time: Add rq_stats snapshot

Add snapshot of runqueue stats module as of commit <e56fe938419e>
(Merge "uapi: Introduce V4L2_FLAG_CVPMETADATA_SKIP flag").

Added #ifdefery to allow rq_stats to actually be optional.

Change-Id: I3352a472c5b0ad61cc04317a1d6f26549bfcdc04
Signed-off-by: Elliot Berman <eberman@codeaurora.org>

drivers/soc/qcom/Kconfig

@@ -282,6 +282,14 @@ config QCOM_RPMHPD
 	  value to RPMh which then translates it into corresponding voltage
 	  for the voltage rail.
 
+config QCOM_RUN_QUEUE_STATS
+       bool "Enable collection and exporting of QTI Run Queue stats to userspace"
+       help
+        This option enables the driver to periodically collecting the statistics
+        of kernel run queue information and calculate the load of the system.
+        This information is exported to usespace via sysfs entries and userspace
+        algorithms uses info and decide when to turn on/off the cpu cores.
+
 config QCOM_RPMPD
 	bool "Qualcomm RPM Power domain driver"
 	depends on QCOM_SMD_RPM=y

drivers/soc/qcom/Makefile

@@ -33,6 +33,7 @@ obj-$(CONFIG_QCOM_SECURE_BUFFER) += secure_buffer.o
 obj-$(CONFIG_QCOM_SOCINFO)	+= socinfo.o
 obj-$(CONFIG_QCOM_WCNSS_CTRL) += wcnss_ctrl.o
 obj-$(CONFIG_QCOM_IPCC) += qcom_ipcc.o
+obj-$(CONFIG_QCOM_RUN_QUEUE_STATS) += rq_stats.o
 obj-$(CONFIG_QCOM_APR) += apr.o
 obj-$(CONFIG_QCOM_LLCC) += llcc-slice.o
 obj-$(CONFIG_QCOM_LAHAINA_LLCC) += llcc-lahaina.o

drivers/soc/qcom/rq_stats.c

@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2010-2015, 2017, 2019, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/rq_stats.h>
+
+#define MAX_LONG_SIZE 24
+#define DEFAULT_DEF_TIMER_JIFFIES 5
+
+struct rq_data rq_info;
+struct workqueue_struct *rq_wq;
+spinlock_t rq_lock;
+
+static void def_work_fn(struct work_struct *work)
+{
+	/* Notify polling threads on change of value */
+	sysfs_notify(rq_info.kobj, NULL, "def_timer_ms");
+}
+
+static ssize_t show_def_timer_ms(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	int64_t diff;
+	unsigned int udiff;
+
+	diff = ktime_to_ns(ktime_get()) - rq_info.def_start_time;
+	do_div(diff, 1000 * 1000);
+	udiff = (unsigned int) diff;
+
+	return snprintf(buf, MAX_LONG_SIZE, "%u\n", udiff);
+}
+
+static ssize_t store_def_timer_ms(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	unsigned int val = 0;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	rq_info.def_timer_jiffies = msecs_to_jiffies(val);
+
+	rq_info.def_start_time = ktime_to_ns(ktime_get());
+	return count;
+}
+
+static struct kobj_attribute def_timer_ms_attr =
+	__ATTR(def_timer_ms, 0600, show_def_timer_ms,
+			store_def_timer_ms);
+
+static struct attribute *rq_attrs[] = {
+	&def_timer_ms_attr.attr,
+	NULL,
+};
+
+static struct attribute_group rq_attr_group = {
+	.attrs = rq_attrs,
+};
+
+static int init_rq_attribs(void)
+{
+	int err;
+
+	rq_info.attr_group = &rq_attr_group;
+
+	/* Create /sys/devices/system/cpu/cpu0/rq-stats/... */
+	rq_info.kobj = kobject_create_and_add("rq-stats",
+			&get_cpu_device(0)->kobj);
+	if (!rq_info.kobj)
+		return -ENOMEM;
+
+	err = sysfs_create_group(rq_info.kobj, rq_info.attr_group);
+	if (err)
+		kobject_put(rq_info.kobj);
+	else
+		kobject_uevent(rq_info.kobj, KOBJ_ADD);
+
+	return err;
+}
+
+static int __init msm_rq_stats_init(void)
+{
+	int ret;
+
+#ifndef CONFIG_SMP
+	/* Bail out if this is not an SMP Target */
+	rq_info.init = 0;
+	return -EPERM;
+#endif
+
+	rq_wq = create_singlethread_workqueue("rq_stats");
+	WARN_ON(!rq_wq);
+	INIT_WORK(&rq_info.def_timer_work, def_work_fn);
+	spin_lock_init(&rq_lock);
+	rq_info.def_timer_jiffies = DEFAULT_DEF_TIMER_JIFFIES;
+	rq_info.def_timer_last_jiffy = 0;
+	ret = init_rq_attribs();
+
+	rq_info.init = 1;
+
+	return ret;
+}
+late_initcall(msm_rq_stats_init);

include/linux/rq_stats.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2011,2013-2014,2019, The Linux Foundation. All rights reserved.
+ */
+
+#ifdef CONFIG_QCOM_RUN_QUEUE_STATS
+
+struct rq_data {
+	unsigned long def_timer_jiffies;
+	unsigned long def_timer_last_jiffy;
+	int64_t def_start_time;
+	struct attribute_group *attr_group;
+	struct kobject *kobj;
+	struct work_struct def_timer_work;
+	int init;
+};
+
+extern struct rq_data rq_info;
+extern struct workqueue_struct *rq_wq;
+extern spinlock_t rq_lock;
+
+#endif

kernel/time/tick-sched.c

@@ -23,6 +23,7 @@
 #include <linux/module.h>
 #include <linux/irq_work.h>
 #include <linux/posix-timers.h>
+#include <linux/rq_stats.h>
 #include <linux/timer.h>
 #include <linux/context_tracking.h>
 #include <linux/mm.h>
@@ -1284,6 +1285,18 @@ void tick_irq_enter(void)
  * High resolution timer specific code
  */
 #ifdef CONFIG_HIGH_RES_TIMERS
+#ifdef CONFIG_QCOM_RUN_QUEUE_STATS
+static void wakeup_user(void)
+{
+	unsigned long jiffy_gap;
+
+	jiffy_gap = jiffies - rq_info.def_timer_last_jiffy;
+	if (jiffy_gap >= rq_info.def_timer_jiffies) {
+		rq_info.def_timer_last_jiffy = jiffies;
+		queue_work(rq_wq, &rq_info.def_timer_work);
+	}
+}
+#endif
 /*
  * We rearm the timer until we get disabled by the idle code.
  * Called with interrupts disabled.
@@ -1301,8 +1314,18 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
 	 * Do not call, when we are not in irq context and have
 	 * no valid regs pointer
 	 */
-	if (regs)
+	if (regs) {
 		tick_sched_handle(ts, regs);
+#ifdef CONFIG_QCOM_RUN_QUEUE_STATS
+		if (rq_info.init == 1 &&
+				tick_do_timer_cpu == smp_processor_id()) {
+			/*
+			 * wakeup user if needed
+			 */
+			wakeup_user();
+		}
+#endif
+	}
 	else
 		ts->next_tick = 0;