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x68000:writing_drivers [2014/07/10 19:53] – eidisx68000:writing_drivers [2019/08/27 20:45] (current) – external edit 127.0.0.1
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 The following information was kindly contributed by our forum member **Lydux**. The following information was kindly contributed by our forum member **Lydux**.
 +
 +Original thread can be found here:
 +http://nfggames.com/forum2/index.php?topic=5417.0
  
 So I've decided to share with you some of my study and work. So I've decided to share with you some of my study and work.
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 **Note :** the following contains very hard stuff ! I might be confusing sometimes, sorry in advance. Don't hesitate to ask for help if you do not understand something. Thank you. **Note :** the following contains very hard stuff ! I might be confusing sometimes, sorry in advance. Don't hesitate to ask for help if you do not understand something. Thank you.
- 
- 
- 
----- 
  
 **Terminology :** **Terminology :**
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   * Char : 1 character = 1 byte   * Char : 1 character = 1 byte
   * All data types are CPU specific : M68K family. So, byte ordering is always "Big Endian" and a pointer is 32 bits (long).   * All data types are CPU specific : M68K family. So, byte ordering is always "Big Endian" and a pointer is 32 bits (long).
- 
----- 
  
 ====== Compilation flags, libraries and startup code ====== ====== Compilation flags, libraries and startup code ======
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     * 0x0002 : STDOUT device. The driver will redefine the stdout, for example : screen, serial output, printers,...     * 0x0002 : STDOUT device. The driver will redefine the stdout, for example : screen, serial output, printers,...
     * 0x0001 : STDIN device. The driver will redefine the stdin : keyboard or serial input.     * 0x0001 : STDIN device. The driver will redefine the stdin : keyboard or serial input.
-    strategy routine (long): A pointer to the very first routine the kernel will execute ! This will initiate the driver loading. +  * __strategy routine (long)__: A pointer to the very first routine the kernel will execute ! This will initiate the driver loading. 
-    interrupt routine (long): A pointer to a routine that will perform the communication between the kernel and the device. +  * __interrupt routine (long)__: A pointer to a routine that will perform the communication between the kernel and the device. 
-    driver name (8 chars): An unique identifier, also used by userspace application when executing IOCTL commands.+  * __driver name (8 chars)__: An unique identifier, also used by userspace application when executing IOCTL commands.
  
  
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 The small allocated kernel memory area will change on every kernel request. Only the first 13 bytes is a fixed structure describing the request itself, and the remaining are the request parameters. Note that the some Request Packet structure members are filled by the kernel (input), others are by the drivers as the result of the request (output). The small allocated kernel memory area will change on every kernel request. Only the first 13 bytes is a fixed structure describing the request itself, and the remaining are the request parameters. Note that the some Request Packet structure members are filled by the kernel (input), others are by the drivers as the result of the request (output).
 +
 Request packet structure header (fixed first 13 bytes) : Request packet structure header (fixed first 13 bytes) :
  
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   * __Requested unit__ (byte, input) : The unit number this packet target. An unique loaded driver might handle more than one device. Ex : the FDD driver handle 2 or 4 floppy drives.   * __Requested unit__ (byte, input) : The unit number this packet target. An unique loaded driver might handle more than one device. Ex : the FDD driver handle 2 or 4 floppy drives.
   * __Request command code__ (byte, input) : The kernel request command code that the interrupt routine MUST analyze and dispatch/proceed. See "Generic command codes and parameters" and "Extend command codes" bellow.   * __Request command code__ (byte, input) : The kernel request command code that the interrupt routine MUST analyze and dispatch/proceed. See "Generic command codes and parameters" and "Extend command codes" bellow.
-  * __Result status__ (word, output) : These are combination of return flags notifying the success or failure of the request. On failure, this manifest by the famous centered white box with a message, and the user is invited to type "A"bort, "R"etry or "I"gnore. A driver must always fill this member on every command execution ! See "Command execution result flags" bellow for a list of acceptable flags.+  * __Result status__ (word, output) : These are combination of return flags notifying the success or failure of the request. On failure, this manifest by the famous centered white box with a message, and the user is invited to type "A"bort, "R"etry or "I"gnore. **A driver must always fill this member on every command execution !** See "Command execution result flags" bellow for a list of acceptable flags.
