[PATCH v2 00/18] auxdisplay: ht16k33: Add character display support

[PATCH v2 00/18] auxdisplay: ht16k33: Add character display support

[Geert Uytterhoeven]

	Hi all,

The Holtek HT16K33 LED controller is not only used for driving
dot-matrix displays, but also for driving segment displays.
The current auxdisplay driver is limited to dot-matrix displays, which
are exposed as a frame buffer device.

This patch series extends the driver to 4-digit 7-segment and quad
14-segment alphanumeric displays, allowing the user to display and
scroll text messages.

List of patches:
  - Patch 1 provides font data for displaying ASCII characters on
    14-segment displays,
  - Patch 2 updates the HT16K33 DT bindings for segment displays,
  - Patches 3-5 contain a bug fix and small improvements for the
    Imagination Technologies ASCII LCD Display driver,
  - Patch 6 extracts the character line display core support from the
    Imagination Technologies ASCII LCD Display driver, for reuse,
  - Patches 7-8 contain cleanups and improvements for the character line
    display core driver,
  - Patches 9-16 contain a bug fix, cleanups and improvements for the
    HT16K33 driver, to prepare for segment display support,
  - Patch 17 adds support for 7/14-segment displays to the HT16K33
    driver,
  - Patch 18 adds segment display LED support to the HT16K33 driver,
    to make use of hardware blinking, and to expose display color.

Changes compared to v1[1]:
  - Fix type of color to uint32,
  - "refresh-rate-hz" is still required for dot-matrix displays.
  - Move "select LINEDISP" for HT16K33 symbol to correct patch,
  - Add backwards compatibility "message" symlink to img-ascii-lcd,
  - Connect backlight to fbdev in ht16k33 dot-matrix mode,
  - Set "err = -EINVAL" in switch() case that cannot happen,
  - Use "auxdisplay" instead of DRIVER_NAME in LED name.

This series has been tested using an Adafruit 0.54" Quad Alphanumeric
Red FeatherWing Display, plugged into an OrangeCrab ECP5-based FPGA
board running linux-on-litex-vexriscv.
7-segment display support is based purely on schematics, and has not
been tested on actual hardware.  The changes to img-ascii-lcd.c are also
untested, due to lack of hardware.

Thanks for your comments!

[1] "[PATCH 00/17] auxdisplay: ht16k33: Add character display support"
    https://lore.kernel.org/r/20210322144848.1065067-1-geert@linux-m68k.org/

Geert Uytterhoeven (18):
  uapi: Add <linux/map_to_14segment.h>
  dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays
  auxdisplay: img-ascii-lcd: Fix lock-up when displaying empty string
  auxdisplay: img-ascii-lcd: Add helper variable dev
  auxdisplay: img-ascii-lcd: Convert device attribute to sysfs_emit()
  auxdisplay: Extract character line display core support
  auxdisplay: linedisp: Use kmemdup_nul() helper
  auxdisplay: linedisp: Add support for changing scroll rate
  auxdisplay: ht16k33: Connect backlight to fbdev
  auxdisplay: ht16k33: Use HT16K33_FB_SIZE in ht16k33_initialize()
  auxdisplay: ht16k33: Remove unneeded error check in keypad probe()
  auxdisplay: ht16k33: Convert to simple i2c probe function
  auxdisplay: ht16k33: Add helper variable dev
  auxdisplay: ht16k33: Move delayed work
  auxdisplay: ht16k33: Extract ht16k33_brightness_set()
  auxdisplay: ht16k33: Extract frame buffer probing
  auxdisplay: ht16k33: Add support for segment displays
  auxdisplay: ht16k33: Add segment display LED support

 .../bindings/auxdisplay/holtek,ht16k33.yaml   |  31 +-
 drivers/auxdisplay/Kconfig                    |   8 +
 drivers/auxdisplay/Makefile                   |   1 +
 drivers/auxdisplay/ht16k33.c                  | 458 ++++++++++++++----
 drivers/auxdisplay/img-ascii-lcd.c            | 206 ++------
 drivers/auxdisplay/line-display.c             | 261 ++++++++++
 drivers/auxdisplay/line-display.h             |  43 ++
 include/uapi/linux/map_to_14segment.h         | 239 +++++++++
 8 files changed, 989 insertions(+), 258 deletions(-)
 create mode 100644 drivers/auxdisplay/line-display.c
 create mode 100644 drivers/auxdisplay/line-display.h
 create mode 100644 include/uapi/linux/map_to_14segment.h

-- 
2.25.1

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

[PATCH v2 01/18] uapi: Add <linux/map_to_14segment.h>

[Geert Uytterhoeven]

Add a header file providing translation primitives and tables for the
conversion of (ASCII) characters to a 14-segments notation, as used by
14-segment alphanumeric displays.

