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/SOURCES

@@ -1274,6 +1274,7 @@ target/arm/tms320dm320/sansa-connect/tnetv105_cppi.c
 target/arm/tms320dm320/sansa-connect/tnetv105_usb_drv.c
 target/arm/tms320dm320/sansa-connect/usb-sansaconnect.c
 target/arm/tms320dm320/sansa-connect/avr-sansaconnect.c
+target/arm/tms320dm320/sansa-connect/cryptomem-sansaconnect.c
 target/arm/tms320dm320/sansa-connect/backlight-sansaconnect.c
 target/arm/tms320dm320/sansa-connect/pcm-sansaconnect.c
 target/arm/tms320dm320/sansa-connect/wifi-sansaconnect.c

firmware/drivers/generic_i2c.c

@@ -198,6 +198,40 @@ end:
     return ret;
 }
 
+int i2c_write_read_data(int bus_index, int bus_address,
+                        const unsigned char* buf_write, int count_write,
+                        unsigned char* buf_read, int count_read)
+{
+    int i;
+    int ret = 0;
+    const struct i2c_interface *iface = i2c_if[bus_index];
+
+    i2c_start(iface);
+    if (!i2c_outb(iface, bus_address))
+    {
+        ret = -2;
+        goto end;
+    }
+
+    for(i = 0;i < count_write;i++)
+    {
+        if (!i2c_outb(iface, buf_write[i]))
+        {
+            ret = -3;
+            goto end;
+        }
+    }
+
+    for(i = 0;i < count_read-1;i++)
+        buf_read[i] = i2c_inb(iface, true);
+
+    buf_read[i] = i2c_inb(iface, false);
+
+end:
+    i2c_stop(iface);
+    return ret;
+}
+
 /* returns bus index which can be used as a handle, or <0 on error */
 int i2c_add_node(const struct i2c_interface *iface)
 {

firmware/export/generic_i2c.h

@@ -49,5 +49,15 @@ int i2c_write_data(int bus_index, int bus_address, int address,
 int i2c_read_data(int bus_index, int bus_address, int address,
                   unsigned char* buf, int count);
 
+/* Special function for devices that can appear on I2C bus but do not
+ * comply to I2C specification. Such devices include AT88SC6416C crypto
+ * memory. To read data from AT88SC6416C, a write I2C transaction starts,
+ * 3 bytes are written and then, in the middle of transaction, the device
+ * starts sending data.
+ */
+int i2c_write_read_data(int bus_index, int bus_address,
+                        const unsigned char* buf_write, int count_write,
+                        unsigned char* buf_read, int count_read);
+
 #endif /* _GEN_I2C_ */
 

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_ */

firmware/usbstack/usb_core.c

@@ -62,6 +62,10 @@
 #include "ocotp-imx233.h"
 #endif
 
+#ifdef SANSA_CONNECT
+#include "cryptomem-sansaconnect.h"
+#endif
+
 #ifndef USB_MAX_CURRENT
 #define USB_MAX_CURRENT 500
 #endif
@@ -327,6 +331,22 @@ static void set_serial_descriptor(void)
     }
     usb_string_iSerial.bLength = 2 + 2 * (1 + IMX233_NUM_OCOTP_OPS * 8);
 }
+#elif defined(SANSA_CONNECT)
+static void set_serial_descriptor(void)
+{
+    char deviceid[32];
+    short* p = &usb_string_iSerial.wString[1];
+    int i;
+
+    if(!cryptomem_read_deviceid(deviceid)) {
+        for(i = 0; i < 32; i++) {
+            *p++ = deviceid[i];
+        }
+        usb_string_iSerial.bLength = 2 + 2 * (1 + 32);
+    } else {
+        device_descriptor.iSerialNumber = 0;
+    }
+}
 #elif (CONFIG_STORAGE & STORAGE_ATA)
 /* If we don't know the device serial number, use the one
  * from the disk */