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(v: &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(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 | |
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: &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 | |
94 | static 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 | |
117 | static 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 | |
129 | static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = { |
130 | { .compatible = "atmel,atsha204" , }, |
131 | { .compatible = "atmel,atsha204a" , }, |
132 | { /* sentinel */ } |
133 | }; |
134 | MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids); |
135 | |
136 | static const struct i2c_device_id atmel_sha204a_id[] = { |
137 | { "atsha204" , 0 }, |
138 | { "atsha204a" , 0 }, |
139 | { /* sentinel */ } |
140 | }; |
141 | MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id); |
142 | |
143 | static 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 | |
152 | static int __init atmel_sha204a_init(void) |
153 | { |
154 | return i2c_add_driver(&atmel_sha204a_driver); |
155 | } |
156 | |
157 | static void __exit atmel_sha204a_exit(void) |
158 | { |
159 | atmel_i2c_flush_queue(); |
160 | i2c_del_driver(driver: &atmel_sha204a_driver); |
161 | } |
162 | |
163 | module_init(atmel_sha204a_init); |
164 | module_exit(atmel_sha204a_exit); |
165 | |
166 | MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>" ); |
167 | MODULE_LICENSE("GPL v2" ); |
168 | |