From: Johan Hovold <johan@kernel.org>
Date: Mon, 11 May 2026 14:37:14 +0000 (+0200)
Subject: i2c: core: clean up bus id allocation
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a378a2bc73e3b71ed2e2bfccaaee81199de0f49f;p=thirdparty%2Flinux.git

i2c: core: clean up bus id allocation

Clean up bus id allocation by using a common helper and deferring it
until it is needed during adapter registration.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 38f425aecef86..2cd384433d83e 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1517,23 +1517,48 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
 }
 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
 
+static int i2c_allocate_adapter_id(struct i2c_adapter *adap)
+{
+	int id, start, end;
+
+	if (adap->nr == -1) {
+		start = __i2c_first_dynamic_bus_num;
+		end = 0;
+	} else {
+		start = adap->nr;
+		end = adap->nr + 1;
+	}
+
+	mutex_lock(&core_lock);
+	id = idr_alloc(&i2c_adapter_idr, NULL, start, end, GFP_KERNEL);
+	mutex_unlock(&core_lock);
+	if (id < 0) {
+		if (adap->nr != -1 && id == -ENOSPC)
+			id = -EBUSY;
+		pr_err("adapter '%s': failed to allocate id: %d\n", adap->name, id);
+		return id;
+	}
+
+	adap->nr = id;
+
+	return 0;
+}
+
 static int i2c_register_adapter(struct i2c_adapter *adap)
 {
-	int res = -EINVAL;
+	int res;
 
 	/* Can't register until after driver model init */
-	if (WARN_ON(!is_registered)) {
-		res = -EAGAIN;
-		goto out_list;
-	}
+	if (WARN_ON(!is_registered))
+		return -EAGAIN;
 
 	/* Sanity checks */
 	if (WARN(!adap->name[0], "i2c adapter has no name"))
-		goto out_list;
+		return -EINVAL;
 
 	if (!adap->algo) {
 		pr_err("adapter '%s': no algo supplied!\n", adap->name);
-		goto out_list;
+		return -EINVAL;
 	}
 
 	if (!adap->lock_ops)
@@ -1554,13 +1579,17 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res) {
 		pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
 		       adap->name, res);
-		goto out_list;
+		return res;
 	}
 
-	res = dev_set_name(&adap->dev, "i2c-%d", adap->nr);
+	res = i2c_allocate_adapter_id(adap);
 	if (res)
 		goto err_remove_irq_domain;
 
+	res = dev_set_name(&adap->dev, "i2c-%d", adap->nr);
+	if (res)
+		goto err_free_id;
+
 	adap->dev.bus = &i2c_bus_type;
 	adap->dev.type = &i2c_adapter_type;
 	device_initialize(&adap->dev);
@@ -1624,33 +1653,14 @@ err_put_adap:
 	init_completion(&adap->dev_released);
 	put_device(&adap->dev);
 	wait_for_completion(&adap->dev_released);
-err_remove_irq_domain:
-	i2c_host_notify_irq_teardown(adap);
-out_list:
+err_free_id:
 	mutex_lock(&core_lock);
 	idr_remove(&i2c_adapter_idr, adap->nr);
 	mutex_unlock(&core_lock);
-	return res;
-}
-
-/**
- * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
- * @adap: the adapter to register (with adap->nr initialized)
- * Context: can sleep
- *
- * See i2c_add_numbered_adapter() for details.
- */
-static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
-{
-	int id;
-
-	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, NULL, adap->nr, adap->nr + 1, GFP_KERNEL);
-	mutex_unlock(&core_lock);
-	if (WARN(id < 0, "couldn't get idr"))
-		return id == -ENOSPC ? -EBUSY : id;
+err_remove_irq_domain:
+	i2c_host_notify_irq_teardown(adap);
 
-	return i2c_register_adapter(adap);
+	return res;
 }
 
 /**
@@ -1673,17 +1683,8 @@ int i2c_add_adapter(struct i2c_adapter *adapter)
 	int id;
 
 	id = of_alias_get_id(dev->of_node, "i2c");
-	if (id >= 0) {
-		adapter->nr = id;
-		return __i2c_add_numbered_adapter(adapter);
-	}
-
-	mutex_lock(&core_lock);
-	id = idr_alloc(&i2c_adapter_idr, NULL,
-		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
-	mutex_unlock(&core_lock);
-	if (WARN(id < 0, "couldn't get idr"))
-		return id;
+	if (id < 0)
+		id = -1;
 
 	adapter->nr = id;
 
@@ -1719,7 +1720,7 @@ int i2c_add_numbered_adapter(struct i2c_adapter *adap)
 	if (adap->nr == -1) /* -1 means dynamically assign bus id */
 		return i2c_add_adapter(adap);
 
-	return __i2c_add_numbered_adapter(adap);
+	return i2c_register_adapter(adap);
 }
 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);