This patch implements a back-end cpuidle driver for
powernv calling power7_nap and snooze idle states.
This can be extended by adding more idle states
in the future to the existing framework.
Signed-off-by: Deepthi Dharwar <deepthi@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/platforms/powernv/Kconfig | 9 +
arch/powerpc/platforms/powernv/Makefile | 1
arch/powerpc/platforms/powernv/processor_idle.c | 239 +++++++++++++++++++++++
3 files changed, 249 insertions(+)
create mode 100644 arch/powerpc/platforms/powernv/processor_idle.c
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index c24684c..ace2d22 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -20,3 +20,12 @@ config PPC_POWERNV_RTAS
default y
select PPC_ICS_RTAS
select PPC_RTAS
+
+config POWERNV_IDLE
+ bool "CPUIdle driver for powernv platform"
+ depends on CPU_IDLE
+ depends on PPC_POWERNV
+ default y
+ help
+ Select this option to enable processor idle state management
+ through cpuidle subsystem.
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index 7fe5951..c0e44eb 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -4,3 +4,4 @@ obj-y += opal-rtc.o opal-nvram.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o
obj-$(CONFIG_EEH) += eeh-ioda.o eeh-powernv.o
+obj-$(CONFIG_POWERNV_IDLE) += processor_idle.o
diff --git a/arch/powerpc/platforms/powernv/processor_idle.c b/arch/powerpc/platforms/powernv/processor_idle.c
new file mode 100644
index 0000000..f43ad91a
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/processor_idle.c
@@ -0,0 +1,239 @@
+/*
+ * processor_idle - idle state cpuidle driver.
+ */
+
+#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 <linux/notifier.h>
+
+#include <asm/machdep.h>
+#include <asm/runlatch.h>
+
+struct cpuidle_driver powernv_idle_driver = {
+ .name = "powernv_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 *powernv_cpuidle_devices;
+static struct cpuidle_state *cpuidle_state_table;
+
+static int snooze_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ int cpu = dev->cpu;
+
+ local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
+ while ((!need_resched()) && cpu_online(cpu)) {
+ ppc64_runlatch_off();
+ HMT_very_low();
+ }
+
+ HMT_medium();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb();
+ return index;
+}
+
+
+static int nap_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ ppc64_runlatch_off();
+ power7_idle();
+ return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state powernv_states[MAX_IDLE_STATE_COUNT] = {
+ { /* Snooze */
+ .name = "snooze",
+ .desc = "snooze",
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 0,
+ .target_residency = 0,
+ .enter = &snooze_loop },
+ { /* Nap */
+ .name = "Nap",
+ .desc = "Nap",
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 10,
+ .target_residency = 100,
+ .enter = &nap_loop },
+};
+
+static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
+ unsigned long action, void *hcpu)
+{
+ int hotcpu = (unsigned long)hcpu;
+ struct cpuidle_device *dev =
+ per_cpu_ptr(powernv_cpuidle_devices, hotcpu);
+
+ if (dev && cpuidle_get_driver()) {
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ cpuidle_pause_and_lock();
+ cpuidle_enable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ cpuidle_pause_and_lock();
+ cpuidle_disable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ default:
+ return NOTIFY_DONE;
+ }
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block setup_hotplug_notifier = {
+ .notifier_call = powernv_cpuidle_add_cpu_notifier,
+};
+
+/*
+ * powernv_cpuidle_driver_init()
+ */
+static int powernv_cpuidle_driver_init(void)
+{
+ int idle_state;
+ struct cpuidle_driver *drv = &powernv_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];
+
+ drv->state_count += 1;
+ }
+
+ return 0;
+}
+
+/* powernv_idle_devices_uninit(void)
+ * unregister cpuidle devices and de-allocate memory
+ */
+static void powernv_idle_devices_uninit(void)
+{
+ int i;
+ struct cpuidle_device *dev;
+
+ for_each_possible_cpu(i) {
+ dev = per_cpu_ptr(powernv_cpuidle_devices, i);
+ cpuidle_unregister_device(dev);
+ }
+
+ free_percpu(powernv_cpuidle_devices);
+ return;
+}
+
+/* powernv_idle_devices_init()
+ * allocate, initialize and register cpuidle device
+ */
+static int powernv_idle_devices_init(void)
+{
+ int i;
+ struct cpuidle_driver *drv = &powernv_idle_driver;
+ struct cpuidle_device *dev;
+
+ powernv_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+ if (powernv_cpuidle_devices == NULL)
+ return -ENOMEM;
+
+ for_each_possible_cpu(i) {
+ dev = per_cpu_ptr(powernv_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;
+}
+
+/*
+ * powernv_idle_probe()
+ * Choose state table for shared versus dedicated partition
+ */
+static int powernv_idle_probe(void)
+{
+
+ if (cpuidle_disable != IDLE_NO_OVERRIDE)
+ return -ENODEV;
+
+ cpuidle_state_table = powernv_states;
+ return 0;
+}
+
+static int __init powernv_processor_idle_init(void)
+{
+ int retval;
+
+ retval = powernv_idle_probe();
+ if (retval)
+ return retval;
+
+ powernv_cpuidle_driver_init();
+ retval = cpuidle_register_driver(&powernv_idle_driver);
+ if (retval) {
+ printk(KERN_DEBUG "Registration of powernv driver failed.\n");
+ return retval;
+ }
+
+ retval = powernv_idle_devices_init();
+ if (retval) {
+ powernv_idle_devices_uninit();
+ cpuidle_unregister_driver(&powernv_idle_driver);
+ return retval;
+ }
+
+ register_cpu_notifier(&setup_hotplug_notifier);
+ printk(KERN_DEBUG "powernv_idle_driver registered\n");
+
+ return 0;
+}
+
+static void __exit powernv_processor_idle_exit(void)
+{
+
+ unregister_cpu_notifier(&setup_hotplug_notifier);
+ powernv_idle_devices_uninit();
+ cpuidle_unregister_driver(&powernv_idle_driver);
+
+ return;
+}
+
+module_init(powernv_processor_idle_init);
+module_exit(powernv_processor_idle_exit);
+
+MODULE_AUTHOR("Deepthi Dharwar <deepthi@xxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Cpuidle driver for POWERNV");
+MODULE_LICENSE("GPL");
