Subject: [PATCH v4 09/12] crypto: atmel-i2c - move shared client allocation logic to core

From: Lothar Rubusch <[email-masked]>
Date: Fri, 22 May 2026 23:01:31 +0000

Migrate the I2C client allocation and runtime load-balancing routines out
of the ECC driver code and into the central atmel-i2c core library module.

Export the symmetric lifecycle helper interfaces atmel_i2c_client_alloc()
and atmel_i2c_client_free() using EXPORT_SYMBOL_GPL() to expose a unified
client management API. This consolidation enables the dynamic selection
subsystem (which chooses the least-loaded client device based on the active
transformation count) to be shared by both the ECC driver and upcoming
Atmel crypto modules.

Refactor the ECC driver's transformation context initialization (init_tfm)
and teardown (exit_tfm) paths to use this centralized core API.

No functional change is intended.

Signed-off-by: Lothar Rubusch <[email-masked]>
---
 drivers/crypto/atmel-ecc.c | 51 +++-----------------------------------
 drivers/crypto/atmel-i2c.c | 47 +++++++++++++++++++++++++++++++++++
 drivers/crypto/atmel-i2c.h |  3 +++
 3 files changed, 53 insertions(+), 48 deletions(-)

diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index d2490693a198..16e607cd06c4 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -205,51 +205,6 @@ static int atmel_ecdh_compute_shared_secret(struct kpp_request *req)
 	return ret;
 }
 
-static struct i2c_client *atmel_ecc_i2c_client_alloc(void)
-{
-	struct atmel_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL;
-	struct i2c_client *client = ERR_PTR(-ENODEV);
-	int min_tfm_cnt = INT_MAX;
-	int tfm_cnt;
-
-	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
-
-	if (list_empty(&atmel_i2c_mgmt.i2c_client_list)) {
-		spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
-		return ERR_PTR(-ENODEV);
-	}
-
-	list_for_each_entry(i2c_priv, &atmel_i2c_mgmt.i2c_client_list,
-			    i2c_client_list_node) {
-		if (!i2c_priv->ready)
-			continue;
-		tfm_cnt = atomic_read(&i2c_priv->tfm_count);
-		if (tfm_cnt < min_tfm_cnt) {
-			min_tfm_cnt = tfm_cnt;
-			min_i2c_priv = i2c_priv;
-		}
-		if (!min_tfm_cnt)
-			break;
-	}
-
-	if (min_i2c_priv) {
-		atomic_inc(&min_i2c_priv->tfm_count);
-		client = min_i2c_priv->client;
-	}
-
-	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
-
-	return client;
-}
-
-static void atmel_ecc_i2c_client_free(struct i2c_client *client)
-{
-	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
-
-	if (atomic_dec_and_test(&i2c_priv->tfm_count))
-		complete(&i2c_priv->remove_done);
-}
-
 static int atmel_ecdh_init_tfm(struct crypto_kpp *tfm)
 {
 	const char *alg = kpp_alg_name(tfm);
@@ -257,7 +212,7 @@ static int atmel_ecdh_init_tfm(struct crypto_kpp *tfm)
 	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
 
 	ctx->curve_id = ECC_CURVE_NIST_P256;
-	ctx->client = atmel_ecc_i2c_client_alloc();
+	ctx->client = atmel_i2c_client_alloc();
 	if (IS_ERR(ctx->client)) {
 		pr_err("tfm - i2c_client binding failed\n");
 		return PTR_ERR(ctx->client);
@@ -267,7 +222,7 @@ static int atmel_ecdh_init_tfm(struct crypto_kpp *tfm)
 	if (IS_ERR(fallback)) {
 		dev_err(&ctx->client->dev, "Failed to allocate transformation for '%s': %ld\n",
 			alg, PTR_ERR(fallback));
-		atmel_ecc_i2c_client_free(ctx->client);
+		atmel_i2c_client_free(ctx->client);
 		return PTR_ERR(fallback);
 	}
 
@@ -284,7 +239,7 @@ static void atmel_ecdh_exit_tfm(struct crypto_kpp *tfm)
 	kfree(ctx->public_key);
 	if (ctx->fallback)
 		crypto_free_kpp(ctx->fallback);
-	atmel_ecc_i2c_client_free(ctx->client);
+	atmel_i2c_client_free(ctx->client);
 }
 
 static unsigned int atmel_ecdh_max_size(struct crypto_kpp *tfm)
diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c
index db818ce55033..92d3e28f9d9a 100644
--- a/drivers/crypto/atmel-i2c.c
+++ b/drivers/crypto/atmel-i2c.c
@@ -57,6 +57,53 @@ static void atmel_i2c_checksum(struct atmel_i2c_cmd *cmd)
 	*__crc16 = cpu_to_le16(bitrev16(crc16(0, data, len)));
 }
 
+struct i2c_client *atmel_i2c_client_alloc(void)
+{
+	struct atmel_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL;
+	struct i2c_client *client = ERR_PTR(-ENODEV);
+	int min_tfm_cnt = INT_MAX;
+	int tfm_cnt;
+
+	spin_lock(&atmel_i2c_mgmt.i2c_list_lock);
+
+	if (list_empty(&atmel_i2c_mgmt.i2c_client_list)) {
+		spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+		return ERR_PTR(-ENODEV);
+	}
+
+	list_for_each_entry(i2c_priv, &atmel_i2c_mgmt.i2c_client_list,
+			    i2c_client_list_node) {
+		if (!i2c_priv->ready)
+			continue;
+		tfm_cnt = atomic_read(&i2c_priv->tfm_count);
+		if (tfm_cnt < min_tfm_cnt) {
+			min_tfm_cnt = tfm_cnt;
+			min_i2c_priv = i2c_priv;
+		}
+		if (!min_tfm_cnt)
+			break;
+	}
+
+	if (min_i2c_priv) {
+		atomic_inc(&min_i2c_priv->tfm_count);
+		client = min_i2c_priv->client;
+	}
+
+	spin_unlock(&atmel_i2c_mgmt.i2c_list_lock);
+
+	return client;
+}
+EXPORT_SYMBOL_GPL(atmel_i2c_client_alloc);
+
+void atmel_i2c_client_free(struct i2c_client *client)
+{
+	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
+
+	if (atomic_dec_and_test(&i2c_priv->tfm_count))
+		complete(&i2c_priv->remove_done);
+}
+EXPORT_SYMBOL_GPL(atmel_i2c_client_free);
+
 void atmel_i2c_init_read_config_cmd(struct atmel_i2c_cmd *cmd)
 {
 	cmd->word_addr = COMMAND;
diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h
index 07fd2248e20b..ddab80bc1a72 100644
--- a/drivers/crypto/atmel-i2c.h
+++ b/drivers/crypto/atmel-i2c.h
@@ -193,6 +193,9 @@ 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);
 
+struct i2c_client *atmel_i2c_client_alloc(void);
+void atmel_i2c_client_free(struct i2c_client *client);
+
 void atmel_i2c_deactivate_client(struct atmel_i2c_client_priv *i2c_priv);
 void atmel_i2c_unregister_client(struct atmel_i2c_client_priv *i2c_priv);
 
-- 
2.39.5