i2c: use client addresses directly in ATR interface

The I2C Address Translator (ATR) module defines mappings from i2c_client
structs to aliases. However, only the physical address of each i2c_client
struct is actually relevant to the workings of the ATR module. Moreover,
some drivers require address translation functionality but do not allocate
i2c_client structs, accessing the adapter directly instead. The SFP
subsystem is an example of this.

Replace the "i2c_client" field of the i2c_atr_alias_pair struct with a u16
"addr" field. Rewrite helper functions and callbacks as needed.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

1 files changed, 19 insertions, 33 deletions

diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
index 8fe9ddff8e96..118fd7d764dc 100644
--- a/drivers/i2c/i2c-atr.c
+++ b/drivers/i2c/i2c-atr.c
@@ -21,16 +21,16 @@
 #define ATR_MAX_SYMLINK_LEN 11	/* Longest name is 10 chars: "channel-99" */
 
 /**
- * struct i2c_atr_alias_pair - Holds the alias assigned to a client.
+ * struct i2c_atr_alias_pair - Holds the alias assigned to a client address.
  * @node:   List node
- * @client: Pointer to the client on the child bus
+ * @addr:   Address of the client on the child bus.
  * @alias:  I2C alias address assigned by the driver.
  *          This is the address that will be used to issue I2C transactions
  *          on the parent (physical) bus.
  */
 struct i2c_atr_alias_pair {
 	struct list_head node;
-	const struct i2c_client *client;
+	u16 addr;
 	u16 alias;
 };
 
@@ -98,26 +98,12 @@ struct i2c_atr {
 };
 
 static struct i2c_atr_alias_pair *
-i2c_atr_find_mapping_by_client(const struct list_head *list,
-			       const struct i2c_client *client)
-{
-	struct i2c_atr_alias_pair *c2a;
-
-	list_for_each_entry(c2a, list, node) {
-		if (c2a->client == client)
-			return c2a;
-	}
-
-	return NULL;
-}
-
-static struct i2c_atr_alias_pair *
 i2c_atr_find_mapping_by_addr(const struct list_head *list, u16 phys_addr)
 {
 	struct i2c_atr_alias_pair *c2a;
 
 	list_for_each_entry(c2a, list, node) {
-		if (c2a->client->addr == phys_addr)
+		if (c2a->addr == phys_addr)
 			return c2a;
 	}
 
@@ -313,8 +299,8 @@ static void i2c_atr_release_alias(struct i2c_atr *atr, u16 alias)
 	dev_warn(atr->dev, "Unable to find mapped alias\n");
 }
 
-static int i2c_atr_attach_client(struct i2c_adapter *adapter,
-				 const struct i2c_client *client)
+static int i2c_atr_attach_addr(struct i2c_adapter *adapter,
+			       u16 addr)
 {
 	struct i2c_atr_chan *chan = adapter->algo_data;
 	struct i2c_atr *atr = chan->atr;
@@ -334,14 +320,14 @@ static int i2c_atr_attach_client(struct i2c_adapter *adapter,
 		goto err_release_alias;
 	}
 
-	ret = atr->ops->attach_client(atr, chan->chan_id, client, alias);
+	ret = atr->ops->attach_addr(atr, chan->chan_id, addr, alias);
 	if (ret)
 		goto err_free;
 
-	dev_dbg(atr->dev, "chan%u: client 0x%02x mapped at alias 0x%02x (%s)\n",
-		chan->chan_id, client->addr, alias, client->name);
+	dev_dbg(atr->dev, "chan%u: using alias 0x%02x for addr 0x%02x\n",
+		chan->chan_id, alias, addr);
 
-	c2a->client = client;
+	c2a->addr = addr;
 	c2a->alias = alias;
 	list_add(&c2a->node, &chan->alias_list);
 
@@ -355,16 +341,16 @@ err_release_alias:
 	return ret;
 }
 
-static void i2c_atr_detach_client(struct i2c_adapter *adapter,
-				  const struct i2c_client *client)
+static void i2c_atr_detach_addr(struct i2c_adapter *adapter,
+				u16 addr)
 {
 	struct i2c_atr_chan *chan = adapter->algo_data;
 	struct i2c_atr *atr = chan->atr;
 	struct i2c_atr_alias_pair *c2a;
 
-	atr->ops->detach_client(atr, chan->chan_id, client);
+	atr->ops->detach_addr(atr, chan->chan_id, addr);
 
-	c2a = i2c_atr_find_mapping_by_client(&chan->alias_list, client);
+	c2a = i2c_atr_find_mapping_by_addr(&chan->alias_list, addr);
 	if (!c2a) {
 		 /* This should never happen */
 		dev_warn(atr->dev, "Unable to find address mapping\n");
@@ -374,8 +360,8 @@ static void i2c_atr_detach_client(struct i2c_adapter *adapter,
 	i2c_atr_release_alias(atr, c2a->alias);
 
 	dev_dbg(atr->dev,
-		"chan%u: client 0x%02x unmapped from alias 0x%02x (%s)\n",
-		chan->chan_id, client->addr, c2a->alias, client->name);
+		"chan%u: detached alias 0x%02x from addr 0x%02x\n",
+		chan->chan_id, c2a->alias, addr);
 
 	list_del(&c2a->node);
 	kfree(c2a);
@@ -405,7 +391,7 @@ static int i2c_atr_bus_notifier_call(struct notifier_block *nb,
 
 	switch (event) {
 	case BUS_NOTIFY_ADD_DEVICE:
-		ret = i2c_atr_attach_client(client->adapter, client);
+		ret = i2c_atr_attach_addr(client->adapter, client->addr);
 		if (ret)
 			dev_err(atr->dev,
 				"Failed to attach remote client '%s': %d\n",
@@ -413,7 +399,7 @@ static int i2c_atr_bus_notifier_call(struct notifier_block *nb,
 		break;
 
 	case BUS_NOTIFY_REMOVED_DEVICE:
-		i2c_atr_detach_client(client->adapter, client);
+		i2c_atr_detach_addr(client->adapter, client->addr);
 		break;
 
 	default:
@@ -506,7 +492,7 @@ struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
 	if (max_adapters > ATR_MAX_ADAPTERS)
 		return ERR_PTR(-EINVAL);
 
-	if (!ops || !ops->attach_client || !ops->detach_client)
+	if (!ops || !ops->attach_addr || !ops->detach_addr)
 		return ERR_PTR(-EINVAL);
 
 	atr = kzalloc(struct_size(atr, adapter, max_adapters), GFP_KERNEL);