This follows the spirit of include/uapi/linux/map_to_7segment.h.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.

You can find an image of the full character set at
https://drive.google.com/file/d/1h3EYFBWHIjh8B_cwPA5ocAD-lFYipRie/view

Note that all non-empty characters are unique, except for "[" and "C",
and "|" and ":".
---
 include/uapi/linux/map_to_14segment.h | 239 ++++++++++++++++++++++++++
 1 file changed, 239 insertions(+)
 create mode 100644 include/uapi/linux/map_to_14segment.h

diff --git a/include/uapi/linux/map_to_14segment.h b/include/uapi/linux/map_to_14segment.h
new file mode 100644
index 0000000000000000..957c3c43181043c5
--- /dev/null
+++ b/include/uapi/linux/map_to_14segment.h
@@ -0,0 +1,239 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2021 Glider bv
+ *
+ * Based on include/uapi/linux/map_to_7segment.h:
+
+ * Copyright (c) 2005 Henk Vergonet <Henk.Vergonet@gmail.com>
+ */
+
+#ifndef MAP_TO_14SEGMENT_H
+#define MAP_TO_14SEGMENT_H
+
+/* This file provides translation primitives and tables for the conversion
+ * of (ASCII) characters to a 14-segments notation.
+ *
+ * The 14 segment's wikipedia notation below is used as standard.
+ * See: https://en.wikipedia.org/wiki/Fourteen-segment_display
+ *
+ * Notation:	+---a---+
+ *		|\  |  /|
+ *		f h i j b
+ *		|  \|/  |
+ *		+-g1+-g2+
+ *		|  /|\  |
+ *		e k l m c
+ *		|/  |  \|
+ *		+---d---+
+ *
+ * Usage:
+ *
+ *   Register a map variable, and fill it with a character set:
+ *	static SEG14_DEFAULT_MAP(map_seg14);
+ *
+ *
+ *   Then use for conversion:
+ *	seg14 = map_to_seg14(&map_seg14, some_char);
+ *	...
+ *
+ * In device drivers it is recommended, if required, to make the char map
+ * accessible via the sysfs interface using the following scheme:
+ *
+ * static ssize_t map_seg14_show(struct device *dev,
+ *				 struct device_attribute *attr, char *buf)
+ * {
+ *	memcpy(buf, &map_seg14, sizeof(map_seg14));
+ *	return sizeof(map_seg14);
+ * }
+ * static ssize_t map_seg14_store(struct device *dev,
+ *				  struct device_attribute *attr,
+ *				  const char *buf, size_t cnt)
+ * {
+ *	if (cnt != sizeof(map_seg14))
+ *		return -EINVAL;
+ *	memcpy(&map_seg14, buf, cnt);
+ *	return cnt;
+ * }
+ * static DEVICE_ATTR_RW(map_seg14);
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+
+#include <asm/byteorder.h>
+
+#define BIT_SEG14_A		0
+#define BIT_SEG14_B		1
+#define BIT_SEG14_C		2
+#define BIT_SEG14_D		3
+#define BIT_SEG14_E		4
+#define BIT_SEG14_F		5
+#define BIT_SEG14_G1		6
+#define BIT_SEG14_G2		7
+#define BIT_SEG14_H		8
+#define BIT_SEG14_I		9
+#define BIT_SEG14_J		10
+#define BIT_SEG14_K		11
+#define BIT_SEG14_L		12
+#define BIT_SEG14_M		13
+#define BIT_SEG14_RESERVED1	14
+#define BIT_SEG14_RESERVED2	15
+
+struct seg14_conversion_map {
+	__be16 table[128];
+};
+
+static __inline__ int map_to_seg14(struct seg14_conversion_map *map, int c)
+{
+	return c >= 0 && c < sizeof(map->table) ? __be16_to_cpu(map->table[c])
+						: -EINVAL;
+}
+
+#define SEG14_CONVERSION_MAP(_name, _map)	\
+	struct seg14_conversion_map _name = { .table = { _map } }
+
+/*
+ * It is recommended to use a facility that allows user space to redefine
+ * custom character sets for LCD devices. Please use a sysfs interface
+ * as described above.
+ */
+#define MAP_TO_SEG14_SYSFS_FILE	"map_seg14"
+
+/*******************************************************************************
+ * ASCII conversion table
+ ******************************************************************************/
+
+#define _SEG14(sym, a, b, c, d, e, f, g1, g2, h, j, k, l, m, n)	\
+	__cpu_to_be16( a << BIT_SEG14_A  |  b << BIT_SEG14_B  |	\
+		       c << BIT_SEG14_C  |  d << BIT_SEG14_D  |	\
+		       e << BIT_SEG14_E  |  f << BIT_SEG14_F  |	\
+		      g1 << BIT_SEG14_G1 | g2 << BIT_SEG14_G2 |	\
+		       h << BIT_SEG14_H  |  j << BIT_SEG14_I  |	\
+		       k << BIT_SEG14_J  |  l << BIT_SEG14_K  |	\
+		       m << BIT_SEG14_L  |  n << BIT_SEG14_M )
+
+#define _MAP_0_32_ASCII_SEG14_NON_PRINTABLE				\
+	0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+
+#define _MAP_33_47_ASCII_SEG14_SYMBOL				\
+	_SEG14('!', 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('"', 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0),	\
+	_SEG14('#', 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('$', 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('%', 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0),	\
+	_SEG14('&', 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1),	\
+	_SEG14('\'',0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0),	\
+	_SEG14('(', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1),	\
+	_SEG14(')', 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0),	\
+	_SEG14('*', 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1),	\
+	_SEG14('+', 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0),	\
+	_SEG14(',', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0),	\
+	_SEG14('-', 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('.', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('/', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0),
+
+#define _MAP_48_57_ASCII_SEG14_NUMERIC				\
+	_SEG14('0', 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0),	\
+	_SEG14('1', 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0),	\
+	_SEG14('2', 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('3', 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('4', 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('5', 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('6', 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('7', 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0),	\
