xref: /openbmc/linux/arch/arc/kernel/smp.c (revision fb960bd2)
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/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 
28 #include <asm/processor.h>
29 #include <asm/setup.h>
30 #include <asm/mach_desc.h>
31 
32 #ifndef CONFIG_ARC_HAS_LLSC
33 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
34 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
35 
36 EXPORT_SYMBOL_GPL(smp_atomic_ops_lock);
37 EXPORT_SYMBOL_GPL(smp_bitops_lock);
38 #endif
39 
40 struct plat_smp_ops  __weak plat_smp_ops;
41 
42 /* XXX: per cpu ? Only needed once in early seconday boot */
43 struct task_struct *secondary_idle_tsk;
44 
45 /* Called from start_kernel */
46 void __init smp_prepare_boot_cpu(void)
47 {
48 }
49 
50 /*
51  * Called from setup_arch() before calling setup_processor()
52  *
53  * - Initialise the CPU possible map early - this describes the CPUs
54  *   which may be present or become present in the system.
55  * - Call early smp init hook. This can initialize a specific multi-core
56  *   IP which is say common to several platforms (hence not part of
57  *   platform specific int_early() hook)
58  */
59 void __init smp_init_cpus(void)
60 {
61 	unsigned int i;
62 
63 	for (i = 0; i < NR_CPUS; i++)
64 		set_cpu_possible(i, true);
65 
66 	if (plat_smp_ops.init_early_smp)
67 		plat_smp_ops.init_early_smp();
68 }
69 
70 /* called from init ( ) =>  process 1 */
71 void __init smp_prepare_cpus(unsigned int max_cpus)
72 {
73 	int i;
74 
75 	/*
76 	 * if platform didn't set the present map already, do it now
77 	 * boot cpu is set to present already by init/main.c
78 	 */
79 	if (num_present_cpus() <= 1) {
80 		for (i = 0; i < max_cpus; i++)
81 			set_cpu_present(i, true);
82 	}
83 }
84 
85 void __init smp_cpus_done(unsigned int max_cpus)
86 {
87 
88 }
89 
90 /*
91  * Default smp boot helper for Run-on-reset case where all cores start off
92  * together. Non-masters need to wait for Master to start running.
93  * This is implemented using a flag in memory, which Non-masters spin-wait on.
94  * Master sets it to cpu-id of core to "ungate" it.
95  */
96 static volatile int wake_flag;
97 
98 #ifdef CONFIG_ISA_ARCOMPACT
99 
100 #define __boot_read(f)		f
101 #define __boot_write(f, v)	f = v
102 
103 #else
104 
105 #define __boot_read(f)		arc_read_uncached_32(&f)
106 #define __boot_write(f, v)	arc_write_uncached_32(&f, v)
107 
108 #endif
109 
110 static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
111 {
112 	BUG_ON(cpu == 0);
113 
114 	__boot_write(wake_flag, cpu);
115 }
116 
117 void arc_platform_smp_wait_to_boot(int cpu)
118 {
119 	/* for halt-on-reset, we've waited already */
120 	if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
121 		return;
122 
123 	while (__boot_read(wake_flag) != cpu)
124 		;
125 
126 	__boot_write(wake_flag, 0);
127 }
128 
129 const char *arc_platform_smp_cpuinfo(void)
130 {
131 	return plat_smp_ops.info ? : "";
132 }
133 
134 /*
135  * The very first "C" code executed by secondary
136  * Called from asm stub in head.S
137  * "current"/R25 already setup by low level boot code
138  */
139 void start_kernel_secondary(void)
140 {
141 	struct mm_struct *mm = &init_mm;
142 	unsigned int cpu = smp_processor_id();
143 
144 	/* MMU, Caches, Vector Table, Interrupts etc */
145 	setup_processor();
146 
147 	mmget(mm);
148 	mmgrab(mm);
149 	current->active_mm = mm;
150 	cpumask_set_cpu(cpu, mm_cpumask(mm));
151 
152 	/* Some SMP H/w setup - for each cpu */
153 	if (plat_smp_ops.init_per_cpu)
154 		plat_smp_ops.init_per_cpu(cpu);
155 
156 	if (machine_desc->init_per_cpu)
157 		machine_desc->init_per_cpu(cpu);
158 
159 	notify_cpu_starting(cpu);
160 	set_cpu_online(cpu, true);
161 
162 	pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
163 
164 	local_irq_enable();
165 	preempt_disable();
166 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
167 }
168 
169 /*
170  * Called from kernel_init( ) -> smp_init( ) - for each CPU
171  *
172  * At this point, Secondary Processor  is "HALT"ed:
173  *  -It booted, but was halted in head.S
174  *  -It was configured to halt-on-reset
175  *  So need to wake it up.
