Linux MTD driver for PCMCIA Flash cards

This driver allows linear mapped Flash, RAM and ROM based PCMCIA cards to be used under Linux as MTD devices. It only works with 8 & 16 bit cards (ISA) and not 32bit Cardbus cards.

The driver simply maps out the address space of the card and then tries each of the MTD chip probe routines in sequence until it finds a device it understands. It is a replacement for the memory_cs module from the pcmcia-cs package but uses the chip drivers from the MTD subsystem, and presents an MTD device rather than block and char devices. A flash filesystem such as jffs2 can then be used on top of it or the mtdblock and mtdchar modules can be used to give more direct access.

NOTE Currently this driver is very alpha software, so please use with caution!

Setup

Checkout the latest MTD CVS source tree, and patch it into your kernel source. Then apply the patch below.
The MTD CVS tree instructions can be found at linux-mtd.infradead.org

Then in the Linux kernel configuration under the MTD menu, select 'Mapping drivers for chip access' and select 'PCMCIA MTD driver' and select the chip drivers as required in the 'RAM/ROM/Flash chip drivers' section.

NOTE The PCMCIA MTD driver has only been tested as a module, so it best to compile it as so.

Rebuild and install the modules etc then edit your /etc/pcmcia/config file to add the following:
device "pcmciamtd" class "memory" module "pcmciamtd"

And for each card type you have bind it to pcmciamtd (by default they are bound to memory_cs) eg:

#
# Memory cards
#
card "Anonymous Memory"
  anonymous
  bind "pcmciamtd"

card "Memory Card"
  function memory_card
  bind "pcmciamtd"

card "IBM 2MB SRAM"
  version "IBM", "2MB SRAM"
  bind "pcmciamtd"

and then restart cardmgr.

Note If the module is bound to the Anonymous memory then it may be used for any card that can not be identified, which may not always be desirable.

Module Options

If the card has a CIS then this will be read and used to get the parameters for the card. However, a lot of memory cards do not have a CIS so options can be used to override the settings for the card.

buswidth Set buswidth (1 = 8 bit, 2 = 16 bit, default = 2)

mem_speed Set memory access speed in ns

force_size Force size of card in MB (1-64 default = 64)

vpp Set Vpp in 1/10ths eg 33 = 3.3V 120 = 12V (Dangerous)

setvpp Set Vpp (0=Never, 1=On writes, 2=Always on, default=0)

mem_type Set Memory type (0 = Flash, 1 = RAM, 2 = ROM, default = 0)

debug Debug level 0 - 5 (default = MTD debug)

buswidth sets the memory window into 8 or 16bit mode. By default it uses 16bit mode, however the correct usage is dependant on the card's hardware.

memspeed sets the access speed of the memory in nanoseconds. This option should not be needed unless the card doesnt work with the default.

force_size sets the size of the memory area to search if it cannot be determined from the CIS. The probe routine looks for flash chips in this area and may find a smaller flash memory area than was set with force_size.

vpp set the Vpp used to power the card optionally for programming the card during write and erase. This is very card specific and some cards can require different Vpp voltages. This can be apparent if the card can be read, but not be written or erased. Currently the only way to find out the required voltages is to enable debugging in the probe routines and see the model numbers of the chips that are found. The voltages are set in 1/10ths of a volt so to set Vpp to 5.0 volts, use vpp=50. This option can damage hardware if voltages are incorrectly set!

setvpp enables setting of Vpp. Not all flash chips require Vpp whilst others do. setvpp allows three modes: 0 sets the Vpp to 0 volts permanently, 1 enables the set_vpp()function to be called everytime the chip driver wants to write to the chip to set the Vpp on and off and 2 sets the Vpp on permanently. Enabling the set_vpp() can slow down writes quite considerably as every write requires a PCMCIA subsystem call to set the Vpp on and off. However not all flash chips require or want the Vpp to be enabled permanently.

mem_type sets the probe routines to call. 0 will use the jedec_probe and cfi_probe. This probe can fail if no supported flash chips are found. Using 1 or 2 will always succed as the RAM and ROM probe routines dont actually probe and just return true.

debug sets the debug level. This is only compiled in if CONFIG_MTD_DEBUG is set. 0 is quiet, 5 is very noisy.

If the card does not appear to work, then try using the memory_cs module. If this works then please report this as a bug (include as much information as possible about the hardware).

Patch against 2.4.19
patch-2.4.19-pcmciamtd.diff

This driver is now in kerenel 2.5.44. These patches fix removal of the card and cleaning up on exit. They also handle the card being removed whilst in use (and just returning fail to the chip drivers).

Patch against 2.4.19
patch-2.4.19-pcmciamtd-2.diff
Patch against 2.5.44
patch-2.5.44-pcmciamtd.diff

Simon Evans

Last modified: Sun Oct 27 17:18:16 GMT 2002

buswidth	Set buswidth (1 = 8 bit, 2 = 16 bit, default = 2)
mem_speed	Set memory access speed in ns
force_size	Force size of card in MB (1-64 default = 64)
vpp	Set Vpp in 1/10ths eg 33 = 3.3V 120 = 12V (Dangerous)
setvpp	Set Vpp (0=Never, 1=On writes, 2=Always on, default=0)
mem_type	Set Memory type (0 = Flash, 1 = RAM, 2 = ROM, default = 0)
debug	Debug level 0 - 5 (default = MTD debug)