msfdp(7) —

NAME

msfdp − MegaScan FDP-6120 driver

DESCRIPTION

The MegaScan FDP-6120 kernel driver facilitates accessing the MegaScan FDP-6120 board. It is a regular character-based driver that manages one FDP-6120 board. It is used by programs that draw using the graphics modes of FDP-6120.

CONFIGURATION

The sdevice(4) file /etc/conf/sdevice.d/msfdp describes the I/O port addresses and the memory addresses of the FDP-6120 board. The seventh and eighth fields in this file describe the starting and ending input/output port addresses. The ninth and tenth fields in this file describe the starting and ending memory addresses. All of these fields are given in hexadecimal. The default sdevice file entry is:

msfdp Y 1 0 0 0 300 30f a0000 a7fff

As an example, if you want to change the default sdevice to use addresses of C00000- FFFFFF and I/O ports of 200-20f, then the following sdevice file is used:

msfdp Y 1 0 0 0 200 20f c00000 ffffff

If you change the default sdevice entry, you will have to build a new kernel and boot it for these changes to become effective.

PROGRAMMING INTERFACE

The MegaScan FDP-6120 device is opened by a call to open. Currently, only minor device 0 is supported. If a non-zero minor device is specified, then an error will occur and errno will be set to ENOENT. Only one user is allowed to open the FDP-6120 board at a time, unless the subsequent user is the superuser. If a subsequent open is attempted by another user who is not the superuser, an error will result and errno will be set to EPERM.

Read and write interfaces are provided to access the memory of the Texas Instruments 34020 processor in the FDP-6120. Seek addresses are specified in bytes. Because addresses on a 34020 processor are given in bits, it is necessary to divide the bit address by 8 to get a byte address. The state of the 34020 is saved before each read and write, and restored when completed.

The following ioctl calls allow a user program to access the FDP-6120 board directly:

MSFDP_GET_INFO
This ioctl returns a structure containing the addresses of the board described in the section “Configuration” above. The structure returned is:

typedef struct msfdp_info {
char*msfdp_addr;/* physical address */
char*msfdp_endaddr; /* physical address */
shortmsfdp_csr;/* i/o port */
shortmsfdp_endcsr; /* i/o port */
} msfdp_info_t;

This structure is filled in with information in the seventh through tenth fields of the sdevice file. It is stored at the location specified by the argument that is passed.

MSFDP_MAP_BOARD
This ioctl allows the process to have direct access to the FDP-6120 memory as well as allowing the user process to do in and out instructions at the I/O ports specified in the sdevice file. The argument passed is the address of the memory to map to the FDP-6120 board. It must be page (4096 byte) aligned and span a length specified by the sdevice file (which is also a multiple of 4096 bytes). The memory that had existed at the argument passed will be irretrievably deleted, and the current contents of the FDP-6120 memory will be placed at those locations. One way of allocating the virtual memory in the user’s address space that will be mapped to the FDP-6120 memory is to call malloc requesting (length + 4096) bytes. Then, using the address that malloc returns, round it up to the next page (4K) boundary and use the result as the argument to this ioctl.

MSFDP_UNMAP_BOARD
This ioctl call unmaps the direct access to the FDP-6120 memory as well as preventing the process from doing in and out instructions at the I/O ports specified in the sdevice file. The map must have been set up with MSFDP_MAP_BOARD by the current process. The argument passed should be the same one given to MSFDP_MAP_BOARD. The memory where the FDP-6120 memory had been becomes zeros.

FILES

/dev/msfdp

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