   * __Reserved (8 bytes)__ : Reserved area, don't touch it !   * __Reserved (8 bytes)__ : Reserved area, don't touch it !
  
  
-Command execution result flags : +**Command execution result flags :** 
-This list contains all acceptable values to fill the result status flags in the request packet header. + 
-S_**** flags will display (or hide) the "A"bort, "R"etry and "I"gnore line, and E_**** will show an appropriate error message.+This list contains all acceptable values to fill the result status flags in the request packet header. S_**** flags will display (or hide) the "A"bort, "R"etry and "I"gnore line, and E_**** will show an appropriate error message. 
 "Result status" member can be any combination of S_**** flags (ORed together), but only one E_**** can be set. "Result status" member can be any combination of S_**** flags (ORed together), but only one E_**** can be set.
  
-    0x1000 - S_ABORT : "A"bort the whole request. +  * 0x1000 - S_ABORT : "A"bort the whole request. 
-    0x2000 - S_RETRY : Allow to "R"etry the request. +  * 0x2000 - S_RETRY : Allow to "R"etry the request. 
-    0x4000 - S_IGNORE : The failed request can be safelly "I"gnored. +  * 0x4000 - S_IGNORE : The failed request can be safelly "I"gnored. 
-    0x0000 - E_OK : No error +  * 0x0000 - E_OK : No error 
-    0x0001 - E_UNIT : The unit is unknown +  * 0x0001 - E_UNIT : The unit is unknown 
-    0x0002 - E_NOTRDY : Unit isn't ready +  * 0x0002 - E_NOTRDY : Unit isn't ready 
-    0x0003 - E_CMD : Unknow command code +  * 0x0003 - E_CMD : Unknow command code 
-    0x0004 - E_CRC : CRC error +  * 0x0004 - E_CRC : CRC error 
-    0x0005 - E_LENGTH : Bad length +  * 0x0005 - E_LENGTH : Bad length 
-    0x0006 - E_SEEK :  Seek Error +  * 0x0006 - E_SEEK :  Seek Error 
-    0x0007 - E_MEDIA :  Unknown Media +  * 0x0007 - E_MEDIA :  Unknown Media 
-    0x0008 - E_NOTFND : Sector Not Found +  * 0x0008 - E_NOTFND : Sector Not Found 
-    0x0009 - E_PAPER : No Paper +  * 0x0009 - E_PAPER : No Paper 
-    0x000A - E_WRITE : Write Fault +  * 0x000A - E_WRITE : Write Fault 
-    0x000B - E_READ : Read Fault +  * 0x000B - E_READ : Read Fault 
-    0x000C - E_FAILURE : General Failure +  * 0x000C - E_FAILURE : General Failure 
-    0x000D - E_WRPRT : Write Protect +  * 0x000D - E_WRPRT : Write Protect 
-    0x000E - E_DISK : Disk Change+  * 0x000E - E_DISK : Disk Change 
 + 
 +====== Generic command codes and parameters ====== 
 + 
 +Each possible request command code in the request packet header have their own set of parameters. Again some are filled by the kernel, and others by the driver. 
 + 
 +Note that some request command code are available only for character device drivers, some only for block device drivers and some on both. Remote device drivers have their own set of command code. 
 +Command parameters structure always start at position 14 within the request packet. 
