Revert "i2c: Replace list-based mechanism for handling userspace-created clients"

This reverts commit 3cfe39b. Mux
handling is not sufficiently implemented. It needs more time.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Author: Wolfram Sang

drivers/i2c/i2c-core-base.c

@@ -1300,28 +1300,21 @@ new_device_store(struct device *dev, struct device_attribute *attr,
 		info.flags |= I2C_CLIENT_SLAVE;
 	}
 
-	info.flags |= I2C_CLIENT_USER;
-
 	client = i2c_new_client_device(adap, &info);
 	if (IS_ERR(client))
 		return PTR_ERR(client);
 
+	/* Keep track of the added device */
+	mutex_lock(&adap->userspace_clients_lock);
+	list_add_tail(&client->detected, &adap->userspace_clients);
+	mutex_unlock(&adap->userspace_clients_lock);
 	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
 		 info.type, info.addr);
 
 	return count;
 }
 static DEVICE_ATTR_WO(new_device);
 
-static int __i2c_find_user_addr(struct device *dev, const void *addrp)
-{
-	struct i2c_client *client = i2c_verify_client(dev);
-	unsigned short addr = *(unsigned short *)addrp;
-
-	return client && client->flags & I2C_CLIENT_USER &&
-	       i2c_encode_flags_to_addr(client) == addr;
-}
-
 /*
  * And of course let the users delete the devices they instantiated, if
  * they got it wrong. This interface can only be used to delete devices
@@ -1336,7 +1329,7 @@ delete_device_store(struct device *dev, struct device_attribute *attr,
 		    const char *buf, size_t count)
 {
 	struct i2c_adapter *adap = to_i2c_adapter(dev);
-	struct device *child_dev;
+	struct i2c_client *client, *next;
 	unsigned short addr;
 	char end;
 	int res;
@@ -1352,19 +1345,28 @@ delete_device_store(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 	}
 
-	mutex_lock(&core_lock);
 	/* Make sure the device was added through sysfs */
-	child_dev = device_find_child(&adap->dev, &addr, __i2c_find_user_addr);
-	if (child_dev) {
-		i2c_unregister_device(i2c_verify_client(child_dev));
-		put_device(child_dev);
-	} else {
-		dev_err(dev, "Can't find userspace-created device at %#x\n", addr);
-		count = -ENOENT;
+	res = -ENOENT;
+	mutex_lock_nested(&adap->userspace_clients_lock,
+			  i2c_adapter_depth(adap));
+	list_for_each_entry_safe(client, next, &adap->userspace_clients,
+				 detected) {
+		if (i2c_encode_flags_to_addr(client) == addr) {
+			dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
+				 "delete_device", client->name, client->addr);
+
+			list_del(&client->detected);
+			i2c_unregister_device(client);
+			res = count;
+			break;
+		}
 	}
-	mutex_unlock(&core_lock);
+	mutex_unlock(&adap->userspace_clients_lock);
 
-	return count;
+	if (res < 0)
+		dev_err(dev, "%s: Can't find device in list\n",
+			"delete_device");
+	return res;
 }
 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
 				  delete_device_store);
@@ -1535,6 +1537,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	adap->locked_flags = 0;
 	rt_mutex_init(&adap->bus_lock);
 	rt_mutex_init(&adap->mux_lock);
+	mutex_init(&adap->userspace_clients_lock);
+	INIT_LIST_HEAD(&adap->userspace_clients);
 
 	/* Set default timeout to 1 second if not already set */
 	if (adap->timeout == 0)
@@ -1726,6 +1730,7 @@ static int __unregister_dummy(struct device *dev, void *dummy)
 void i2c_del_adapter(struct i2c_adapter *adap)
 {
 	struct i2c_adapter *found;
+	struct i2c_client *client, *next;
 
 	/* First make sure that this adapter was ever added */
 	mutex_lock(&core_lock);
@@ -1738,6 +1743,18 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 
 	i2c_acpi_remove_space_handler(adap);
 
+	/* Remove devices instantiated from sysfs */
+	mutex_lock_nested(&adap->userspace_clients_lock,
+			  i2c_adapter_depth(adap));
+	list_for_each_entry_safe(client, next, &adap->userspace_clients,
+				 detected) {
+		dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
+			client->addr);
+		list_del(&client->detected);
+		i2c_unregister_device(client);
+	}
+	mutex_unlock(&adap->userspace_clients_lock);
+
 	/* Detach any active clients. This can't fail, thus we do not
 	 * check the returned value. This is a two-pass process, because
 	 * we can't remove the dummy devices during the first pass: they

include/linux/i2c.h

@@ -313,6 +313,8 @@ struct i2c_driver {
  * @dev: Driver model device node for the slave.
  * @init_irq: IRQ that was set at initialization
  * @irq: indicates the IRQ generated by this device (if any)
+ * @detected: member of an i2c_driver.clients list or i2c-core's
+ *	userspace_devices list
  * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
  *	calls it to pass on slave events to the slave driver.
  * @devres_group_id: id of the devres group that will be created for resources
@@ -333,7 +335,6 @@ struct i2c_client {
 #define I2C_CLIENT_HOST_NOTIFY	0x40	/* We want to use I2C host notify */
 #define I2C_CLIENT_WAKE		0x80	/* for board_info; true iff can wake */
 #define I2C_CLIENT_AUTO		0x100	/* client was auto-detected */
-#define I2C_CLIENT_USER		0x200	/* client was userspace-created */
 #define I2C_CLIENT_SCCB		0x9000	/* Use Omnivision SCCB protocol */
 					/* Must match I2C_M_STOP|IGNORE_NAK */
 
@@ -345,6 +346,7 @@ struct i2c_client {
 	struct device dev;		/* the device structure		*/
 	int init_irq;			/* irq set at initialization	*/
 	int irq;			/* irq issued by device		*/
+	struct list_head detected;
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	i2c_slave_cb_t slave_cb;	/* callback for slave mode	*/
 #endif
@@ -751,6 +753,9 @@ struct i2c_adapter {
 	char name[48];
 	struct completion dev_released;
 
+	struct mutex userspace_clients_lock;
+	struct list_head userspace_clients;
+
 	struct i2c_bus_recovery_info *bus_recovery_info;
 	const struct i2c_adapter_quirks *quirks;