Staging: add dt3155 driver

This is a driver for the DT3155 Digitizer

Signed-off-by: Scott Smedley <ss@aao.gov.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/dt3155/Makefile

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+
+ifeq ($(shell [[ `uname -r | cut -f 1,2 -d\.` < 2.6 ]] && echo pre2.6),pre2.6)
+# system with a pre 2.6 kernel _don't_ use kbuild.
+all:
+	$(MAKE) -f Makefile.pre-2.6
+
+clean:
+	rm -f *.o
+
+else
+# systems with a 2.6 or later kernel use kbuild.
+ifneq ($(KERNELRELEASE),)
+obj-m	:= dt3155.o
+dt3155-objs := dt3155_drv.o dt3155_isr.o dt3155_io.o allocator.o
+
+else
+KDIR	:= /lib/modules/$(shell uname -r)/build
+PWD		:= $(shell pwd)
+
+all:
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+
+clean:
+	rm -rf *.o *.mod *.mod.c *.ko  .dt3155* .allocator.o.cmd  .tmp_versions
+
+endif
+endif

drivers/staging/dt3155/allocator.README

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+
+The allocator shown here  exploits high memory. This document explains
+how  a user can  deal   with drivers uses   this  allocator and how  a
+programmer can link in the module.
+
+The module is being used by my pxc and pxdrv device drivers (as well as
+other ones), available from ftp.systemy.it/pub/develop and
+ftp.linux.it/pub/People/Rubini
+
+	User's manual
+	=============
+
+
+One of the most compelling problems with any DMA-capable device is the
+allocation  of a suitable  memory buffer. The "allocator" module tries
+to deal with  the problem in  a clean way.  The module is  able to use
+high   memory  (above the  one   used in  normal   operation)  for DMA
+allocation.
+
+To prevent  the  kernel for using   high memory,  so  that it  remains
+available for  DMA, you should  pass a  command  line argument to  the
+kernel.  Command line arguments  can be passed to  Lilo, to Loadlin or
+to whichever loader  you are using  (unless it's very poor in design).
+For Lilo, either use  "append=" in  /etc/lilo.conf or add  commandline
+arguments to the  interactive prompt. For  example, I have a 32MB  box
+and reserve two megs for DMA:
+
+In lilo.conf:
+	image = /zImage
+	label = linux
+	append = "mem=30M"
+
+Or, interactively:
+	LILO: linux mem=30M
+
+Once  the kernel is booted  with the  right command-line argument, any
+driver  linked   with  the  allocator   module  will  be able   to get
+DMA-capable memory without  much  trouble (unless the  various drivers
+need more memory than available).
+
+The module implements an alloc/free  mechanism,  so that it can  serve
+multiple drivers  at the  same time. Note  however that  the allocator
+uses all of  high memory and assumes to  be the only piece of software
+using such memory.
+
+
+	Programmer's manual
+	===================
+
+The allocator,  as  released, is designed  to  be linked  to  a device
+driver.  In this  case, the driver  must call allocator_init()  before
+using   the  allocator   and  must  call   allocator_cleanup()  before
+unloading.  This is  usually  done   from within  init_module()    and
+cleanup_module(). If the allocator is linked to  a driver, it won't be
+possible for several drivers to allocate high DMA memory, as explained
+above.
+
+It is possible, on the other hand, to compile the module as a standalone
+module, so that several modules can rely on the allocator for they DMA
+buffers. To compile the allocator as a standalone module, do the
+following in this directory (or provide a suitable Makefile, or edit
+the source code):
+
+	make allocator.o CC="gcc -Dallocator_init=init_module -Dallocator_cleanup=cleanup_module -include /usr/include/linux/module.h"
+
+The previous commandline  tells   to include <linux/module.h>  in  the
+first place,  and to rename the init  and cleanup function to the ones
+needed for  module loading and  unloading.  Drivers using a standalone
+allocator won't need to call allocator_init() nor allocator_cleanup().
+
+The allocator exports the following functions (declared in allocator.h):
+
+   unsigned long allocator_allocate_dma (unsigned long kilobytes,
+					 int priority);
+
+	This function returns a physical address, over high_memory,
+	which corresponds to an area of at least "kilobytes" kilobytes.
+	The area will be owned by the module calling the function.
+	The returned address can be passed to device boards, to instruct
+	their DMA controllers, via phys_to_bus(). The address can be used
+	by C code after vremap()/ioremap(). The "priority" argument should
+	be GFP_KERNEL or GFP_ATOMIC, according to the context of the
+	caller; it is used to call kmalloc(), as the allocator must keep
+	track of any region it gives away. In case of error the function
+	returns 0, and the caller is expected to issue a -ENOMEM error.
+
+
+   void allocator_free_dma (unsigned long address);
+
+	This function is the reverse of the previous one. If a driver
+	doesn't free the DMA memory it allocated, the allocator will
+	consider such memory as busy. Note, however, that
+	allocator_cleanup() calls kfree() on every region it reclaimed,
+	so that a driver with the allocator linked in can avoid calling
+	allocator_free_dma() at unload time.
+
+
+