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
68 static inline void smp_init_cpus(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 extern arch_spinlock_t smp_bitops_lock;
109
110 #define atomic_ops_lock(flags) do { \
111 local_irq_save(flags); \
112 arch_spin_lock(&smp_atomic_ops_lock); \
113 } while (0)
114
115 #define atomic_ops_unlock(flags) do { \
116 arch_spin_unlock(&smp_atomic_ops_lock); \
117 local_irq_restore(flags); \
118 } while (0)
119
120 #define bitops_lock(flags) do { \
121 local_irq_save(flags); \
122 arch_spin_lock(&smp_bitops_lock); \
123 } while (0)
124
125 #define bitops_unlock(flags) do { \
126 arch_spin_unlock(&smp_bitops_lock); \
127 local_irq_restore(flags); \
128 } while (0)
129
130 #else /* !CONFIG_SMP */
131
132 #define atomic_ops_lock(flags) local_irq_save(flags)
133 #define atomic_ops_unlock(flags) local_irq_restore(flags)
134
135 #define bitops_lock(flags) local_irq_save(flags)
136 #define bitops_unlock(flags) local_irq_restore(flags)
137
138 #endif /* !CONFIG_SMP */
139
140 #endif /* !CONFIG_ARC_HAS_LLSC */
141
142 #endif