1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4  */
5 
6 #ifndef __ASM_ARC_SMP_H
7 #define __ASM_ARC_SMP_H
8 
9 #ifdef CONFIG_SMP
10 
11 #include <linux/types.h>
12 #include <linux/init.h>
13 #include <linux/threads.h>
14 
15 #define raw_smp_processor_id() (current_thread_info()->cpu)
16 
17 /* including cpumask.h leads to cyclic deps hence this Forward declaration */
18 struct cpumask;
19 
20 /*
21  * APIs provided by arch SMP code to generic code
22  */
23 extern void arch_send_call_function_single_ipi(int cpu);
24 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
25 
26 /*
27  * APIs provided by arch SMP code to rest of arch code
28  */
29 extern void __init smp_init_cpus(void);
30 extern void first_lines_of_secondary(void);
31 extern const char *arc_platform_smp_cpuinfo(void);
32 
33 /*
34  * API expected BY platform smp code (FROM arch smp code)
35  *
36  * smp_ipi_irq_setup:
37  *	Takes @cpu and @hwirq to which the arch-common ISR is hooked up
38  */
39 extern int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq);
40 
41 /*
42  * struct plat_smp_ops	- SMP callbacks provided by platform to ARC SMP
43  *
44  * @info:		SoC SMP specific info for /proc/cpuinfo etc
45  * @init_early_smp:	A SMP specific h/w block can init itself
46  * 			Could be common across platforms so not covered by
47  * 			mach_desc->init_early()
48  * @init_per_cpu:	Called for each core so SMP h/w block driver can do
49  * 			any needed setup per cpu (e.g. IPI request)
50  * @cpu_kick:		For Master to kickstart a cpu (optionally at a PC)
51  * @ipi_send:		To send IPI to a @cpu
52  * @ips_clear:		To clear IPI received at @irq
53  */
54 struct plat_smp_ops {
55 	const char 	*info;
56 	void		(*init_early_smp)(void);
57 	void		(*init_per_cpu)(int cpu);
58 	void		(*cpu_kick)(int cpu, unsigned long pc);
59 	void		(*ipi_send)(int cpu);
60 	void		(*ipi_clear)(int irq);
61 };
62 
63 /* TBD: stop exporting it for direct population by platform */
64 extern struct plat_smp_ops  plat_smp_ops;
65 
66 #else /* CONFIG_SMP */
67 
smp_init_cpus(void)68 static inline void smp_init_cpus(void) {}
arc_platform_smp_cpuinfo(void)69 static inline const char *arc_platform_smp_cpuinfo(void)
70 {
71 	return "";
72 }
73 
74 #endif  /* !CONFIG_SMP */
75 
76 /*
77  * ARC700 doesn't support atomic Read-Modify-Write ops.
78  * Originally Interrupts had to be disabled around code to gaurantee atomicity.
79  * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
80  * based on retry-if-irq-in-atomic (with hardware assist).
81  * However despite these, we provide the IRQ disabling variant
82  *
83  * (1) These insn were introduced only in 4.10 release. So for older released
84  *	support needed.
85  *
86  * (2) In a SMP setup, the LLOCK/SCOND atomicity across CPUs needs to be
87  *	gaurantted by the platform (not something which core handles).
88  *	Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
89  *	disabling for atomicity.
90  *
91  *	However exported spinlock API is not usable due to cyclic hdr deps
92  *	(even after system.h disintegration upstream)
93  *	asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
94  *		-> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
95  *
96  *	So the workaround is to use the lowest level arch spinlock API.
97  *	The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
98  *	but same is not true for ARCH backend, hence the need for 2 variants
99  */
100 #ifndef CONFIG_ARC_HAS_LLSC
101 
102 #include <linux/irqflags.h>
103 #ifdef CONFIG_SMP
104 
105 #include <asm/spinlock.h>
106 
107 extern arch_spinlock_t smp_atomic_ops_lock;
108 
109 #define atomic_ops_lock(flags)	do {		\
110 	local_irq_save(flags);			\
111 	arch_spin_lock(&smp_atomic_ops_lock);	\
112 } while (0)
113 
114 #define atomic_ops_unlock(flags) do {		\
115 	arch_spin_unlock(&smp_atomic_ops_lock);	\
116 	local_irq_restore(flags);		\
117 } while (0)
118 
119 #else /* !CONFIG_SMP */
120 
121 #define atomic_ops_lock(flags)		local_irq_save(flags)
122 #define atomic_ops_unlock(flags)	local_irq_restore(flags)
123 
124 #endif /* !CONFIG_SMP */
125 
126 #endif	/* !CONFIG_ARC_HAS_LLSC */
127 
128 #endif
129