MEMORY_CS(4)

NAME
memory_cs - MTD-aware PCMCIA memory card driver

SYNOPSIS
insmod memory_cs.o [pc_debug=n] [mem_speed=n] [word_width=n]

DESCRIPTION
Memory_cs is the Card Services driver for PCMCIA memory cards, and also provides direct memory access for other types of cards. It provides character-mode and block-mode for accessing any card's attribute and common memory address spaces, analogous to /dev/mem. Memory_cs will allocate a free major device number when it is loaded. It provides two types of minor devices: "direct" character-mode devices for raw access a card's entire PCMCIA common and attribute memory spaces, and "indirect" devices for accessing specific memory partitions via an appropriate Memory Technology Driver. The bitwise layout of minor device numbers is 'ddddxarr'. 'dddd' is the device number, with one card counting as one memory device. memory, and 'rr' is the region number (for indirect devices). When memory_cs is bound to a card, it will report its major and minor device numbers to cardmgr(8).

The default memory card initialization script creates character special device files for the direct common memory and attribute memory devices. It also creates character special devices for accessing the first attribute and common memory partitions, and a block device for accessing the first common memory partition. These devices have the following names:

/dev/mem#c
    Common memory direct access, character special device.

/dev/mem#a
    Attribute memory direct access, character special device.

/dev/mem#c0c
    Common memory region 0, character special device.

/dev/mem#c0b
    Common memory region 0, block special device.

/dev/mem#a0c
    Attribute memory region 0, character special device.

The block special device for a card's common memory can be used to create a filesystem on a card, and the device can be mounted in much the same way as a floppy disk. In some cases, you may need to explicitly specify the card's capacity when creating a filesystem.

The character special devices can be used to read and write arbitrary numbers of bytes to arbitrary locations. For devices that need to be explicitly erased before writing, if a write request is aligned and sized on erase block boundaries for the target memory card, the driver will erase the target region before writing to the card.

Since any PCMCIA card can be accessed as a memory card, memory_cs can be bound to any card regardless of function, and regardless of what other drivers might also be bound to that card. For example, this driver can be bound to a card and then used to read out the contents of the card's attribute memory.

PARAMETERS

pc_debug=n
    Selects the PCMCIA debugging level. This parameter is only available if the module is compiled with debugging enabled. A non-zero value enables debugging.

mem_speed=n
    Sets the access speed of the shared memory window for direct access devices, in nanoseconds. The default is 0 (i.e., no extra wait states). Values of up to 1000 are legal.

word_width=n
    A flag indicating if direct access devices should be configured for 8-bit (if 0) or 16-bit (if 1) transfers. The default is 1 (16-bit).

AUTHOR
David Hinds - dhinds@hyper.stanford.edu

SEE ALSO
cardmgr(8), pcmcia(5).