x86/speculation/mds: Fix documentation typo
[linux/fpc-iii.git] / arch / arc / kernel / smp.c
blob115eecc0d9a4a640b972796ef5f3a706d53917a4
1 /*
2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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.
8 * RajeshwarR: Dec 11, 2007
9 * -- Added support for Inter Processor Interrupts
11 * Vineetg: Nov 1st, 2007
12 * -- Initial Write (Borrowed heavily from ARM)
15 #include <linux/spinlock.h>
16 #include <linux/sched/mm.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 <linux/irqdomain.h>
26 #include <linux/export.h>
27 #include <linux/of_fdt.h>
29 #include <asm/processor.h>
30 #include <asm/setup.h>
31 #include <asm/mach_desc.h>
33 #ifndef CONFIG_ARC_HAS_LLSC
34 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
35 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
37 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock);
38 EXPORT_SYMBOL_GPL(smp_bitops_lock);
39 #endif
41 struct plat_smp_ops __weak plat_smp_ops;
43 /* XXX: per cpu ? Only needed once in early seconday boot */
44 struct task_struct *secondary_idle_tsk;
46 /* Called from start_kernel */
47 void __init smp_prepare_boot_cpu(void)
51 static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
53 unsigned long dt_root = of_get_flat_dt_root();
54 const char *buf;
56 buf = of_get_flat_dt_prop(dt_root, name, NULL);
57 if (!buf)
58 return -EINVAL;
60 if (cpulist_parse(buf, cpumask))
61 return -EINVAL;
63 return 0;
67 * Read from DeviceTree and setup cpu possible mask. If there is no
68 * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist.
70 static void __init arc_init_cpu_possible(void)
72 struct cpumask cpumask;
74 if (arc_get_cpu_map("possible-cpus", &cpumask)) {
75 pr_warn("Failed to get possible-cpus from dtb, pretending all %u cpus exist\n",
76 NR_CPUS);
78 cpumask_setall(&cpumask);
81 if (!cpumask_test_cpu(0, &cpumask))
82 panic("Master cpu (cpu[0]) is missed in cpu possible mask!");
84 init_cpu_possible(&cpumask);
88 * Called from setup_arch() before calling setup_processor()
90 * - Initialise the CPU possible map early - this describes the CPUs
91 * which may be present or become present in the system.
92 * - Call early smp init hook. This can initialize a specific multi-core
93 * IP which is say common to several platforms (hence not part of
94 * platform specific int_early() hook)
96 void __init smp_init_cpus(void)
98 arc_init_cpu_possible();
100 if (plat_smp_ops.init_early_smp)
101 plat_smp_ops.init_early_smp();
104 /* called from init ( ) => process 1 */
105 void __init smp_prepare_cpus(unsigned int max_cpus)
108 * if platform didn't set the present map already, do it now
109 * boot cpu is set to present already by init/main.c
111 if (num_present_cpus() <= 1)
112 init_cpu_present(cpu_possible_mask);
115 void __init smp_cpus_done(unsigned int max_cpus)
121 * Default smp boot helper for Run-on-reset case where all cores start off
122 * together. Non-masters need to wait for Master to start running.
123 * This is implemented using a flag in memory, which Non-masters spin-wait on.
124 * Master sets it to cpu-id of core to "ungate" it.
126 static volatile int wake_flag;
128 #ifdef CONFIG_ISA_ARCOMPACT
130 #define __boot_read(f) f
131 #define __boot_write(f, v) f = v
133 #else
135 #define __boot_read(f) arc_read_uncached_32(&f)
136 #define __boot_write(f, v) arc_write_uncached_32(&f, v)
138 #endif
140 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
142 BUG_ON(cpu == 0);
144 __boot_write(wake_flag, cpu);
147 void arc_platform_smp_wait_to_boot(int cpu)
149 /* for halt-on-reset, we've waited already */
150 if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
151 return;
153 while (__boot_read(wake_flag) != cpu)
156 __boot_write(wake_flag, 0);
159 const char *arc_platform_smp_cpuinfo(void)
161 return plat_smp_ops.info ? : "";
165 * The very first "C" code executed by secondary
166 * Called from asm stub in head.S
167 * "current"/R25 already setup by low level boot code
169 void start_kernel_secondary(void)
171 struct mm_struct *mm = &init_mm;
172 unsigned int cpu = smp_processor_id();
174 /* MMU, Caches, Vector Table, Interrupts etc */
175 setup_processor();
177 mmget(mm);
178 mmgrab(mm);
179 current->active_mm = mm;
180 cpumask_set_cpu(cpu, mm_cpumask(mm));
182 /* Some SMP H/w setup - for each cpu */
183 if (plat_smp_ops.init_per_cpu)
184 plat_smp_ops.init_per_cpu(cpu);
186 if (machine_desc->init_per_cpu)
187 machine_desc->init_per_cpu(cpu);
189 notify_cpu_starting(cpu);
190 set_cpu_online(cpu, true);
192 pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
194 local_irq_enable();
195 preempt_disable();
196 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
200 * Called from kernel_init( ) -> smp_init( ) - for each CPU
202 * At this point, Secondary Processor is "HALT"ed:
203 * -It booted, but was halted in head.S
204 * -It was configured to halt-on-reset
205 * So need to wake it up.
