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
9#ifndef __ASM_ARC_SMP_H
10#define __ASM_ARC_SMP_H
11
12#ifdef CONFIG_SMP
13
14#include <linux/types.h>
15#include <linux/init.h>
16#include <linux/threads.h>
17
18#define raw_smp_processor_id() (current_thread_info()->cpu)
19
20/* including cpumask.h leads to cyclic deps hence this Forward declaration */
21struct cpumask;
22
23/*
24 * APIs provided by arch SMP code to generic code
25 */
26extern void arch_send_call_function_single_ipi(int cpu);
27extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
28
29/*
30 * APIs provided by arch SMP code to rest of arch code
31 */
32extern void __init smp_init_cpus(void);
33extern void first_lines_of_secondary(void);
34extern const char *arc_platform_smp_cpuinfo(void);
35
36/*
37 * API expected BY platform smp code (FROM arch smp code)
38 *
39 * smp_ipi_irq_setup:
40 *	Takes @cpu and @irq to which the arch-common ISR is hooked up
41 */
42extern int smp_ipi_irq_setup(int cpu, int irq);
43
44/*
45 * struct plat_smp_ops	- SMP callbacks provided by platform to ARC SMP
46 *
47 * @info:		SoC SMP specific info for /proc/cpuinfo etc
48 * @cpu_kick:		For Master to kickstart a cpu (optionally at a PC)
49 * @ipi_send:		To send IPI to a @cpu
50 * @ips_clear:		To clear IPI received at @irq
51 */
52struct plat_smp_ops {
53	const char 	*info;
54	void		(*cpu_kick)(int cpu, unsigned long pc);
55	void		(*ipi_send)(int cpu);
56	void		(*ipi_clear)(int irq);
57};
58
59/* TBD: stop exporting it for direct population by platform */
60extern struct plat_smp_ops  plat_smp_ops;
61
62#else /* CONFIG_SMP */
63
64static inline void smp_init_cpus(void) {}
65static inline const char *arc_platform_smp_cpuinfo(void)
66{
67	return "";
68}
69
70#endif  /* !CONFIG_SMP */
71
72/*
73 * ARC700 doesn't support atomic Read-Modify-Write ops.
74 * Originally Interrupts had to be disabled around code to gaurantee atomicity.
75 * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
76 * based on retry-if-irq-in-atomic (with hardware assist).
77 * However despite these, we provide the IRQ disabling variant
78 *
79 * (1) These insn were introduced only in 4.10 release. So for older released
80 *	support needed.
81 *
82 * (2) In a SMP setup, the LLOCK/SCOND atomiticity across CPUs needs to be
83 *	gaurantted by the platform (not something which core handles).
84 *	Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
85 *	disabling for atomicity.
86 *
87 *	However exported spinlock API is not usable due to cyclic hdr deps
88 *	(even after system.h disintegration upstream)
89 *	asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
90 *		-> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
91 *
92 *	So the workaround is to use the lowest level arch spinlock API.
93 *	The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
94 *	but same is not true for ARCH backend, hence the need for 2 variants
95 */
96#ifndef CONFIG_ARC_HAS_LLSC
97
98#include <linux/irqflags.h>
99#ifdef CONFIG_SMP
100
101#include <asm/spinlock.h>
102
103extern arch_spinlock_t smp_atomic_ops_lock;
104extern arch_spinlock_t smp_bitops_lock;
105
106#define atomic_ops_lock(flags)	do {		\
107	local_irq_save(flags);			\
108	arch_spin_lock(&smp_atomic_ops_lock);	\
109} while (0)
110
111#define atomic_ops_unlock(flags) do {		\
112	arch_spin_unlock(&smp_atomic_ops_lock);	\
113	local_irq_restore(flags);		\
114} while (0)
115
116#define bitops_lock(flags)	do {		\
117	local_irq_save(flags);			\
118	arch_spin_lock(&smp_bitops_lock);	\
119} while (0)
120
121#define bitops_unlock(flags) do {		\
122	arch_spin_unlock(&smp_bitops_lock);	\
123	local_irq_restore(flags);		\
124} while (0)
125
126#else /* !CONFIG_SMP */
127
128#define atomic_ops_lock(flags)		local_irq_save(flags)
129#define atomic_ops_unlock(flags)	local_irq_restore(flags)
130
131#define bitops_lock(flags)		local_irq_save(flags)
132#define bitops_unlock(flags)		local_irq_restore(flags)
133
134#endif /* !CONFIG_SMP */
135
136#endif	/* !CONFIG_ARC_HAS_LLSC */
137
138#endif
139