samsung: Add state notifier driver

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: Luca Grifo <lg@linux.com>
Signed-off-by: djb77 <dwayne.bakewell@gmail.com>

drivers/soc/samsung/Kconfig

@@ -176,6 +176,10 @@ config EXYNOS_DVFS_MANAGER
 	  Enable DVFS Manager for Exynos SoC.
 	  This module controls constraint between each DVFS domains.
 
+config STATE_NOTIFIER
+	bool "State Notifier"
+	default n
+
 endif #SOC_SAMSUNG
 
 config SEC_INCELL

drivers/soc/samsung/Makefile

@@ -57,3 +57,6 @@ obj-$(CONFIG_EXYNOS_HDCP2)	+= exynos-hdcp/
 
 #incell
 obj-$(CONFIG_SEC_INCELL) += sec_incell.o
+
+# state notifier
+obj-$(CONFIG_STATE_NOTIFIER)	+= state_notifier.o

drivers/soc/samsung/state_notifier.c

@@ -0,0 +1,129 @@
+/*
+ * State Notifier Driver
+ *
+ * Copyright (c) 2013-2016, Pranav Vashi <neobuddy89@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/state_notifier.h>
+
+#define DEFAULT_SUSPEND_DEFER_TIME 	10
+#define STATE_NOTIFIER			"state_notifier"
+
+/*
+ * debug = 1 will print all
+ */
+static unsigned int debug = 1;
+module_param_named(debug_mask, debug, uint, 0644);
+
+#define dprintk(msg...)		\
+do {				\
+	if (debug)		\
+		pr_info(msg);	\
+} while (0)
+
+static bool enabled = 1;
+module_param_named(enabled, enabled, bool, 0664);
+static unsigned int suspend_defer_time = DEFAULT_SUSPEND_DEFER_TIME;
+module_param_named(suspend_defer_time, suspend_defer_time, uint, 0664);
+static struct delayed_work suspend_work;
+static struct workqueue_struct *susp_wq;
+struct work_struct resume_work;
+bool state_suspended;
+module_param_named(state_suspended, state_suspended, bool, 0444);
+static bool suspend_in_progress;
+
+static BLOCKING_NOTIFIER_HEAD(state_notifier_list);
+
+/**
+ *	state_register_client - register a client notifier
+ *	@nb: notifier block to callback on events
+ */
+int state_register_client(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&state_notifier_list, nb);
+}
+EXPORT_SYMBOL(state_register_client);
+
+/**
+ *	state_unregister_client - unregister a client notifier
+ *	@nb: notifier block to callback on events
+ */
+int state_unregister_client(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&state_notifier_list, nb);
+}
+EXPORT_SYMBOL(state_unregister_client);
+
+/**
+ *	state_notifier_call_chain - notify clients on state_events
+ *	@val: Value passed unmodified to notifier function
+ *	@v: pointer passed unmodified to notifier function
+ *
+ */
+int state_notifier_call_chain(unsigned long val, void *v)
+{
+	return blocking_notifier_call_chain(&state_notifier_list, val, v);
+}
+EXPORT_SYMBOL_GPL(state_notifier_call_chain);
+
+static void _suspend_work(struct work_struct *work)
+{
+	state_suspended = true;
+	state_notifier_call_chain(STATE_NOTIFIER_SUSPEND, NULL);
+	suspend_in_progress = false;
+	dprintk("%s: suspend completed.\n", STATE_NOTIFIER);
+}
+
+static void _resume_work(struct work_struct *work)
+{
+	state_suspended = false;
+	state_notifier_call_chain(STATE_NOTIFIER_ACTIVE, NULL);
+	dprintk("%s: resume completed.\n", STATE_NOTIFIER);
+}
+
+void state_suspend(void)
+{
+	dprintk("%s: suspend called.\n", STATE_NOTIFIER);
+	if (state_suspended || suspend_in_progress || !enabled)
+		return;
+
+	suspend_in_progress = true;
+
+	queue_delayed_work_on(0, susp_wq, &suspend_work, 
+		msecs_to_jiffies(suspend_defer_time * 1000));
+}
+
+void state_resume(void)
+{
+	dprintk("%s: resume called.\n", STATE_NOTIFIER);
+	cancel_delayed_work_sync(&suspend_work);
+	suspend_in_progress = false;
+
+	if (state_suspended)
+		queue_work_on(0, susp_wq, &resume_work);
+}
+
+static int __init state_notifier_init(void)
+{
+	susp_wq = create_singlethread_workqueue("state_susp_wq");
+	if (!susp_wq)
+		pr_err("State Notifier failed to allocate suspend workqueue\n");
+
+	INIT_DELAYED_WORK(&suspend_work, _suspend_work);
+	INIT_WORK(&resume_work, _resume_work);
+
+	return 0;
+}
+
+subsys_initcall(state_notifier_init);
+
+MODULE_AUTHOR("Pranav Vashi <neobuddy89@gmail.com>");
+MODULE_DESCRIPTION("State Notifier Driver");
+MODULE_LICENSE("GPLv2");

include/linux/state_notifier.h

@@ -0,0 +1,20 @@
+#ifndef __LINUX_STATE_NOTIFIER_H
+#define __LINUX_STATE_NOTIFIER_H
+
+#include <linux/notifier.h>
+
+#define STATE_NOTIFIER_ACTIVE		0x01
+#define STATE_NOTIFIER_SUSPEND		0x02
+
+struct state_event {
+	void *data;
+};
+
+extern bool state_suspended;
+extern void state_suspend(void);
+extern void state_resume(void);
+int state_register_client(struct notifier_block *nb);
+int state_unregister_client(struct notifier_block *nb);
+int state_notifier_call_chain(unsigned long val, void *v);
+
+#endif /* _LINUX_STATE_NOTIFIER_H */