207 * Essential requirements being where to run from (PC) and stack (SP)
209 int __cpu_up(unsigned int cpu, struct task_struct *idle)
211 unsigned long wait_till;
213 secondary_idle_tsk = idle;
215 pr_info("Idle Task [%d] %p", cpu, idle);
216 pr_info("Trying to bring up CPU%u ...\n", cpu);
218 if (plat_smp_ops.cpu_kick)
219 plat_smp_ops.cpu_kick(cpu,
220 (unsigned long)first_lines_of_secondary);
221 else
222 arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
224 /* wait for 1 sec after kicking the secondary */
225 wait_till = jiffies + HZ;
226 while (time_before(jiffies, wait_till)) {
227 if (cpu_online(cpu))
228 break;
231 if (!cpu_online(cpu)) {
232 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
233 return -1;
236 secondary_idle_tsk = NULL;
238 return 0;
242 * not supported here
244 int setup_profiling_timer(unsigned int multiplier)
246 return -EINVAL;
249 /*****************************************************************************/
250 /* Inter Processor Interrupt Handling */
251 /*****************************************************************************/
253 enum ipi_msg_type {
254 IPI_EMPTY = 0,
255 IPI_RESCHEDULE = 1,
256 IPI_CALL_FUNC,
257 IPI_CPU_STOP,
261 * In arches with IRQ for each msg type (above), receiver can use IRQ-id to
262 * figure out what msg was sent. For those which don't (ARC has dedicated IPI
263 * IRQ), the msg-type needs to be conveyed via per-cpu data
266 static DEFINE_PER_CPU(unsigned long, ipi_data);
268 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
270 unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
271 unsigned long old, new;
272 unsigned long flags;
274 pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
276 local_irq_save(flags);
279 * Atomically write new msg bit (in case others are writing too),
280 * and read back old value
282 do {
283 new = old = ACCESS_ONCE(*ipi_data_ptr);
284 new |= 1U << msg;
285 } while (cmpxchg(ipi_data_ptr, old, new) != old);
288 * Call the platform specific IPI kick function, but avoid if possible:
289 * Only do so if there's no pending msg from other concurrent sender(s).
290 * Otherwise, recevier will see this msg as well when it takes the
291 * IPI corresponding to that msg. This is true, even if it is already in
292 * IPI handler, because !@old means it has not yet dequeued the msg(s)
293 * so @new msg can be a free-loader
295 if (plat_smp_ops.ipi_send && !old)
296 plat_smp_ops.ipi_send(cpu);
298 local_irq_restore(flags);
301 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
303 unsigned int cpu;
305 for_each_cpu(cpu, callmap)
306 ipi_send_msg_one(cpu, msg);
309 void smp_send_reschedule(int cpu)
311 ipi_send_msg_one(cpu, IPI_RESCHEDULE);
314 void smp_send_stop(void)
316 struct cpumask targets;
317 cpumask_copy(&targets, cpu_online_mask);
318 cpumask_clear_cpu(smp_processor_id(), &targets);
319 ipi_send_msg(&targets, IPI_CPU_STOP);
322 void arch_send_call_function_single_ipi(int cpu)
324 ipi_send_msg_one(cpu, IPI_CALL_FUNC);
327 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
329 ipi_send_msg(mask, IPI_CALL_FUNC);
333 * ipi_cpu_stop - handle IPI from smp_send_stop()
335 static void ipi_cpu_stop(void)
337 machine_halt();
340 static inline int __do_IPI(unsigned long msg)
342 int rc = 0;
344 switch (msg) {
345 case IPI_RESCHEDULE:
346 scheduler_ipi();
347 break;
349 case IPI_CALL_FUNC:
350 generic_smp_call_function_interrupt();
351 break;
353 case IPI_CPU_STOP:
354 ipi_cpu_stop();
355 break;
357 default:
358 rc = 1;
361 return rc;
365 * arch-common ISR to handle for inter-processor interrupts
366 * Has hooks for platform specific IPI
368 irqreturn_t do_IPI(int irq, void *dev_id)
370 unsigned long pending;
371 unsigned long __maybe_unused copy;
373 pr_debug("IPI [%ld] received on cpu %d\n",
374 *this_cpu_ptr(&ipi_data), smp_processor_id());
376 if (plat_smp_ops.ipi_clear)
377 plat_smp_ops.ipi_clear(irq);
380 * "dequeue" the msg corresponding to this IPI (and possibly other
381 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
383 copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
385 do {
386 unsigned long msg = __ffs(pending);
387 int rc;
389 rc = __do_IPI(msg);
390 if (rc)
391 pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
392 pending &= ~(1U << msg);
393 } while (pending);
395 return IRQ_HANDLED;
399 * API called by platform code to hookup arch-common ISR to their IPI IRQ
401 * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
402 * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
403 * request_percpu_irq() below will fail
405 static DEFINE_PER_CPU(int, ipi_dev);
407 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq)
409 int *dev = per_cpu_ptr(&ipi_dev, cpu);
410 unsigned int virq = irq_find_mapping(NULL, hwirq);
412 if (!virq)
413 panic("Cannot find virq for root domain and hwirq=%lu", hwirq);
415 /* Boot cpu calls request, all call enable */
416 if (!cpu) {
417 int rc;
419 rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev);
420 if (rc)
421 panic("Percpu IRQ request failed for %u\n", virq);
424 enable_percpu_irq(virq, 0);
426 return 0;