crypto: atmel-sha204a - add reading from otp zone

Provide a read function reading the otp zone. The otp zone can be used for
storing serial numbers. The otp zone, as also data zone, are only
accessible if the chip was locked before. Locking the chip is a post
production customization and has to be done manually i.e. not by this
driver. Without this step the chip is pretty much not usable, where
putting or not putting data into the otp zone is optional.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
index c77f482d2a97..563a0493b492 100644
--- a/drivers/crypto/atmel-sha204a.c
+++ b/drivers/crypto/atmel-sha204a.c
@@ -91,6 +91,29 @@ 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 -ret;
+	}
+
+	memcpy(otp, cmd.data+1, 4);
+
+	return ret;
+}
+
 static int atmel_sha204a_probe(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv;