CH375 ISA-USB block driver for Linux 2.2
========================================

A Linux 2.2 kernel module for CH375 based ISA to USB boards, ported from
FreddyV's DOS driver CH375 V0.22. It lets an old PC (386 and up) read and
write a USB mass-storage device - a USB stick, card reader or USB disk -
plugged straight into the board.

The CH375 chip handles the USB side itself, so no USB support is needed in
the kernel. The board has no IRQ; the driver polls the chip.

Tested on a Book386 (386SX, 16 MB) with Linux 2.2.26 and a 4 GB stick
holding a FAT16 partition.

Supported:      USB mass storage, one device per board, up to 15 partitions
Not supported:  hubs, keyboards/mice, printers, network adapters,
                the 16-bit LoTech board variant


Files
-----

  ch375.c         the driver source  (block device, major 60)
  ch375.o         the binary driver for Book386 Linux 
  ch375_hw.h      CH375 protocol, ported from the DOS driver
  Makefile        builds the module for 2.2.6 and 2.2.26
  sim/ch375sim.c  userspace chip simulator for testing the protocol code


Building
--------

You need gcc (2.7.2.3 or egcs 1.1.2 work) and the source of the kernel
the module will run on. A module only loads on the kernel version it was
built for.

1. Prepare the kernel headers (once). You don't need to build the kernel:

     cd /usr/src
     tar xzf linux-2.2.26.tar.gz
     cd linux-2.2.26
     cp arch/i386/defconfig .config

   Edit .config so that these lines read:

     CONFIG_M386=y
     # CONFIG_M686 is not set
     # CONFIG_SMP is not set

   If you have your kernel's own .config, use it instead. Then run:

     yes "" | make oldconfig
     make symlinks include/linux/version.h

2. Build the module:

     cd ch375-linux
     make ch375-2.2.26.o     # for a 2.2.26 kernel
     make ch375.o            # for a 2.2.6 kernel (/usr/src/linux)
     make test               # optional: run the simulator test

   Or by hand, for any 2.2 kernel tree:

     gcc -D__KERNEL__ -DMODULE -I/usr/src/linux-2.2.26/include \
         -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer \
         -fno-strength-reduce -pipe -m386 -DCPU=386 \
         -c ch375.c -o ch375-2.2.26.o


Usage
-----

1. Plug in the USB device, then load the module:

     insmod ch375-2.2.26.o io=0x260

   dmesg should show the chip, the disk size and the partitions, e.g.:

     ch375: chip version 0xb7 at 0x260, bus mode 2, ... (built for 2.2.26)
     ch375a: 7946240 sectors (3880 MB)
      ch375a: ch375a1 ch375a2

2. Create the device files (once; Linux 2.2 does not create them for you):

     mknod /dev/ch375a  b 60 0      # whole device
     mknod /dev/ch375a1 b 60 1      # partition 1
     mknod /dev/ch375a2 b 60 2      # partition 2 (and so on up to 15)

3. Mount a partition:

     mkdir -p /mnt/usb
     mount -t msdos /dev/ch375a1 /mnt/usb    # or -t vfat for long names

4. Before unplugging the device or unloading the module:

     umount /mnt/usb
     rmmod ch375

Module options:

  io=0x260    I/O base of the board (data port; command port is io+1)
  speed=0     extra delay per port access, like the DOS driver's % option;
              raise it if transfers are unreliable
  sectors=N   disk size in 512-byte sectors, if the device reports it wrongly

To load it at boot, copy the module to
/lib/modules/2.2.26/block/ch375.o and add
"insmod  ch375 io=0x260" and the mount command to /etc/rc on the Book386
However the USB stick must be attached to the USB port, otherwise you need 
to load it manually !