 + 
 +===== 0x00 - Initialize ===== 
 + 
 +**Command ID :** 0x00 (C_INIT) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** 
 + 
 +This is the initialize command and is called only once after driver loading. On initialize, the driver must perform eventual device detection and initialization, specify the number of unit it will handle, process its own arguments passed by CONFIG.SYS, and specify its eventual memory heap size. On return from this command, this finish the whole driver initialization process, and the kernel will continue to the next driver or continue its execution. 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  18  |  Long  |Pointer to a null terminated string containing arguments passed via CONFIG.SYS  | 
 +|  22  |  Byte  |Block device driver only. Not sure of the meaning, but this probably contains the drive number the kernel want to initialize.  | 
 + 
 +  
 +**Output parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  13  |  Byte  |Block device driver only. The amount of "units" this driver will handle. Ex : amount of partitions in all detected hard drives  | 
 +|  14  |  Long  |Pointer to the end of the used memory space. This memory space include every segment sizes used by the driver : TEXT, DATA, BSS, as well as eventual HEAP. A very important parameter ! Any wrong value written here will crash the kernel. Normally, my toolchain provides a symbol usable for this parameter : "_end". "_end" points to the last byte of the relocated BSS segment, so you can directly pass its address if you don't use HEAP, or pass "_end" address + the amount of memory you need for HEAP. See DDK samples for more infos.  | 
 +|  18  |  Long  |Block device driver only. Pointer to an array of BPB (Bios Parameter Block). Basically, a BPB describes the FAT volume on the physical disk, so determine the size of a partition or media. For more information about BPB, see wikipedia : http://en.wikipedia.org/wiki/BIOS_parameter_block Note that the X68000 BPB is slightly different than PC BPB. I will describe it later.  | 
 + 
 +===== 0x01 - Media Check ===== 
 + 
 +**Command ID :** 0x01 (C_MEDIACHK) 
 + 
 +**Availability :** Block 
 + 
 +**Description :** Before performing IO operations on a block device, the kernel will process this command code to ensure the target media is still available and ready. 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  13  |  Byte  |Last known media type ID. See standard media type list bellow.  | 
 + 
 +  
 +**Output parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  14  |  Byte  |Media status. Possible values are :  | 
 +|  |  -1  |M_CHANGED : Media was changed  | 
 +|  |  0  |M_DONT_KNOW : Media state unknown  | 
 +|  |  1  |M_NOT_CHANGED : Media still in and ready  | 
 + 
 +**Human68K standard media type list :** 
 + 
 +Note : this list isn't exhaustive ! A driver can provide its own set. So, a program or driver should never rely on these values to determine the media type. 
 + 
 +I will not explain them, names pretty much speak for themselves. 
 + 
 +  * 0xE0 - MD_2DD_10 
 +  * 0xE5 - MD_1D_9 
 +  * 0xE6 - MD_2D_9 
 +  * 0xE7 - MD_1D_8 
 +  * 0xE8 - MD_2D_8 
 +  * 0xEA - MD_2HT 
 +  * 0xEB - MD_2HS 
 +  * 0xEC - MD_2HDE 
 +  * 0xEE - MD_1DD_9 
 +  * 0xEF - MD_1DD_8 
 +  * 0xF4 - MD_DAT 
 +  * 0xF5 - MD_CDROM 
 +  * 0xF6 - MD_MO 
 +  * 0xF7 - MD_SCSIHD 
 +  * 0xF8 - MD_SASIHD 
 +  * 0xF9 - MD_RAMDISK 
 +  * 0xFA - MD_2HQ 
 +  * 0xFB - MD_2DD_8 
 +  * 0xFC - MD_2DD_9 
 +  * 0xFD - MD_2HC 
 +  * 0xFE - MD_2HD 
 + 
 + 
 +===== 0x02 - Build BPB ===== 
 + 
 + 
 +**Command ID :** 0x02 (C_BLDBPB) 
 + 
 +**Availability :** Block 
 + 
 +**Description :** This command is proceed when a media have previously been reported as "changed" by the "Media Check" command code. It's used to fetch the newer unit BPB. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  18  |  Long  |  Pointer to the requested unit BPB  | 
 +  
 + 
 +===== 0x03 - IOCTL input ===== 
 + 
 +**Command ID :** 0x03 (C_IOCTLIN) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Request the driver to read raw arbitrary datas from the specified unit. This request is initiated by an userspace application (IOCTL). 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  14  |  Long  |Pointer to a buffer that'll contain readed data from the unit. The driver is responsible of filling this buffer.  | 
 +|  18  |  Long  |Buffer size  | 
 +  
 +**Output parameters :** none 
 + 
 +===== 0x04 - Input (read) ===== 
 + 
 +**Command ID :** 0x04 (C_INPUT) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Request the driver to read data from the specified unit. This request is initiated by the kernel. 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  13  |  Byte  |Block device driver only. Media type.  |     
 +|  14  |  Long  |Pointer to a buffer that'll contain the readed data from the unit.The driver is responsible of filling this buffer.  | 
 +|  18  |  Long  |Block device driver : number of sector to read. A sector length is normally specified by the BPB.  | 
 +| | |Character device driver : Buffer size.  |  
 +|  22  |  Long  |Block device driver only : logical start sector to read from.  | 
 + 
 +**Output parameters :** none  
 + 
 +Note for block device driver : as the kernel is responsible for handling the FAT, you just have to seek to the specified start sector location and read the wanted amount of data from there according to the requested amount of sectors and the BPB. However, the driver is still responsible of the logical to physical partition translation ! So, seek correctly. 
