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/*
* Spin Table SMP initialisation
*
* Copyright (C) 2013 ARM Ltd.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>
#include <asm/cputype.h>
#include <asm/smp_plat.h>
extern void secondary_holding_pen(void);
volatile unsigned long secondary_holding_pen_release = INVALID_HWID;
static phys_addr_t cpu_release_addr[NR_CPUS];
static DEFINE_RAW_SPINLOCK(boot_lock);
/*
* Write secondary_holding_pen_release in a way that is guaranteed to be
* visible to all observers, irrespective of whether they're taking part
* in coherency or not. This is necessary for the hotplug code to work
* reliably.
*/
static void write_pen_release(u64 val)
{
void *start = (void *)&secondary_holding_pen_release;
unsigned long size = sizeof(secondary_holding_pen_release);
secondary_holding_pen_release = val;
__flush_dcache_area(start, size);
}
static int smp_spin_table_cpu_init(struct device_node *dn, unsigned int cpu)
{
/*
* Determine the address from which the CPU is polling.
*/
if (of_property_read_u64(dn, "cpu-release-addr",
&cpu_release_addr[cpu])) {
pr_err("CPU %d: missing or invalid cpu-release-addr property\n",
cpu);
return -1;
}
return 0;
}
static int smp_spin_table_cpu_prepare(unsigned int cpu)
{
void **release_addr;
if (!cpu_release_addr[cpu])
return -ENODEV;
release_addr = __va(cpu_release_addr[cpu]);
/*
* We write the release address as LE regardless of the native
* endianess of the kernel. Therefore, any boot-loaders that
* read this address need to convert this address to the
* boot-loader's endianess before jumping. This is mandated by
* the boot protocol.
*/
release_addr[0] = (void *) cpu_to_le64(__pa(secondary_holding_pen));
__flush_dcache_area(release_addr, sizeof(release_addr[0]));
/*
* Send an event to wake up the secondary CPU.
*/
sev();
return 0;
}
static int smp_spin_table_cpu_boot(unsigned int cpu)
{
unsigned long timeout;
/*
* Set synchronisation state between this boot processor
* and the secondary one
*/
raw_spin_lock(&boot_lock);
/*
* Update the pen release flag.
*/
write_pen_release(cpu_logical_map(cpu));
/*
* Send an event, causing the secondaries to read pen_release.
*/
sev();
timeout = jiffies + (1 * HZ);
while (time_before(jiffies, timeout)) {
if (secondary_holding_pen_release == INVALID_HWID)
break;
udelay(10);
}
/*
* Now the secondary core is starting up let it run its
* calibrations, then wait for it to finish
*/
raw_spin_unlock(&boot_lock);
return secondary_holding_pen_release != INVALID_HWID ? -ENOSYS : 0;
}
static void smp_spin_table_cpu_postboot(void)
{
/*
* Let the primary processor know we're out of the pen.
*/
write_pen_release(INVALID_HWID);
/*
* Synchronise with the boot thread.
*/
raw_spin_lock(&boot_lock);
raw_spin_unlock(&boot_lock);
}
const struct cpu_operations smp_spin_table_ops = {
.name = "spin-table",
.cpu_init = smp_spin_table_cpu_init,
.cpu_prepare = smp_spin_table_cpu_prepare,
.cpu_boot = smp_spin_table_cpu_boot,
.cpu_postboot = smp_spin_table_cpu_postboot,
};
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