powerpc/cpuidle: cpuidle driver for pSeries
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>
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
new file mode 100644
index 0000000..f7e3e87
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -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");