soc: qcom: Add snapshot of rq_stats driver

This is a snapshot of the rq_stats driver as of msm-5.15
commit <908a517b050d> ("Merge "sched/walt: remove duplicate
definitions of rt_task_arrival_time"").

Change-Id: I83cc75fe4dcbb843810628825df7ef0d5516b2bb
Signed-off-by: Huang Yiwei <quic_hyiwei@quicinc.com>

drivers/soc/qcom/Kconfig

@@ -136,6 +136,14 @@ config QCOM_RPMPD
 	  value to RPM which then translates it into corresponding voltage
 	  for the voltage rail.
 
+config QCOM_RUN_QUEUE_STATS
+       tristate "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_SMEM
 	tristate "Qualcomm Shared Memory Manager (SMEM)"
 	depends on ARCH_QCOM || COMPILE_TEST

drivers/soc/qcom/Makefile

@@ -29,3 +29,4 @@ obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o
 obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
 obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
 obj-$(CONFIG_MSM_BOOT_STATS) += boot_stats.o
+obj-$(CONFIG_QCOM_RUN_QUEUE_STATS) += rq_stats.o

drivers/soc/qcom/rq_stats.c

@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2010-2015, 2017, 2019-2021, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+#include <trace/hooks/sched.h>
+
+#define MAX_LONG_SIZE 24
+#define DEFAULT_DEF_TIMER_JIFFIES 5
+
+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;
+};
+
+static struct rq_data rq_info;
+static struct workqueue_struct *rq_wq;
+spinlock_t rq_lock;
+
+static void wakeup_user(void *ignore, void *extra)
+{
+	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);
+	}
+}
+
+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 scnprintf(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 */
+	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();
+
+	register_trace_android_vh_jiffies_update(wakeup_user, NULL);
+
+	return ret;
+}
+late_initcall(msm_rq_stats_init);
+
+static __exit void msm_rq_stats_exit(void)
+{
+	destroy_workqueue(rq_wq);
+	kobject_del(rq_info.kobj);
+}
+module_exit(msm_rq_stats_exit);
+
+MODULE_DESCRIPTION("QCOM Run Queue Stats");
+MODULE_LICENSE("GPL v2");