+	_SEG14('8', 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('9', 1, 1, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0),
+
+#define _MAP_58_64_ASCII_SEG14_SYMBOL				\
+	_SEG14(':', 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0),	\
+	_SEG14(';', 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0),	\
+	_SEG14('<', 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1),	\
+	_SEG14('=', 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('>', 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0),	\
+	_SEG14('?', 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0),	\
+	_SEG14('@', 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0),
+
+#define _MAP_65_90_ASCII_SEG14_ALPHA_UPPER			\
+	_SEG14('A', 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('B', 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('C', 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('D', 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('E', 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('F', 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('G', 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('H', 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('I', 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('J', 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('K', 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1),	\
+	_SEG14('L', 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('M', 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0),	\
+	_SEG14('N', 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1),	\
+	_SEG14('O', 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('P', 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('Q', 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('R', 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('S', 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('T', 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('U', 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('V', 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0),	\
+	_SEG14('W', 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1),	\
+	_SEG14('X', 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1),	\
+	_SEG14('Y', 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0),	\
+	_SEG14('Z', 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0),
+
+#define _MAP_91_96_ASCII_SEG14_SYMBOL				\
+	_SEG14('[', 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('\\',0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1),	\
+	_SEG14(']', 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('^', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1),	\
+	_SEG14('_', 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('`', 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0),
+
+#define _MAP_97_122_ASCII_SEG14_ALPHA_LOWER			\
+	_SEG14('a', 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0),	\
+	_SEG14('b', 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('c', 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('d', 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0),	\
+	_SEG14('e', 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0),	\
+	_SEG14('f', 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0),	\
+	_SEG14('g', 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0),	\
+	_SEG14('h', 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0),	\
+	_SEG14('i', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0),	\
+	_SEG14('j', 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0),	\
+	_SEG14('k', 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1),	\
+	_SEG14('l', 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('m', 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0),	\
+	_SEG14('n', 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0),	\
+	_SEG14('o', 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('p', 0, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0),	\
+	_SEG14('q', 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0),	\
+	_SEG14('r', 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('s', 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1),	\
+	_SEG14('t', 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('u', 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0),	\
+	_SEG14('v', 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0),	\
+	_SEG14('w', 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1),	\
+	_SEG14('x', 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1),	\
+	_SEG14('y', 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0),	\
+	_SEG14('z', 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0),
+
+#define _MAP_123_126_ASCII_SEG14_SYMBOL				\
+	_SEG14('{', 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0),	\
+	_SEG14('|', 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0),	\
+	_SEG14('}', 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1),	\
+	_SEG14('~', 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0),
+
+/* Maps */
+#define MAP_ASCII14SEG_ALPHANUM			\
+	_MAP_0_32_ASCII_SEG14_NON_PRINTABLE	\
+	_MAP_33_47_ASCII_SEG14_SYMBOL		\
+	_MAP_48_57_ASCII_SEG14_NUMERIC		\
+	_MAP_58_64_ASCII_SEG14_SYMBOL		\
+	_MAP_65_90_ASCII_SEG14_ALPHA_UPPER	\
+	_MAP_91_96_ASCII_SEG14_SYMBOL		\
+	_MAP_97_122_ASCII_SEG14_ALPHA_LOWER	\
+	_MAP_123_126_ASCII_SEG14_SYMBOL
+
+#define SEG14_DEFAULT_MAP(_name)		\
+	SEG14_CONVERSION_MAP(_name, MAP_ASCII14SEG_ALPHANUM)
+
+#endif	/* MAP_TO_14SEGMENT_H */
-- 
2.25.1

[PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

[Geert Uytterhoeven]

The Holtek HT16K33 LED controller is not only used for driving
dot-matrix displays, but also for driving segment displays.

