Sansa Connect: Use deviceid in USB Serial Number

Atmel AT88SC6416C CryptoMemory is almost I2C compatible. The device
is connected to bitbanged I2C bus shared with compliant I2C devices.

Change-Id: Iec54702db1bdfb93c01291eef18ec60391c63b16

firmware/target/arm/tms320dm320/i2c-dm320.c

@@ -294,4 +294,12 @@ int i2c_read_bytes(unsigned short address, unsigned short reg,
     return i2c_read_data(dm320_i2c_bus, address, reg, buf, count);
 }
 
+int i2c_write_read_bytes(unsigned short address,
+                         const unsigned char* buf_write, int count_write,
+                         unsigned char* buf_read, int count_read)
+{
+    return i2c_write_read_data(dm320_i2c_bus, address, buf_write, count_write,
+                               buf_read, count_read);
+}
+
 #endif

firmware/target/arm/tms320dm320/i2c-dm320.h

@@ -31,6 +31,9 @@ int i2c_read(unsigned short address, unsigned char* buf, int count);
 #ifdef HAVE_SOFTWARE_I2C
 int i2c_read_bytes(unsigned short address, unsigned short reg,
                    unsigned char* buf, int count);
+int i2c_write_read_bytes(unsigned short address,
+                         const unsigned char* buf_write, int count_write,
+                         unsigned char* buf_read, int count_read);
 #endif
 
 #endif

firmware/target/arm/tms320dm320/sansa-connect/cryptomem-sansaconnect.c

@@ -0,0 +1,80 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id: $
+*
+* Copyright (C) 2021 by Tomasz Moń
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License
+* as published by the Free Software Foundation; either version 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+
+#include <ctype.h>
+#include "cryptomem-sansaconnect.h"
+#include "i2c-dm320.h"
+
+/* Command values */
+#define WRITE_USER_ZONE  0xB0
+#define READ_USER_ZONE   0xB2
+#define SYSTEM_WRITE     0xB4
+#define SYSTEM_READ      0xB6
+#define VERIFY_CRYPTO    0xB8
+#define VERIFY_PASSWORD  0xBA
+
+/* SYSTEM_WRITE ADDR 1 values */
+#define WRITE_CONFIG     0x00
+#define WRITE_FUSES      0x01
+#define SEND_CHECKSUM    0x02
+#define SET_USER_ZONE    0x03
+
+int cryptomem_read_deviceid(char deviceid[32])
+{
+    int ret;
+    unsigned int i;
+    unsigned char cmd_data[3];
+
+    /* It is assumed that other I2C communication has already taken place
+     * (e.g. power_init()) before this function is called and thus we don't
+     * have to send atleast 5 dummy clock cycles here.
+     */
+
+    cmd_data[0] = SET_USER_ZONE;
+    cmd_data[1] = 0;
+    cmd_data[2] = 0;
+    ret = i2c_write(SYSTEM_WRITE, cmd_data, sizeof(cmd_data));
+    if (ret < 0)
+    {
+        return ret;
+    }
+
+    cmd_data[0] = 0;
+    cmd_data[1] = 0;
+    cmd_data[2] = 32;
+    ret = i2c_write_read_bytes(READ_USER_ZONE, cmd_data, sizeof(cmd_data),
+                               deviceid, 32);
+    if (ret < 0)
+    {
+        return ret;
+    }
+
+    /* Verify that deviceid contains only printable ASCII characters */
+    for (i = 0; i < 32; i++)
+    {
+        if (!isprint(deviceid[i]))
+        {
+            return -1;
+        }
+    }
+
+    return 0;
+}

firmware/target/arm/tms320dm320/sansa-connect/cryptomem-sansaconnect.h

@@ -0,0 +1,27 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id: $
+*
+* Copyright (C) 2021 by Tomasz Moń
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License
+* as published by the Free Software Foundation; either version 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+
+#ifndef _CRYPTOMEM_SANSACONNECT_H_
+#define _CRYPTOMEM_SANSACONNECT_H_
+
+int cryptomem_read_deviceid(char deviceid[32]);
+
+#endif /* _CRYPTOMEM_SANSACONNECT_H_ */