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 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED; 33 34 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock); 35 EXPORT_SYMBOL_GPL(smp_bitops_lock); 36 #endif 37 38 struct plat_smp_ops __weak plat_smp_ops; 39 40 /* XXX: per cpu ? Only needed once in early seconday boot */ 41 struct task_struct *secondary_idle_tsk; 42 43 /* Called from start_kernel */ 44 void __init smp_prepare_boot_cpu(void) 45 { 46 } 47 48 static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask) 49 { 50 unsigned long dt_root = of_get_flat_dt_root(); 51 const char *buf; 52 53 buf = of_get_flat_dt_prop(dt_root, name, NULL); 54 if (!buf) 55 return -EINVAL; 56 57 if (cpulist_parse(buf, cpumask)) 58 return -EINVAL; 59 60 return 0; 61 } 62 63 /* 64 * Read from DeviceTree and setup cpu possible mask. If there is no 65 * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist. 66 */ 67 static void __init arc_init_cpu_possible(void) 68 { 69 struct cpumask cpumask; 70 71 if (arc_get_cpu_map("possible-cpus", &cpumask)) { 72 pr_warn("Failed to get possible-cpus from dtb, pretending all %u cpus exist\n", 73 NR_CPUS); 74 75 cpumask_setall(&cpumask); 76 } 77 78 if (!cpumask_test_cpu(0, &cpumask)) 79 panic("Master cpu (cpu[0]) is missed in cpu possible mask!"); 80 81 init_cpu_possible(&cpumask); 82 } 83 84 /* 85 * Called from setup_arch() before calling setup_processor() 86 * 87 * - Initialise the CPU possible map early - this describes the CPUs 88 * which may be present or become present in the system. 89 * - Call early smp init hook. This can initialize a specific multi-core 90 * IP which is say common to several platforms (hence not part of 91 * platform specific int_early() hook) 92 */ 93 void __init smp_init_cpus(void) 94 { 95 arc_init_cpu_possible(); 96 97 if (plat_smp_ops.init_early_smp) 98 plat_smp_ops.init_early_smp(); 99 } 100 101 /* called from init ( ) => process 1 */ 102 void __init smp_prepare_cpus(unsigned int max_cpus) 103 { 104 /* 105 * if platform didn't set the present map already, do it now 106 * boot cpu is set to present already by init/main.c 107 */ 108 if (num_present_cpus() <= 1) 109 init_cpu_present(cpu_possible_mask); 110 } 111 112 void __init smp_cpus_done(unsigned int max_cpus) 113 { 114 115 } 116 117 /* 118 * Default smp boot helper for Run-on-reset case where all cores start off 119 * together. Non-masters need to wait for Master to start running. 120 * This is implemented using a flag in memory, which Non-masters spin-wait on. 121 * Master sets it to cpu-id of core to "ungate" it. 122 */ 123 static volatile int wake_flag; 124 125 #ifdef CONFIG_ISA_ARCOMPACT 126 127 #define __boot_read(f) f 128 #define __boot_write(f, v) f = v 129 130 #else 131 132 #define __boot_read(f) arc_read_uncached_32(&f) 133 #define __boot_write(f, v) arc_write_uncached_32(&f, v) 134 135 #endif 136 137 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc) 138 { 139 BUG_ON(cpu == 0); 140 141 __boot_write(wake_flag, cpu); 142 } 143 144 void arc_platform_smp_wait_to_boot(int cpu) 145 { 146 /* for halt-on-reset, we've waited already */ 147 if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET)) 148 return; 149 150 while (__boot_read(wake_flag) != cpu) 151 ; 152 153 __boot_write(wake_flag, 0); 154 } 155 156 const char *arc_platform_smp_cpuinfo(void) 157 { 158 return plat_smp_ops.info ? : ""; 