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Subject[v10 PATCH 8/9]: pSeries: implement pSeries processor idle module
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-12-02 15:24:27]:

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
dedicated_snooze_loop or dedicated_cede_loop for dedicated lpar and
shared_cede_loop for shared lpar processor based on the
decision taken by the cpuidle governor.

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/system.h | 6
arch/powerpc/kernel/sysfs.c | 2
arch/powerpc/platforms/pseries/Makefile | 1
arch/powerpc/platforms/pseries/processor_idle.c | 196 ++++++++++++++++++++++++
arch/powerpc/platforms/pseries/pseries.h | 6
5 files changed, 211 insertions(+)
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_CPU_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 +42,8 @@ extern unsigned long rtas_poweron_auto;

extern void find_udbg_vterm(void);

+DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
+
+extern struct cpuidle_driver pseries_idle_driver;
+
#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 +1,196 @@
+/*
+ * 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/system.h>
+#include <asm/machdep.h>
+#include <asm/firmware.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 cpuidle_device, pseries_dev);
+
+#define IDLE_STATE_COUNT 2
+
+/* pSeries Idle state Flags */
+#define PSERIES_DEDICATED_SNOOZE (0x01)
+#define PSERIES_DEDICATED_CEDE (0x02)
+#define PSERIES_SHARED_CEDE (0x03)
+
+static int pseries_idle_init(struct cpuidle_device *dev)
+{
+ return cpuidle_register_device(dev);
+}
+
+static void shared_cede_loop(void)
+{
+ get_lppaca()->idle = 1;
+ cede_processor();
+ get_lppaca()->idle = 0;
+}
+
+static void dedicated_snooze_loop(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 dedicated_cede_loop(void)
+{
+ ppc64_runlatch_off();
+ HMT_medium();
+ cede_processor();
+}
+
+static void pseries_cpuidle_loop(struct cpuidle_device *dev,
+ struct cpuidle_state *st)
+{
+ unsigned long in_purr, out_purr;
+
+ get_lppaca()->idle = 1;
+ get_lppaca()->donate_dedicated_cpu = 1;
+ in_purr = mfspr(SPRN_PURR);
+
+ if (st->flags & PSERIES_SHARED_CEDE)
+ shared_cede_loop();
+ else if (st->flags & PSERIES_DEDICATED_SNOOZE)
+ dedicated_snooze_loop();
+ else
+ dedicated_cede_loop();
+
+ out_purr = mfspr(SPRN_PURR);
+ get_lppaca()->wait_state_cycles += out_purr - in_purr;
+ get_lppaca()->donate_dedicated_cpu = 0;
+ get_lppaca()->idle = 0;
+}
+
+static int pseries_setup_cpuidle(struct cpuidle_device *dev, int cpu)
+{
+ int i;
+ struct cpuidle_state *state;
+
+ dev->cpu = cpu;
+
+ if (get_lppaca()->shared_proc) {
+ state = &dev->states[0];
+ snprintf(state->name, CPUIDLE_NAME_LEN, "IDLE");
+ state->enter = pseries_cpuidle_loop;
+ strncpy(state->desc, "shared_cede", CPUIDLE_DESC_LEN);
+ state->flags = PSERIES_SHARED_CEDE;
+ state->exit_latency = 0;
+ state->target_residency = 0;
+ return 0;
+ }
+
+ for (i = 0; i < IDLE_STATE_COUNT; i++) {
+ state = &dev->states[i];
+
+ snprintf(state->name, CPUIDLE_NAME_LEN, "CEDE%d", i);
+ state->enter = pseries_cpuidle_loop;
+
+ switch (i) {
+ case 0:
+ strncpy(state->desc, "snooze", CPUIDLE_DESC_LEN);
+ state->flags = PSERIES_DEDICATED_SNOOZE;
+ state->exit_latency = 0;
+ state->target_residency = 0;
+ break;
+
+ case 1:
+ strncpy(state->desc, "cede", CPUIDLE_DESC_LEN);
+ state->flags = PSERIES_DEDICATED_CEDE;
+ state->exit_latency = 1;
+ state->target_residency =
+ __get_cpu_var(smt_snooze_delay);
+ break;
+ }
+ }
+ dev->state_count = IDLE_STATE_COUNT;
+
+ return 0;
+}
+
+void update_smt_snooze_delay(int snooze)
+{
+ int cpu;
+ for_each_online_cpu(cpu)
+ per_cpu(pseries_dev, cpu).states[0].target_residency = snooze;
+}
+
+static int __init pseries_processor_idle_init(void)
+{
+ int cpu;
+ int result;
+
+ result = cpuidle_register_driver(&pseries_idle_driver);
+
+ if (result < 0)
+ return result;
+
+ printk(KERN_DEBUG "pSeries idle driver registered\n");
+
+ if (!firmware_has_feature(FW_FEATURE_SPLPAR)) {
+ printk(KERN_DEBUG "Using default idle\n");
+ return 0;
+ }
+
+ for_each_online_cpu(cpu) {
+ pseries_setup_cpuidle(&per_cpu(pseries_dev, cpu), cpu);
+ pseries_idle_init(&per_cpu(pseries_dev, cpu));
+ }
+
+ printk(KERN_DEBUG "Using cpuidle idle loop\n");
+
+ return 0;
+}
+
+device_initcall(pseries_processor_idle_init);
Index: linux.trees.git/arch/powerpc/include/asm/system.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/include/asm/system.h
+++ linux.trees.git/arch/powerpc/include/asm/system.h
@@ -549,5 +549,11 @@ extern struct dentry *powerpc_debugfs_ro

void cpu_idle_wait(void);

+#ifdef CONFIG_CPU_IDLE
+extern void update_smt_snooze_delay(int snooze);
+#else
+static inline void update_smt_snooze_delay(int snooze) {}
+#endif
+
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_SYSTEM_H */
Index: linux.trees.git/arch/powerpc/kernel/sysfs.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/kernel/sysfs.c
+++ linux.trees.git/arch/powerpc/kernel/sysfs.c
@@ -18,6 +18,7 @@
#include <asm/machdep.h>
#include <asm/smp.h>
#include <asm/pmc.h>
+#include <asm/system.h>

#include "cacheinfo.h"

@@ -51,6 +52,7 @@ static ssize_t store_smt_snooze_delay(st
return -EINVAL;

per_cpu(smt_snooze_delay, cpu->sysdev.id) = snooze;
+ update_smt_snooze_delay(snooze);

return count;
}

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