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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(&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
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
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);
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
94static 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 = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
113 if (ret)
114 dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
115
116 return ret;
117}
118
119static 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
131 return 0;
132}
133
134static const struct of_device_id atmel_sha204a_dt_ids[] = {
135 { .compatible = "atmel,atsha204a", },
136 { }
137};
138MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
139
140static const struct i2c_device_id atmel_sha204a_id[] = {
141 { "atsha204a", 0 },
142 { }
143};
144MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
145
146static struct i2c_driver atmel_sha204a_driver = {
147 .probe = atmel_sha204a_probe,
148 .remove = atmel_sha204a_remove,
149 .id_table = atmel_sha204a_id,
150
151 .driver.name = "atmel-sha204a",
152 .driver.of_match_table = of_match_ptr(atmel_sha204a_dt_ids),
153};
154
155static int __init atmel_sha204a_init(void)
156{
157 return i2c_add_driver(&atmel_sha204a_driver);
158}
159
160static void __exit atmel_sha204a_exit(void)
161{
162 flush_scheduled_work();
163 i2c_del_driver(&atmel_sha204a_driver);
164}
165
166module_init(atmel_sha204a_init);
167module_exit(atmel_sha204a_exit);
168
169MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
170MODULE_LICENSE("GPL v2");
171
