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, 24 insertions, 0 deletions

diff --git a/drivers/crypto/atmel-i2c.c b/drivers/crypto/atmel-i2c.c
index a0d0d4f2ab25a..a895e4289efa0 100644
--- a/drivers/crypto/atmel-i2c.c
+++ b/drivers/crypto/atmel-i2c.c
@@ -70,6 +70,30 @@ void atmel_i2c_init_read_config_cmd(struct atmel_i2c_cmd *cmd)
 }
 EXPORT_SYMBOL(atmel_i2c_init_read_config_cmd);
 
+int atmel_i2c_init_read_otp_cmd(struct atmel_i2c_cmd *cmd, u16 addr)
+{
+	if (addr < 0 || addr > OTP_ZONE_SIZE)
+		return -1;
+
+	cmd->word_addr = COMMAND;
+	cmd->opcode = OPCODE_READ;
+	/*
+	 * Read the word from OTP zone that may contain e.g. serial
+	 * numbers or similar if persistently pre-initialized and locked
+	 */
+	cmd->param1 = OTP_ZONE;
+	cmd->param2 = cpu_to_le16(addr);
+	cmd->count = READ_COUNT;
+
+	atmel_i2c_checksum(cmd);
+
+	cmd->msecs = MAX_EXEC_TIME_READ;
+	cmd->rxsize = READ_RSP_SIZE;
+
+	return 0;
+}
+EXPORT_SYMBOL(atmel_i2c_init_read_otp_cmd);
+
 void atmel_i2c_init_random_cmd(struct atmel_i2c_cmd *cmd)
 {
 	cmd->word_addr = COMMAND;