1 files changed, 77 insertions, 2 deletions

diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
index c77f482d2a97..0fcf4a39de27 100644
--- a/drivers/crypto/atmel-sha204a.c
+++ b/drivers/crypto/atmel-sha204a.c
@@ -91,6 +91,62 @@ static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
 	return max;
 }
 
+static int atmel_sha204a_otp_read(struct i2c_client *client, u16 addr, u8 *otp)
+{
+	struct atmel_i2c_cmd cmd;
+	int ret = -1;
+
+	if (atmel_i2c_init_read_otp_cmd(&cmd, addr) < 0) {
+		dev_err(&client->dev, "failed, invalid otp address %04X\n",
+			addr);
+		return ret;
+	}
+
+	ret = atmel_i2c_send_receive(client, &cmd);
+
+	if (cmd.data[0] == 0xff) {
+		dev_err(&client->dev, "failed, device not ready\n");
+		return -EINVAL;
+	}
+
+	memcpy(otp, cmd.data+1, 4);
+
+	return ret;
+}
+
+static ssize_t otp_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	u16 addr;
+	u8 otp[OTP_ZONE_SIZE];
+	char *str = buf;
+	struct i2c_client *client = to_i2c_client(dev);
+	int i;
+
+	for (addr = 0; addr < OTP_ZONE_SIZE/4; addr++) {
+		if (atmel_sha204a_otp_read(client, addr, otp + addr * 4) < 0) {
+			dev_err(dev, "failed to read otp zone\n");
+			break;
+		}
+	}
+
+	for (i = 0; i < addr*2; i++)
+		str += sprintf(str, "%02X", otp[i]);
+	str += sprintf(str, "\n");
+	return str - buf;
+}
+static DEVICE_ATTR_RO(otp);
+
+static struct attribute *atmel_sha204a_attrs[] = {
+	&dev_attr_otp.attr,
+	NULL
+};
+
+static const struct attribute_group atmel_sha204a_groups = {
+	.name = "atsha204a",
+	.attrs = atmel_sha204a_attrs,
+};
+
 static int atmel_sha204a_probe(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv;
@@ -107,10 +163,26 @@ static int atmel_sha204a_probe(struct i2c_client *client)
 	i2c_priv->hwrng.name = dev_name(&client->dev);
 	i2c_priv->hwrng.read = atmel_sha204a_rng_read;
 
+	/*
+	 * According to review by Bill Cox [1], this HWRNG has very low entropy.
+	 * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html
+	 */
+	i2c_priv->hwrng.quality = 1;
+
 	ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
 	if (ret)
 		dev_warn(&client->dev, "failed to register RNG (%d)\n", ret);
 
+	/* otp read out */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	ret = sysfs_create_group(&client->dev.kobj, &atmel_sha204a_groups);
+	if (ret) {
+		dev_err(&client->dev, "failed to register sysfs entry\n");
+		return ret;
+	}
+
 	return ret;
 }
 
@@ -123,6 +195,8 @@ static void atmel_sha204a_remove(struct i2c_client *client)
 		return;
 	}
 
+	sysfs_remove_group(&client->dev.kobj, &atmel_sha204a_groups);
+
 	kfree((void *)i2c_priv->hwrng.priv);
 }
 
@@ -134,8 +208,8 @@ static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
 MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
 
 static const struct i2c_device_id atmel_sha204a_id[] = {
-	{ "atsha204", 0 },
-	{ "atsha204a", 0 },
+	{ "atsha204" },
+	{ "atsha204a" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(i2c, atmel_sha204a_id);
@@ -164,4 +238,5 @@ module_init(atmel_sha204a_init);
 module_exit(atmel_sha204a_exit);
 
 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
+MODULE_DESCRIPTION("Microchip / Atmel SHA204A (I2C) driver");
 MODULE_LICENSE("GPL v2");