159 } 160 161 /* 162 * The very first "C" code executed by secondary 163 * Called from asm stub in head.S 164 * "current"/R25 already setup by low level boot code 165 */ 166 void start_kernel_secondary(void) 167 { 168 struct mm_struct *mm = &init_mm; 169 unsigned int cpu = smp_processor_id(); 170 171 /* MMU, Caches, Vector Table, Interrupts etc */ 172 setup_processor(); 173 174 mmget(mm); 175 mmgrab(mm); 176 current->active_mm = mm; 177 cpumask_set_cpu(cpu, mm_cpumask(mm)); 178 179 /* Some SMP H/w setup - for each cpu */ 180 if (plat_smp_ops.init_per_cpu) 181 plat_smp_ops.init_per_cpu(cpu); 182 183 if (machine_desc->init_per_cpu) 184 machine_desc->init_per_cpu(cpu); 185 186 notify_cpu_starting(cpu); 187 set_cpu_online(cpu, true); 188 189 pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu); 190 191 local_irq_enable(); 192 preempt_disable(); 193 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); 194 } 195 196 /* 197 * Called from kernel_init( ) -> smp_init( ) - for each CPU 198 * 199 * At this point, Secondary Processor is "HALT"ed: 200 * -It booted, but was halted in head.S 201 * -It was configured to halt-on-reset 202 * So need to wake it up. 203 * 204 * Essential requirements being where to run from (PC) and stack (SP) 205 */ 206 int __cpu_up(unsigned int cpu, struct task_struct *idle) 207 { 208 unsigned long wait_till; 209 210 secondary_idle_tsk = idle; 211 212 pr_info("Idle Task [%d] %p", cpu, idle); 213 pr_info("Trying to bring up CPU%u ...\n", cpu); 214 215 if (plat_smp_ops.cpu_kick) 216 plat_smp_ops.cpu_kick(cpu, 217 (unsigned long)first_lines_of_secondary); 218 else 219 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL); 220 221 /* wait for 1 sec after kicking the secondary */ 222 wait_till = jiffies + HZ; 223 while (time_before(jiffies, wait_till)) { 224 if (cpu_online(cpu)) 225 break; 226 } 227 228 if (!cpu_online(cpu)) { 229 pr_info("Timeout: CPU%u FAILED to come up !!!\n", cpu); 230 return -1; 231 } 232 233 secondary_idle_tsk = NULL; 234 235 return 0; 236 } 237 238 /* 239 * not supported here 240 */ 241 int setup_profiling_timer(unsigned int multiplier) 242 { 243 return -EINVAL; 244 } 245 246 /*****************************************************************************/ 247 /* Inter Processor Interrupt Handling */ 248 /*****************************************************************************/ 249 250 enum ipi_msg_type { 251 IPI_EMPTY = 0, 252 IPI_RESCHEDULE = 1, 253 IPI_CALL_FUNC, 254 IPI_CPU_STOP, 255 }; 256 257 /* 258 * In arches with IRQ for each msg type (above), receiver can use IRQ-id to 259 * figure out what msg was sent. For those which don't (ARC has dedicated IPI 260 * IRQ), the msg-type needs to be conveyed via per-cpu data 261 */ 262 263 static DEFINE_PER_CPU(unsigned long, ipi_data); 264 265 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg) 266 { 267 unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu); 268 unsigned long old, new; 269 unsigned long flags; 270 271 pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu); 272 273 local_irq_save(flags); 274 275 /* 276 * Atomically write new msg bit (in case others are writing too), 277 * and read back old value 278 */ 279 do { 280 new = old = READ_ONCE(*ipi_data_ptr); 281 new |= 1U << msg; 282 } while (cmpxchg(ipi_data_ptr, old, new) != old); 283 284 /* 285 * Call the platform specific IPI kick function, but avoid if possible: 286 * Only do so if there's no pending msg from other concurrent sender(s). 