Document compatible values for the Adafruit 7-segment[1] and
14-segment[2] FeatherWing expansion boards with red displays.  According
to the schematics, all other Adafruit 7-segment and 14-segment display
backpack and FeatherWing expansion boards (including bare boards and
boards fitted with displays) are compatible with these two boards.
Add a "color" property to support the different color variants.

[1] https://www.adafruit.com/product/3108
[2] https://www.adafruit.com/product/3130

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - Fix type of color to uint32,
  - "refresh-rate-hz" is still required for dot-matrix displays.

Alternatives I considered:
  1. Document the attached display type in a child node.
     I.e. specify segment type, number of characters, and wiring.
     Especially the latter would become really complex, due to the sheer
     amount of possible wiring combinations.
     Using this method, you also loose the ability to just connect a
     display to an i2c bus, and instantiate the device from sysfs,
     without using DT:

	echo adafruit,3130 0x70 > /sys/class/i2c/i2c-adapter/.../new_device

  2. Do not use the "color" property, but document all Adafruit
     7-segment and 14-segment display backpack and FeatherWing expansion
     boards.
     This would lead to a myriad of compatible values:

      - items:
	  - enum:
	      - adafruit,878      # 0.56" 4-Digit 7-Segment Display Backpack (Red)
	      - adafruit,879      # 0.56" 4-Digit 7-Segment Display Backpack (Yellow)
	      - adafruit,880      # 0.56" 4-Digit 7-Segment Display Backpack (Green)
	      - adafruit,881      # 0.56" 4-Digit 7-Segment Display Backpack (Blue)
	      - adafruit,1002     # 0.56" 4-Digit 7-Segment Display Backpack (White)
	  - const: adafruit,877   # 0.56" 4-Digit 7-Segment Backpack
	  - const: holtek,ht16k33

      - items:
	  - enum:
	      - adafruit,1268     # 1.2" 4-Digit 7-Segment Display Backpack (Green)
	      - adafruit,1269     # 1.2" 4-Digit 7-Segment Display Backpack (Yellow)
	      - adafruit,1270     # 1.2" 4-Digit 7-Segment Display Backpack (Red)
	  - const: adafruit,1271  # 1.2" 4-Digit 7-Segment Backpack
	  - const: holtek,ht16k33

      - items:
	  - enum:
	      - adafruit,1911     # 0.54" Quad Alphanumeric Display Backpack (Red)
	      - adafruit,1912     # 0.54" Quad Alphanumeric Display Backpack (Blue)
	      - adafruit,2157     # 0.54" Quad Alphanumeric Display Backpack (White)
	      - adafruit,2158     # 0.54" Quad Alphanumeric Display Backpack (Yellow)
	      - adafruit,2159     # 0.54" Quad Alphanumeric Display Backpack (Yellow-Green)
	      - adafruit,2160     # 0.54" Quad Alphanumeric Display Backpack (Green)
	  - const: adafruit,1910  # 0.54" Quad 14-segment Alphanumeric Backpack
	  - const: holtek,ht16k33

      - items:
	  - enum:
	      - adafruit,3106     # 0.56" 4-Digit 7-Segment FeatherWing Display (Blue)
	      - adafruit,3107     # 0.56" 4-Digit 7-Segment FeatherWing Display (Green)
	      - adafruit,3108     # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
	      - adafruit,3109     # 0.56" 4-Digit 7-Segment FeatherWing Display (White)
	      - adafruit,3110     # 0.56" 4-Digit 7-Segment FeatherWing Display (Yellow)
	  - const: adafruit,3088  # 0.56" 4-Digit 7-Segment FeatherWing
	  - const: holtek,ht16k33

      - items:
	  - enum:
	      - adafruit,3127     # 0.54" Quad Alphanumeric FeatherWing Display (White)
	      - adafruit,3128     # 0.54" Quad Alphanumeric FeatherWing Display (Blue)
	      - adafruit,3129     # 0.54" Quad Alphanumeric FeatherWing Display (Green)
	      - adafruit,3130     # 0.54" Quad Alphanumeric FeatherWing Display (Red)
	      - adafruit,3131     # 0.54" Quad Alphanumeric FeatherWing Display (Yellow)
	      - adafruit,3132     # 0.54" Quad Alphanumeric FeatherWing Display (Yellow-Green)
	  - const: adafruit,3089  # 0.54" Quad 14-segment Alphanumeric FeatherWing
	  - const: holtek,ht16k33
---
 .../bindings/auxdisplay/holtek,ht16k33.yaml   | 31 +++++++++++++++++--
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
index 64ffff460026040f..616aca817874bdc8 100644
--- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
+++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
@@ -14,14 +14,23 @@ allOf:
 
