Hi all, Character LCDs are currently typically driven from userspace, either directly through bit-banging, or via some kind of serial (UART/i2c) interface. This patch series adds kernel support for character LCDs using an Hitachi HD44780 Character LCD Controller where its M6800 bus interface is connected to GPIOs. It does so after extracting the character LCD core support from the existing Parallel port LCD/Keypad Panel driver into its own subdriver. - Patch 1 extracts the character LCD core support from the panel driver into an auxdisplay charlcd subdriver, - Patches 2 and 3 add new features to the character LCD core driver (support for 4-bit interfaces and displays with more than 2 lines), - Patch 4 adds DT bindings for describing HD44780 Character LCDs, - Patch 5 adds a driver for HD44780 Character LCDs connected to GPIOs, using the new character LCD core. Note that Linux has other support for HD44780 Character LCDs, but none of it is generic: - drivers/misc/arm-charlcd.c involves a custom IP block for interfacing to the LCD controller, - drivers/parisc/led.c is tightly coupled to LED handling on various HP PA-RISC machines. This has been tested using a 20x4 character LCD with backlight, using both 8-bit and 4-bit wiring to one or two 74HC595 shift registers connected to an SPI master controller. Regression testing on original "panel" hardware would be appreciated. Changes compared to v1: - Dropped accepted patches (panel driver fixes, cleanups, and improvements), - Move backlight mutex initialization before call to charlcd_init_display(), to prevent locking an uninitialized mutex (reported by 0day). - Added rationale for not yet supporting memory-mapped configurations, - Drop the dependency on OF by switching to the device property API, - Depend on GPIOLIB || COMPILE_TEST. Thanks! Geert Uytterhoeven (5): auxdisplay: charlcd: Extract character LCD core from misc/panel auxdisplay: charlcd: Add support for 4-bit interfaces auxdisplay: charlcd: Add support for displays with more than two lines dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 auxdisplay: Add HD44780 Character LCD support .../devicetree/bindings/auxdisplay/hit,hd44780.txt | 44 ++ drivers/auxdisplay/Kconfig | 14 + drivers/auxdisplay/Makefile | 2 + drivers/auxdisplay/charlcd.c | 818 ++++++++++++++++++++ drivers/auxdisplay/hd44780.c | 325 ++++++++ drivers/misc/Kconfig | 1 + drivers/misc/panel.c | 827 +++------------------ include/misc/charlcd.h | 42 ++ 8 files changed, 1338 insertions(+), 735 deletions(-) create mode 100644 Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt create mode 100644 drivers/auxdisplay/charlcd.c create mode 100644 drivers/auxdisplay/hd44780.c create mode 100644 include/misc/charlcd.h -- 2.7.4 Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html