powerpc/cpuidle: cpuidle driver for pSeries
authorDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Wed, 30 Nov 2011 02:46:42 +0000 (02:46 +0000)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>
Thu, 8 Dec 2011 02:56:31 +0000 (13:56 +1100)
This patch implements a back-end cpuidle driver for pSeries
based on pseries_dedicated_idle_loop and pseries_shared_idle_loop
routines.  The driver is built only if CONFIG_CPU_IDLE is set. This
cpuidle driver uses global registration of idle states and
not per-cpu.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Trinabh Gupta <g.trinabh@gmail.com>
Signed-off-by: Arun R Bharadwaj <arun.r.bharadwaj@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/include/asm/system.h
arch/powerpc/kernel/sysfs.c
arch/powerpc/platforms/pseries/Kconfig
arch/powerpc/platforms/pseries/Makefile
arch/powerpc/platforms/pseries/processor_idle.c [new file with mode: 0644]
arch/powerpc/platforms/pseries/pseries.h
arch/powerpc/platforms/pseries/setup.c
arch/powerpc/platforms/pseries/smp.c

index ff666803879944086d8a06dc5ec5f4359ecd83a3..f56a0a75d989a5bc797b60b507c521722417a40d 100644 (file)
@@ -223,6 +223,14 @@ extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask);
 extern int powersave_nap;      /* set if nap mode can be used in idle loop */
 void cpu_idle_wait(void);
 
+#ifdef CONFIG_PSERIES_IDLE
+extern void update_smt_snooze_delay(int snooze);
+extern int pseries_notify_cpuidle_add_cpu(int cpu);
+#else
+static inline void update_smt_snooze_delay(int snooze) {}
+static inline int pseries_notify_cpuidle_add_cpu(int cpu) { return 0; }
+#endif
+
 /*
  * Atomic exchange
  *
index f579be552094da634776de58b31255d4a3d81706..6fdf5ffe8c44665df26c5750576a84ac74c4c6fa 100644 (file)
@@ -18,6 +18,7 @@
 #include <asm/machdep.h>
 #include <asm/smp.h>
 #include <asm/pmc.h>
+#include <asm/system.h>
 
 #include "cacheinfo.h"
 
@@ -51,6 +52,7 @@ static ssize_t store_smt_snooze_delay(struct sys_device *dev,
                return -EINVAL;
 
        per_cpu(smt_snooze_delay, cpu->sysdev.id) = snooze;
+       update_smt_snooze_delay(snooze);
 
        return count;
 }
index c81f6bb9c10fc0ae33b57e134735d4a8fa12a25c..ae7b6d41fed363580575aa4ea6b56d053b702c84 100644 (file)
@@ -120,3 +120,12 @@ config DTL
          which are accessible through a debugfs file.
 
          Say N if you are unsure.
+
+config PSERIES_IDLE
+       tristate "Cpuidle driver for pSeries platforms"
+       depends on CPU_IDLE
+       depends on PPC_PSERIES
+       default y
+       help
+         Select this option to enable processor idle state management
+         through cpuidle subsystem.
index 3556e402cbf51123f0181a85179e3744fddaed48..236db46b407803786b0633e9fd589569ec7c8f6f 100644 (file)
@@ -22,6 +22,7 @@ obj-$(CONFIG_PHYP_DUMP)               += phyp_dump.o
 obj-$(CONFIG_CMM)              += cmm.o
 obj-$(CONFIG_DTL)              += dtl.o
 obj-$(CONFIG_IO_EVENT_IRQ)     += io_event_irq.o
+obj-$(CONFIG_PSERIES_IDLE)     += processor_idle.o
 
