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1// SPDX-License-Identifier: GPL-2.02/*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(&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(&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_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 117static 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}138static DEVICE_ATTR_RO(otp);139 140static struct attribute *atmel_sha204a_attrs[] = {141 &dev_attr_otp.attr,142 NULL143};144 145static const struct attribute_group atmel_sha204a_groups = {146 .name = "atsha204a",147 .attrs = atmel_sha204a_attrs,148};149 150static 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 183static 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 197static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {198 { .compatible = "atmel,atsha204", },199 { .compatible = "atmel,atsha204a", },200 { /* sentinel */ }201};202MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);203 204static const struct i2c_device_id atmel_sha204a_id[] = {205 { "atsha204", 0 },206 { "atsha204a", 0 },207 { /* sentinel */ }208};209MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);210 211static 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 220static int __init atmel_sha204a_init(void)221{222 return i2c_add_driver(&atmel_sha204a_driver);223}224 225static void __exit atmel_sha204a_exit(void)226{227 atmel_i2c_flush_queue();228 i2c_del_driver(&atmel_sha204a_driver);229}230 231module_init(atmel_sha204a_init);232module_exit(atmel_sha204a_exit);233 234MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");235MODULE_DESCRIPTION("Microchip / Atmel SHA204A (I2C) driver");236MODULE_LICENSE("GPL v2");237