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[84.74.0.139]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48fce385ea5sm3194025e9.14.2026.05.12.15.44.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2026 15:44:12 -0700 (PDT) From: Lothar Rubusch To: thorsten.blum@linux.dev, herbert@gondor.apana.org.au, davem@davemloft.net, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@tuxon.dev Cc: linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, l.rubusch@gmail.com Subject: [PATCH 05/12] crypto: atmel - move RNG support into common i2c core Date: Tue, 12 May 2026 22:43:42 +0000 Message-Id: <20260512224349.64621-6-l.rubusch@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260512224349.64621-1-l.rubusch@gmail.com> References: <20260512224349.64621-1-l.rubusch@gmail.com> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Move the hardware RNG implementation from atmel-sha204a into the shared atmel-i2c core. The ATSHA204(A) and ATECC devices provide compatible RANDOM commands through the common Atmel I2C interface. Consolidate the RNG handling in the core driver and provide a shared atmel_i2c_register_rng() helper for registering the hwrng device. This removes duplicated RNG code from atmel-sha204a and enables RNG support for other compatible Atmel devices, including the ECC family. Signed-off-by: Lothar Rubusch --- drivers/crypto/atmel-ecc.c | 12 ++++ drivers/crypto/atmel-i2c.c | 93 ++++++++++++++++++++++++++ drivers/crypto/atmel-i2c.h | 4 +- drivers/crypto/atmel-sha204a.c | 115 +++++---------------------------- 4 files changed, 123 insertions(+), 101 deletions(-) diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c index 7793f7b4e97e..67fa5975fa7f 100644 --- a/drivers/crypto/atmel-ecc.c +++ b/drivers/crypto/atmel-ecc.c @@ -306,6 +306,13 @@ static int atmel_ecc_probe(struct i2c_client *client) &atmel_i2c_mgmt.i2c_client_list); spin_unlock(&atmel_i2c_mgmt.i2c_list_lock); + /* register rng */ + ret = atmel_i2c_register_rng(i2c_priv, &client->dev); + if (ret) { + dev_err(&client->dev, "failed to register hw_random\n"); + goto err_list_del; + } + /* register algorithms */ ret = crypto_register_kpp(&atmel_ecdh_nist_p256); if (ret) { @@ -349,6 +356,11 @@ static void atmel_ecc_remove(struct i2c_client *client) atmel_i2c_flush_queue(); crypto_unregister_kpp(&atmel_ecdh_nist_p256); + + if (i2c_priv->hwrng.priv) { + kfree((void *)i2c_priv->hwrng.priv); + i2c_priv->hwrng.priv = 0; + } } static const struct atmel_i2c_of_match_data atecc508a_match_data = { diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c index 7fa7cf9ab3c1..d451017171d8 100644 --- a/drivers/crypto/atmel-i2c.c +++ b/drivers/crypto/atmel-i2c.c @@ -208,6 +208,99 @@ int atmel_i2c_init_ecdh_cmd(struct atmel_i2c_cmd *cmd, } EXPORT_SYMBOL(atmel_i2c_init_ecdh_cmd); +static void atmel_i2c_rng_done(struct atmel_i2c_work_data *work_data, + void *areq, int status) +{ + struct atmel_i2c_client_priv *i2c_priv = work_data->ctx; + struct hwrng *rng = areq; + + if (status) + dev_warn_ratelimited(&i2c_priv->client->dev, + "i2c transaction failed (%d)\n", + status); + + rng->priv = (unsigned long)work_data; + atomic_dec(&i2c_priv->tfm_count); +} + +static int atmel_i2c_rng_read_nonblocking(struct hwrng *rng, void *buf, + size_t max) +{ + struct atmel_i2c_client_priv *i2c_priv = container_of(rng, + struct atmel_i2c_client_priv, + hwrng); + const struct atmel_i2c_of_match_data *data = i2c_priv->data; + struct atmel_i2c_work_data *work_data; + + /* keep maximum 1 asynchronous read in flight at any time */ + if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1)) + return 0; + + if (rng->priv) { + work_data = (struct atmel_i2c_work_data *)rng->priv; + max = min(RANDOM_RSP_SIZE - CMD_OVERHEAD_SIZE, max); + memcpy(buf, &work_data->cmd.data[RSP_DATA_IDX], max); + rng->priv = 0; + } else { + work_data = kmalloc_obj(*work_data, GFP_ATOMIC); + if (!work_data) { + atomic_dec(&i2c_priv->tfm_count); + return -ENOMEM; + } + work_data->ctx = i2c_priv; + work_data->client = i2c_priv->client; + + max = 0; + } + + atmel_i2c_init_random_cmd(&work_data->cmd, &data->timings); + atmel_i2c_enqueue(work_data, atmel_i2c_rng_done, rng); + + return max; +} + +static int atmel_i2c_rng_read(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct atmel_i2c_client_priv *i2c_priv = container_of(rng, + struct atmel_i2c_client_priv, + hwrng); + const struct atmel_i2c_of_match_data *data = i2c_priv->data; + struct atmel_i2c_cmd cmd; + int ret; + + if (!wait) + return atmel_i2c_rng_read_nonblocking(rng, buf, max); + + atmel_i2c_init_random_cmd(&cmd, &data->timings); + + ret = atmel_i2c_send_receive(i2c_priv->client, &cmd); + if (ret) + return ret; + + max = min(RANDOM_RSP_SIZE - CMD_OVERHEAD_SIZE, max); + memcpy(buf, &cmd.data[RSP_DATA_IDX], max); + + return max; +} + +int atmel_i2c_register_rng(struct atmel_i2c_client_priv *i2c_priv, + struct device *dev) +{ + const struct atmel_i2c_of_match_data *data = i2c_priv->data; + + memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng)); + + i2c_priv->hwrng.name = dev_name(dev); + i2c_priv->hwrng.read = atmel_i2c_rng_read; + + if (data->needs_legacy_hwrng) + i2c_priv->hwrng.quality = data->needs_legacy_hwrng; + + return devm_hwrng_register(dev, &i2c_priv->hwrng); +} +EXPORT_SYMBOL(atmel_i2c_register_rng); + /* * After wake and after execution of a command, there will be error, status, or * result bytes in the device's output register that can be retrieved by the diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h index 5224a62c16c9..5f6c9ff0cf64 100644 --- a/drivers/crypto/atmel-i2c.h +++ b/drivers/crypto/atmel-i2c.h @@ -66,7 +66,7 @@ struct atmel_i2c_max_exec_timings { }; struct atmel_i2c_of_match_data { - const unsigned short *legacy_hwrng; + const unsigned short needs_legacy_hwrng; struct atmel_i2c_max_exec_timings timings; }; @@ -209,6 +209,8 @@ 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, const struct atmel_i2c_max_exec_timings *timings); +int atmel_i2c_register_rng(struct atmel_i2c_client_priv *i2c_priv, + struct device *dev); struct i2c_client *atmel_i2c_client_alloc(enum atmel_i2c_capability cap); void atmel_i2c_unregister_client(struct atmel_i2c_client_priv *i2c_priv); diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index febf9891b167..ae24d8fbabf9 100644 --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -19,88 +19,6 @@ #include #include "atmel-i2c.h" -/* - * According to review by Bill Cox [1], the ATSHA204 has very low entropy. - * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html - */ -static const unsigned short atsha204_quality = 1; - -static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data, - void *areq, int status) -{ - struct atmel_i2c_client_priv *i2c_priv = work_data->ctx; - struct hwrng *rng = areq; - - if (status) - dev_warn_ratelimited(&i2c_priv->client->dev, - "i2c transaction failed (%d)\n", - status); - - rng->priv = (unsigned long)work_data; - atomic_dec(&i2c_priv->tfm_count); -} - -static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *buf, - size_t max) -{ - struct atmel_i2c_client_priv *i2c_priv = container_of(rng, - struct atmel_i2c_client_priv, - hwrng); - const struct atmel_i2c_of_match_data *data = i2c_priv->data; - struct atmel_i2c_work_data *work_data; - - /* keep maximum 1 