 properties:
   compatible:
-    const: holtek,ht16k33
+    oneOf:
+      - items:
+          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
+          - const: holtek,ht16k33
+
+      - items:
+          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
+          - const: holtek,ht16k33
+
+      - const: holtek,ht16k33     # Generic 16*8 LED controller with dot-matrix display
 
   reg:
     maxItems: 1
 
   refresh-rate-hz:
     maxItems: 1
-    description: Display update interval in Hertz
+    description: Display update interval in Hertz for dot-matrix displays
 
   interrupts:
     maxItems: 1
@@ -41,10 +50,26 @@ properties:
     default: 16
     description: Initial brightness level
 
+  color:
+    description:
+      Color of the display.  Use one of the LED_COLOR_ID_* prefixed definitions
+      from the header include/dt-bindings/leds/common.h.  The default is red.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 9
+    default: 1
+
 required:
   - compatible
   - reg
-  - refresh-rate-hz
+
+if:
+  properties:
+    compatible:
+      const: holtek,ht16k33
+then:
+  required:
+    - refresh-rate-hz
 
 additionalProperties: false
 
-- 
2.25.1

Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

[Rob Herring]

On Fri, Jun 25, 2021 at 02:58:46PM +0200, Geert Uytterhoeven wrote:
> The Holtek HT16K33 LED controller is not only used for driving
> dot-matrix displays, but also for driving segment displays.
> 
> Document compatible values for the Adafruit 7-segment[1] and
> 14-segment[2] FeatherWing expansion boards with red displays.  According
> to the schematics, all other Adafruit 7-segment and 14-segment display
> backpack and FeatherWing expansion boards (including bare boards and
> boards fitted with displays) are compatible with these two boards.
> Add a "color" property to support the different color variants.
> 
> [1] https://www.adafruit.com/product/3108
> [2] https://www.adafruit.com/product/3130
> 
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> v2:
>   - Fix type of color to uint32,
>   - "refresh-rate-hz" is still required for dot-matrix displays.
> 
> Alternatives I considered:
>   1. Document the attached display type in a child node.
>      I.e. specify segment type, number of characters, and wiring.
>      Especially the latter would become really complex, due to the sheer
>      amount of possible wiring combinations.
>      Using this method, you also loose the ability to just connect a
>      display to an i2c bus, and instantiate the device from sysfs,
>      without using DT:
> 
> 	echo adafruit,3130 0x70 > /sys/class/i2c/i2c-adapter/.../new_device
> 
>   2. Do not use the "color" property, but document all Adafruit
>      7-segment and 14-segment display backpack and FeatherWing expansion
>      boards.
>      This would lead to a myriad of compatible values:
> 
>       - items:
> 	  - enum:
> 	      - adafruit,878      # 0.56" 4-Digit 7-Segment Display Backpack (Red)
> 	      - adafruit,879      # 0.56" 4-Digit 7-Segment Display Backpack (Yellow)
> 	      - adafruit,880      # 0.56" 4-Digit 7-Segment Display Backpack (Green)
> 	      - adafruit,881      # 0.56" 4-Digit 7-Segment Display Backpack (Blue)
> 	      - adafruit,1002     # 0.56" 4-Digit 7-Segment Display Backpack (White)
> 	  - const: adafruit,877   # 0.56" 4-Digit 7-Segment Backpack
> 	  - const: holtek,ht16k33
> 
>       - items:
> 	  - enum:
> 	      - adafruit,1268     # 1.2" 4-Digit 7-Segment Display Backpack (Green)
> 	      - adafruit,1269     # 1.2" 4-Digit 7-Segment Display Backpack (Yellow)
> 	      - adafruit,1270     # 1.2" 4-Digit 7-Segment Display Backpack (Red)
> 	  - const: adafruit,1271  # 1.2" 4-Digit 7-Segment Backpack
> 	  - const: holtek,ht16k33
> 
>       - items:
> 	  - enum:
> 	      - adafruit,1911     # 0.54" Quad Alphanumeric Display Backpack (Red)
> 	      - adafruit,1912     # 0.54" Quad Alphanumeric Display Backpack (Blue)
> 	      - adafruit,2157     # 0.54" Quad Alphanumeric Display Backpack (White)
> 	      - adafruit,2158     # 0.54" Quad Alphanumeric Display Backpack (Yellow)
> 	      - adafruit,2159     # 0.54" Quad Alphanumeric Display Backpack (Yellow-Green)
> 	      - adafruit,2160     # 0.54" Quad Alphanumeric Display Backpack (Green)
> 	  - const: adafruit,1910  # 0.54" Quad 14-segment Alphanumeric Backpack
> 	  - const: holtek,ht16k33
> 
>       - items:
> 	  - enum:
> 	      - adafruit,3106     # 0.56" 4-Digit 7-Segment FeatherWing Display (Blue)
> 	      - adafruit,3107     # 0.56" 4-Digit 7-Segment FeatherWing Display (Green)
> 	      - adafruit,3108     # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> 	      - adafruit,3109     # 0.56" 4-Digit 7-Segment FeatherWing Display (White)
> 	      - adafruit,3110     # 0.56" 4-Digit 7-Segment FeatherWing Display (Yellow)
> 	  - const: adafruit,3088  # 0.56" 4-Digit 7-Segment FeatherWing
> 	  - const: holtek,ht16k33
> 
>       - items:
> 	  - enum:
> 	      - adafruit,3127     # 0.54" Quad Alphanumeric FeatherWing Display (White)
> 	      - adafruit,3128     # 0.54" Quad Alphanumeric FeatherWing Display (Blue)
> 	      - adafruit,3129     # 0.54" Quad Alphanumeric FeatherWing Display (Green)
> 	      - adafruit,3130     # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> 	      - adafruit,3131     # 0.54" Quad Alphanumeric FeatherWing Display (Yellow)
> 	      - adafruit,3132     # 0.54" Quad Alphanumeric FeatherWing Display (Yellow-Green)
> 	  - const: adafruit,3089  # 0.54" Quad 14-segment Alphanumeric FeatherWing
> 	  - const: holtek,ht16k33
> ---
>  .../bindings/auxdisplay/holtek,ht16k33.yaml   | 31 +++++++++++++++++--
>  1 file changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> index 64ffff460026040f..616aca817874bdc8 100644
> --- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> +++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> @@ -14,14 +14,23 @@ allOf:
>  
>  properties:
>    compatible:
> -    const: holtek,ht16k33
> +    oneOf:
> +      - items:
> +          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> +          - const: holtek,ht16k33
> +
> +      - items:
> +          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> +          - const: holtek,ht16k33

