staging: comedi: split out PCMCIA support into new module

Setting the `CONFIG_COMEDI_PCMCIA_DRIVERS` kernel configuration option
makes the main "comedi" module depend on the "pcmcia" module, but many
machines don't have PCMCIA slots and only a few low-level Comedi drivers
need PCMCIA support.  The Comedi PCMCIA support functions are all in
"comedi_pcmcia.c".  Turn it into a separate module so we don't have to
pull in the other PCMCIA support modules unnecessarily.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/Kconfig

@@ -1076,11 +1076,14 @@ config COMEDI_NI_TIOCMD
 endif # COMEDI_PCI_DRIVERS
 
 menuconfig COMEDI_PCMCIA_DRIVERS
-	bool "Comedi PCMCIA drivers"
+	tristate "Comedi PCMCIA drivers"
 	depends on PCMCIA
 	---help---
 	  Enable support for comedi PCMCIA drivers.
 
+	  To compile this support as a module, choose M here: the module will
+	  be called comedi_pcmcia.
+
 if COMEDI_PCMCIA_DRIVERS
 
 config COMEDI_CB_DAS16_CS

drivers/staging/comedi/Makefile

@@ -3,11 +3,12 @@ ccflags-$(CONFIG_COMEDI_DEBUG)		:= -DDEBUG
 comedi-y				:= comedi_fops.o range.o drivers.o \
 					   comedi_buf.o
 comedi-$(CONFIG_COMEDI_PCI_DRIVERS)	+= comedi_pci.o
-comedi-$(CONFIG_COMEDI_PCMCIA_DRIVERS)	+= comedi_pcmcia.o
 comedi-$(CONFIG_COMEDI_USB_DRIVERS)	+= comedi_usb.o
 comedi-$(CONFIG_PROC_FS)		+= proc.o
 comedi-$(CONFIG_COMPAT)			+= comedi_compat32.o
 
+obj-$(CONFIG_COMEDI_PCMCIA_DRIVERS)	+= comedi_pcmcia.o
+
 obj-$(CONFIG_COMEDI)			+= comedi.o
 
 obj-$(CONFIG_COMEDI)			+= kcomedilib/

drivers/staging/comedi/comedi_pcmcia.c

@@ -16,6 +16,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/module.h>
 #include <linux/kernel.h>
 
 #include <pcmcia/cistpl.h>
@@ -154,3 +155,18 @@ void comedi_pcmcia_driver_unregister(struct comedi_driver *comedi_driver,
 	comedi_driver_unregister(comedi_driver);
 }
 EXPORT_SYMBOL_GPL(comedi_pcmcia_driver_unregister);
+
+static int __init comedi_pcmcia_init(void)
+{
+	return 0;
+}
+module_init(comedi_pcmcia_init);
+
+static void __exit comedi_pcmcia_exit(void)
+{
+}
+module_exit(comedi_pcmcia_exit);
+
+MODULE_AUTHOR("http://www.comedi.org");
+MODULE_DESCRIPTION("Comedi PCMCIA interface module");
+MODULE_LICENSE("GPL");