original development tree for Linux kernel GTP module; now long in mainline.
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linux-gtp/arch/arm/mach-spear13xx/hotplug.c

119 lines
2.3 KiB

/*
* linux/arch/arm/mach-spear13xx/hotplug.c
*
* Copyright (C) 2012 ST Microelectronics Ltd.
* Deepak Sikri <deepak.sikri@st.com>
*
* based upon linux/arch/arm/mach-realview/hotplug.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/smp_plat.h>
extern volatile int pen_release;
static inline void cpu_enter_lowpower(void)
{
unsigned int v;
flush_cache_all();
asm volatile(
" mcr p15, 0, %1, c7, c5, 0\n"
" dsb\n"
/*
* Turn off coherency
*/
" mrc p15, 0, %0, c1, c0, 1\n"
" bic %0, %0, #0x20\n"
" mcr p15, 0, %0, c1, c0, 1\n"
" mrc p15, 0, %0, c1, c0, 0\n"
" bic %0, %0, %2\n"
" mcr p15, 0, %0, c1, c0, 0\n"
: "=&r" (v)
: "r" (0), "Ir" (CR_C)
: "cc", "memory");
}
static inline void cpu_leave_lowpower(void)
{
unsigned int v;
asm volatile("mrc p15, 0, %0, c1, c0, 0\n"
" orr %0, %0, %1\n"
" mcr p15, 0, %0, c1, c0, 0\n"
" mrc p15, 0, %0, c1, c0, 1\n"
" orr %0, %0, #0x20\n"
" mcr p15, 0, %0, c1, c0, 1\n"
: "=&r" (v)
: "Ir" (CR_C)
: "cc");
}
static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
{
for (;;) {
wfi();
if (pen_release == cpu) {
/*
* OK, proper wakeup, we're done
*/
break;
}
/*
* Getting here, means that we have come out of WFI without
* having been woken up - this shouldn't happen
*
* Just note it happening - when we're woken, we can report
* its occurrence.
*/
(*spurious)++;
}
}
int platform_cpu_kill(unsigned int cpu)
{
return 1;
}
/*
* platform-specific code to shutdown a CPU
*
* Called with IRQs disabled
*/
void __cpuinit platform_cpu_die(unsigned int cpu)
{
int spurious = 0;
/*
* we're ready for shutdown now, so do it
*/
cpu_enter_lowpower();
platform_do_lowpower(cpu, &spurious);
/*
* bring this CPU back into the world of cache
* coherency, and then restore interrupts
*/
cpu_leave_lowpower();
if (spurious)
pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
}
int platform_cpu_disable(unsigned int cpu)
{
/*
* we don't allow CPU 0 to be shutdown (it is still too special
* e.g. clock tick interrupts)
*/
return cpu == 0 ? -EPERM : 0;
}