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