gpio: gpio driver for max7301 SPI GPIO expander

Maxim's MAX7301 is an SPI GPIO expander with 28 GPIOs.  Note: MAX7301's
interrupt feature is not supported yet.

[akpm@linux-foundation.org: coding-style fixes]
[g.liakhovetski@pengutronix.de: Fix inaccuracies in comments, check spi_setup()
return code, mask off high byte in max7301_read()]
Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/spi/max7301.h b/include/linux/spi/max7301.h
new file mode 100644
index 0000000..6dfd83f
--- /dev/null
+++ b/include/linux/spi/max7301.h
@@ -0,0 +1,9 @@
+#ifndef LINUX_SPI_MAX7301_H
+#define LINUX_SPI_MAX7301_H
+
+struct max7301_platform_data {
+	/* number assigned to the first GPIO */
+	unsigned	base;
+};
+
+#endif