1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 4 * 5 * RajeshwarR: Dec 11, 2007 6 * -- Added support for Inter Processor Interrupts 7 * 8 * Vineetg: Nov 1st, 2007 9 * -- Initial Write (Borrowed heavily from ARM) 10 */ 11 12 #include <linux/spinlock.h> 13 #include <linux/sched/mm.h> 14 #include <linux/interrupt.h> 15 #include <linux/profile.h> 16 #include <linux/mm.h> 17 #include <linux/cpu.h> 18 #include <linux/irq.h> 19 #include <linux/atomic.h> 20 #include <linux/cpumask.h> 21 #include <linux/reboot.h> 22 #include <linux/irqdomain.h> 23 #include <linux/export.h> 24 #include <linux/of_fdt.h> 25 26 #include <asm/processor.h> 27 #include <asm/setup.h> 28 #include <asm/mach_desc.h> 29 30 #ifndef CONFIG_ARC_HAS_LLSC 31 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED; 32 33 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock); 34 #endif 35 36 struct plat_smp_ops __weak plat_smp_ops; 37 38 /* XXX: per cpu ? Only needed once in early secondary boot */ 39 struct task_struct *secondary_idle_tsk; 40 41 /* Called from start_kernel */ 42 void __init smp_prepare_boot_cpu(void) 43 { 44 } 45 46 static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask) 47 { 48 unsigned long dt_root = of_get_flat_dt_root(); 49 const char *buf; 50 51 buf = of_get_flat_dt_prop(dt_root, name, NULL); 52 if (!buf) 53 return -EINVAL; 54 55 if (cpulist_parse(buf, cpumask)) 56 return -EINVAL; 57 58 return 0; 59 } 60 61 /* 62 * Read from DeviceTree and setup cpu possible mask. If there is no 63 * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist. 64 */ 65 static void __init arc_init_cpu_possible(void) 66 { 67 struct cpumask cpumask; 68 69 if (arc_get_cpu_map("possible-cpus", &cpumask)) { 70 pr_warn("Failed to get possible-cpus from dtb, pretending all %u cpus exist\n", 71 NR_CPUS); 72 73 cpumask_setall(&cpumask); 74 } 75 76 if (!cpumask_test_cpu(0, &cpumask)) 77 panic("Master cpu (cpu[0]) is missed in cpu possible mask!"); 78 79 init_cpu_possible(&cpumask); 80 } 81 82 /* 83 * Called from setup_arch() before calling setup_processor() 84 * 85 * - Initialise the CPU possible map early - this describes the CPUs 86 * which may be present or become present in the system. 87 * - Call early smp init hook. This can initialize a specific multi-core 88 * IP which is say common to several platforms (hence not part of 89 * platform specific int_early() hook) 90 */ 91 void __init smp_init_cpus(void) 92 { 93 arc_init_cpu_possible(); 94 95 if (plat_smp_ops.init_early_smp) 96 plat_smp_ops.init_early_smp(); 97 } 98 99 /* called from init ( ) => process 1 */ 100 void __init smp_prepare_cpus(unsigned int max_cpus) 101 { 102 /* 103 * if platform didn't set the present map already, do it now 104 * boot cpu is set to present already by init/main.c 105 */ 106 if (num_present_cpus() <= 1) 107 init_cpu_present(cpu_possible_mask); 108 } 109 110 void __init smp_cpus_done(unsigned int max_cpus) 111 { 112 113 } 114 115 /* 116 * Default smp boot helper for Run-on-reset case where all cores start off 117 * together. Non-masters need to wait for Master to start running. 