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
one memory device. 'x' is set if this is a direct-access device, 'a'
is set for attribute 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).
force_size=n
Explicitly specifies the size of a simple SRAM card, skipping the
default (and sometimes unreliable) size check.
This takes an argument of type (region_info_t *), defined in
<pcmcia/bulkmem.h>. The structure will be filled in with memory
region information for this device, such as access speed, erase block
size, and JEDEC identifiers.
MEMERASE
This takes an argument of type (erase_info_t *), specifying the
offset and length of a memory region to be erased.
