 138 } 139 core_initcall(twd_clk_init); 140 141 static void twd_calibrate_rate(void) 142 { 143 unsigned long count; 144 u64 waitjiffies; 145 146 /* 147 * If this is the first time round, we need to work out how fast 148 * the timer ticks 149 */ 150 if (twd_timer_rate == 0) { 151 pr_info("Calibrating local timer... "); 152 153 /* Wait for a tick to start */ 154 waitjiffies = get_jiffies_64() + 1; 155 156 while (get_jiffies_64() < waitjiffies) 157 udelay(10); 158 159 /* OK, now the tick has started, let's get the timer going */ 160 waitjiffies += 5; 161 162 /* enable, no interrupt or reload */ 163 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); 164 165 /* maximum value */ 166 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); 167 168 while (get_jiffies_64() < waitjiffies) 169 udelay(10); 170 171 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER); 172 173 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); 174 175 pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000, 176 (twd_timer_rate / 10000) % 100); 177 } 178 } 179 180 static irqreturn_t twd_handler(int irq, void *dev_id) 181 { 182 struct clock_event_device *evt = dev_id; 183 184 if (twd_timer_ack()) { 185 evt->event_handler(evt); 186 return IRQ_HANDLED; 187 } 188 189 return IRQ_NONE; 190 } 191 192 static void twd_get_clock(struct device_node *np) 193 { 194 int err; 195 196 if (np) 197 twd_clk = of_clk_get(np, 0); 198 else 199 twd_clk = clk_get_sys("smp_twd", NULL); 200 201 if (IS_ERR(twd_clk)) { 202 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); 203 return; 204 } 205 206 err = clk_prepare_enable(twd_clk); 207 if (err) { 208 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); 209 clk_put(twd_clk); 210 return; 211 } 212 213 twd_timer_rate = clk_get_rate(twd_clk); 214 } 215 216 /* 217 * Setup the local clock events for a CPU. 218 */ 219 static void twd_timer_setup(void) 220 { 221 struct clock_event_device *clk = raw_cpu_ptr(twd_evt); 222 int cpu = smp_processor_id(); 223 224 /* 225 * If the basic setup for this CPU has been done before don't 226 * bother with the below. 227 */ 228 if (per_cpu(percpu_setup_called, cpu)) { 229 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 230 clockevents_register_device(clk); 231 enable_percpu_irq(clk->irq, 0); 232 return; 233 } 234 per_cpu(percpu_setup_called, cpu) = true; 235 236 twd_calibrate_rate(); 237 238 /* 239 * The following is done once per CPU the first time .setup() is 240 * called. 241 */ 242 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 243 244 clk->name = "local_timer"; 245 clk->features = twd_features; 246 clk->rating = 350; 247 clk->set_state_shutdown = twd_shutdown; 248 clk->set_state_periodic = twd_set_periodic; 249 clk->set_state_oneshot = twd_set_oneshot; 250 clk->tick_resume = twd_shutdown; 251 clk->set_next_event = twd_set_next_event; 252 clk->irq = twd_ppi; 253 clk->cpumask = cpumask_of(cpu); 254 255 clockevents_config_and_register(clk, twd_timer_rate, 256 0xf, 0xffffffff); 257 enable_percpu_irq(clk->irq, 0); 258 } 259 260 static int twd_timer_starting_cpu(unsigned int cpu) 261 { 262 twd_timer_setup(); 263 return 0; 264 } 265 266 static int twd_timer_dying_cpu(unsigned int cpu) 267 { 268 twd_timer_stop(); 269 return 0; 270 } 271 272 static int __init twd_local_timer_common_register(struct device_node *np) 273 { 274 int err; 275 276 twd_evt = alloc_percpu(struct clock_event_device); 277 if (!twd_evt) { 278 err = -ENOMEM; 279 goto out_free; 280 } 281 282 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt); 283 if (err) { 284 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err); 285 goto out_free; 286 } 287 288 cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING, 289 "arm/timer/twd:starting", 290 twd_timer_starting_cpu, twd_timer_dying_cpu); 291 292 twd_get_clock(np); 293 if (!of_property_read_bool(np, "always-on")) 294 twd_features |= CLOCK_EVT_FEAT_C3STOP; 295 296 /* 297 * Immediately configure the timer on the boot CPU, unless we need 298 * jiffies to be incrementing to calibrate the rate in which case 299 * setup the timer in late_time_init. 300 */ 301 if (twd_timer_rate) 302 twd_timer_setup(); 303 else 304 late_time_init = twd_timer_setup; 305 306 return 0; 307 308 out_free: 309 iounmap(twd_base); 310 twd_base = NULL; 311 free_percpu(twd_evt); 312 313 return err; 314 } 315 316 static int __init twd_local_timer_of_register(struct device_node *np) 317 { 318 int err; 319 320 twd_ppi = irq_of_parse_and_map(np, 0); 321 if (!twd_ppi) { 322 err = -EINVAL; 323 goto out; 324 } 325 326 twd_base = of_iomap(np, 0); 327 if (!twd_base) { 328 err = -ENOMEM; 329 goto out; 330 } 331 332 err = twd_local_timer_common_register(np); 333 334 out: 335 WARN(err, "twd_local_timer_of_register failed (%d)\n", err); 336 return err; 337 } 338 TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); 339 TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); 340 TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register); 341