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