 + 
 +===== 0x05 - Read no wait ===== 
 + 
 +**Command ID :** 0x05 (C_NDREAD) 
 + 
 +**Availability :** Character 
 + 
 +**Description :** To check furthermore. A strange command code that allow a driver to send back a device prereaded byte. Maybe dedicated command to some simple interrupt driven device. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  13  |  Byte  |Prereaded byte  | 
 + 
 +===== 0x05 - Drive control/Status packet ===== 
 + 
 +**Command ID :** 0x05 (C_DRVCTL) 
 + 
 +**Availability :** Block 
 + 
 +**Description :** //To check furthermore.// This seems to be really X68000 specific floppy drive command, or some kind of kernel hack by Human68k developpers. It does some kind of IOCTL, but internally to the kernel to dis/allow and control of FDD ejection, LEDs or media write protection control... 
 + 
 +===== 0x06 - Input status ===== 
 + 
 +**Command ID :** 0x06 (C_ISTAT) 
 + 
 +**Availability :** Character 
 + 
 +**Description :** Kernel perform this command before the INPUT one to check if reading on the specified unit is actually possible or not. There is no parameter. Just fill the result flags in the request packet header accordingly. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** none 
 + 
 +===== 0x07 - Input flush ===== 
 + 
 +**Command ID :** 0x07 (C_IFLUSH) 
 + 
 +**Availability :** Character 
 + 
 +**Description :** Request the driver to flush the specified unit input buffer. There is no parameter. Just fill the result flags in the request packet header accordingly. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** none 
 + 
 +===== 0x08 - Output (write) ===== 
 + 
 +**Command ID :** 0x08 (C_OUTPUT) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Request the driver to write data to a specified unit. This request is initiated by the kernel. 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  14  |  Long  |Pointer to a buffer that contains data to write to the unit.| 
 +|  18  |  Long  |Block device driver : number of sector to write. A sector length is normally specified by the BPB.  | 
 +| | |Character device driver : Buffer size.  |  
 +|  22  |  Long  |Block device driver only : logical start sector to write to.  |  
 + 
 +**Output parameters :** none 
 + 
 +Note for block device driver : as the kernel is responsible for handling the FAT, you just have to seek to the specified start sector location and read the wanted amount of data from there according to the requested amount of sectors and the BPB. However, the driver is still responsible of the logical to physical partition translation ! So, seek correctly. 
 + 
 +===== 0x09 - Output with verify ===== 
 + 
 +**Command ID :** 0x09 (C_OUTVFY) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Same as "0x08 - Output (write)", but the driver must also read the data buffer back to ensure the data as been correctly written. 
 + 
 +**Input parameters :** same as the "0x08 - Output (write)" 
 + 
 +===== 0x0A - Output status ===== 
 + 
 +**Command ID :** 0x0A (C_OSTAT) 
 + 
 +**Availability :** Character 
 + 
 +**Description :** Kernel perform this command before the OUTPUT one to check if writing to the specified unit is actually possible or not. There is no parameter. Just fill the result flags in the request packet header accordingly. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** none 
 + 
 +===== 0x0B - Output flush ===== 
 + 
 +**Command ID :** 0x0B (C_OFLUSH) 
 + 
 +**Availability :** Character 
 + 
 +**Description :** Request the driver to flush the specified unit output buffer. There is no parameter. Just fill the result flags in the request packet header accordingly. 
