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ARC: smp: Move default boot kick/wait code out of MCIP into common code 

For non halt-on-reset case, all cores start of simultaneously in @stext.
Master core0 proceeds with kernel boot, while other spin-wait on
@wake_flag being set by master once it is ready. So NO hardware assist
is needed for master to "kick" the others.

This patch moves this soft implementation out of mcip.c (as there is no
hardware assist) into common smp.c

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
hifive-unleashed-5.1
Vineet Gupta 2015-10-09 12:16:02 +05:30
parent d0890ea5b6
commit f33e9c434b
2 changed files with 21 additions and 43 deletions
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18
arch/arc/kernel/mcip.c
View File

@ -97,26 +97,8 @@ static void mcip_ipi_clear(int irq)
#endif
}
volatile int wake_flag;
static void mcip_wakeup_cpu(int cpu, unsigned long pc)
{
BUG_ON(cpu == 0);
wake_flag = cpu;
}
void arc_platform_smp_wait_to_boot(int cpu)
{
while (wake_flag != cpu)
;
wake_flag = 0;
__asm__ __volatile__("j @first_lines_of_secondary \n");
}
struct plat_smp_ops plat_smp_ops = {
.info = smp_cpuinfo_buf,
.cpu_kick = mcip_wakeup_cpu,
.ipi_send = mcip_ipi_send,
.ipi_clear = mcip_ipi_clear,
};

46
arch/arc/kernel/smp.c
View File

@ -72,35 +72,29 @@ void __init smp_cpus_done(unsigned int max_cpus)
}
/*
* After power-up, a non Master CPU needs to wait for Master to kick start it
*
* The default implementation halts
*
* This relies on platform specific support allowing Master to directly set
* this CPU's PC (to be @first_lines_of_secondary() and kick start it.
*
* In lack of such h/w assist, platforms can override this function
* - make this function busy-spin on a token, eventually set by Master
* (from arc_platform_smp_wakeup_cpu())
* - Once token is available, jump to @first_lines_of_secondary
* (using inline asm).
*
* Alert: can NOT use stack here as it has not been determined/setup for CPU.
* If it turns out to be elaborate, it's better to code it in assembly
*
* Default smp boot helper for Run-on-reset case where all cores start off
* together. Non-masters need to wait for Master to start running.
* This is implemented using a flag in memory, which Non-masters spin-wait on.
* Master sets it to cpu-id of core to "ungate" it.
*/
void __weak arc_platform_smp_wait_to_boot(int cpu)
static volatile int wake_flag;
static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
{
/*
* As a hack for debugging - since debugger will single-step over the
* FLAG insn - wrap the halt itself it in a self loop
*/
__asm__ __volatile__(
"1: \n"
" flag 1 \n"
" b 1b \n");
BUG_ON(cpu == 0);
wake_flag = cpu;
}
void arc_platform_smp_wait_to_boot(int cpu)
{
while (wake_flag != cpu)
;
wake_flag = 0;
__asm__ __volatile__("j @first_lines_of_secondary \n");
}
const char *arc_platform_smp_cpuinfo(void)
{
return plat_smp_ops.info ? : "";
@ -161,6 +155,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
if (plat_smp_ops.cpu_kick)
plat_smp_ops.cpu_kick(cpu,
(unsigned long)first_lines_of_secondary);
else
arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
/* wait for 1 sec after kicking the secondary */
wait_till = jiffies + HZ;