auxdisplay: charlcd: Add support for 4-bit interfaces

In 4-bit mode, 8-bit commands and data are written using two raw writes
to the data interface: high nibble first, low nibble last.  This must be
handled by the low-level driver.

However, as we don't know in which mode (4-bit or 8-bit) nor 4-bit phase
the LCD was left, initialization must always be handled using raw
writes, and needs to configure the LCD for 8-bit mode first.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/misc/charlcd.h b/include/misc/charlcd.h
index c40047b673c9..23f61850f363 100644
--- a/include/misc/charlcd.h
+++ b/include/misc/charlcd.h
@@ -14,6 +14,7 @@ struct charlcd {
         const struct charlcd_ops *ops;
         const unsigned char *char_conv; /* Optional */
 
+        int ifwidth;                    /* 4-bit or 8-bit (default) */
         int height;
         int width;
         int bwidth;                     /* Default set by charlcd_alloc() */
@@ -28,6 +29,7 @@ struct charlcd_ops {
         void (*write_data)(struct charlcd *lcd, int data);
 
         /* Optional */
+        void (*write_cmd_raw4)(struct charlcd *lcd, int cmd);   /* 4-bit only */
         void (*clear_fast)(struct charlcd *lcd);
         void (*backlight)(struct charlcd *lcd, int on);
 };