gpio: add bt8xxgpio driver

This adds the bt8xxgpio driver.  The purpose of the bt8xxgpio driver is to
export all of the 24 GPIO pins available on Brooktree 8xx chips to the
kernel GPIO infrastructure.

This makes it possible to use a physically modified BT8xx card as
cheap digital GPIO card.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Cc: David Brownell <david-b@pacbell.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/bt8xxgpio.txt

@@ -0,0 +1,67 @@
+===============================================================
+==  BT8XXGPIO driver                                         ==
+==                                                           ==
+==  A driver for a selfmade cheap BT8xx based PCI GPIO-card  ==
+==                                                           ==
+==  For advanced documentation, see                          ==
+==  http://www.bu3sch.de/btgpio.php                          ==
+===============================================================
+
+
+A generic digital 24-port PCI GPIO card can be built out of an ordinary
+Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The
+Brooktree chip is used in old analog Hauppauge WinTV PCI cards. You can easily
+find them used for low prices on the net.
+
+The bt8xx chip does have 24 digital GPIO ports.
+These ports are accessible via 24 pins on the SMD chip package.
+
+
+==============================================
+==  How to physically access the GPIO pins  ==
+==============================================
+
+The are several ways to access these pins. One might unsolder the whole chip
+and put it on a custom PCI board, or one might only unsolder each individual
+GPIO pin and solder that to some tiny wire. As the chip package really is tiny
+there are some advanced soldering skills needed in any case.
+
+The physical pinouts are drawn in the following ASCII art.
+The GPIO pins are marked with G00-G23
+
+                                           G G G G G G G G G G G G     G G G G G G
+                                           0 0 0 0 0 0 0 0 0 0 1 1     1 1 1 1 1 1
+                                           0 1 2 3 4 5 6 7 8 9 0 1     2 3 4 5 6 7
+           | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+           ---------------------------------------------------------------------------
+         --|                               ^                                     ^   |--
+         --|                               pin 86                           pin 67   |--
+         --|                                                                         |--
+         --|                                                               pin 61 >  |-- G18
+         --|                                                                         |-- G19
+         --|                                                                         |-- G20
+         --|                                                                         |-- G21
+         --|                                                                         |-- G22
+         --|                                                               pin 56 >  |-- G23
+         --|                                                                         |--
+         --|                           Brooktree 878/879                             |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|                                                                         |--
+         --|   O                                                                     |--
+         --|                                                                         |--
+           ---------------------------------------------------------------------------
+           | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+           ^
+           This is pin 1
+

MAINTAINERS

@@ -1043,6 +1043,12 @@ M:	fujita.tomonori@lab.ntt.co.jp
 L:	linux-scsi@vger.kernel.org
 S:	Supported
 
+BT8XXGPIO DRIVER
+P:	Michael Buesch
+M:	mb@bu3sch.de
+W:	http://bu3sch.de/btgpio.php
+S:	Maintained
+
 BTTV VIDEO4LINUX DRIVER
 P:	Mauro Carvalho Chehab
 M:	mchehab@infradead.org

drivers/gpio/Kconfig

@@ -83,6 +83,24 @@ config GPIO_PCF857X
 	  This driver provides an in-kernel interface to those GPIOs using
 	  platform-neutral GPIO calls.
 
+comment "PCI GPIO expanders:"
+
+config GPIO_BT8XX
+	tristate "BT8XX GPIO abuser"
+	depends on PCI && VIDEO_BT848=n
+	help
+	  The BT8xx frame grabber chip has 24 GPIO pins than can be abused
+	  as a cheap PCI GPIO card.
+
+	  This chip can be found on Miro, Hauppauge and STB TV-cards.
+
+	  The card needs to be physically altered for using it as a
+	  GPIO card. For more information on how to build a GPIO card
+	  from a BT8xx TV card, see the documentation file at
+	  Documentation/bt8xxgpio.txt
+
+	  If unsure, say N.
+
 comment "SPI GPIO expanders:"
 
 config GPIO_MAX7301

drivers/gpio/Makefile

@@ -8,3 +8,4 @@ obj-$(CONFIG_GPIO_MAX7301)	+= max7301.o
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
 obj-$(CONFIG_GPIO_PCA953X)	+= pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
+obj-$(CONFIG_GPIO_BT8XX)	+= bt8xxgpio.o