xref: /openbmc/linux/arch/arc/include/asm/smp.h (revision 12eb4683)
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 */
21 struct cpumask;
22 
23 /*
24  * APIs provided by arch SMP code to generic code
25  */
26 extern void arch_send_call_function_single_ipi(int cpu);
27 extern 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  */
32 extern void __init smp_init_cpus(void);
33 extern void first_lines_of_secondary(void);
34 extern 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  */
42 extern 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 @cpumask
50  * @ips_clear:		To clear IPI received by @cpu at @irq
51  */
52 struct plat_smp_ops {
53 	const char 	*info;
54 	void		(*cpu_kick)(int cpu, unsigned long pc);
55 	void		(*ipi_send)(void *callmap);
56 	void		(*ipi_clear)(int cpu, int irq);
57 };
58 
59 /* TBD: stop exporting it for direct population by platform */
60 extern struct plat_smp_ops  plat_smp_ops;
61 
62 #endif  /* CONFIG_SMP */
63 
64 /*
65  * ARC700 doesn't support atomic Read-Modify-Write ops.
66  * Originally Interrupts had to be disabled around code to gaurantee atomicity.
67  * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
68  * based on retry-if-irq-in-atomic (with hardware assist).
69  * However despite these, we provide the IRQ disabling variant
70  *
71  * (1) These insn were introduced only in 4.10 release. So for older released
72  *	support needed.
73  *
74  * (2) In a SMP setup, the LLOCK/SCOND atomiticity across CPUs needs to be
75  *	gaurantted by the platform (not something which core handles).
76  *	Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
77  *	disabling for atomicity.
78  *
79  *	However exported spinlock API is not usable due to cyclic hdr deps
80  *	(even after system.h disintegration upstream)
81  *	asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
82  *		-> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
83  *
84  *	So the workaround is to use the lowest level arch spinlock API.
85  *	The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
86  *	but same is not true for ARCH backend, hence the need for 2 variants
87  */
88 #ifndef CONFIG_ARC_HAS_LLSC
89 
90 #include <linux/irqflags.h>
91 #ifdef CONFIG_SMP
92 
93 #include <asm/spinlock.h>
94 
95 extern arch_spinlock_t smp_atomic_ops_lock;
96 extern arch_spinlock_t smp_bitops_lock;
97 
98 #define atomic_ops_lock(flags)	do {		\
99 	local_irq_save(flags);			\
100 	arch_spin_lock(&smp_atomic_ops_lock);	\
101 } while (0)
102 
103 #define atomic_ops_unlock(flags) do {		\
104 	arch_spin_unlock(&smp_atomic_ops_lock);	\
105 	local_irq_restore(flags);		\
106 } while (0)
107 
108 #define bitops_lock(flags)	do {		\
109 	local_irq_save(flags);			\
110 	arch_spin_lock(&smp_bitops_lock);	\
111 } while (0)
112 
113 #define bitops_unlock(flags) do {		\
114 	arch_spin_unlock(&smp_bitops_lock);	\
115 	local_irq_restore(flags);		\
116 } while (0)
117 
118 #else /* !CONFIG_SMP */
119 
120 #define atomic_ops_lock(flags)		local_irq_save(flags)
121 #define atomic_ops_unlock(flags)	local_irq_restore(flags)
122 
123 #define bitops_lock(flags)		local_irq_save(flags)
124 #define bitops_unlock(flags)		local_irq_restore(flags)
125 
126 #endif /* !CONFIG_SMP */
127 
128 #endif	/* !CONFIG_ARC_HAS_LLSC */
129 
130 #endif
131