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Commit 0d2808f3 authored by Matt Redfearn's avatar Matt Redfearn Committed by Ralf Baechle
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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: default avatarMatt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: default avatarPaul 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent 9736c615

arch/mips/kernel/smp-cps.c

+27 −5
Original line number Diff line number Diff line
@@ -412,14 +412,16 @@ static enum { 


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 @@ void play_dead(void) 
	complete(&cpu_death_chosen);



	if (cpu_death == CPU_DEATH_HALT) {

		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 wait_for_sibling_halt(void *ptr_cpu) 
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 @@ static void cps_cpu_die(unsigned int cpu) 
		 * 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 @@ static void cps_cpu_die(unsigned int cpu) 
					       (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));

	}

}