MIPS: smp-cps: Add support for CPU hotplug of MIPSr6 processors
Introduce support for hotplug of Virtual Processors in MIPSr6 systems.
The method is simpler than the VPE parallel from the now-deprecated MT
ASE, it can now simply write the VP_STOP register with the mask of VPs
to halt, and use the VP_RUNNING register to determine when the VP has
halted.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13752/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index 006e99d..234e7e7 100644
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -412,14 +412,16 @@
void play_dead(void)
{
- unsigned cpu, core;
+ unsigned int cpu, core, vpe_id;
local_irq_disable();
idle_task_exit();
cpu = smp_processor_id();
cpu_death = CPU_DEATH_POWER;
- if (cpu_has_mipsmt) {
+ pr_debug("CPU%d going offline\n", cpu);
+
+ if (cpu_has_mipsmt || cpu_has_vp) {
core = cpu_data[cpu].core;
/* Look for another online VPE within the core */
@@ -440,10 +442,21 @@
complete(&cpu_death_chosen);
if (cpu_death == CPU_DEATH_HALT) {
- /* Halt this TC */
- write_c0_tchalt(TCHALT_H);
- instruction_hazard();
+ vpe_id = cpu_vpe_id(&cpu_data[cpu]);
+
+ pr_debug("Halting core %d VP%d\n", core, vpe_id);
+ if (cpu_has_mipsmt) {
+ /* Halt this TC */
+ write_c0_tchalt(TCHALT_H);
+ instruction_hazard();
+ } else if (cpu_has_vp) {
+ write_cpc_cl_vp_stop(1 << vpe_id);
+
+ /* Ensure that the VP_STOP register is written */
+ wmb();
+ }
} else {
+ pr_debug("Gating power to core %d\n", core);
/* Power down the core */
cps_pm_enter_state(CPS_PM_POWER_GATED);
}
@@ -470,6 +483,7 @@
static void cps_cpu_die(unsigned int cpu)
{
unsigned core = cpu_data[cpu].core;
+ unsigned int vpe_id = cpu_vpe_id(&cpu_data[cpu]);
unsigned stat;
int err;
@@ -498,10 +512,12 @@
* in which case the CPC will refuse to power down the core.
*/
do {
+ mips_cm_lock_other(core, vpe_id);
mips_cpc_lock_other(core);
stat = read_cpc_co_stat_conf();
stat &= CPC_Cx_STAT_CONF_SEQSTATE_MSK;
mips_cpc_unlock_other();
+ mips_cm_unlock_other();
} while (stat != CPC_Cx_STAT_CONF_SEQSTATE_D0 &&
stat != CPC_Cx_STAT_CONF_SEQSTATE_D2 &&
stat != CPC_Cx_STAT_CONF_SEQSTATE_U2);
@@ -518,6 +534,12 @@
(void *)(unsigned long)cpu, 1);
if (err)
panic("Failed to call remote sibling CPU\n");
+ } else if (cpu_has_vp) {
+ do {
+ mips_cm_lock_other(core, vpe_id);
+ stat = read_cpc_co_vp_running();
+ mips_cm_unlock_other();
+ } while (stat & (1 << vpe_id));
}
}