[PATCH v2 06/12] crypto: atmel-i2c - introduce shared teardown helpers and fix queue flush

[Lothar Rubusch <l.rubusch@gmail.com>]

Introduce atmel_i2c_deactivate_client() and atmel_i2c_unregister_client()
helpers in the atmel-i2c core library to modularize client teardown. This
encapsulates common client state tracking and list manipulation operations.

Convert the ECC driver's error recovery and device removal paths to utilize
these new helpers, ensuring consistent execution ordering when modifying
device-readiness states and deleting linked-list nodes.

Inside the unregistration helper, use list_empty_careful() to safely
validate the membership state of the individual node before triggering
list_del_init().

Additionally, migrate the atmel_i2c_flush_queue() call out of the module
exit path. It now runs inside the core unregistration helper under the
protection of the management spinlock. This configuration ensures the
shared workqueue is only flushed when the global client list becomes
completely empty, enabling proper scaling for multi-driver setups.

Export both new tracking symbols via EXPORT_SYMBOL_GPL() to match the
existing core driver licensing standard.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
---
 drivers/crypto/atmel-ecc.c | 13 +++----------
 drivers/crypto/atmel-i2c.c | 22 ++++++++++++++++++++++
 drivers/crypto/atmel-i2c.h |  3 +++
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index 33b90667c872..29706e4bfa04 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -336,9 +336,7 @@ static int atmel_ecc_probe(struct i2c_client *client)
 	if (atmel_ecc_kpp_refcnt == 0) {
 		ret = crypto_register_kpp(&atmel_ecdh_nist_p256);
 		if (ret) {
-			spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
-			list_del(&i2c_priv->i2c_client_list_node);
-			spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+			atmel_i2c_unregister_client(i2c_priv);
 
 			dev_err(&client->dev, "%s alg registration failed\n",
 				atmel_ecdh_nist_p256.base.cra_driver_name);
@@ -363,9 +361,7 @@ static void atmel_ecc_remove(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
 
-	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
-	i2c_priv->ready = false;
-	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+	atmel_i2c_deactivate_client(i2c_priv);
 
 	/*
 	 * Note, the Linux Crypto Core automatically blocks until all active
@@ -378,9 +374,7 @@ static void atmel_ecc_remove(struct i2c_client *client)
 		crypto_unregister_kpp(&atmel_ecdh_nist_p256);
 	mutex_unlock(&atmel_ecc_kpp_lock);
 
-	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
-	list_del(&i2c_priv->i2c_client_list_node);
-	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+	atmel_i2c_unregister_client(i2c_priv);
 }
 
 static const struct of_device_id atmel_ecc_dt_ids[] = {
@@ -414,7 +408,6 @@ static int __init atmel_ecc_init(void)
 
 static void __exit atmel_ecc_exit(void)
 {
-	atmel_i2c_flush_queue();
 	i2c_del_driver(&atmel_ecc_driver);
 }
 
diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c
index db24f65ae90e..c73ef3cadf0e 100644
--- a/drivers/crypto/atmel-i2c.c
+++ b/drivers/crypto/atmel-i2c.c
@@ -354,6 +354,28 @@ static int device_sanity_check(struct i2c_client *client)
 	return ret;
 }
 
+void atmel_i2c_deactivate_client(struct atmel_i2c_client_priv *i2c_priv)
+{
+	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
+	i2c_priv->ready = false;
+	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+}
+EXPORT_SYMBOL_GPL(atmel_i2c_deactivate_client);
+
+void atmel_i2c_unregister_client(struct atmel_i2c_client_priv *i2c_priv)
+{
+	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
+
+	if (!list_empty_careful(&i2c_priv->i2c_client_list_node))
+		list_del_init(&i2c_priv->i2c_client_list_node);
+
+	if (list_empty(&atmel_i2c_mgmt.i2c_client_list))
+		atmel_i2c_flush_queue();
+
+	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+}
+EXPORT_SYMBOL_GPL(atmel_i2c_unregister_client);
+
 int atmel_i2c_probe(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv;
diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h
index d54bd836e0f5..351306c426aa 100644
--- a/drivers/crypto/atmel-i2c.h
+++ b/drivers/crypto/atmel-i2c.h
@@ -192,4 +192,7 @@ void atmel_i2c_init_genkey_cmd(struct atmel_i2c_cmd *cmd, u16 keyid);
 int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd,
 			    struct scatterlist *pubkey);
 
+void atmel_i2c_deactivate_client(struct atmel_i2c_client_priv *i2c_priv);
+void atmel_i2c_unregister_client(struct atmel_i2c_client_priv *i2c_priv);
+
 #endif /* __ATMEL_I2C_H__ */
-- 
2.39.5