psxdev core - device driver and filesystem

PSXDEV core components

The psxdev-core package installs the basic PSXDEV filesystem hierarchy (typically in /opt/psxdev), the PSXDEV kernel device driver sources and a compiled version of the driver (only during RPM install!) and as a bonus a small file magic configuration.

The driver sources are located in /opt/psxdev/pccl. Each time you have compiled a new kernel it is necessary to enter into this directory and do a make install, which simply builds and installs a recent version of the pccl.o module against the new kernel. You could also reinstall the psxdev-core RPM package with the --force option, but that is not the recommended way. I don't think that the pccl module will ever make it into the kernel...

The file /opt/psxdev/share/magic can be used to check typical PSX data files like PS-X EXE, TIM, BS, STR, and many more. You need the file package installed for this and you surely want to merge the PSXDEV magic entries with the global magic entries located in /usr/share/magic! This is not yet done during the installation process.

The /proc/pccl process information pseudo-filesystem

PSXDEV comes with an extension to the linux /proc pseudo-filesystem. If you do not know what the /proc pseudo-filesystem is, you should read the manual page of proc (man proc). To be short, /proc/pccl is an application which looks like a filesystem and is available as soon as the kernel driver is installed!

/proc/pccl
|-- 0
|   |-- config		driver configuration
|   |-- fullmem		pseudo-mirrored ram (full 32-bit)
|   |-- mem			pseudo-mirrored main ram
|   |-- status		CAETLA status
|   |-- version		CAETLA versions
|   `-- vram		pseudo-mirrored video ram
|-- 1
|   |-- config
|   |-- fullmem
|   |-- mem			-"-
|   |-- status
|   |-- version
|   `-- vram
|-- 2
|   |-- config
|   |-- fullmem
|   |-- mem			-"-
|   |-- status
|   |-- version
|   `-- vram
|-- 3
|   |-- config
|   |-- fullmem
|   |-- mem			-"-
|   |-- status
|   |-- version
|   `-- vram
`-- readme		a small static copyright notice

• config
  You can read and write configurations from/to this file. So if you cat /proc/pccl/0/config you'll get the current configuration. The most important reason for this is currently the need to specify the VRAM dimensions for a snapshot during a game. Just echo "width=320" > /proc/pccl/0/config to set single options.
• mem
  This special file represents the main memory of the PSX, located from 0x80000000-0x801FFFFF. You can search for strings in it, i.e. psx-strings /proc/pccl/0/mem but the coolest application is to use a memory editor with it. A very good program for this purpose is hexedit. Or just copy this file to /tmp to take a snapshot and so on.
• fullmem
  This is the same as above, but this time the full 32-bit address range. This is a very very useful file for applications, since they are allowed to lseek() anywhere into existing address ranges and read/write from them, like the cache, the ROM and the HW registers. I mainly implemented this new file interface for debuggers and real time utilities.
• status
  This file is only readable and returns the current state of the communication link. Example output:

  Status (PS/PAR) = (0x00) : CAETLA
  Status (CAETLA) = (0x40) : NOTIFY_HBP
  Execution Flags = (0x00) :
  

• version
  This file is like the status file, but it will retrieve the version numbers of the caetla subsystems. example output:

  caetla firmware     :  0.33
  CD-ROM manager      :  0.1
  memory card manager :  0.5
  frame buffer viewer :  0.2
  cheat code selector :  0.2
  debug utility       :  0.5
  configuration menu  :  0.2
  main menu           :  0.33
  

• vram
  This file is very useful. It represents the contents of the VRAM. Unlike the /proc/pccl/?/mem file, it has a file format - TIM. This means you can drop TIM images on this file and they will be uploaded! Example:

  #
  # upload all TIM images of your
  # project directly into the VRAM
  #
  bash> find *.tim -printf "cp %f /proc/pccl/0/vram\n" | sh
  

  You can of course copy all types of TIM images to this file; files with a palette and direct color images. If you read from this file, you'll get a screen snapshot, even during a game! If you are in the caetla frame buffer viewer, /proc/pccl/0/vram uses the selected dimensions (unfortunately no palette pictures for now!). During a game you have to specify the image dimensions with the config file. Example:

  # we want to download 320x240 images from 0,0 in 16-Bit
  bash> echo "width=320"  > /proc/pccl/0/config
  bash> echo "height=240" > /proc/pccl/0/config
  bash> echo "x=0"        > /proc/pccl/0/config
  bash> echo "y=0"        > /proc/pccl/0/config
  
  # now we can take pictures just by copying from the vram file !
  bash> cp /proc/pccl/0/vram /tmp/image.tim
  
  # directly view an image
  bash> timtoppm /proc/pccl/0/vram | xv -
  

The /dev/pccl kernel device driver interface

The PSXDEV pccl device driver is accessible through the device nodes

• /dev/pccl0 - first PC commslink board
• /dev/pccl1 - second PC commslink board
• /dev/pccl2 - third PC commslink board
• /dev/pccl3 - fourth PC commslink board
• /dev/pccl - a symbolic link to the first board (/dev/pccl0)

The PCCL API is a linux wrapper for the CAETLA API. All CAETLA protocol commands are available as ioctl() commands. So a minimal and also typical program which uses /dev/pccl would be:

/** software reset the PlayStation **/

#include <pccl.h>        /* load device driver api */
#include <sys/ioctl.h>   /* needed for the ioctl() */

main()
{
	int pccl;
             
	// open the device driver always in read/write mode,
	// since we want to communicate with it!
             
	pccl = open("/dev/pccl",O_RDWR);
	if (pccl != -1)
	{
		// reset the PlayStation
		ioctl (pccl, CAEIOC_RESET);
             
		close (pccl);
	}
	else perror("/dev/pccl");
}

If you want to code an application which uses the /dev/pccl API, you should check the <pccl.h> header file and read the PCCL API reference.