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 <[email protected]>
Tested-by: Tomi Valkeinen <[email protected]>
Signed-off-by: Romain Gantois <[email protected]>
Acked-by: Andi Shyti <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Author: rgantois

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;
 };
 
@@ -97,27 +97,13 @@ struct i2c_atr {
 	struct i2c_adapter *adapter[] __counted_by(max_adapters);
 };
 
-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 @@ static int i2c_atr_attach_client(struct i2c_adapter *adapter,
 	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);
@@ -405,15 +391,15 @@ 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",
 				dev_name(dev), ret);
 		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);

drivers/media/i2c/ds90ub960.c

@@ -1049,8 +1049,8 @@ static int ub960_ind_update_bits(struct ub960_data *priv, u8 block, u8 reg,
  * I2C-ATR (address translator)
  */
 
-static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id,
-				   const struct i2c_client *client, u16 alias)
+static int ub960_atr_attach_addr(struct i2c_atr *atr, u32 chan_id,
+				 u16 addr, u16 alias)
 {
 	struct ub960_data *priv = i2c_atr_get_driver_data(atr);
 	struct ub960_rxport *rxport = priv->rxports[chan_id];
@@ -1069,21 +1069,21 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id,
 		return -EADDRNOTAVAIL;
 	}
 
-	rxport->aliased_addrs[reg_idx] = client->addr;
+	rxport->aliased_addrs[reg_idx] = addr;
 
 	ub960_rxport_write(priv, chan_id, UB960_RR_SLAVE_ID(reg_idx),
-			   client->addr << 1);
+			   addr << 1);
 	ub960_rxport_write(priv, chan_id, UB960_RR_SLAVE_ALIAS(reg_idx),
 			   alias << 1);
 
 	dev_dbg(dev, "rx%u: client 0x%02x assigned alias 0x%02x at slot %u\n",
-		rxport->nport, client->addr, alias, reg_idx);
+		rxport->nport, addr, alias, reg_idx);
 
 	return 0;
 }
 
-static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id,
-				    const struct i2c_client *client)
+static void ub960_atr_detach_addr(struct i2c_atr *atr, u32 chan_id,
+				  u16 addr)
 {
 	struct ub960_data *priv = i2c_atr_get_driver_data(atr);
 	struct ub960_rxport *rxport = priv->rxports[chan_id];
@@ -1093,13 +1093,13 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id,
 	guard(mutex)(&rxport->aliased_addrs_lock);
 
 	for (reg_idx = 0; reg_idx < ARRAY_SIZE(rxport->aliased_addrs); reg_idx++) {
-		if (rxport->aliased_addrs[reg_idx] == client->addr)
+		if (rxport->aliased_addrs[reg_idx] == addr)
 			break;
 	}
 
 	if (reg_idx == ARRAY_SIZE(rxport->aliased_addrs)) {
 		dev_err(dev, "rx%u: client 0x%02x is not mapped!\n",
-			rxport->nport, client->addr);
+			rxport->nport, addr);
 		return;
 	}
 
@@ -1108,12 +1108,12 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id,
 	ub960_rxport_write(priv, chan_id, UB960_RR_SLAVE_ALIAS(reg_idx), 0);
 
 	dev_dbg(dev, "rx%u: client 0x%02x released at slot %u\n", rxport->nport,
-		client->addr, reg_idx);
+		addr, reg_idx);
 }
 
 static const struct i2c_atr_ops ub960_atr_ops = {
-	.attach_client = ub960_atr_attach_client,
-	.detach_client = ub960_atr_detach_client,
+	.attach_addr = ub960_atr_attach_addr,
+	.detach_addr = ub960_atr_detach_addr,
 };
 
 static int ub960_init_atr(struct ub960_data *priv)

include/linux/i2c-atr.h

@@ -20,20 +20,20 @@ struct i2c_atr;
 
 /**
  * struct i2c_atr_ops - Callbacks from ATR to the device driver.
- * @attach_client: Notify the driver of a new device connected on a child
- *                 bus, with the alias assigned to it. The driver must
- *                 configure the hardware to use the alias.
- * @detach_client: Notify the driver of a device getting disconnected. The
- *                 driver must configure the hardware to stop using the
- *                 alias.
+ * @attach_addr: Notify the driver of a new device connected on a child
+ *               bus, with the alias assigned to it. The driver must
+ *               configure the hardware to use the alias.
+ * @detach_addr: Notify the driver of a device getting disconnected. The
+ *               driver must configure the hardware to stop using the
+ *               alias.
  *
  * All these functions return 0 on success, a negative error code otherwise.
  */
 struct i2c_atr_ops {
-	int (*attach_client)(struct i2c_atr *atr, u32 chan_id,
-			     const struct i2c_client *client, u16 alias);
-	void (*detach_client)(struct i2c_atr *atr, u32 chan_id,
-			      const struct i2c_client *client);
+	int (*attach_addr)(struct i2c_atr *atr, u32 chan_id,
+			   u16 addr, u16 alias);
+	void (*detach_addr)(struct i2c_atr *atr, u32 chan_id,
+			    u16 addr);
 };
 
 /**