118 * This is implemented using a flag in memory, which Non-masters spin-wait on. 119 * Master sets it to cpu-id of core to "ungate" it. 120 */ 121 static volatile int wake_flag; 122 123 #ifdef CONFIG_ISA_ARCOMPACT 124 125 #define __boot_read(f) f 126 #define __boot_write(f, v) f = v 127 128 #else 129 130 #define __boot_read(f) arc_read_uncached_32(&f) 131 #define __boot_write(f, v) arc_write_uncached_32(&f, v) 132 133 #endif 134 135 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc) 136 { 137 BUG_ON(cpu == 0); 138 139 __boot_write(wake_flag, cpu); 140 } 141 142 void arc_platform_smp_wait_to_boot(int cpu) 143 { 144 /* for halt-on-reset, we've waited already */ 145 if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET)) 146 return; 147 148 while (__boot_read(wake_flag) != cpu) 149 ; 150 151 __boot_write(wake_flag, 0); 152 } 153 154 const char *arc_platform_smp_cpuinfo(void) 155 { 156 return plat_smp_ops.info ? : ""; 157 } 158 159 /* 160 * The very first "C" code executed by secondary 161 * Called from asm stub in head.S 162 * "current"/R25 already setup by low level boot code 163 */ 164 void start_kernel_secondary(void) 165 { 166 struct mm_struct *mm = &init_mm; 167 unsigned int cpu = smp_processor_id(); 168 169 /* MMU, Caches, Vector Table, Interrupts etc */ 170 setup_processor(); 171 172 mmget(mm); 173 mmgrab(mm); 174 current->active_mm = mm; 175 cpumask_set_cpu(cpu, mm_cpumask(mm)); 176 177 /* Some SMP H/w setup - for each cpu */ 178 if (plat_smp_ops.init_per_cpu) 179 plat_smp_ops.init_per_cpu(cpu); 180 181 if (machine_desc->init_per_cpu) 182 machine_desc->init_per_cpu(cpu); 183 184 notify_cpu_starting(cpu); 185 set_cpu_online(cpu, true); 186 187 pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu); 188 189 local_irq_enable(); 190 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); 191 } 192 193 /* 194 * Called from kernel_init( ) -> smp_init( ) - for each CPU 195 * 196 * At this point, Secondary Processor is "HALT"ed: 197 * -It booted, but was halted in head.S 198 * -It was configured to halt-on-reset 199 * So need to wake it up. 200 * 201 * Essential requirements being where to run from (PC) and stack (SP) 202 */ 203 int __cpu_up(unsigned int cpu, struct task_struct *idle) 204 { 205 unsigned long wait_till; 206 207 secondary_idle_tsk = idle; 208 209 pr_info("Idle Task [%d] %p", cpu, idle); 210 pr_info("Trying to bring up CPU%u ...\n", cpu); 211 212 if (plat_smp_ops.cpu_kick) 213 plat_smp_ops.cpu_kick(cpu, 214 (unsigned long)first_lines_of_secondary); 215 else 216 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL); 217 218 /* wait for 1 sec after kicking the secondary */ 219 wait_till = jiffies + HZ; 220 while (time_before(jiffies, wait_till)) { 221 if (cpu_online(cpu)) 222 break; 223 } 224 225 if (!cpu_online(cpu)) { 226 pr_info("Timeout: CPU%u FAILED to come up !!!\n", cpu); 227 return -1; 228 } 229 230 secondary_idle_tsk = NULL; 231 232 return 0; 233 } 234 235 /*****************************************************************************/ 236 /* Inter Processor Interrupt Handling */ 237 /*****************************************************************************/ 238 239 enum ipi_msg_type { 240 IPI_EMPTY = 0, 241 IPI_RESCHEDULE = 1, 242 IPI_CALL_FUNC, 243 IPI_CPU_STOP, 244 }; 245 246 /* 247 * In arches with IRQ for each msg type (above), receiver can use IRQ-id to 248 * figure out what msg was sent. For those which don't (ARC has dedicated IPI 249 * IRQ), the msg-type needs to be conveyed via per-cpu data 250 */ 251 252 static DEFINE_PER_CPU(unsigned long, ipi_data); 253 254 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg) 255 { 256 unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu); 257 unsigned long old, new; 258 unsigned long flags; 259 260 pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu); 261 262 local_irq_save(flags); 263 264 /* 265 * Atomically write new msg bit (in case others are writing too), 266 * and read back old value 267 */ 268 do { 269 new = old = *ipi_data_ptr; 270 new |= 1U << msg; 271 } while (cmpxchg(ipi_data_ptr, old, new) != old); 272 273 /* 274 * Call the platform specific IPI kick function, but avoid if possible: 275 * Only do so if there's no pending msg from other concurrent sender(s). 