1 files changed, 127 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/pSeries_setup.c b/arch/ppc64/kernel/pSeries_setup.c
index 44d9af72d225..849ed9ba7856 100644
--- a/arch/ppc64/kernel/pSeries_setup.c
+++ b/arch/ppc64/kernel/pSeries_setup.c
@@ -418,6 +418,133 @@ static int __init pSeries_probe(int platform)
         return 1;
 }
 
+DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
+
+int dedicated_idle(void)
+{
+        long oldval;
+        struct paca_struct *lpaca = get_paca(), *ppaca;
+        unsigned long start_snooze;
+        unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
+        unsigned int cpu = smp_processor_id();
+
+        ppaca = &paca[cpu ^ 1];
+
+        while (1) {
+                /*
+                 * Indicate to the HV that we are idle. Now would be
+                 * a good time to find other work to dispatch.
+                 */
+                lpaca->lppaca.idle = 1;
+
+                oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+                if (!oldval) {
+                        set_thread_flag(TIF_POLLING_NRFLAG);
+                        start_snooze = __get_tb() +
+                                *smt_snooze_delay * tb_ticks_per_usec;
+                        while (!need_resched() && !cpu_is_offline(cpu)) {
+                                /*
+                                 * Go into low thread priority and possibly
+                                 * low power mode.
+                                 */
+                                HMT_low();
+                                HMT_very_low();
+
+                                if (*smt_snooze_delay == 0 ||
+                                    __get_tb() < start_snooze)
+                                        continue;
+
+                                HMT_medium();
+
+                                if (!(ppaca->lppaca.idle)) {
+                                        local_irq_disable();
+
+                                        /*
+                                         * We are about to sleep the thread
+                                         * and so wont be polling any
+                                         * more.
+                                         */
+                                        clear_thread_flag(TIF_POLLING_NRFLAG);
+
+                                        /*
+                                         * SMT dynamic mode. Cede will result
+                                         * in this thread going dormant, if the
+                                         * partner thread is still doing work.
+                                         * Thread wakes up if partner goes idle,
+                                         * an interrupt is presented, or a prod
+                                         * occurs.  Returning from the cede
+                                         * enables external interrupts.
+                                         */
+                                        if (!need_resched())
+                                                cede_processor();
+                                        else
+                                                local_irq_enable();
+                                } else {
+                                        /*
+                                         * Give the HV an opportunity at the
+                                         * processor, since we are not doing
+                                         * any work.
+                                         */
+                                        poll_pending();
+                                }
+                        }
+
+                        clear_thread_flag(TIF_POLLING_NRFLAG);
+                } else {
+                        set_need_resched();
+                }
+
+                HMT_medium();
+                lpaca->lppaca.idle = 0;
+                schedule();
+                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+                        cpu_die();
+        }
+        return 0;
+}
+
+static int shared_idle(void)
+{
+        struct paca_struct *lpaca = get_paca();
+        unsigned int cpu = smp_processor_id();
+
+        while (1) {
+                /*
+                 * Indicate to the HV that we are idle. Now would be
+                 * a good time to find other work to dispatch.
+                 */
+                lpaca->lppaca.idle = 1;
+
+                while (!need_resched() && !cpu_is_offline(cpu)) {
+                        local_irq_disable();
+
+                        /*
+                         * Yield the processor to the hypervisor.  We return if
+                         * an external interrupt occurs (which are driven prior
+                         * to returning here) or if a prod occurs from another
+                         * processor. When returning here, external interrupts
+                         * are enabled.
+                         *
+                         * Check need_resched() again with interrupts disabled
+                         * to avoid a race.
+                         */
+                        if (!need_resched())
+                                cede_processor();
+                        else
+                                local_irq_enable();
+                }
+
+                HMT_medium();
+                lpaca->lppaca.idle = 0;
+                schedule();
+                if (cpu_is_offline(smp_processor_id()) &&
+                    system_state == SYSTEM_RUNNING)
+                        cpu_die();
+        }
+
+        return 0;
+}
+
 struct machdep_calls __initdata pSeries_md = {
         .probe                  = pSeries_probe,
         .setup_arch             = pSeries_setup_arch,