drivers/crypto/atmel-sha204a.c

   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_otp_read(struct i2c_client *client, u16 addr, u8 *otp)
  95 {
  96         struct atmel_i2c_cmd cmd;
  97         int ret = -1;
  98
  99         if (atmel_i2c_init_read_otp_cmd(&cmd, addr) < 0) {
 100                 dev_err(&client->dev, "failed, invalid otp address %04X\n",
 101                         addr);
 102                 return ret;
 103         }
 104
 105         ret = atmel_i2c_send_receive(client, &cmd);
 106
 107         if (cmd.data[0] == 0xff) {
 108                 dev_err(&client->dev, "failed, device not ready\n");
 109                 return -EINVAL;
 110         }
 111
 112         memcpy(otp, cmd.data+1, 4);
 113
 114         return ret;
 115 }
 116
 117 static ssize_t otp_show(struct device *dev,
 118                         struct device_attribute *attr, char *buf)
 119 {
 120         u16 addr;
 121         u8 otp[OTP_ZONE_SIZE];
 122         char *str = buf;
 123         struct i2c_client *client = to_i2c_client(dev);
 124         int i;
 125
 126         for (addr = 0; addr < OTP_ZONE_SIZE/4; addr++) {
 127                 if (atmel_sha204a_otp_read(client, addr, otp + addr * 4) < 0) {
 128                         dev_err(dev, "failed to read otp zone\n");
 129                         break;
 130                 }
 131         }
 132
 133         for (i = 0; i < addr*2; i++)
 134                 str += sprintf(str, "%02X", otp[i]);
 135         str += sprintf(str, "\n");
 136         return str - buf;
 137 }
 138 static DEVICE_ATTR_RO(otp);
 139
 140 static struct attribute *atmel_sha204a_attrs[] = {
 141         &dev_attr_otp.attr,
 142         NULL
 143 };
 144
 145 static const struct attribute_group atmel_sha204a_groups = {
 146         .name = "atsha204a",
 147         .attrs = atmel_sha204a_attrs,
 148 };
 149
 150 static int atmel_sha204a_probe(struct i2c_client *client)
 151 {
 152         struct atmel_i2c_client_priv *i2c_priv;
 153         int ret;
 154
 155         ret = atmel_i2c_probe(client);
 156         if (ret)
 157                 return ret;
 158
 159         i2c_priv = i2c_get_clientdata(client);
 160
 161         memset(&i2c_priv->hwrng, 0, sizeof(i2c_priv->hwrng));
 162
 163         i2c_priv->hwrng.name = dev_name(&client->dev);
 164         i2c_priv->hwrng.read = atmel_sha204a_rng_read;
 165
 166         ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
 167         if (ret)
 168                 dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
 169
 170         /* otp read out */
 171         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 172                 return -ENODEV;
 173
 174         ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups);
 175         if (ret) {
 176                 dev_err(&client->dev, "failed to register sysfs entry\n");
 177                 return ret;
 178         }
 179
 180         return ret;
 181 }
 182
 183 static void atmel_sha204a_remove(struct i2c_client *client)
 184 {
 185         struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
 186
 187         if (atomic_read(&i2c_priv->tfm_count)) {
 188                 dev_emerg(&client->dev, "Device is busy, will remove it anyhow\n");
 189                 return;
 190         }
 191
 192         sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups);
 193
 194         kfree((void *)i2c_priv->hwrng.priv);
 195 }
 196
 197 static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
 198         { .compatible = "atmel,atsha204", },
 199         { .compatible = "atmel,atsha204a", },
 200         { /* sentinel */ }
 201 };
 202 MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
 203
 204 static const struct i2c_device_id atmel_sha204a_id[] = {
 205         { "atsha204" },
 206         { "atsha204a" },
 207         { /* sentinel */ }
 208 };
 209 MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
 210
 211 static struct i2c_driver atmel_sha204a_driver = {
 212         .probe                  = atmel_sha204a_probe,
 213         .remove                 = atmel_sha204a_remove,
 214         .id_table               = atmel_sha204a_id,
 215
 216         .driver.name            = "atmel-sha204a",
 217         .driver.of_match_table  = of_match_ptr(atmel_sha204a_dt_ids),
 218 };
 219
 220 static int __init atmel_sha204a_init(void)
 221 {
 222         return i2c_add_driver(&atmel_sha204a_driver);
 223 }
 224
 225 static void __exit atmel_sha204a_exit(void)
 226 {
 227         atmel_i2c_flush_queue();
 228         i2c_del_driver(&atmel_sha204a_driver);
 229 }
 230
 231 module_init(atmel_sha204a_init);
 232 module_exit(atmel_sha204a_exit);
 233
 234 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 235 MODULE_DESCRIPTION("Microchip / Atmel SHA204A (I2C) driver");
 236 MODULE_LICENSE("GPL v2");