[PATCH 00/13] Add HD44780 Character LCD support

[Geert Uytterhoeven <geert@linux-m68k.org>]

	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 fixes a bug in the existing panel driver,
  - Patches 2-8 perform clean ups and improvements to the panel driver,
  - Patch 9 extract the character LCD core support from the panel driver
    into an auxdisplay charlcd subdriver,
  - Patches 10-11 add new features to the character LCD core driver
    (4-bit interface support and support for displays with more than 2
    lines),
  - Patch 12 adds DT bindings for describing HD44780 Character LCDs,
  - Patch 13 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.

Thanks for your comments!

Geert Uytterhoeven (13):
  misc: panel: Fix LCD_FLAG_F/LCD_FLAG_N exchange
  misc: panel: Remove PANEL_VERSION
  misc: panel: Remove unused LCD_FLAG_S and LCD_FLAG_ID
  misc: panel: Remove reference to misc device support
  misc: panel: Move all suboptions into a big if section
  misc: panel: Remove always-true check from panel_detach()
  misc: panel: Add lcd_home() helper
  misc: panel: Abstract temporary backlight handling
  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                       | 326 ++++++++
 drivers/misc/Kconfig                               |  45 +-
 drivers/misc/panel.c                               | 852 +++------------------
 include/misc/charlcd.h                             |  42 +
 8 files changed, 1374 insertions(+), 769 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

-- 
1.9.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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