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da001fb6 AB |
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 | ||
21 | static 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(&i2c_priv->tfm_count); | |
34 | } | |
35 | ||
36 | static 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(&i2c_priv->tfm_count, 1, 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(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(&work_data->cmd); | |
65 | atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); | |
66 | ||
67 | return max; | |
68 | } | |
69 | ||
70 | static 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); | |
83 | ||
84 | ret = atmel_i2c_send_receive(i2c_priv->client, &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 | ||
94 | static int atmel_sha204a_probe(struct i2c_client *client, | |
95 | const struct i2c_device_id *id) | |
96 | { | |
97 | struct atmel_i2c_client_priv *i2c_priv; | |
98 | int ret; | |
99 | ||
100 | ret = atmel_i2c_probe(client, id); | |
101 | if (ret) | |
102 | return ret; | |
103 | ||
104 | i2c_priv = i2c_get_clientdata(client); | |
105 | ||
106 | memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng)); | |
107 | ||
108 | i2c_priv->hwrng.name = dev_name(&client->dev); | |
109 | i2c_priv->hwrng.read = atmel_sha204a_rng_read; | |
110 | i2c_priv->hwrng.quality = 1024; | |
111 | ||
112 | ret = hwrng_register(&i2c_priv->hwrng); | |
113 | if (ret) | |
114 | dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); | |
115 | ||
116 | return ret; | |
117 | } | |
118 | ||
119 | static int atmel_sha204a_remove(struct i2c_client *client) | |
120 | { | |
121 | struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); | |
122 | ||
123 | if (atomic_read(&i2c_priv->tfm_count)) { | |
124 | dev_err(&client->dev, "Device is busy\n"); | |
125 | return -EBUSY; | |
126 | } | |
127 | ||
128 | if (i2c_priv->hwrng.priv) | |
129 | kfree((void *)i2c_priv->hwrng.priv); | |
130 | hwrng_unregister(&i2c_priv->hwrng); | |
131 | ||
132 | return 0; | |
133 | } | |
134 | ||
135 | static const struct of_device_id atmel_sha204a_dt_ids[] = { | |
136 | { .compatible = "atmel,atsha204a", }, | |
137 | { /* sentinel */ } | |
138 | }; | |
139 | MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids); | |
140 | ||
141 | static const struct i2c_device_id atmel_sha204a_id[] = { | |
142 | { "atsha204a", 0 }, | |
143 | { /* sentinel */ } | |
144 | }; | |
145 | MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id); | |
146 | ||
147 | static struct i2c_driver atmel_sha204a_driver = { | |
148 | .probe = atmel_sha204a_probe, | |
149 | .remove = atmel_sha204a_remove, | |
150 | .id_table = atmel_sha204a_id, | |
151 | ||
152 | .driver.name = "atmel-sha204a", | |
153 | .driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids), | |
154 | }; | |
155 | ||
156 | static int __init atmel_sha204a_init(void) | |
157 | { | |
158 | return i2c_add_driver(&atmel_sha204a_driver); | |
159 | } | |
160 | ||
161 | static void __exit atmel_sha204a_exit(void) | |
162 | { | |
163 | flush_scheduled_work(); | |
164 | i2c_del_driver(&atmel_sha204a_driver); | |
165 | } | |
166 | ||
167 | module_init(atmel_sha204a_init); | |
168 | module_exit(atmel_sha204a_exit); | |
169 | ||
170 | MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); | |
171 | MODULE_LICENSE("GPL v2"); |