287 * Otherwise, recevier will see this msg as well when it takes the 288 * IPI corresponding to that msg. This is true, even if it is already in 289 * IPI handler, because !@old means it has not yet dequeued the msg(s) 290 * so @new msg can be a free-loader 291 */ 292 if (plat_smp_ops.ipi_send && !old) 293 plat_smp_ops.ipi_send(cpu); 294 295 local_irq_restore(flags); 296 } 297 298 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg) 299 { 300 unsigned int cpu; 301 302 for_each_cpu(cpu, callmap) 303 ipi_send_msg_one(cpu, msg); 304 } 305 306 void smp_send_reschedule(int cpu) 307 { 308 ipi_send_msg_one(cpu, IPI_RESCHEDULE); 309 } 310 311 void smp_send_stop(void) 312 { 313 struct cpumask targets; 314 cpumask_copy(&targets, cpu_online_mask); 315 cpumask_clear_cpu(smp_processor_id(), &targets); 316 ipi_send_msg(&targets, IPI_CPU_STOP); 317 } 318 319 void arch_send_call_function_single_ipi(int cpu) 320 { 321 ipi_send_msg_one(cpu, IPI_CALL_FUNC); 322 } 323 324 void arch_send_call_function_ipi_mask(const struct cpumask *mask) 325 { 326 ipi_send_msg(mask, IPI_CALL_FUNC); 327 } 328 329 /* 330 * ipi_cpu_stop - handle IPI from smp_send_stop() 331 */ 332 static void ipi_cpu_stop(void) 333 { 334 machine_halt(); 335 } 336 337 static inline int __do_IPI(unsigned long msg) 338 { 339 int rc = 0; 340 341 switch (msg) { 342 case IPI_RESCHEDULE: 343 scheduler_ipi(); 344 break; 345 346 case IPI_CALL_FUNC: 347 generic_smp_call_function_interrupt(); 348 break; 349 350 case IPI_CPU_STOP: 351 ipi_cpu_stop(); 352 break; 353 354 default: 355 rc = 1; 356 } 357 358 return rc; 359 } 360 361 /* 362 * arch-common ISR to handle for inter-processor interrupts 363 * Has hooks for platform specific IPI 364 */ 365 irqreturn_t do_IPI(int irq, void *dev_id) 366 { 367 unsigned long pending; 368 unsigned long __maybe_unused copy; 369 370 pr_debug("IPI [%ld] received on cpu %d\n", 371 *this_cpu_ptr(&ipi_data), smp_processor_id()); 372 373 if (plat_smp_ops.ipi_clear) 374 plat_smp_ops.ipi_clear(irq); 375 376 /* 377 * "dequeue" the msg corresponding to this IPI (and possibly other 378 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above) 379 */ 380 copy = pending = xchg(this_cpu_ptr(&ipi_data), 0); 381 382 do { 383 unsigned long msg = __ffs(pending); 384 int rc; 385 386 rc = __do_IPI(msg); 387 if (rc) 388 pr_info("IPI with bogus msg %ld in %ld\n", msg, copy); 389 pending &= ~(1U << msg); 390 } while (pending); 391 392 return IRQ_HANDLED; 393 } 394 395 /* 396 * API called by platform code to hookup arch-common ISR to their IPI IRQ 397 * 398 * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map 399 * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise 400 * request_percpu_irq() below will fail 401 */ 402 static DEFINE_PER_CPU(int, ipi_dev); 403 404 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq) 405 { 406 int *dev = per_cpu_ptr(&ipi_dev, cpu); 407 unsigned int virq = irq_find_mapping(NULL, hwirq); 408 409 if (!virq) 410 panic("Cannot find virq for root domain and hwirq=%lu", hwirq); 411 412 /* Boot cpu calls request, all call enable */ 413 if (!cpu) { 414 int rc; 415 416 rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev); 417 if (rc) 418 panic("Percpu IRQ request failed for %u\n", virq); 419 } 420 421 enable_percpu_irq(virq, 0); 422 423 return 0; 424 } 425