[PATCH v1] powernv/cpuidle: Back-end cpuidle driver for powernv platform for idle state management.

[PATCH v1] powernv/cpuidle: Back-end cpuidle driver for powernv platform for idle state management.

[Deepthi Dharwar]

Following patch ports the cpuidle framework for powernv
platform and also implements a cpuidle back-end powernv 
idle driver calling on to power7_nap and snooze idle states.

Moving the idle states over to cpuidle framework can take advantage 
of advanced heuristics, tunables and features provided by cpuidle 
framework. Additional idle states can be exploited using the cpuidle 
framework. The statistics and tracing infrastructure provided by 
the cpuidle framework also helps in enabling power management 
related tools and help tune the system and applications.

This series aims to maintain compatibility and functionality to
existing powernv idle cpu management code.  There are no new functions
or idle states added as part of this series. This can be extended by 
adding more states to this existing framework.

For POWERNV platform to hook into CPUIDLE framework, one
needs to enable CONFIG_POWERNV_IDLE. 

This patch series applies on pseries cpuidle backend driver
fixes patchset posted earlier.
pseries/cpuidle: pseries cpuidle backend driver clean-ups.

 Deepthi Dharwar (1):
      powernv/cpuidle: Back-end cpuidle driver for powernv platform.


 arch/powerpc/platforms/powernv/setup.c |   13 ++
 drivers/cpuidle/Kconfig.powerpc        |    9 ++
 drivers/cpuidle/Makefile               |    1 
 drivers/cpuidle/cpuidle-powernv.c      |  169 ++++++++++++++++++++++++++++++++
 4 files changed, 191 insertions(+), 1 deletion(-)
 create mode 100644 drivers/cpuidle/cpuidle-powernv.c


-- Deepthi

[PATCH v1] powernv/cpuidle: Back-end cpuidle driver for powernv platform.

[Deepthi Dharwar]

Following patch ports the cpuidle framework for powernv
platform and also implements a cpuidle back-end powernv
idle driver calling on to power7_nap and snooze idle states.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/setup.c |   13 ++
 drivers/cpuidle/Kconfig.powerpc        |    9 ++
 drivers/cpuidle/Makefile               |    1 
 drivers/cpuidle/cpuidle-powernv.c      |  169 ++++++++++++++++++++++++++++++++
 4 files changed, 191 insertions(+), 1 deletion(-)
 create mode 100644 drivers/cpuidle/cpuidle-powernv.c

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 19884b2..764a14e 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -26,6 +26,7 @@
 #include <linux/of_fdt.h>
 #include <linux/interrupt.h>
 #include <linux/bug.h>
+#include <linux/cpuidle.h>
 
 #include <asm/machdep.h>
 #include <asm/firmware.h>
@@ -214,6 +215,16 @@ static int __init pnv_probe(void)
 	return 1;
 }
 
+void powernv_idle(void)
+{
+	/* Hook to cpuidle framework if available, else
+	 * call on default platform idle code
+	 */
+	if (cpuidle_idle_call()) {
+		power7_idle();
+	}
+}
+
 define_machine(powernv) {
 	.name			= "PowerNV",
 	.probe			= pnv_probe,
@@ -223,7 +234,7 @@ define_machine(powernv) {
 	.show_cpuinfo		= pnv_show_cpuinfo,
 	.progress		= pnv_progress,
 	.machine_shutdown	= pnv_shutdown,
-	.power_save             = power7_idle,
+	.power_save             = powernv_idle,
 	.calibrate_decr		= generic_calibrate_decr,
 #ifdef CONFIG_KEXEC
 	.kexec_cpu_down		= pnv_kexec_cpu_down,
diff --git a/drivers/cpuidle/Kconfig.powerpc b/drivers/cpuidle/Kconfig.powerpc
index 8147de5..66c3a09 100644
--- a/drivers/cpuidle/Kconfig.powerpc
+++ b/drivers/cpuidle/Kconfig.powerpc
@@ -9,3 +9,12 @@ config PSERIES_CPUIDLE
 	help
 	  Select this option to enable processor idle state management
 	  through cpuidle subsystem.
+
+config POWERNV_CPUIDLE
+	bool "Cpuidle driver for powernv platforms"
+	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/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index a6331ad..f71ae1b 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_ARM_AT91_CPUIDLE)          += cpuidle-at91.o
 ###############################################################################
 # POWERPC drivers
 obj-$(CONFIG_PSERIES_CPUIDLE)		+= cpuidle-pseries.o
+obj-$(CONFIG_POWERNV_CPUIDLE)		+= cpuidle-powernv.o
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
new file mode 100644
index 0000000..78fd174
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -0,0 +1,169 @@
+/*
+ *  cpuidle-powernv - idle state cpuidle driver.
+ *  Adapted from drivers/cpuidle/cpuidle-pseries
+ *
+ */
+
+#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/firmware.h>
+
+struct cpuidle_driver powernv_idle_driver = {
+	.name             = "powernv_idle",
+	.owner            = THIS_MODULE,
+};
+
+static int max_idle_state;
+static struct cpuidle_state *cpuidle_state_table;
+
+static int snooze_loop(struct cpuidle_device *dev,
+			struct cpuidle_driver *drv,
+			int index)
+{
+	local_irq_enable();
+	set_thread_flag(TIF_POLLING_NRFLAG);
+
+	while (!need_resched()) {
+		HMT_low();
+		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)
+{
+	power7_idle();
+	return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state powernv_states[] = {
+	{ /* 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(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; ++idle_state) {
+		/* 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_probe()
+ * Choose state table for shared versus dedicated partition
+ */
+static int powernv_idle_probe(void)
+{
+
+	if (cpuidle_disable != IDLE_NO_OVERRIDE)
+		return -ENODEV;
+
+	if (firmware_has_feature(FW_FEATURE_OPALv3)) {
+		cpuidle_state_table = powernv_states;
+		max_idle_state = ARRAY_SIZE(powernv_states);
+ 	} else
+ 		return -ENODEV;
+
+	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(&powernv_idle_driver, NULL);
+	if (retval) {
+		printk(KERN_DEBUG "Registration of powernv driver failed.\n");
+		return retval;
+	}
+
+	register_cpu_notifier(&setup_hotplug_notifier);
+	printk(KERN_DEBUG "powernv_idle_driver registered\n");
+	return 0;
+}
+
+device_initcall(powernv_processor_idle_init);