 ifeq ($(CONFIG_PPC_PSERIES),y)
 obj-$(CONFIG_SUSPEND)          += suspend.o
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
new file mode 100644 (file)
index 0000000..f7e3e87
--- /dev/null
@@ -0,0 +1,326 @@
+/*
+ *  processor_idle - idle state cpuidle driver.
+ *  Adapted from drivers/idle/intel_idle.c and
+ *  drivers/acpi/processor_idle.c
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/cpuidle.h>
+#include <linux/cpu.h>
+
+#include <asm/paca.h>
+#include <asm/reg.h>
+#include <asm/system.h>
+#include <asm/machdep.h>
+#include <asm/firmware.h>
+
+#include "plpar_wrappers.h"
+#include "pseries.h"
+
+struct cpuidle_driver pseries_idle_driver = {
+       .name =         "pseries_idle",
+       .owner =        THIS_MODULE,
+};
+
+#define MAX_IDLE_STATE_COUNT   2
+
+static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
+static struct cpuidle_device __percpu *pseries_cpuidle_devices;
+static struct cpuidle_state *cpuidle_state_table;
+
+void update_smt_snooze_delay(int snooze)
+{
+       struct cpuidle_driver *drv = cpuidle_get_driver();
+       if (drv)
+               drv->states[0].target_residency = snooze;
+}
+
+static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
+{
+
+       *kt_before = ktime_get_real();
+       *in_purr = mfspr(SPRN_PURR);
+       /*
+        * Indicate to the HV that we are idle. Now would be
+        * a good time to find other work to dispatch.
+        */
+       get_lppaca()->idle = 1;
+}
+
+static inline  s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
+{
+       get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
+       get_lppaca()->idle = 0;
+
+       return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
+}
+
+static int snooze_loop(struct cpuidle_device *dev,
+                       struct cpuidle_driver *drv,
+                       int index)
+{
+       unsigned long in_purr;
+       ktime_t kt_before;
+       unsigned long start_snooze;
+       long snooze = drv->states[0].target_residency;
+
+       idle_loop_prolog(&in_purr, &kt_before);
+
+       if (snooze) {
+               start_snooze = get_tb() + snooze * tb_ticks_per_usec;
+               local_irq_enable();
+               set_thread_flag(TIF_POLLING_NRFLAG);
+
+               while ((snooze < 0) || (get_tb() < start_snooze)) {
+                       if (need_resched() || cpu_is_offline(dev->cpu))
+                               goto out;
+                       ppc64_runlatch_off();
+                       HMT_low();
+                       HMT_very_low();
+               }
+
+               HMT_medium();
+               clear_thread_flag(TIF_POLLING_NRFLAG);
+               smp_mb();
+               local_irq_disable();
+       }
+
+out:
+       HMT_medium();
+       dev->last_residency =
+               (int)idle_loop_epilog(in_purr, kt_before);
+       return index;
+}
+
+static int dedicated_cede_loop(struct cpuidle_device *dev,
+                               struct cpuidle_driver *drv,
+                               int index)
+{
+       unsigned long in_purr;
+       ktime_t kt_before;
+
+       idle_loop_prolog(&in_purr, &kt_before);
+       get_lppaca()->donate_dedicated_cpu = 1;
+
+       ppc64_runlatch_off();
+       HMT_medium();
+       cede_processor();
+
+       get_lppaca()->donate_dedicated_cpu = 0;
+       dev->last_residency =
+               (int)idle_loop_epilog(in_purr, kt_before);
+       return index;
+}
+
+static int shared_cede_loop(struct cpuidle_device *dev,
+                       struct cpuidle_driver *drv,
+                       int index)
+{
+       unsigned long in_purr;
+       ktime_t kt_before;
+
+       idle_loop_prolog(&in_purr, &kt_before);
+
+       /*
+        * 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.
+        */
+       cede_processor();
+
+       dev->last_residency =
+               (int)idle_loop_epilog(in_purr, kt_before);
+       return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
+       { /* Snooze */
+               .name = "snooze",
+               .desc = "snooze",
+               .flags = CPUIDLE_FLAG_TIME_VALID,
+               .exit_latency = 0,
+               .target_residency = 0,
+               .enter = &snooze_loop },
+       { /* CEDE */
+               .name = "CEDE",
+               .desc = "CEDE",
+               .flags = CPUIDLE_FLAG_TIME_VALID,
+               .exit_latency = 1,
+               .target_residency = 10,
+               .enter = &dedicated_cede_loop },
+};
+
+/*
+ * States for shared partition case.
+ */
+static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
+       { /* Shared Cede */
+               .name = "Shared Cede",
+               .desc = "Shared Cede",
+               .flags = CPUIDLE_FLAG_TIME_VALID,
+               .exit_latency = 0,
+               .target_residency = 0,
+               .enter = &shared_cede_loop },
+};
+
+int pseries_notify_cpuidle_add_cpu(int cpu)
+{
+       struct cpuidle_device *dev =
+                       per_cpu_ptr(pseries_cpuidle_devices, cpu);
+       if (dev && cpuidle_get_driver()) {
