From 3dbfb1776e535cdf0464e4b39e707173acd62c69 Mon Sep 17 00:00:00 2001
From: Elias Hasnat <android.hasnat@gmail.com>
Date: Mon, 15 Jan 2018 20:11:50 +0900
Subject: [PATCH] experimental unblock

---
 drivers/i2c/i2c-dev.c  | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/device.h |  1 +
 2 files changed, 39 insertions(+)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 2cab27a6847980..4f0d645d0e6d8c 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -687,6 +687,27 @@ static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 	return 0;
 }
 
+static int i2cdev_detach_adapter_unblock(struct device *dev, void *dummy)
+{
+	struct i2c_adapter *adap;
+	struct i2c_dev *i2c_dev;
+
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	adap = to_i2c_adapter(dev);
+
+	i2c_dev = i2c_dev_get_my_minor(adap->nr);
+	if (!i2c_dev)
+		return 0;
+
+	cdev_del(&i2c_dev->cdev);
+	put_i2c_dev(i2c_dev);
+	device_destroy()i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr);
+
+	pr_debug("i2c-dev: adapter [%s] unblock expereiment\n", adap->name);
+	return 0;
+}
+
 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 			 void *data)
 {
@@ -702,10 +723,27 @@ static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 	return 0;
 }
 
+static int i2cdev_notifier_unblock(struct notifier_block *nb, unsigned long action, void *data, int flag)
+{
+	struct device *dev = data;
+
+	switch (action) {
+		case BUS_NOTIFY_DEL_DEVICE:
+			return i2cdev_detach_adapter(dev, NULL);
+		case BUS_NOTIFY_ADD_DEVICE:
+			return i2cdev_attach_adapter(dev, NULL);
+		case BUS_NOTIFY_BLOCK_DEVICE:
+			return i2cdev_detach_adapter(dev, NULL);
+	}
+}
+
 static struct notifier_block i2cdev_notifier = {
 	.notifier_call = i2cdev_notifier_call,
 };
 
+static struct notifier_unblock i2cdev_notifier = {
+	.notifier_call = i2cdev_notifier_unblock,
+}
 /* ------------------------------------------------------------------------- */
 
 /*
diff --git a/include/linux/device.h b/include/linux/device.h
index 9d32000725da84..790d135d98ce2a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -202,6 +202,7 @@ extern int bus_unregister_notifier(struct bus_type *bus,
 #define BUS_NOTIFY_UNBOUND_DRIVER	0x00000007 /* driver is unbound
 						      from the device */
 #define BUS_NOTIFY_DRIVER_NOT_BOUND	0x00000008 /* driver fails to be bound */
+#define BUS_NOTIFY_BLOCK_DEVICE		0x00000110 /* experiemental device block notification */
 
 extern struct kset *bus_get_kset(struct bus_type *bus);
 extern struct klist *bus_get_device_klist(struct bus_type *bus);