gpio: add driver for MAX7300 I2C GPIO extender

Add the MAX7300-I2C variant of the MAX7301-SPI version.  Both chips share
the same core logic, so the generic part of the in-kernel SPI-driver is
refactored into a generic part.  The I2C and SPI specific funtions are
then wrapped into seperate drivers picking up the generic part.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Juergen Beisert <j.beisert@pengutronix.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/spi/max7301.h b/include/linux/spi/max7301.h
index 6dfd83f19b4b..34af0a3477bf 100644
--- a/include/linux/spi/max7301.h
+++ b/include/linux/spi/max7301.h
@@ -1,9 +1,27 @@
 #ifndef LINUX_SPI_MAX7301_H
 #define LINUX_SPI_MAX7301_H
 
+#include <linux/gpio.h>
+
+/*
+ * Some registers must be read back to modify.
+ * To save time we cache them here in memory
+ */
+struct max7301 {
+        struct mutex    lock;
+        u8              port_config[8]; /* field 0 is unused */
+        u32             out_level;      /* cached output levels */
+        struct gpio_chip chip;
+        struct device *dev;
+        int (*write)(struct device *dev, unsigned int reg, unsigned int val);
+        int (*read)(struct device *dev, unsigned int reg);
+};
+
 struct max7301_platform_data {
         /* number assigned to the first GPIO */
         unsigned        base;
 };
 
+extern int __max730x_remove(struct device *dev);
+extern int __max730x_probe(struct max7301 *ts);
 #endif