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


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