+               cpuidle_disable_device(dev);
+               cpuidle_enable_device(dev);
+       }
+       return 0;
+}
+
+/*
+ * pseries_cpuidle_driver_init()
+ */
+static int pseries_cpuidle_driver_init(void)
+{
+       int idle_state;
+       struct cpuidle_driver *drv = &pseries_idle_driver;
+
+       drv->state_count = 0;
+
+       for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
+
+               if (idle_state > max_idle_state)
+                       break;
+
+               /* is the state not enabled? */
+               if (cpuidle_state_table[idle_state].enter == NULL)
+                       continue;
+
+               drv->states[drv->state_count] = /* structure copy */
+                       cpuidle_state_table[idle_state];
+
+               if (cpuidle_state_table == dedicated_states)
+                       drv->states[drv->state_count].target_residency =
+                               __get_cpu_var(smt_snooze_delay);
+
+               drv->state_count += 1;
+       }
+
+       return 0;
+}
+
+/* pseries_idle_devices_uninit(void)
+ * unregister cpuidle devices and de-allocate memory
+ */
+static void pseries_idle_devices_uninit(void)
+{
+       int i;
+       struct cpuidle_device *dev;
+
+       for_each_possible_cpu(i) {
+               dev = per_cpu_ptr(pseries_cpuidle_devices, i);
+               cpuidle_unregister_device(dev);
+       }
+
+       free_percpu(pseries_cpuidle_devices);
+       return;
+}
+
+/* pseries_idle_devices_init()
+ * allocate, initialize and register cpuidle device
+ */
+static int pseries_idle_devices_init(void)
+{
+       int i;
+       struct cpuidle_driver *drv = &pseries_idle_driver;
+       struct cpuidle_device *dev;
+
+       pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+       if (pseries_cpuidle_devices == NULL)
+               return -ENOMEM;
+
+       for_each_possible_cpu(i) {
+               dev = per_cpu_ptr(pseries_cpuidle_devices, i);
+               dev->state_count = drv->state_count;
+               dev->cpu = i;
+               if (cpuidle_register_device(dev)) {
+                       printk(KERN_DEBUG \
+                               "cpuidle_register_device %d failed!\n", i);
+                       return -EIO;
+               }
+       }
+
+       return 0;
+}
+
+/*
+ * pseries_idle_probe()
+ * Choose state table for shared versus dedicated partition
+ */
+static int pseries_idle_probe(void)
+{
+
+       if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+               return -ENODEV;
+
+       if (max_idle_state == 0) {
+               printk(KERN_DEBUG "pseries processor idle disabled.\n");
+               return -EPERM;
+       }
+
+       if (get_lppaca()->shared_proc)
+               cpuidle_state_table = shared_states;
+       else
+               cpuidle_state_table = dedicated_states;
+
+       return 0;
+}
+
+static int __init pseries_processor_idle_init(void)
+{
+       int retval;
+
+       retval = pseries_idle_probe();
+       if (retval)
+               return retval;
+
+       pseries_cpuidle_driver_init();
+       retval = cpuidle_register_driver(&pseries_idle_driver);
+       if (retval) {
+               printk(KERN_DEBUG "Registration of pseries driver failed.\n");
+               return retval;
+       }
+
+       retval = pseries_idle_devices_init();
+       if (retval) {
+               pseries_idle_devices_uninit();
+               cpuidle_unregister_driver(&pseries_idle_driver);
+               return retval;
+       }
+
+       printk(KERN_DEBUG "pseries_idle_driver registered\n");
+
+       return 0;
+}
+
+static void __exit pseries_processor_idle_exit(void)
+{
+
+       pseries_idle_devices_uninit();
+       cpuidle_unregister_driver(&pseries_idle_driver);
+
+       return;
+}
+
+module_init(pseries_processor_idle_init);
+module_exit(pseries_processor_idle_exit);
+
+MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
+MODULE_DESCRIPTION("Cpuidle driver for POWER");
+MODULE_LICENSE("GPL");
index 24c7162f11d9ff7c431540ea44beb667d9e44849..9a3dda07566f1ff90c46737aff9887f0572dc912 100644 (file)
@@ -57,4 +57,7 @@ extern struct device_node *dlpar_configure_connector(u32);
 extern int dlpar_attach_node(struct device_node *);
 extern int dlpar_detach_node(struct device_node *);
 
+/* Snooze Delay, pseries_idle */
+DECLARE_PER_CPU(long, smt_snooze_delay);
+
 #endif /* _PSERIES_PSERIES_H */
index 01df08dbc43c6280dc117e9cfd1e7d6b3393394b..f2446da7f2d55e8016b4e8da4f375c418aea1b28 100644 (file)
@@ -585,9 +585,6 @@ static int __init pSeries_probe(void)
        return 1;
 }
 
-
-DECLARE_PER_CPU(long, smt_snooze_delay);
-
 static void pseries_dedicated_idle_sleep(void)
 { 
        unsigned int cpu = smp_processor_id();
index 26e93fd4c62b4e8d0037ab31fb6209cb788b1340..bbc3c42f67301dccb414e4203a9186a92b834aa6 100644 (file)
@@ -148,6 +148,7 @@ static void __devinit smp_xics_setup_cpu(int cpu)
        set_cpu_current_state(cpu, CPU_STATE_ONLINE);
        set_default_offline_state(cpu);
 #endif
+       pseries_notify_cpuidle_add_cpu(cpu);
 }
 
 static int __devinit smp_pSeries_kick_cpu(int nr)