176  *
177  * Essential requirements being where to run from (PC) and stack (SP)
178 */
179 int __cpu_up(unsigned int cpu, struct task_struct *idle)
180 {
181 	unsigned long wait_till;
182 
183 	secondary_idle_tsk = idle;
184 
185 	pr_info("Idle Task [%d] %p", cpu, idle);
186 	pr_info("Trying to bring up CPU%u ...\n", cpu);
187 
188 	if (plat_smp_ops.cpu_kick)
189 		plat_smp_ops.cpu_kick(cpu,
190 				(unsigned long)first_lines_of_secondary);
191 	else
192 		arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
193 
194 	/* wait for 1 sec after kicking the secondary */
195 	wait_till = jiffies + HZ;
196 	while (time_before(jiffies, wait_till)) {
197 		if (cpu_online(cpu))
198 			break;
199 	}
200 
201 	if (!cpu_online(cpu)) {
202 		pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
203 		return -1;
204 	}
205 
206 	secondary_idle_tsk = NULL;
207 
208 	return 0;
209 }
210 
211 /*
212  * not supported here
213  */
214 int setup_profiling_timer(unsigned int multiplier)
215 {
216 	return -EINVAL;
217 }
218 
219 /*****************************************************************************/
220 /*              Inter Processor Interrupt Handling                           */
221 /*****************************************************************************/
222 
223 enum ipi_msg_type {
224 	IPI_EMPTY = 0,
225 	IPI_RESCHEDULE = 1,
226 	IPI_CALL_FUNC,
227 	IPI_CPU_STOP,
228 };
229 
230 /*
231  * In arches with IRQ for each msg type (above), receiver can use IRQ-id  to
232  * figure out what msg was sent. For those which don't (ARC has dedicated IPI
233  * IRQ), the msg-type needs to be conveyed via per-cpu data
234  */
235 
236 static DEFINE_PER_CPU(unsigned long, ipi_data);
237 
238 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
239 {
240 	unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
241 	unsigned long old, new;
242 	unsigned long flags;
243 
244 	pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
245 
246 	local_irq_save(flags);
247 
248 	/*
249 	 * Atomically write new msg bit (in case others are writing too),
250 	 * and read back old value
251 	 */
252 	do {
253 		new = old = READ_ONCE(*ipi_data_ptr);
254 		new |= 1U << msg;
255 	} while (cmpxchg(ipi_data_ptr, old, new) != old);
256 
257 	/*
258 	 * Call the platform specific IPI kick function, but avoid if possible:
259 	 * Only do so if there's no pending msg from other concurrent sender(s).
260 	 * Otherwise, recevier will see this msg as well when it takes the
261 	 * IPI corresponding to that msg. This is true, even if it is already in
262 	 * IPI handler, because !@old means it has not yet dequeued the msg(s)
263 	 * so @new msg can be a free-loader
264 	 */
265 	if (plat_smp_ops.ipi_send && !old)
266 		plat_smp_ops.ipi_send(cpu);
267 
268 	local_irq_restore(flags);
269 }
270 
271 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
272 {
273 	unsigned int cpu;
274 
275 	for_each_cpu(cpu, callmap)
276 		ipi_send_msg_one(cpu, msg);
277 }
278 
279 void smp_send_reschedule(int cpu)
280 {
281 	ipi_send_msg_one(cpu, IPI_RESCHEDULE);
282 }
283 
284 void smp_send_stop(void)
285 {
286 	struct cpumask targets;
287 	cpumask_copy(&targets, cpu_online_mask);
288 	cpumask_clear_cpu(smp_processor_id(), &targets);
289 	ipi_send_msg(&targets, IPI_CPU_STOP);
290 }
291 
292 void arch_send_call_function_single_ipi(int cpu)
293 {
294 	ipi_send_msg_one(cpu, IPI_CALL_FUNC);
295 }
296 
297 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
298 {
299 	ipi_send_msg(mask, IPI_CALL_FUNC);
300 }
301 
302 /*
303  * ipi_cpu_stop - handle IPI from smp_send_stop()
304  */
305 static void ipi_cpu_stop(void)
306 {
307 	machine_halt();
308 }
309 
310 static inline int __do_IPI(unsigned long msg)
311 {
312 	int rc = 0;
313 
314 	switch (msg) {
315 	case IPI_RESCHEDULE:
316 		scheduler_ipi();
317 		break;
318 
319 	case IPI_CALL_FUNC:
320 		generic_smp_call_function_interrupt();
321 		break;
322 
323 	case IPI_CPU_STOP:
324 		ipi_cpu_stop();
325 		break;
326 
327 	default:
328 		rc = 1;
329 	}
330 
331 	return rc;
332 }
333 
334 /*
335  * arch-common ISR to handle for inter-processor interrupts
336  * Has hooks for platform specific IPI
337  */
338 irqreturn_t do_IPI(int irq, void *dev_id)
339 {
340 	unsigned long pending;
341 	unsigned long __maybe_unused copy;
342 
343 	pr_debug("IPI [%ld] received on cpu %d\n",
344 		 *this_cpu_ptr(&ipi_data), smp_processor_id());
345 
346 	if (plat_smp_ops.ipi_clear)
347 		plat_smp_ops.ipi_clear(irq);
348 
349 	/*
350 	 * "dequeue" the msg corresponding to this IPI (and possibly other
351 	 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
352 	 */
353 	copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
354 
355 	do {
356 		unsigned long msg = __ffs(pending);
357 		int rc;
358 
359 		rc = __do_IPI(msg);
360 		if (rc)
361 			pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
362 		pending &= ~(1U << msg);
363 	} while (pending);
364 
365 	return IRQ_HANDLED;
366 }
367 
368 /*
369  * API called by platform code to hookup arch-common ISR to their IPI IRQ
370  *
371  * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
372  * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
373  * request_percpu_irq() below will fail
374  */
375 static DEFINE_PER_CPU(int, ipi_dev);
376 
377 int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq)
378 {
379 	int *dev = per_cpu_ptr(&ipi_dev, cpu);
380 	unsigned int virq = irq_find_mapping(NULL, hwirq);
381 
382 	if (!virq)
383 		panic("Cannot find virq for root domain and hwirq=%lu", hwirq);
384 
385 	/* Boot cpu calls request, all call enable */
386 	if (!cpu) {
387 		int rc;
388 
389 		rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev);
390 		if (rc)
391 			panic("Percpu IRQ request failed for %u\n", virq);
392 	}
393 
394 	enable_percpu_irq(virq, 0);
395 
396 	return 0;
397 }
398