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Subject[PATCH 4/4]: CPUIDLE/POWER: Implement Pseries Processor Idle module
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-08-27 17:19:08]:

This patch creates arch/powerpc/platforms/pseries/processor_idle.c,
which implements the cpuidle infrastructure for pseries.
It implements a pseries_cpuidle_loop() which would be the main idle loop
called from cpu_idle(). It makes decision of entering either snooze or nap
state based on the decision taken by the cpuidle governor.

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
---
arch/powerpc/platforms/pseries/Makefile | 1
arch/powerpc/platforms/pseries/processor_idle.c | 178 ++++++++++++++++++++++++
arch/powerpc/platforms/pseries/pseries.h | 14 +
arch/powerpc/platforms/pseries/setup.c | 3
4 files changed, 193 insertions(+), 3 deletions(-)
Index: linux.trees.git/arch/powerpc/platforms/pseries/Makefile
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/Makefile
+++ linux.trees.git/arch/powerpc/platforms/pseries/Makefile
@@ -26,3 +26,4 @@ obj-$(CONFIG_HCALL_STATS) += hvCall_inst
obj-$(CONFIG_PHYP_DUMP) += phyp_dump.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_DTL) += dtl.o
+obj-$(CONFIG_PSERIES_PROCESSOR_IDLE) += processor_idle.o
Index: linux.trees.git/arch/powerpc/platforms/pseries/pseries.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/pseries.h
+++ linux.trees.git/arch/powerpc/platforms/pseries/pseries.h
@@ -10,6 +10,8 @@
#ifndef _PSERIES_PSERIES_H
#define _PSERIES_PSERIES_H

+#include <linux/cpuidle.h>
+
extern void __init fw_feature_init(const char *hypertas, unsigned long len);

struct pt_regs;
@@ -40,4 +42,16 @@ extern unsigned long rtas_poweron_auto;

extern void find_udbg_vterm(void);

+DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
+
+#ifdef CONFIG_PSERIES_PROCESSOR_IDLE
+struct pseries_processor_power {
+ struct cpuidle_device dev;
+ int count;
+ int id;
+};
+
+extern struct cpuidle_driver pseries_idle_driver;
+#endif
+
#endif /* _PSERIES_PSERIES_H */
Index: linux.trees.git/arch/powerpc/platforms/pseries/processor_idle.c
===================================================================
--- /dev/null
+++ linux.trees.git/arch/powerpc/platforms/pseries/processor_idle.c
@@ -0,0 +1,178 @@
+/*
+ * processor_idle - idle state cpuidle driver.
+ * Adapted from drivers/acpi/processor_idle.c
+ *
+ * Arun R Bharadwaj <arun@linux.vnet.ibm.com>
+ *
+ * Copyright (C) 2009 IBM Corporation.
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/cpuidle.h>
+
+#include <asm/paca.h>
+#include <asm/reg.h>
+#include <asm/machdep.h>
+
+#include "plpar_wrappers.h"
+#include "pseries.h"
+
+MODULE_AUTHOR("Arun R Bharadwaj");
+MODULE_DESCRIPTION("pSeries Idle State Driver");
+MODULE_LICENSE("GPL");
+
+struct cpuidle_driver pseries_idle_driver = {
+ .name = "pseries_idle",
+ .owner = THIS_MODULE,
+};
+
+DEFINE_PER_CPU(struct pseries_processor_power, power);
+
+#define IDLE_STATE_COUNT 2
+
+static int pseries_idle_init(struct pseries_processor_power *power)
+{
+ return cpuidle_register_device(&power->dev);
+}
+
+static void snooze(void)
+{
+ local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ while (!need_resched()) {
+ ppc64_runlatch_off();
+ HMT_low();
+ HMT_very_low();
+ }
+ HMT_medium();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb();
+ local_irq_disable();
+}
+
+static void nap(void)
+{
+ ppc64_runlatch_off();
+ HMT_medium();
+ cede_processor();
+}
+
+static int pseries_cpuidle_loop(struct cpuidle_device *dev,
+ struct cpuidle_state *st)
+{
+ ktime_t t1, t2;
+ s64 diff;
+ int ret;
+ unsigned long in_purr, out_purr;
+
+ get_lppaca()->idle = 1;
+ get_lppaca()->donate_dedicated_cpu = 1;
+ in_purr = mfspr(SPRN_PURR);
+
+ t1 = ktime_get();
+
+ if (strcmp(st->desc, "snooze") == 0)
+ snooze();
+ else
+ nap();
+
+ t2 = ktime_get();
+ diff = ktime_to_us(ktime_sub(t2, t1));
+ if (diff > INT_MAX)
+ diff = INT_MAX;
+
+ ret = (int) diff;
+
+ out_purr = mfspr(SPRN_PURR);
+ get_lppaca()->wait_state_cycles += out_purr - in_purr;
+ get_lppaca()->donate_dedicated_cpu = 0;
+ get_lppaca()->idle = 0;
+
+ return ret;
+}
+
+static int pseries_setup_cpuidle(struct pseries_processor_power *power)
+{
+ int i;
+ struct cpuidle_state *state;
+ struct cpuidle_device *dev = &power->dev;
+
+ dev->cpu = power->id;
+
+ dev->enabled = 0;
+ for (i = 0; i < IDLE_STATE_COUNT; i++) {
+ state = &dev->states[i];
+
+ snprintf(state->name, CPUIDLE_NAME_LEN, "IDLE%d", i);
+ state->enter = pseries_cpuidle_loop;
+
+ switch (i) {
+ case 0:
+ strncpy(state->desc, "snooze", CPUIDLE_DESC_LEN);
+ state->exit_latency = 0;
+ state->target_residency = 0;
+ break;
+
+ case 1:
+ strncpy(state->desc, "nap", CPUIDLE_DESC_LEN);
+ state->exit_latency = 1;
+ state->target_residency =
+ __get_cpu_var(smt_snooze_delay);
+ break;
+ }
+ }
+
+ power->dev.state_count = i;
+ return 0;
+}
+
+static int pseries_get_power_info(struct pseries_processor_power *power,
+ int cpu)
+{
+ power->id = cpu;
+ power->count = IDLE_STATE_COUNT;
+ return 0;
+}
+
+static int __init pseries_processor_idle_init(void)
+{
+ int cpu;
+ int result = cpuidle_register_driver(&pseries_idle_driver);
+
+ if (result < 0)
+ return result;
+
+ printk(KERN_DEBUG "pSeries idle driver registered\n");
+
+ for_each_online_cpu(cpu) {
+ pseries_get_power_info(&per_cpu(power, cpu), cpu);
+ pseries_setup_cpuidle(&per_cpu(power, cpu));
+ pseries_idle_init(&per_cpu(power, cpu));
+ }
+
+ printk(KERN_DEBUG "Using cpuidle idle loop\n");
+ ppc_md.power_save = cpuidle_pm_idle;
+ return 0;
+}
+
+late_initcall(pseries_processor_idle_init);
Index: linux.trees.git/arch/powerpc/platforms/pseries/setup.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/setup.c
+++ linux.trees.git/arch/powerpc/platforms/pseries/setup.c
@@ -500,9 +500,6 @@ static int __init pSeries_probe(void)
return 1;
}

-
-DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
-
static void pseries_dedicated_idle_sleep(void)
{
unsigned int cpu = smp_processor_id();

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