276 * Otherwise, receiver will see this msg as well when it takes the 277 * IPI corresponding to that msg. This is true, even if it is already in 278 * IPI handler, because !@old means it has not yet dequeued the msg(s) 279 * so @new msg can be a free-loader 280 */ 281 if (plat_smp_ops.ipi_send && !old) 282 plat_smp_ops.ipi_send(cpu); 283 284 local_irq_restore(flags); 285 } 286 287 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg) 288 { 289 unsigned int cpu; 290 291 for_each_cpu(cpu, callmap) 292 ipi_send_msg_one(cpu, msg); 293 } 294 295 void arch_smp_send_reschedule(int cpu) 296 { 297 ipi_send_msg_one(cpu, IPI_RESCHEDULE); 298 } 299 300 void smp_send_stop(void) 301 { 302 struct cpumask targets; 303 cpumask_copy(&targets, cpu_online_mask); 304 cpumask_clear_cpu(smp_processor_id(), &targets); 305 ipi_send_msg(&targets, IPI_CPU_STOP); 306 } 307 308 void arch_send_call_function_single_ipi(int cpu) 309 { 310 ipi_send_msg_one(cpu, IPI_CALL_FUNC); 311 } 312 313 void arch_send_call_function_ipi_mask(const struct cpumask *mask) 314 { 315 ipi_send_msg(mask, IPI_CALL_FUNC); 316 } 317 318 /* 319 * ipi_cpu_stop - handle IPI from smp_send_stop() 320 */ 321 static void ipi_cpu_stop(void) 322 { 323 machine_halt(); 324 } 325 326 static inline int __do_IPI(unsigned long msg) 327 { 328 int rc = 0; 329 330 switch (msg) { 331 case IPI_RESCHEDULE: 332 scheduler_ipi(); 333 break; 334 335 case IPI_CALL_FUNC: 336 generic_smp_call_function_interrupt(); 337 break; 338 339 case IPI_CPU_STOP: 340 ipi_cpu_stop(); 341 break; 342 343 default: 344 rc = 1; 345 } 346 347 return rc; 348 } 349 350 /* 351 * arch-common ISR to handle for inter-processor interrupts 352 * Has hooks for platform specific IPI 353 */ 354 irqreturn_t do_IPI(int irq, void *dev_id) 355 { 356 unsigned long pending; 357 unsigned long __maybe_unused copy; 358 359 pr_debug("IPI [%ld] received on cpu %d\n", 360 *this_cpu_ptr(&ipi_data), smp_processor_id()); 361 362 if (plat_smp_ops.ipi_clear) 363 plat_smp_ops.ipi_clear(irq); 364 365 /* 366 * "dequeue" the msg corresponding to this IPI (and possibly other 367 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above) 368 */ 369 copy = pending = xchg(this_cpu_ptr(&ipi_data), 0); 370 371 do { 372 unsigned long msg = __ffs(pending); 373 int rc; 374 375 rc = __do_IPI(msg); 376 if (rc) 377 pr_info("IPI with bogus msg %ld in %ld\n", msg, copy); 378 pending &= ~(1U << msg); 379 } while (pending); 380 381 return IRQ_HANDLED; 382 } 383 384 /* 385 * API called by platform code to hookup arch-common ISR to their IPI IRQ 386 * 387 * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map 388 * function needs to call irq_set_percpu_devid() for IPI IRQ, otherwise 389 * request_percpu_irq() below will fail 390 */ 391 static DEFINE_PER_CPU(int, ipi_dev); 392 393 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq) 394 { 395 int *dev = per_cpu_ptr(&ipi_dev, cpu); 396 unsigned int virq = irq_find_mapping(NULL, hwirq); 397 398 if (!virq) 399 panic("Cannot find virq for root domain and hwirq=%lu", hwirq); 400 401 /* Boot cpu calls request, all call enable */ 402 if (!cpu) { 403 int rc; 404 405 rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev); 406 if (rc) 407 panic("Percpu IRQ request failed for %u\n", virq); 408 } 409 410 enable_percpu_irq(virq, 0); 411 412 return 0; 413 } 414