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0462b447 RK |
1 | /* |
2 | * linux/arch/arm/plat-versatile/platsmp.c | |
3 | * | |
4 | * Copyright (C) 2002 ARM Ltd. | |
5 | * All Rights Reserved | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | #include <linux/init.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/delay.h> | |
14 | #include <linux/device.h> | |
15 | #include <linux/jiffies.h> | |
16 | #include <linux/smp.h> | |
17 | ||
18 | #include <asm/cacheflush.h> | |
0f7b332f | 19 | #include <asm/hardware/gic.h> |
0462b447 RK |
20 | |
21 | /* | |
22 | * control for which core is the next to come out of the secondary | |
23 | * boot "holding pen" | |
24 | */ | |
25 | volatile int __cpuinitdata pen_release = -1; | |
26 | ||
27 | /* | |
28 | * Write pen_release in a way that is guaranteed to be visible to all | |
29 | * observers, irrespective of whether they're taking part in coherency | |
30 | * or not. This is necessary for the hotplug code to work reliably. | |
31 | */ | |
32 | static void __cpuinit write_pen_release(int val) | |
33 | { | |
34 | pen_release = val; | |
35 | smp_wmb(); | |
36 | __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release)); | |
37 | outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1)); | |
38 | } | |
39 | ||
40 | static DEFINE_SPINLOCK(boot_lock); | |
41 | ||
42 | void __cpuinit platform_secondary_init(unsigned int cpu) | |
43 | { | |
44 | /* | |
45 | * if any interrupts are already enabled for the primary | |
46 | * core (e.g. timer irq), then they will not have been enabled | |
47 | * for us: do so | |
48 | */ | |
49 | gic_secondary_init(0); | |
50 | ||
51 | /* | |
52 | * let the primary processor know we're out of the | |
53 | * pen, then head off into the C entry point | |
54 | */ | |
55 | write_pen_release(-1); | |
56 | ||
57 | /* | |
58 | * Synchronise with the boot thread. | |
59 | */ | |
60 | spin_lock(&boot_lock); | |
61 | spin_unlock(&boot_lock); | |
62 | } | |
63 | ||
64 | int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle) | |
65 | { | |
66 | unsigned long timeout; | |
67 | ||
68 | /* | |
69 | * Set synchronisation state between this boot processor | |
70 | * and the secondary one | |
71 | */ | |
72 | spin_lock(&boot_lock); | |
73 | ||
74 | /* | |
75 | * This is really belt and braces; we hold unintended secondary | |
76 | * CPUs in the holding pen until we're ready for them. However, | |
77 | * since we haven't sent them a soft interrupt, they shouldn't | |
78 | * be there. | |
79 | */ | |
80 | write_pen_release(cpu); | |
81 | ||
82 | /* | |
83 | * Send the secondary CPU a soft interrupt, thereby causing | |
84 | * the boot monitor to read the system wide flags register, | |
85 | * and branch to the address found there. | |
86 | */ | |
0f7b332f | 87 | gic_raise_softirq(cpumask_of(cpu), 1); |
0462b447 RK |
88 | |
89 | timeout = jiffies + (1 * HZ); | |
90 | while (time_before(jiffies, timeout)) { | |
91 | smp_rmb(); | |
92 | if (pen_release == -1) | |
93 | break; | |
94 | ||
95 | udelay(10); | |
96 | } | |
97 | ||
98 | /* | |
99 | * now the secondary core is starting up let it run its | |
100 | * calibrations, then wait for it to finish | |
101 | */ | |
102 | spin_unlock(&boot_lock); | |
103 | ||
104 | return pen_release != -1 ? -ENOSYS : 0; | |
105 | } |