1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Microchip / Atmel SHA204A (I2C) driver.
4 *
5 * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
6 */
7
8#include <linux/delay.h>
9#include <linux/device.h>
10#include <linux/err.h>
11#include <linux/errno.h>
12#include <linux/i2c.h>
13#include <linux/init.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/scatterlist.h>
17#include <linux/slab.h>
18#include <linux/workqueue.h>
19#include "atmel-i2c.h"
20
21static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data,
22 void *areq, int status)
23{
24 struct atmel_i2c_client_priv *i2c_priv = work_data->ctx;
25 struct hwrng *rng = areq;
26
27 if (status)
28 dev_warn_ratelimited(&i2c_priv->client->dev,
29 "i2c transaction failed (%d)\n",
30 status);
31
32 rng->priv = (unsigned long)work_data;
33 atomic_dec(v: &i2c_priv->tfm_count);
34}
35
36static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data,
37 size_t max)
38{
39 struct atmel_i2c_client_priv *i2c_priv;
40 struct atmel_i2c_work_data *work_data;
41
42 i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
43
44 /* keep maximum 1 asynchronous read in flight at any time */
45 if (!atomic_add_unless(v: &i2c_priv->tfm_count, a: 1, u: 1))
46 return 0;
47
48 if (rng->priv) {
49 work_data = (struct atmel_i2c_work_data *)rng->priv;
50 max = min(sizeof(work_data->cmd.data), max);
51 memcpy(data, &work_data->cmd.data, max);
52 rng->priv = 0;
53 } else {
54 work_data = kmalloc(size: sizeof(*work_data), GFP_ATOMIC);
55 if (!work_data)
56 return -ENOMEM;
57
58 work_data->ctx = i2c_priv;
59 work_data->client = i2c_priv->client;
60
61 max = 0;
62 }
63
64 atmel_i2c_init_random_cmd(cmd: &work_data->cmd);
65 atmel_i2c_enqueue(work_data, cbk: atmel_sha204a_rng_done, areq: rng);
66
67 return max;
68}
69
70static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
71 bool wait)
72{
73 struct atmel_i2c_client_priv *i2c_priv;
74 struct atmel_i2c_cmd cmd;
75 int ret;
76
77 if (!wait)
78 return atmel_sha204a_rng_read_nonblocking(rng, data, max);
79
80 i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng);
81
82 atmel_i2c_init_random_cmd(cmd: &cmd);
83
84 ret = atmel_i2c_send_receive(client: i2c_priv->client, cmd: &cmd);
85 if (ret)
86 return ret;
87
88 max = min(sizeof(cmd.data), max);
89 memcpy(data, cmd.data, max);
90
91 return max;
92}
93
94static int atmel_sha204a_probe(struct i2c_client *client)
95{
96 struct atmel_i2c_client_priv *i2c_priv;
97 int ret;
98
99 ret = atmel_i2c_probe(client);
100 if (ret)
101 return ret;
102
103 i2c_priv = i2c_get_clientdata(client);
104
105 memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
106
107 i2c_priv->hwrng.name = dev_name(dev: &client->dev);
108 i2c_priv->hwrng.read = atmel_sha204a_rng_read;
109
110 ret = devm_hwrng_register(dev: &client->dev, rng: &i2c_priv->hwrng);
111 if (ret)
112 dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
113
114 return ret;
115}
116
117static void atmel_sha204a_remove(struct i2c_client *client)
118{
119 struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
120
121 if (atomic_read(v: &i2c_priv->tfm_count)) {
122 dev_emerg(&client->dev, "Device is busy, will remove it anyhow\n");
123 return;
124 }
125
126 kfree(objp: (void *)i2c_priv->hwrng.priv);
127}
128
129static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
130 { .compatible = "atmel,atsha204", },
131 { .compatible = "atmel,atsha204a", },
132 { /* sentinel */ }
133};
134MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
135
136static const struct i2c_device_id atmel_sha204a_id[] = {
137 { "atsha204", 0 },
138 { "atsha204a", 0 },
139 { /* sentinel */ }
140};
141MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
142
143static struct i2c_driver atmel_sha204a_driver = {
144 .probe = atmel_sha204a_probe,
145 .remove = atmel_sha204a_remove,
146 .id_table = atmel_sha204a_id,
147
148 .driver.name = "atmel-sha204a",
149 .driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids),
150};
151
152static int __init atmel_sha204a_init(void)
153{
154 return i2c_add_driver(&atmel_sha204a_driver);
155}
156
157static void __exit atmel_sha204a_exit(void)
158{
159 atmel_i2c_flush_queue();
160 i2c_del_driver(driver: &atmel_sha204a_driver);
161}
162
163module_init(atmel_sha204a_init);
164module_exit(atmel_sha204a_exit);
165
166MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
167MODULE_LICENSE("GPL v2");
168

source code of linux/drivers/crypto/atmel-sha204a.c