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>
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@ -412,14 +412,16 @@ static enum {
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void play_dead(void)
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{
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unsigned cpu, core;
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unsigned int cpu, core, vpe_id;
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local_irq_disable();
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idle_task_exit();
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cpu = smp_processor_id();
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cpu_death = CPU_DEATH_POWER;
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if (cpu_has_mipsmt) {
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pr_debug("CPU%d going offline\n", cpu);
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if (cpu_has_mipsmt || cpu_has_vp) {
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core = cpu_data[cpu].core;
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/* Look for another online VPE within the core */
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@ -440,10 +442,21 @@ void play_dead(void)
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complete(&cpu_death_chosen);
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if (cpu_death == CPU_DEATH_HALT) {
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/* Halt this TC */
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write_c0_tchalt(TCHALT_H);
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instruction_hazard();
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vpe_id = cpu_vpe_id(&cpu_data[cpu]);
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pr_debug("Halting core %d VP%d\n", core, vpe_id);
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if (cpu_has_mipsmt) {
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/* Halt this TC */
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write_c0_tchalt(TCHALT_H);
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instruction_hazard();
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} else if (cpu_has_vp) {
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write_cpc_cl_vp_stop(1 << vpe_id);
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/* Ensure that the VP_STOP register is written */
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wmb();
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}
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} else {
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pr_debug("Gating power to core %d\n", core);
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/* Power down the core */
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cps_pm_enter_state(CPS_PM_POWER_GATED);
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}
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@ -470,6 +483,7 @@ static void wait_for_sibling_halt(void *ptr_cpu)
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static void cps_cpu_die(unsigned int cpu)
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{
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unsigned core = cpu_data[cpu].core;
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unsigned int vpe_id = cpu_vpe_id(&cpu_data[cpu]);
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unsigned stat;
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int err;
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@ -498,10 +512,12 @@ static void cps_cpu_die(unsigned int cpu)
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* in which case the CPC will refuse to power down the core.
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*/
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do {
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mips_cm_lock_other(core, vpe_id);
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mips_cpc_lock_other(core);
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stat = read_cpc_co_stat_conf();
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stat &= CPC_Cx_STAT_CONF_SEQSTATE_MSK;
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mips_cpc_unlock_other();
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mips_cm_unlock_other();
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} while (stat != CPC_Cx_STAT_CONF_SEQSTATE_D0 &&
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stat != CPC_Cx_STAT_CONF_SEQSTATE_D2 &&
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stat != CPC_Cx_STAT_CONF_SEQSTATE_U2);
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@ -518,6 +534,12 @@ static void cps_cpu_die(unsigned int cpu)
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(void *)(unsigned long)cpu, 1);
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if (err)
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panic("Failed to call remote sibling CPU\n");
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} else if (cpu_has_vp) {
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do {
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mips_cm_lock_other(core, vpe_id);
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stat = read_cpc_co_vp_running();
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mips_cm_unlock_other();
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} while (stat & (1 << vpe_id));
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}
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}
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