These 2 entries can be combined. Or make the comment a 'description'.

> +
> +      - const: holtek,ht16k33     # Generic 16*8 LED controller with dot-matrix display
>  
>    reg:
>      maxItems: 1
>  
>    refresh-rate-hz:
>      maxItems: 1
> -    description: Display update interval in Hertz
> +    description: Display update interval in Hertz for dot-matrix displays
>  
>    interrupts:
>      maxItems: 1
> @@ -41,10 +50,26 @@ properties:
>      default: 16
>      description: Initial brightness level
>  
> +  color:
> +    description:
> +      Color of the display.  Use one of the LED_COLOR_ID_* prefixed definitions
> +      from the header include/dt-bindings/leds/common.h.  The default is red.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 9
> +    default: 1
> +
>  required:
>    - compatible
>    - reg
> -  - refresh-rate-hz
> +
> +if:
> +  properties:
> +    compatible:
> +      const: holtek,ht16k33

Isn't this always true?

> +then:
> +  required:
> +    - refresh-rate-hz
>  
>  additionalProperties: false
>  
> -- 
> 2.25.1
> 
> 

Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

[Geert Uytterhoeven]

Hi Rob,

Note that you commented on v2, while I posted v3 yesterday.

On Wed, Jul 14, 2021 at 10:36 PM Rob Herring <robh@kernel.org> wrote:
> On Fri, Jun 25, 2021 at 02:58:46PM +0200, Geert Uytterhoeven wrote:
> > The Holtek HT16K33 LED controller is not only used for driving
> > dot-matrix displays, but also for driving segment displays.
> >
> > Document compatible values for the Adafruit 7-segment[1] and
> > 14-segment[2] FeatherWing expansion boards with red displays.  According
> > to the schematics, all other Adafruit 7-segment and 14-segment display
> > backpack and FeatherWing expansion boards (including bare boards and
> > boards fitted with displays) are compatible with these two boards.
> > Add a "color" property to support the different color variants.
> >
> > [1] https://www.adafruit.com/product/3108
> > [2] https://www.adafruit.com/product/3130
> >
> > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

> > --- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > +++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > @@ -14,14 +14,23 @@ allOf:
> >
> >  properties:
> >    compatible:
> > -    const: holtek,ht16k33
> > +    oneOf:
> > +      - items:
> > +          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> > +          - const: holtek,ht16k33
> > +
> > +      - items:
> > +          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> > +          - const: holtek,ht16k33
>
> These 2 entries can be combined.

Right.  This split dates back from when I considered adding all
possible compatible values.  It can indeed be simplified to:

          - enum:
              - adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing
Display (Red)
              - adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing
Display (Red)
          - const: holtek,ht16k33

> Or make the comment a 'description'.

What do you mean?

