Added ability to write protect Mass Storage disk write operations from the host OS.

[pub/USBasp.git] / Demos / Device / LowLevel / MassStorage / Lib / SCSI.c

diff --git a/Demos/Device/LowLevel/MassStorage/Lib/SCSI.c b/Demos/Device/LowLevel/MassStorage/Lib/SCSI.c
index 598c689..63f1ec3 100644 (file)
--- a/Demos/Device/LowLevel/MassStorage/Lib/SCSI.c
+++ b/Demos/Device/LowLevel/MassStorage/Lib/SCSI.c
@@ -111,6 +111,9 @@ bool SCSI_DecodeSCSICommand(void)
                case SCSI_CMD_READ_10:
                        CommandSuccess = SCSI_Command_ReadWrite_10(DATA_READ);
                        break;
+               case SCSI_CMD_MODE_SENSE_6:
+                       CommandSuccess = SCSI_Command_ModeSense_6();
+                       break;
                case SCSI_CMD_TEST_UNIT_READY:
                case SCSI_CMD_PREVENT_ALLOW_MEDIUM_REMOVAL:
                case SCSI_CMD_VERIFY_10:
@@ -278,9 +281,23 @@ static bool SCSI_Command_Send_Diagnostic(void)
  */
 static bool SCSI_Command_ReadWrite_10(const bool IsDataRead)
 {
-       uint32_t BlockAddress = SwapEndian_32(*(uint32_t*)&CommandBlock.SCSICommandData[2]);
-       uint16_t TotalBlocks  = SwapEndian_16(*(uint16_t*)&CommandBlock.SCSICommandData[7]);
+       uint32_t BlockAddress;
+       uint16_t TotalBlocks;
+
+       /* Check if the disk is write protected or not */
+       if ((IsDataRead == DATA_WRITE) && DISK_READ_ONLY)
+       {
+               /* Block address is invalid, update SENSE key and return command fail */
+               SCSI_SET_SENSE(SCSI_SENSE_KEY_DATA_PROTECT,
+                              SCSI_ASENSE_WRITE_PROTECTED,
+                              SCSI_ASENSEQ_NO_QUALIFIER);
 
+               return false;           
+       }
+
+       BlockAddress = SwapEndian_32(*(uint32_t*)&CommandBlock.SCSICommandData[2]);
+       TotalBlocks  = SwapEndian_16(*(uint16_t*)&CommandBlock.SCSICommandData[7]);
+       
        /* Check if the block address is outside the maximum allowable value for the LUN */
        if (BlockAddress >= LUN_MEDIA_BLOCKS)
        {
@@ -309,3 +326,22 @@ static bool SCSI_Command_ReadWrite_10(const bool IsDataRead)
        return true;
 }
 
+/** Command processing for an issued SCSI MODE SENSE (6) command. This command returns various informational pages about
+ *  the SCSI device, as well as the device's Write Protect status.
+ *
+ *  \return Boolean true if the command completed successfully, false otherwise.
+ */
+static bool SCSI_Command_ModeSense_6(void)
+{
+       /* Send an empty header response with the Write Protect flag status */
+       Endpoint_Write_Byte(0x00);
+       Endpoint_Write_Byte(0x00);
+       Endpoint_Write_Byte(DISK_READ_ONLY ? 0x80 : 0x00);
+       Endpoint_Write_Byte(0x00);
+       Endpoint_ClearIN();
+
+       /* Update the bytes transferred counter and succeed the command */
+       CommandBlock.DataTransferLength -= 4;
+
+       return true;
+}