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.

Geert Uytterhoeven committed 9 years ago

Commit ac201471 parent 39f8ea42 files · +32 −6Browse files

Showing the changes to include/misc (1 of 2 files). Show all

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include/misc/charlcd.h+2−0

@@ -14,6 +14,7 @@ struct charlcd { · 13 unmodified lines
14	14	const struct charlcd_ops *ops;
15	15	const unsigned char char_conv; / Optional */
16	16
	17	+ int ifwidth; /* 4-bit or 8-bit (default) */
17	18	int height;
18	19	int width;
19	20	int bwidth; /* Default set by charlcd_alloc() */
@@ -28,6 +29,7 @@ struct charlcd_ops { · 8 unmodified lines
28	29	void (write_data)(struct charlcd lcd, int data);
29	30
30	31	/* Optional */
	32	+ void (write_cmd_raw4)(struct charlcd lcd, int cmd); /* 4-bit only */
31	33	void (clear_fast)(struct charlcd lcd);
32	34	void (backlight)(struct charlcd lcd, int on);
33	35	};