asynchronous read in flight at any time */ - if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1)) - return 0; - - if (rng->priv) { - work_data = (struct atmel_i2c_work_data *)rng->priv; - max = min(RANDOM_RSP_SIZE - CMD_OVERHEAD_SIZE, max); - memcpy(buf, &work_data->cmd.data[RSP_DATA_IDX], max); - rng->priv = 0; - } else { - work_data = kmalloc_obj(*work_data, GFP_ATOMIC); - if (!work_data) { - atomic_dec(&i2c_priv->tfm_count); - return -ENOMEM; - } - work_data->ctx = i2c_priv; - work_data->client = i2c_priv->client; - - max = 0; - } - - atmel_i2c_init_random_cmd(&work_data->cmd, &data->timings); - atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); - - return max; -} - -static int atmel_sha204a_rng_read(struct hwrng *rng, void *buf, size_t max, - bool wait) -{ - struct atmel_i2c_client_priv *i2c_priv = container_of(rng, - struct atmel_i2c_client_priv, - hwrng); - const struct atmel_i2c_of_match_data *data = i2c_priv->data; - struct atmel_i2c_cmd cmd; - int ret; - - if (!wait) - return atmel_sha204a_rng_read_nonblocking(rng, buf, max); - - atmel_i2c_init_random_cmd(&cmd, &data->timings); - - ret = atmel_i2c_send_receive(i2c_priv->client, &cmd); - if (ret) - return ret; - - max = min(RANDOM_RSP_SIZE - CMD_OVERHEAD_SIZE, max); - memcpy(buf, &cmd.data[RSP_DATA_IDX], max); - - return max; -} - static int atmel_sha204a_otp_read(struct i2c_client *client, u16 addr, u8 *otp) { struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); @@ -169,7 +87,6 @@ static int atmel_sha204a_probe(struct i2c_client *client) { struct atmel_i2c_client_priv *i2c_priv; const struct atmel_i2c_of_match_data *data; - const unsigned short *quality; int ret; ret = atmel_i2c_probe(client); @@ -193,25 +110,16 @@ static int atmel_sha204a_probe(struct i2c_client *client) &atmel_i2c_mgmt.i2c_client_list); spin_unlock(&atmel_i2c_mgmt.i2c_list_lock); - /* register rng */ - memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng)); - - i2c_priv->hwrng.name = dev_name(&client->dev); - i2c_priv->hwrng.read = atmel_sha204a_rng_read; - - quality = i2c_priv->data->legacy_hwrng; - if (quality) - i2c_priv->hwrng.quality = *quality; - - ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng); + ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups); if (ret) { - dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); + dev_err(&client->dev, "failed to register sysfs entry\n"); goto err_list_del; } - ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups); + /* register rng */ + ret = atmel_i2c_register_rng(i2c_priv, &client->dev); if (ret) { - dev_err(&client->dev, "failed to register sysfs entry\n"); + dev_err(&client->dev, "failed to register hw_random\n"); goto err_list_del; } @@ -234,9 +142,12 @@ static void atmel_sha204a_remove(struct i2c_client *client) devm_hwrng_unregister(&client->dev, &i2c_priv->hwrng); atmel_i2c_flush_queue(); - sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups); + if (i2c_priv->hwrng.priv) { + kfree((void *)i2c_priv->hwrng.priv); + i2c_priv->hwrng.priv = 0; + } - kfree((void *)i2c_priv->hwrng.priv); + sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups); } static const struct atmel_i2c_of_match_data atsha204_match_data = { @@ -246,7 +157,11 @@ static const struct atmel_i2c_of_match_data atsha204_match_data = { .max_exec_time_read = 4, .max_exec_time_write = 42, }, - .legacy_hwrng = &atsha204_quality, + /* + * According to review by Bill Cox [1], the ATSHA204 has very low entropy. + * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html + */ + .needs_legacy_hwrng = 1, }; static const struct atmel_i2c_of_match_data atsha204a_match_data = { -- 2.53.0