>
> > +
> > +      - const: holtek,ht16k33     # Generic 16*8 LED controller with dot-matrix display

> >  required:
> >    - compatible
> >    - reg
> > -  - refresh-rate-hz
> > +
> > +if:
> > +  properties:
> > +    compatible:
> > +      const: holtek,ht16k33
>
> Isn't this always true?

It is false if there is more than one compatible value.

>
> > +then:
> > +  required:
> > +    - refresh-rate-hz
> >
> >  additionalProperties: false

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

Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

[Rob Herring]

On Thu, Jul 15, 2021 at 1:12 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Rob,
>
> Note that you commented on v2, while I posted v3 yesterday.
>
> On Wed, Jul 14, 2021 at 10:36 PM Rob Herring <robh@kernel.org> wrote:
> > On Fri, Jun 25, 2021 at 02:58:46PM +0200, Geert Uytterhoeven wrote:
> > > The Holtek HT16K33 LED controller is not only used for driving
> > > dot-matrix displays, but also for driving segment displays.
> > >
> > > Document compatible values for the Adafruit 7-segment[1] and
> > > 14-segment[2] FeatherWing expansion boards with red displays.  According
> > > to the schematics, all other Adafruit 7-segment and 14-segment display
> > > backpack and FeatherWing expansion boards (including bare boards and
> > > boards fitted with displays) are compatible with these two boards.
> > > Add a "color" property to support the different color variants.
> > >
> > > [1] https://www.adafruit.com/product/3108
> > > [2] https://www.adafruit.com/product/3130
> > >
> > > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> > > --- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > > +++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > > @@ -14,14 +14,23 @@ allOf:
> > >
> > >  properties:
> > >    compatible:
> > > -    const: holtek,ht16k33
> > > +    oneOf:
> > > +      - items:
> > > +          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> > > +          - const: holtek,ht16k33
> > > +
> > > +      - items:
> > > +          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> > > +          - const: holtek,ht16k33
> >
> > These 2 entries can be combined.
>
> Right.  This split dates back from when I considered adding all
> possible compatible values.  It can indeed be simplified to:
>
>           - enum:
>               - adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing
> Display (Red)
>               - adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing
> Display (Red)
>           - const: holtek,ht16k33
>
> > Or make the comment a 'description'.
>
> What do you mean?

Adding this:

description: '0.54" Quad Alphanumeric FeatherWing Display (Red)'


> > > +
> > > +      - const: holtek,ht16k33     # Generic 16*8 LED controller with dot-matrix display
>
> > >  required:
> > >    - compatible
> > >    - reg
> > > -  - refresh-rate-hz
> > > +
> > > +if:
> > > +  properties:
> > > +    compatible:
> > > +      const: holtek,ht16k33
> >
> > Isn't this always true?
>
> It is false if there is more than one compatible value.

Ah, yes.

Rob

Re: [PATCH v2 02/18] dt-bindings: auxdisplay: ht16k33: Document Adafruit segment displays

[Geert Uytterhoeven]

Hi Rob,

On Thu, Jul 15, 2021 at 4:32 PM Rob Herring <robh@kernel.org> wrote:
> On Thu, Jul 15, 2021 at 1:12 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Wed, Jul 14, 2021 at 10:36 PM Rob Herring <robh@kernel.org> wrote:
> > > On Fri, Jun 25, 2021 at 02:58:46PM +0200, Geert Uytterhoeven wrote:
> > > > The Holtek HT16K33 LED controller is not only used for driving
> > > > dot-matrix displays, but also for driving segment displays.
> > > >
> > > > Document compatible values for the Adafruit 7-segment[1] and
> > > > 14-segment[2] FeatherWing expansion boards with red displays.  According
> > > > to the schematics, all other Adafruit 7-segment and 14-segment display
> > > > backpack and FeatherWing expansion boards (including bare boards and
> > > > boards fitted with displays) are compatible with these two boards.
> > > > Add a "color" property to support the different color variants.
> > > >
> > > > [1] https://www.adafruit.com/product/3108
> > > > [2] https://www.adafruit.com/product/3130
> > > >
> > > > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> >
> > > > --- a/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > > > +++ b/Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml
> > > > @@ -14,14 +14,23 @@ allOf:
> > > >
> > > >  properties:
> > > >    compatible:
> > > > -    const: holtek,ht16k33
> > > > +    oneOf:
> > > > +      - items:
> > > > +          - const: adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing Display (Red)
> > > > +          - const: holtek,ht16k33
> > > > +
> > > > +      - items:
> > > > +          - const: adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing Display (Red)
> > > > +          - const: holtek,ht16k33
> > >
> > > These 2 entries can be combined.
> >
> > Right.  This split dates back from when I considered adding all
> > possible compatible values.  It can indeed be simplified to:
> >
> >           - enum:
> >               - adafruit,3108  # 0.56" 4-Digit 7-Segment FeatherWing
> > Display (Red)
> >               - adafruit,3130  # 0.54" Quad Alphanumeric FeatherWing
> > Display (Red)
> >           - const: holtek,ht16k33
> >
> > > Or make the comment a 'description'.
> >
> > What do you mean?
>
> Adding this:
>
> description: '0.54" Quad Alphanumeric FeatherWing Display (Red)'

Sorry, I still don't get it.
Note that there are two different adafruit,NNNN compatible values.

