1 /*
2 * Author: Kumar Gala <galak@kernel.crashing.org>
3 *
4 * Copyright 2009 Freescale Semiconductor Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2 of the License, or (at your
9 * option) any later version.
10 */
11
12 #include <linux/stddef.h>
13 #include <linux/kernel.h>
14 #include <linux/smp.h>
15 #include <linux/threads.h>
16 #include <linux/hardirq.h>
17
18 #include <asm/dbell.h>
19 #include <asm/irq_regs.h>
20 #include <asm/kvm_ppc.h>
21
22 #ifdef CONFIG_SMP
23
24 /*
25 * Doorbells must only be used if CPU_FTR_DBELL is available.
26 * msgsnd is used in HV, and msgsndp is used in !HV.
27 *
28 * These should be used by platform code that is aware of restrictions.
29 * Other arch code should use ->cause_ipi.
30 *
31 * doorbell_global_ipi() sends a dbell to any target CPU.
32 * Must be used only by architectures that address msgsnd target
33 * by PIR/get_hard_smp_processor_id.
34 */
doorbell_global_ipi(int cpu)35 void doorbell_global_ipi(int cpu)
36 {
37 u32 tag = get_hard_smp_processor_id(cpu);
38
39 kvmppc_set_host_ipi(cpu, 1);
40 /* Order previous accesses vs. msgsnd, which is treated as a store */
41 ppc_msgsnd_sync();
42 ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
43 }
44
45 /*
46 * doorbell_core_ipi() sends a dbell to a target CPU in the same core.
47 * Must be used only by architectures that address msgsnd target
48 * by TIR/cpu_thread_in_core.
49 */
doorbell_core_ipi(int cpu)50 void doorbell_core_ipi(int cpu)
51 {
52 u32 tag = cpu_thread_in_core(cpu);
53
54 kvmppc_set_host_ipi(cpu, 1);
55 /* Order previous accesses vs. msgsnd, which is treated as a store */
56 ppc_msgsnd_sync();
57 ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
58 }
59
60 /*
61 * Attempt to cause a core doorbell if destination is on the same core.
62 * Returns 1 on success, 0 on failure.
63 */
doorbell_try_core_ipi(int cpu)64 int doorbell_try_core_ipi(int cpu)
65 {
66 int this_cpu = get_cpu();
67 int ret = 0;
68
69 if (cpumask_test_cpu(cpu, cpu_sibling_mask(this_cpu))) {
70 doorbell_core_ipi(cpu);
71 ret = 1;
72 }
73
74 put_cpu();
75
76 return ret;
77 }
78
doorbell_exception(struct pt_regs * regs)79 void doorbell_exception(struct pt_regs *regs)
80 {
81 struct pt_regs *old_regs = set_irq_regs(regs);
82
83 irq_enter();
84
85 ppc_msgsync();
86
87 may_hard_irq_enable();
88
89 kvmppc_set_host_ipi(smp_processor_id(), 0);
90 __this_cpu_inc(irq_stat.doorbell_irqs);
91
92 smp_ipi_demux_relaxed(); /* already performed the barrier */
93
94 irq_exit();
95 set_irq_regs(old_regs);
96 }
97 #else /* CONFIG_SMP */
doorbell_exception(struct pt_regs * regs)98 void doorbell_exception(struct pt_regs *regs)
99 {
100 printk(KERN_WARNING "Received doorbell on non-smp system\n");
101 }
102 #endif /* CONFIG_SMP */
103
104