 + 
 +**Input parameters :** none 
 + 
 +**Output parameters :** none 
 + 
 +===== 0x0C - IOCTL out ===== 
 + 
 +**Command ID :** 0x0C (C_IOCTLOUT) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Request the driver to write raw arbitrary datas to the specified unit. This request is initiated by an userspace application (IOCTL). 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  14  |  Long  |Pointer to a buffer that'll contain data to write to the unit. The userspace program is responsible of filling this buffer.  | 
 +|  18  |  Long  |Buffer size  | 
 + 
 +**Output parameters :** none 
 + 
 +===== 0x13 - Generic IOCTL ===== 
 + 
 +**Command ID :** 0x13 (C_GENIOCTL) 
 + 
 +**Availability :** Block/Character 
 + 
 +**Description :** Perform a IOCTL command understood only by the driver and an userspace program. 
 + 
 +**Input parameters :** 
 + 
 +^  Position  ^  Type  ^  Description  ^ 
 +|  14  |  Long  |Optional pointer to a buffer. That buffer is totally specific to the IOCTL command ID.  | 
 +|  18  |  Word  |IOCTL command ID. There is no restriction to this value.  | 
 + 
 +**Output parameters :** none 
 + 
 +====== Extend command code ====== 
 + 
 +These following request command codes are only performed when the driver header have the "attribute" flag set with the value 0x2000 (Remote device driver). 
 + 
 +I actually do not know very much about them but they seems to be really filesystem level. 
 + 
 +Here is all known command ID : 
 + 
 +  * 0x40 - CR_INIT 
 +  * 0x41 - CR_SEARCH_DIR 
 +  * 0x42 - CR_CREATE_DIR 
 +  * 0x43 - CR_DELETE_DIR 
 +  * 0x44 - CR_RENAME_FILE 
 +  * 0x45 - CR_DELETE_FILE 
 +  * 0x46 - CR_CHMOD 
 +  * 0x47 - CR_FILES 
 +  * 0x48 - CR_NFILES 
 +  * 0x49 - CR_CREATE 
 +  * 0x4A - CR_OPEN 
 +  * 0x4B - CR_CLOS 
 +  * 0x4C - CR_READ 
 +  * 0x4D - CR_WRITE 
 +  * 0x4E - CR_SEEK 
 +  * 0x4F - CR_TIMEMOD 
 +  * 0x50 - CR_GETCAP 
 +  * 0x51 - CR_CONTROL 
 +  * 0x52 - CR_BUILD_BPB 
 +  * 0x53 - CR_IOCTL_IN 
 +  * 0x54 - CR_IOCTL_OUT 
 +  * 0x55 - CR_IOCTL_SPECIAL 
 +  * 0x56 - CR_ABORT 
 +  * 0x57 - CR_MEDIA_CHECK 
 +  * 0x58 - CR_LOCK 
 + 
 +I do have parameters. I will write them later. 
 + 
 + 
 +====== BIOS Parameter Block (BPB) ====== 
 + 
 +I will not explain this structure as there is plenty of informations about it on the internet. 
 + 
 +Starting from wikipedia : http://en.wikipedia.org/wiki/BIOS_parameter_block 
 + 
 +Just read everything you can about FAT12 and FAT16. 95% of these also apply to Human68k. 
 + 
 +Most of difference is the byte ordering, which is big endian instead of little endian. The structure is also a bit different. 
 + 
 +From my ddk.h file : 
 + 
 +<file> 
 +struct bpb { 
 +  UWORD bpb_nbyte; /* Bytes per sector */ 
 +  UBYTE bpb_nsector; /* Sectors per allocation unit */ 
 +  UBYTE bpb_nfat; /* Number of FATs */ 
 +  UWORD bpb_nreserved; /* Number of reserved sectors */ 
 +  UWORD bpb_ndirent; /* Number of root directory entries */ 
 +  UWORD bpb_nsize; /* Size in sectors (16 bits) */ 
 +  UBYTE bpb_mdesc; /* MEDIA Descriptor Byte */ 
 +  UBYTE bpb_nfsect; /* Number of sector per FAT */ 
 +  ULONG bpb_huge; /* Size in sectors if bpb_nsize == 0 (32 bits) */ 
 +}; 
 +</file> 
 + 
 +See ? Only the "number of FAT" and "number of reserved sectors" members are swapped. 
x68000/writing_drivers.1404986009.txt.gz · Last modified: 2019/08/27 20:44 (external edit)