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 disable_percpu_irq(clk->irq); 97 } 98 99 /* 100 * Updates clockevent frequency when the cpu frequency changes. 101 * Called on the cpu that is changing frequency with interrupts disabled. 102 */ 103 static void twd_update_frequency(void *new_rate) 104 { 105 twd_timer_rate = *((unsigned long *) new_rate); 106 107 clockevents_update_freq(raw_cpu_ptr(twd_evt), twd_timer_rate); 108 } 109 110 static int twd_rate_change(struct notifier_block *nb, 111 unsigned long flags, void *data) 112 { 113 struct clk_notifier_data *cnd = data; 114 115 /* 116 * The twd clock events must be reprogrammed to account for the new 117 * frequency. The timer is local to a cpu, so cross-call to the 118 * changing cpu. 119 */ 120 if (flags == POST_RATE_CHANGE) 121 on_each_cpu(twd_update_frequency, 122 (void *)&cnd->new_rate, 1); 123 124 return NOTIFY_OK; 125 } 126 127 static struct notifier_block twd_clk_nb = { 128 .notifier_call = twd_rate_change, 129 }; 130 131 static int twd_clk_init(void) 132 { 133 if (twd_evt && raw_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) 134 return clk_notifier_register(twd_clk, &twd_clk_nb); 135 136 return 0; 137 } 138 core_initcall(twd_clk_init); 139 140 static void twd_calibrate_rate(void) 141 { 142 unsigned long count; 143 u64 waitjiffies; 144 145 /* 146 * If this is the first time round, we need to work out how fast 147 * the timer ticks 148 */ 149 if (twd_timer_rate == 0) { 150 pr_info("Calibrating local timer... "); 151 152 /* Wait for a tick to start */ 153 waitjiffies = get_jiffies_64() + 1; 154 155 while (get_jiffies_64() < waitjiffies) 156 udelay(10); 157 158 /* OK, now the tick has started, let's get the timer going */ 159 waitjiffies += 5; 160 161 /* enable, no interrupt or reload */ 162 writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); 163 164 /* maximum value */ 165 writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); 166 167 while (get_jiffies_64() < waitjiffies) 168 udelay(10); 169 170 count = readl_relaxed(twd_base + TWD_TIMER_COUNTER); 171 172 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); 173 174 pr_cont("%lu.%02luMHz.\n", twd_timer_rate / 1000000, 175 (twd_timer_rate / 10000) % 100); 176 } 177 } 178 179 static irqreturn_t twd_handler(int irq, void *dev_id) 180 { 181 struct clock_event_device *evt = dev_id; 182 183 if (twd_timer_ack()) { 184 evt->event_handler(evt); 185 return IRQ_HANDLED; 186 } 187 188 return IRQ_NONE; 189 } 190 191 static void twd_get_clock(struct device_node *np) 192 { 193 int err; 194 195 if (np) 196 twd_clk = of_clk_get(np, 0); 197 else 198 twd_clk = clk_get_sys("smp_twd", NULL); 199 200 if (IS_ERR(twd_clk)) { 201 pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); 202 return; 203 } 204 205 err = clk_prepare_enable(twd_clk); 206 if (err) { 207 pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); 208 clk_put(twd_clk); 209 return; 210 } 211 212 twd_timer_rate = clk_get_rate(twd_clk); 213 } 214 215 /* 216 * Setup the local clock events for a CPU. 217 */ 218 static void twd_timer_setup(void) 219 { 220 struct clock_event_device *clk = raw_cpu_ptr(twd_evt); 221 int cpu = smp_processor_id(); 222 223 /* 224 * If the basic setup for this CPU has been done before don't 225 * bother with the below. 226 */ 227 if (per_cpu(percpu_setup_called, cpu)) { 228 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 229 clockevents_register_device(clk); 230 enable_percpu_irq(clk->irq, 0); 231 return; 232 } 233 per_cpu(percpu_setup_called, cpu) = true; 234 235 twd_calibrate_rate(); 236 237 /* 238 * The following is done once per CPU the first time .setup() is 239 * called. 240 */ 241 writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 242 243 clk->name = "local_timer"; 244 clk->features = twd_features; 245 clk->rating = 350; 246 clk->set_state_shutdown = twd_shutdown; 247 clk->set_state_periodic = twd_set_periodic; 248 clk->set_state_oneshot = twd_set_oneshot; 249 clk->tick_resume = twd_shutdown; 250 clk->set_next_event = twd_set_next_event; 251 clk->irq = twd_ppi; 252 clk->cpumask = cpumask_of(cpu); 253 254 clockevents_config_and_register(clk, twd_timer_rate, 255 0xf, 0xffffffff); 256 enable_percpu_irq(clk->irq, 0); 257 } 258 259 static int twd_timer_starting_cpu(unsigned int cpu) 260 { 261 twd_timer_setup(); 262 return 0; 263 } 264 265 static int twd_timer_dying_cpu(unsigned int cpu) 266 { 267 twd_timer_stop(); 268 return 0; 269 } 270 271 static int __init twd_local_timer_common_register(struct device_node *np) 272 { 273 int err; 274 275 twd_evt = alloc_percpu(struct clock_event_device); 276 if (!twd_evt) { 277 err = -ENOMEM; 278 goto out_free; 279 } 280 281 err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt); 282 if (err) { 283 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err); 284 goto out_free; 285 } 286 287 cpuhp_setup_state_nocalls(CPUHP_AP_ARM_TWD_STARTING, 288 "arm/timer/twd:starting", 289 twd_timer_starting_cpu, twd_timer_dying_cpu); 290 291 twd_get_clock(np); 292 if (!of_property_read_bool(np, "always-on")) 293 twd_features |= CLOCK_EVT_FEAT_C3STOP; 294 295 /* 296 * Immediately configure the timer on the boot CPU, unless we need 297 * jiffies to be incrementing to calibrate the rate in which case 298 * setup the timer in late_time_init. 299 */ 300 if (twd_timer_rate) 301 twd_timer_setup(); 302 else 303 late_time_init = twd_timer_setup; 304 305 return 0; 306 307 out_free: 308 iounmap(twd_base); 309 twd_base = NULL; 310 free_percpu(twd_evt); 311 312 return err; 313 } 314 315 static int __init twd_local_timer_of_register(struct device_node *np) 316 { 317 int err; 318 319 twd_ppi = irq_of_parse_and_map(np, 0); 320 if (!twd_ppi) { 321 err = -EINVAL; 322 goto out; 323 } 324 325 twd_base = of_iomap(np, 0); 326 if (!twd_base) { 327 err = -ENOMEM; 328 goto out; 329 } 330 331 err = twd_local_timer_common_register(np); 332 333 out: 334 WARN(err, "twd_local_timer_of_register failed (%d)\n", err); 335 return err; 336 } 337 TIMER_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); 338 TIMER_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); 339 TIMER_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register); 340