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crypto: atmel-i2c - add support for SHA204A random number generator
The Linaro/96boards Secure96 mezzanine contains (among other things) an Atmel SHA204A symmetric crypto processor. This chip implements a number of different functionalities, but one that is highly useful for many different 96boards platforms is the random number generator. So let's implement a driver for the SHA204A, and for the time being, implement support for the random number generator only. Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Ard Biesheuvel
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Herbert Xu
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May 30, 2019
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,171 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 | ||
| /* | ||
| * Microchip / Atmel SHA204A (I2C) driver. | ||
| * | ||
| * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org> | ||
| */ | ||
|
|
||
| #include <linux/delay.h> | ||
| #include <linux/device.h> | ||
| #include <linux/err.h> | ||
| #include <linux/errno.h> | ||
| #include <linux/i2c.h> | ||
| #include <linux/init.h> | ||
| #include <linux/kernel.h> | ||
| #include <linux/module.h> | ||
| #include <linux/scatterlist.h> | ||
| #include <linux/slab.h> | ||
| #include <linux/workqueue.h> | ||
| #include "atmel-i2c.h" | ||
|
|
||
| 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 *data, | ||
| size_t max) | ||
| { | ||
| struct atmel_i2c_client_priv *i2c_priv; | ||
| struct atmel_i2c_work_data *work_data; | ||
|
|
||
| i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng); | ||
|
|
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| /* 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(sizeof(work_data->cmd.data), max); | ||
| memcpy(data, &work_data->cmd.data, max); | ||
| rng->priv = 0; | ||
| } else { | ||
| work_data = kmalloc(sizeof(*work_data), GFP_ATOMIC); | ||
| if (!work_data) | ||
| return -ENOMEM; | ||
|
|
||
| work_data->ctx = i2c_priv; | ||
| work_data->client = i2c_priv->client; | ||
|
|
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| max = 0; | ||
| } | ||
|
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| atmel_i2c_init_random_cmd(&work_data->cmd); | ||
| atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); | ||
|
|
||
| return max; | ||
| } | ||
|
|
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| static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max, | ||
| bool wait) | ||
| { | ||
| struct atmel_i2c_client_priv *i2c_priv; | ||
| struct atmel_i2c_cmd cmd; | ||
| int ret; | ||
|
|
||
| if (!wait) | ||
| return atmel_sha204a_rng_read_nonblocking(rng, data, max); | ||
|
|
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| i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng); | ||
|
|
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| atmel_i2c_init_random_cmd(&cmd); | ||
|
|
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| ret = atmel_i2c_send_receive(i2c_priv->client, &cmd); | ||
| if (ret) | ||
| return ret; | ||
|
|
||
| max = min(sizeof(cmd.data), max); | ||
| memcpy(data, cmd.data, max); | ||
|
|
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| return max; | ||
| } | ||
|
|
||
| static int atmel_sha204a_probe(struct i2c_client *client, | ||
| const struct i2c_device_id *id) | ||
| { | ||
| struct atmel_i2c_client_priv *i2c_priv; | ||
| int ret; | ||
|
|
||
| ret = atmel_i2c_probe(client, id); | ||
| if (ret) | ||
| return ret; | ||
|
|
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| i2c_priv = i2c_get_clientdata(client); | ||
|
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| memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng)); | ||
|
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| i2c_priv->hwrng.name = dev_name(&client->dev); | ||
| i2c_priv->hwrng.read = atmel_sha204a_rng_read; | ||
| i2c_priv->hwrng.quality = 1024; | ||
|
|
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| ret = hwrng_register(&i2c_priv->hwrng); | ||
| if (ret) | ||
| dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); | ||
|
|
||
| return ret; | ||
| } | ||
|
|
||
| static int atmel_sha204a_remove(struct i2c_client *client) | ||
| { | ||
| struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | ||
|
|
||
| if (atomic_read(&i2c_priv->tfm_count)) { | ||
| dev_err(&client->dev, "Device is busy\n"); | ||
| return -EBUSY; | ||
| } | ||
|
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| if (i2c_priv->hwrng.priv) | ||
| kfree((void *)i2c_priv->hwrng.priv); | ||
| hwrng_unregister(&i2c_priv->hwrng); | ||
|
|
||
| return 0; | ||
| } | ||
|
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| static const struct of_device_id atmel_sha204a_dt_ids[] = { | ||
| { .compatible = "atmel,atsha204a", }, | ||
| { /* sentinel */ } | ||
| }; | ||
| MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids); | ||
|
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| static const struct i2c_device_id atmel_sha204a_id[] = { | ||
| { "atsha204a", 0 }, | ||
| { /* sentinel */ } | ||
| }; | ||
| MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id); | ||
|
|
||
| static struct i2c_driver atmel_sha204a_driver = { | ||
| .probe = atmel_sha204a_probe, | ||
| .remove = atmel_sha204a_remove, | ||
| .id_table = atmel_sha204a_id, | ||
|
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| .driver.name = "atmel-sha204a", | ||
| .driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids), | ||
| }; | ||
|
|
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| static int __init atmel_sha204a_init(void) | ||
| { | ||
| return i2c_add_driver(&atmel_sha204a_driver); | ||
| } | ||
|
|
||
| static void __exit atmel_sha204a_exit(void) | ||
| { | ||
| flush_scheduled_work(); | ||
| i2c_del_driver(&atmel_sha204a_driver); | ||
| } | ||
|
|
||
| module_init(atmel_sha204a_init); | ||
| module_exit(atmel_sha204a_exit); | ||
|
|
||
| MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); | ||
| MODULE_LICENSE("GPL v2"); |