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