soc: qcom: irq_helper: Add irq helper module

This module provides two APIs which are used to control a boolean
sysfs entry deploy. The irq balancer's blacklist in user space will be
controlled by this sysfs entry.

CRs-Fixed: 1013201
Change-Id: Ie6ec7211c64f3c4f53b9f590e5bcf5fa1937d594
Signed-off-by: Runmin Wang <runminw@codeaurora.org>

drivers/soc/qcom/Kconfig

@@ -374,6 +374,15 @@ config QCOM_WATCHDOG_V2
 	  deadlocks. It does not run during the bootup process, so it will
 	  not catch any early lockups.
 
+config QCOM_IRQ_HELPER
+	bool "QCOM Irq Helper"
+	help
+	  This enables the irq helper module. It exposes two APIs
+	  int irq_blacklist_on(void) and int irq_blacklist_off(void)
+	  to other kernel module.
+	  These two apis will be used to control the black list used
+	  by the irq balancer.
+
 config QCOM_MEMORY_DUMP
 	bool "Qualcomm Memory Dump Support"
 	help

drivers/soc/qcom/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_QCOM_MEMORY_DUMP_V2) += memory_dump_v2.o
 obj-$(CONFIG_QCOM_DCC) += dcc.o
 obj-$(CONFIG_QCOM_WATCHDOG_V2) += watchdog_v2.o
 obj-$(CONFIG_QCOM_COMMON_LOG) += common_log.o
+obj-$(CONFIG_QCOM_IRQ_HELPER) += irq-helper.o
 obj-$(CONFIG_TRACER_PKT)	+=	tracer_pkt.o
 obj-$(CONFIG_ICNSS) += icnss.o wlan_firmware_service_v01.o
 obj-$(CONFIG_SOC_BUS)  +=      socinfo.o

drivers/soc/qcom/irq-helper.c

@@ -0,0 +1,179 @@
+/* Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/cpu.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+
+struct irq_helper {
+	bool enable;
+	bool deploy;
+	uint32_t count;
+	struct kobject kobj;
+	/* spinlock to protect reference count variable 'count' */
+	spinlock_t lock;
+};
+
+struct irq_helper_attr {
+	struct attribute        attr;
+	ssize_t (*show)(struct kobject *kobj, struct attribute *attr,
+			char *buf);
+	size_t (*store)(struct kobject *kobj, struct attribute *attr,
+			const char *buf, size_t count);
+};
+
+#define IRQ_HELPER_ATTR(_name, _mode, _show, _store)    \
+	struct irq_helper_attr irq_helper_##_name =  \
+		__ATTR(_name, _mode, _show, _store)
+
+#define to_irq_helper(kobj) \
+	container_of(kobj, struct irq_helper, kobj)
+
+#define to_irq_helper_attr(_attr) \
+	container_of(_attr, struct irq_helper_attr, attr)
+
+static ssize_t attr_show(struct kobject *kobj, struct attribute *attr,
+		char *buf)
+{
+	struct irq_helper_attr *irq_attr = to_irq_helper_attr(attr);
+	ssize_t ret = -EIO;
+
+	if (irq_attr->show)
+		ret = irq_attr->show(kobj, attr, buf);
+
+	return ret;
+}
+
+static const struct sysfs_ops irq_helper_sysfs_ops = {
+	.show   = attr_show,
+};
+
+static struct kobj_type irq_helper_ktype = {
+	.sysfs_ops  = &irq_helper_sysfs_ops,
+};
+
+static ssize_t show_deploy(struct kobject *kobj, struct attribute *attr,
+		char *buf)
+{
+	struct irq_helper *irq = to_irq_helper(kobj);
+
+	return snprintf(buf, sizeof(irq->deploy), "%u\n", irq->deploy);
+}
+IRQ_HELPER_ATTR(irq_blacklist_on, 0444, show_deploy, NULL);
+
+static struct irq_helper *irq_h;
+
+int irq_blacklist_on(void)
+{
+	bool flag = false;
+
+	if (!irq_h) {
+		pr_err("%s: init function is not called", __func__);
+		return -EPERM;
+	}
+	if (!irq_h->enable) {
+		pr_err("%s: enable bit is not set up", __func__);
+		return -EPERM;
+	}
+	spin_lock(&irq_h->lock);
+	irq_h->count++;
+	if (!irq_h->deploy) {
+		irq_h->deploy = true;
+		flag = true;
+	}
+	spin_unlock(&irq_h->lock);
+	if (flag)
+		sysfs_notify(&irq_h->kobj, NULL, "irq_blacklist_on");
+	return 0;
+}
+EXPORT_SYMBOL(irq_blacklist_on);
+
+int irq_blacklist_off(void)
+{
+	bool flag = false;
+
+	if (!irq_h) {
+		pr_err("%s: init function is not called", __func__);
+		return -EPERM;
+	}
+	if (!irq_h->enable) {
+		pr_err("%s: enable bit is not set up", __func__);
+		return -EPERM;
+	}
+	spin_lock(&irq_h->lock);
+	if (irq_h->count == 0) {
+		pr_err("%s: ref-count is 0, cannot call irq blacklist off.",
+				__func__);
+		spin_unlock(&irq_h->lock);
+		return -EPERM;
+	}
+	irq_h->count--;
+	if (irq_h->count == 0) {
+		irq_h->deploy = false;
+		flag = true;
+	}
+	spin_unlock(&irq_h->lock);
+
+	if (flag)
+		sysfs_notify(&irq_h->kobj, NULL, "irq_blacklist_on");
+	return 0;
+}
+EXPORT_SYMBOL(irq_blacklist_off);
+
+static int __init irq_helper_init(void)
+{
+	int ret;
+
+	irq_h = kzalloc(sizeof(struct irq_helper), GFP_KERNEL);
+	if (!irq_h)
+		return -ENOMEM;
+
+	ret = kobject_init_and_add(&irq_h->kobj, &irq_helper_ktype,
+			kernel_kobj,  "%s", "irq_helper");
+	if (ret) {
+		pr_err("%s:Error in creation kobject_add\n", __func__);
+		goto out_free_irq;
+	}
+
+	ret = sysfs_create_file(&irq_h->kobj,
+			&irq_helper_irq_blacklist_on.attr);
+	if (ret) {
+		pr_err("%s:Error in sysfs_create_file\n", __func__);
+		goto out_put_kobj;
+	}
+
+	spin_lock_init(&irq_h->lock);
+	irq_h->count = 0;
+	irq_h->enable = true;
+	return 0;
+out_put_kobj:
+	koject_put(&irq_h->kobj);
+out_free_irq:
+	kfree(irq_h);
+	return ret;
+}
+module_init(irq_helper_init);
+
+static void __exit irq_helper_exit(void)
+{
+	sysfs_remove_file(&irq_h->kobj, &irq_helper_irq_blacklist_on.attr);
+	kobject_del(&irq_h->kobj);
+	kobject_put(&irq_h->kobj);
+	kfree(irq_h);
+}
+module_exit(irq_helper_exit);
+MODULE_DESCRIPTION("IRQ Helper APIs");