1 files changed, 156 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/pSeries_setup.c b/arch/ppc64/kernel/pSeries_setup.c
index 44d9af72d225..5bec956e44a0 100644
--- a/arch/ppc64/kernel/pSeries_setup.c
+++ b/arch/ppc64/kernel/pSeries_setup.c
@@ -19,6 +19,7 @@
 #undef DEBUG
 
 #include <linux/config.h>
+#include <linux/cpu.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
@@ -82,6 +83,9 @@ int fwnmi_active;  /* TRUE if an FWNMI handler is present */
 extern void pSeries_system_reset_exception(struct pt_regs *regs);
 extern int pSeries_machine_check_exception(struct pt_regs *regs);
 
+static int pseries_shared_idle(void);
+static int pseries_dedicated_idle(void);
+
 static volatile void __iomem * chrp_int_ack_special;
 struct mpic *pSeries_mpic;
 
@@ -229,6 +233,20 @@ static void __init pSeries_setup_arch(void)
 
         if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR)
                 vpa_init(boot_cpuid);
+
+        /* Choose an idle loop */
+        if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
+                if (get_paca()->lppaca.shared_proc) {
+                        printk(KERN_INFO "Using shared processor idle loop\n");
+                        ppc_md.idle_loop = pseries_shared_idle;
+                } else {
+                        printk(KERN_INFO "Using dedicated idle loop\n");
+                        ppc_md.idle_loop = pseries_dedicated_idle;
+                }
+        } else {
+                printk(KERN_INFO "Using default idle loop\n");
+                ppc_md.idle_loop = default_idle;
+        }
 }
 
 static int __init pSeries_init_panel(void)
@@ -418,6 +436,144 @@ static int __init pSeries_probe(int platform)
         return 1;
 }
 
+DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
+
+static inline void dedicated_idle_sleep(unsigned int cpu)
+{
+        struct paca_struct *ppaca = &paca[cpu ^ 1];
+
+        /* Only sleep if the other thread is not idle */
+        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();
+        }
+}
+
+static int pseries_dedicated_idle(void)
+{
+        long oldval;
+        struct paca_struct *lpaca = get_paca();
+        unsigned int cpu = smp_processor_id();
+        unsigned long start_snooze;
+        unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
+
+        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)) {
+                                ppc64_runlatch_off();
+
+                                /*
+                                 * Go into low thread priority and possibly
+                                 * low power mode.
+                                 */
+                                HMT_low();
+                                HMT_very_low();
+
+                                if (*smt_snooze_delay != 0 &&
+                                    __get_tb() > start_snooze) {
+                                        HMT_medium();
+                                        dedicated_idle_sleep(cpu);
+                                }
+
+                        }
+
+                        HMT_medium();
+                        clear_thread_flag(TIF_POLLING_NRFLAG);
+                } else {
+                        set_need_resched();
+                }
+
+                lpaca->lppaca.idle = 0;
+                ppc64_runlatch_on();
+
+                schedule();
+
+                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+                        cpu_die();
+        }
+}
+
+static int pseries_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();
+                        ppc64_runlatch_off();
+
+                        /*
+                         * 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;
+                ppc64_runlatch_on();
+
+                schedule();
+
+                if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+                        cpu_die();
+        }
+
+        return 0;
+}
+
 struct machdep_calls __initdata pSeries_md = {
         .probe                  = pSeries_probe,
         .setup_arch             = pSeries_setup_arch,