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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - arch/arm/plat-versatile/platsmp.c
2 * linux/arch/arm/plat-versatile/platsmp.c
4 * Copyright (C) 2002 ARM Ltd.
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.
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>
18 #include <asm/cacheflush.h>
19 #include <asm/smp_plat.h>
22 * Write pen_release in a way that is guaranteed to be visible to all
23 * observers, irrespective of whether they're taking part in coherency
24 * or not. This is necessary for the hotplug code to work reliably.
26 static void write_pen_release(int val
)
30 sync_cache_w(&pen_release
);
33 static DEFINE_SPINLOCK(boot_lock
);
35 void versatile_secondary_init(unsigned int cpu
)
38 * let the primary processor know we're out of the
39 * pen, then head off into the C entry point
41 write_pen_release(-1);
44 * Synchronise with the boot thread.
46 spin_lock(&boot_lock
);
47 spin_unlock(&boot_lock
);
50 int versatile_boot_secondary(unsigned int cpu
, struct task_struct
*idle
)
52 unsigned long timeout
;
55 * Set synchronisation state between this boot processor
56 * and the secondary one
58 spin_lock(&boot_lock
);
61 * This is really belt and braces; we hold unintended secondary
62 * CPUs in the holding pen until we're ready for them. However,
63 * since we haven't sent them a soft interrupt, they shouldn't
66 write_pen_release(cpu_logical_map(cpu
));
69 * Send the secondary CPU a soft interrupt, thereby causing
70 * the boot monitor to read the system wide flags register,
71 * and branch to the address found there.
73 arch_send_wakeup_ipi_mask(cpumask_of(cpu
));
75 timeout
= jiffies
+ (1 * HZ
);
76 while (time_before(jiffies
, timeout
)) {
78 if (pen_release
== -1)
85 * now the secondary core is starting up let it run its
86 * calibrations, then wait for it to finish
88 spin_unlock(&boot_lock
);
90 return pen_release
!= -1 ? -ENOSYS
: 0;