i2c: atr: split up i2c_atr_get_mapping_by_addr()

The i2c_atr_get_mapping_by_addr() function handles three separate
usecases: finding an existing mapping, creating a new mapping, or
replacing an existing mapping if a new mapping cannot be created
because there aren't enough aliases available.

Split up the function into three different functions handling its
individual usecases to prepare for better usage of each one.

Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Author: Demon000

drivers/i2c/i2c-atr.c

@@ -239,56 +239,40 @@ static void i2c_atr_release_alias(struct i2c_atr_alias_pool *alias_pool, u16 ali
 	spin_unlock(&alias_pool->lock);
 }
 
-/* Must be called with alias_pairs_lock held */
 static struct i2c_atr_alias_pair *
-i2c_atr_get_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
+i2c_atr_find_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
 {
-	struct i2c_atr *atr = chan->atr;
 	struct i2c_atr_alias_pair *c2a;
-	struct list_head *alias_pairs;
-	bool found = false;
-	u16 alias;
-	int ret;
 
 	lockdep_assert_held(&chan->alias_pairs_lock);
 
-	alias_pairs = &chan->alias_pairs;
-
-	list_for_each_entry(c2a, alias_pairs, node) {
+	list_for_each_entry(c2a, &chan->alias_pairs, node) {
 		if (c2a->addr == addr)
 			return c2a;
 	}
 
-	ret = i2c_atr_reserve_alias(chan->alias_pool);
-	if (ret < 0) {
-		// If no free aliases are left, replace an existing one
-		if (unlikely(list_empty(alias_pairs)))
-			return NULL;
-
-		list_for_each_entry_reverse(c2a, alias_pairs, node) {
-			if (!c2a->fixed) {
-				found = true;
-				break;
-			}
-		}
+	return NULL;
+}
 
-		if (!found)
-			return NULL;
+static struct i2c_atr_alias_pair *
+i2c_atr_create_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
+{
+	struct i2c_atr *atr = chan->atr;
+	struct i2c_atr_alias_pair *c2a;
+	u16 alias;
+	int ret;
 
-		atr->ops->detach_addr(atr, chan->chan_id, c2a->addr);
-		c2a->addr = addr;
+	lockdep_assert_held(&chan->alias_pairs_lock);
 
-		// Move updated entry to beginning of list
-		list_move(&c2a->node, alias_pairs);
+	ret = i2c_atr_reserve_alias(chan->alias_pool);
+	if (ret < 0)
+		return NULL;
 
-		alias = c2a->alias;
-	} else {
-		alias = ret;
+	alias = ret;
 
-		c2a = i2c_atr_create_c2a(chan, alias, addr);
-		if (!c2a)
-			goto err_release_alias;
-	}
+	c2a = i2c_atr_create_c2a(chan, alias, addr);
+	if (!c2a)
+		goto err_release_alias;
 
 	ret = atr->ops->attach_addr(atr, chan->chan_id, c2a->addr, c2a->alias);
 	if (ret) {
@@ -306,6 +290,68 @@ i2c_atr_get_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
 	return NULL;
 }
 
+static struct i2c_atr_alias_pair *
+i2c_atr_replace_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
+{
+	struct i2c_atr *atr = chan->atr;
+	struct i2c_atr_alias_pair *c2a;
+	struct list_head *alias_pairs;
+	bool found = false;
+	u16 alias;
+	int ret;
+
+	lockdep_assert_held(&chan->alias_pairs_lock);
+
+	alias_pairs = &chan->alias_pairs;
+
+	if (unlikely(list_empty(alias_pairs)))
+		return NULL;
+
+	list_for_each_entry_reverse(c2a, alias_pairs, node) {
+		if (!c2a->fixed) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found)
+		return NULL;
+
+	atr->ops->detach_addr(atr, chan->chan_id, c2a->addr);
+	c2a->addr = addr;
+
+	list_move(&c2a->node, alias_pairs);
+
+	alias = c2a->alias;
+
+	ret = atr->ops->attach_addr(atr, chan->chan_id, c2a->addr, c2a->alias);
+	if (ret) {
+		dev_err(atr->dev, "failed to attach 0x%02x on channel %d: err %d\n",
+			addr, chan->chan_id, ret);
+		i2c_atr_destroy_c2a(&c2a);
+		i2c_atr_release_alias(chan->alias_pool, alias);
+		return NULL;
+	}
+
+	return c2a;
+}
+
+static struct i2c_atr_alias_pair *
+i2c_atr_get_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
+{
+	struct i2c_atr_alias_pair *c2a;
+
+	c2a = i2c_atr_find_mapping_by_addr(chan, addr);
+	if (c2a)
+		return c2a;
+
+	c2a = i2c_atr_create_mapping_by_addr(chan, addr);
+	if (c2a)
+		return c2a;
+
+	return i2c_atr_replace_mapping_by_addr(chan, addr);
+}
+
 /*
  * Replace all message addresses with their aliases, saving the original
  * addresses.