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 extern void arc_platform_smp_wait_to_boot(int);
33 extern void start_kernel_secondary(void);
34
35 /*
36 * API expected BY platform smp code (FROM arch smp code)
37 *
38 * smp_ipi_irq_setup:
39 * Takes @cpu and @hwirq to which the arch-common ISR is hooked up
40 */
41 extern int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq);
42
43 /*
44 * struct plat_smp_ops - SMP callbacks provided by platform to ARC SMP
45 *
46 * @info: SoC SMP specific info for /proc/cpuinfo etc
47 * @init_early_smp: A SMP specific h/w block can init itself
48 * Could be common across platforms so not covered by
49 * mach_desc->init_early()
50 * @init_per_cpu: Called for each core so SMP h/w block driver can do
51 * any needed setup per cpu (e.g. IPI request)
52 * @cpu_kick: For Master to kickstart a cpu (optionally at a PC)
53 * @ipi_send: To send IPI to a @cpu
54 * @ips_clear: To clear IPI received at @irq
55 */
56 struct plat_smp_ops {
57 const char *info;
58 void (*init_early_smp)(void);
59 void (*init_per_cpu)(int cpu);
60 void (*cpu_kick)(int cpu, unsigned long pc);
61 void (*ipi_send)(int cpu);
62 void (*ipi_clear)(int irq);
63 };
64
65 /* TBD: stop exporting it for direct population by platform */
66 extern struct plat_smp_ops plat_smp_ops;
67
68 #else /* CONFIG_SMP */
69
70 static inline void smp_init_cpus(void) {}
71 static inline const char *arc_platform_smp_cpuinfo(void)
72 {
73 return "";
74 }
75
76 #endif /* !CONFIG_SMP */
77
78 /*
79 * ARC700 doesn't support atomic Read-Modify-Write ops.
80 * Originally Interrupts had to be disabled around code to guarantee atomicity.
81 * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
82 * based on retry-if-irq-in-atomic (with hardware assist).
83 * However despite these, we provide the IRQ disabling variant
84 *
85 * (1) These insn were introduced only in 4.10 release. So for older released
86 * support needed.
87 *
88 * (2) In a SMP setup, the LLOCK/SCOND atomicity across CPUs needs to be
89 * guaranteed by the platform (not something which core handles).
90 * Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
91 * disabling for atomicity.
92 *
93 * However exported spinlock API is not usable due to cyclic hdr deps
94 * (even after system.h disintegration upstream)
95 * asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
96 * -> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
97 *
98 * So the workaround is to use the lowest level arch spinlock API.
99 * The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
100 * but same is not true for ARCH backend, hence the need for 2 variants
101 */
102 #ifndef CONFIG_ARC_HAS_LLSC
103
104 #include <linux/irqflags.h>
105 #ifdef CONFIG_SMP
106
107 #include <asm/spinlock.h>
108
109 extern arch_spinlock_t smp_atomic_ops_lock;
110
111 #define atomic_ops_lock(flags) do { \
112 local_irq_save(flags); \
113 arch_spin_lock(&smp_atomic_ops_lock); \
114 } while (0)
115
116 #define atomic_ops_unlock(flags) do { \
117 arch_spin_unlock(&smp_atomic_ops_lock); \
118 local_irq_restore(flags); \
119 } while (0)
120
121 #else /* !CONFIG_SMP */
122
123 #define atomic_ops_lock(flags) local_irq_save(flags)
124 #define atomic_ops_unlock(flags) local_irq_restore(flags)
125
126 #endif /* !CONFIG_SMP */
127
128 #endif /* !CONFIG_ARC_HAS_LLSC */
129
130 #endif
131
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.