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170 lines
4.0 KiB
170 lines
4.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Microchip / Atmel SHA204A (I2C) driver. |
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* |
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* Copyright (c) 2019 Linaro, Ltd. <[email protected]> |
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*/ |
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#include <linux/delay.h> |
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#include <linux/device.h> |
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#include <linux/err.h> |
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#include <linux/errno.h> |
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#include <linux/i2c.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/scatterlist.h> |
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#include <linux/slab.h> |
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#include <linux/workqueue.h> |
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#include "atmel-i2c.h" |
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static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data, |
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void *areq, int status) |
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{ |
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struct atmel_i2c_client_priv *i2c_priv = work_data->ctx; |
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struct hwrng *rng = areq; |
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if (status) |
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dev_warn_ratelimited(&i2c_priv->client->dev, |
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"i2c transaction failed (%d)\n", |
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status); |
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rng->priv = (unsigned long)work_data; |
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atomic_dec(&i2c_priv->tfm_count); |
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} |
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static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data, |
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size_t max) |
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{ |
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struct atmel_i2c_client_priv *i2c_priv; |
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struct atmel_i2c_work_data *work_data; |
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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 */ |
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if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1)) |
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return 0; |
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if (rng->priv) { |
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work_data = (struct atmel_i2c_work_data *)rng->priv; |
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max = min(sizeof(work_data->cmd.data), max); |
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memcpy(data, &work_data->cmd.data, max); |
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rng->priv = 0; |
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} else { |
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work_data = kmalloc(sizeof(*work_data), GFP_ATOMIC); |
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if (!work_data) |
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return -ENOMEM; |
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work_data->ctx = i2c_priv; |
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work_data->client = i2c_priv->client; |
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max = 0; |
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} |
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atmel_i2c_init_random_cmd(&work_data->cmd); |
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atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); |
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return max; |
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} |
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static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max, |
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bool wait) |
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{ |
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struct atmel_i2c_client_priv *i2c_priv; |
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struct atmel_i2c_cmd cmd; |
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int ret; |
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if (!wait) |
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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); |
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if (ret) |
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return ret; |
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max = min(sizeof(cmd.data), max); |
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memcpy(data, cmd.data, max); |
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return max; |
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} |
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static int atmel_sha204a_probe(struct i2c_client *client, |
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const struct i2c_device_id *id) |
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{ |
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struct atmel_i2c_client_priv *i2c_priv; |
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int ret; |
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ret = atmel_i2c_probe(client, id); |
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if (ret) |
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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); |
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i2c_priv->hwrng.read = atmel_sha204a_rng_read; |
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i2c_priv->hwrng.quality = 1024; |
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ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng); |
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if (ret) |
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dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); |
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return ret; |
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} |
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static int atmel_sha204a_remove(struct i2c_client *client) |
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{ |
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struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); |
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if (atomic_read(&i2c_priv->tfm_count)) { |
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dev_err(&client->dev, "Device is busy\n"); |
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return -EBUSY; |
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} |
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if (i2c_priv->hwrng.priv) |
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kfree((void *)i2c_priv->hwrng.priv); |
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return 0; |
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} |
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static const struct of_device_id atmel_sha204a_dt_ids[] = { |
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{ .compatible = "atmel,atsha204a", }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids); |
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static const struct i2c_device_id atmel_sha204a_id[] = { |
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{ "atsha204a", 0 }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id); |
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static struct i2c_driver atmel_sha204a_driver = { |
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.probe = atmel_sha204a_probe, |
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.remove = atmel_sha204a_remove, |
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.id_table = atmel_sha204a_id, |
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.driver.name = "atmel-sha204a", |
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.driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids), |
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}; |
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static int __init atmel_sha204a_init(void) |
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{ |
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return i2c_add_driver(&atmel_sha204a_driver); |
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} |
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static void __exit atmel_sha204a_exit(void) |
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{ |
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flush_scheduled_work(); |
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i2c_del_driver(&atmel_sha204a_driver); |
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} |
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module_init(atmel_sha204a_init); |
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module_exit(atmel_sha204a_exit); |
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MODULE_AUTHOR("Ard Biesheuvel <[email protected]>"); |
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MODULE_LICENSE("GPL v2");
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