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 * @init_early_smp: A SMP specific h/w block can init itself
49 * Could be common across platforms so not covered by
50 * mach_desc->init_early()
51 * @init_per_cpu: Called for each core so SMP h/w block driver can do
52 * any needed setup per cpu (e.g. IPI request)
53 * @cpu_kick: For Master to kickstart a cpu (optionally at a PC)
54 * @ipi_send: To send IPI to a @cpu
55 * @ips_clear: To clear IPI received at @irq
56 */
57 struct plat_smp_ops {
58 const char *info;
59 void (*init_early_smp)(void);
60 void (*init_per_cpu)(int cpu);
61 void (*cpu_kick)(int cpu, unsigned long pc);
62 void (*ipi_send)(int cpu);
63 void (*ipi_clear)(int irq);
64 };
65
66 /* TBD: stop exporting it for direct population by platform */
67 extern struct plat_smp_ops plat_smp_ops;
68
69 #else /* CONFIG_SMP */
70
smp_init_cpus(void)71 static inline void smp_init_cpus(void) {}
arc_platform_smp_cpuinfo(void)72 static inline const char *arc_platform_smp_cpuinfo(void)
73 {
74 return "";
75 }
76
77 #endif /* !CONFIG_SMP */
78
79 /*
80 * ARC700 doesn't support atomic Read-Modify-Write ops.
81 * Originally Interrupts had to be disabled around code to gaurantee atomicity.
82 * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
83 * based on retry-if-irq-in-atomic (with hardware assist).
84 * However despite these, we provide the IRQ disabling variant
85 *
86 * (1) These insn were introduced only in 4.10 release. So for older released
87 * support needed.
88 *
89 * (2) In a SMP setup, the LLOCK/SCOND atomiticity across CPUs needs to be
90 * gaurantted by the platform (not something which core handles).
91 * Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
92 * disabling for atomicity.
93 *
94 * However exported spinlock API is not usable due to cyclic hdr deps
95 * (even after system.h disintegration upstream)
96 * asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
97 * -> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
98 *
99 * So the workaround is to use the lowest level arch spinlock API.
100 * The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
101 * but same is not true for ARCH backend, hence the need for 2 variants
102 */
103 #ifndef CONFIG_ARC_HAS_LLSC
104
105 #include <linux/irqflags.h>
106 #ifdef CONFIG_SMP
107
108 #include <asm/spinlock.h>
109
110 extern arch_spinlock_t smp_atomic_ops_lock;
111 extern arch_spinlock_t smp_bitops_lock;
112
113 #define atomic_ops_lock(flags) do { \
114 local_irq_save(flags); \
115 arch_spin_lock(&smp_atomic_ops_lock); \
116 } while (0)
117
118 #define atomic_ops_unlock(flags) do { \
119 arch_spin_unlock(&smp_atomic_ops_lock); \
120 local_irq_restore(flags); \
121 } while (0)
122
123 #define bitops_lock(flags) do { \
124 local_irq_save(flags); \
125 arch_spin_lock(&smp_bitops_lock); \
126 } while (0)
127
128 #define bitops_unlock(flags) do { \
129 arch_spin_unlock(&smp_bitops_lock); \
130 local_irq_restore(flags); \
131 } while (0)
132
133 #else /* !CONFIG_SMP */
134
135 #define atomic_ops_lock(flags) local_irq_save(flags)
136 #define atomic_ops_unlock(flags) local_irq_restore(flags)
137
138 #define bitops_lock(flags) local_irq_save(flags)
139 #define bitops_unlock(flags) local_irq_restore(flags)
140
141 #endif /* !CONFIG_SMP */
142
143 #endif /* !CONFIG_ARC_HAS_LLSC */
144
145 #endif
146