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

[PATCH v2 03/18] auxdisplay: img-ascii-lcd: Fix lock-up when displaying empty string

[Geert Uytterhoeven]

While writing an empty string to a device attribute is a no-op, and thus
does not need explicit safeguards, the user can still write a single
newline to an attribute file:

    echo > .../message

If that happens, img_ascii_lcd_display() trims the newline, yielding an
empty string, and causing an infinite loop in img_ascii_lcd_scroll().

Fix this by adding a check for empty strings.  Clear the display in case
one is encountered.

Fixes: 0cad855fbd083ee5 ("auxdisplay: img-ascii-lcd: driver for simple ASCII LCD displays")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
Untested with img-ascii-lcd, but triggered with my initial version of
linedisp.

v2:
  - No changes.
---
 drivers/auxdisplay/img-ascii-lcd.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index 1cce409ce5cacbc8..e33ce0151cdfd150 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -280,6 +280,16 @@ static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
 	if (msg[count - 1] == '\n')
 		count--;
 
+	if (!count) {
+		/* clear the LCD */
+		devm_kfree(&ctx->pdev->dev, ctx->message);
+		ctx->message = NULL;
+		ctx->message_len = 0;
+		memset(ctx->curr, ' ', ctx->cfg->num_chars);
+		ctx->cfg->update(ctx);
+		return 0;
+	}
+
 	new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
 	if (!new_msg)
 		return -ENOMEM;
-- 
2.25.1

[PATCH v2 04/18] auxdisplay: img-ascii-lcd: Add helper variable dev

[Geert Uytterhoeven]

img_ascii_lcd_probe() has many users of "pdev->dev".  Add a shorthand to
simplify the code.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/img-ascii-lcd.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index e33ce0151cdfd150..2b6e41ec57544faa 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -365,26 +365,25 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	const struct img_ascii_lcd_config *cfg;
+	struct device *dev = &pdev->dev;
 	struct img_ascii_lcd_ctx *ctx;
 	int err;
 
-	match = of_match_device(img_ascii_lcd_matches, &pdev->dev);
+	match = of_match_device(img_ascii_lcd_matches, dev);
 	if (!match)
 		return -ENODEV;
 
 	cfg = match->data;
-	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars,
-			   GFP_KERNEL);
+	ctx = devm_kzalloc(dev, sizeof(*ctx) + cfg->num_chars, GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
 
 	if (cfg->external_regmap) {
-		ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node);
+		ctx->regmap = syscon_node_to_regmap(dev->parent->of_node);
 		if (IS_ERR(ctx->regmap))
 			return PTR_ERR(ctx->regmap);
 
-		if (of_property_read_u32(pdev->dev.of_node, "offset",
-					 &ctx->offset))
+		if (of_property_read_u32(dev->of_node, "offset", &ctx->offset))
 			return -EINVAL;
 	} else {
 		ctx->base = devm_platform_ioremap_resource(pdev, 0);
@@ -408,7 +407,7 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
 	if (err)
 		goto out_del_timer;
 
-	err = device_create_file(&pdev->dev, &dev_attr_message);
+	err = device_create_file(dev, &dev_attr_message);
 	if (err)
 		goto out_del_timer;
 
-- 
2.25.1

[PATCH v2 05/18] auxdisplay: img-ascii-lcd: Convert device attribute to sysfs_emit()

[Geert Uytterhoeven]

Convert the "message" device attribute from sprintf() to sysfs_emit(),
as the latter is aware of the PAGE_SIZE buffer.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/img-ascii-lcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index 2b6e41ec57544faa..2b5640b638900a90 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -326,7 +326,7 @@ static ssize_t message_show(struct device *dev, struct device_attribute *attr,
 {
 	struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", ctx->message);
+	return sysfs_emit(buf, "%s\n", ctx->message);
 }
 
 /**
-- 
2.25.1

[PATCH v2 06/18] auxdisplay: Extract character line display core support

[Geert Uytterhoeven]

Extract the character line display core support from the simple ASCII
LCD driver for the MIPS Boston, Malta & SEAD3 development boards into
its own subdriver, so it can be reused for other displays.

As this moves the "message" device attribute in sysfs in a "linedisp.N"
subdirectory, a symlink is added to preserve backwards compatibility.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
Changes to img-ascii-lcd.c are untested due to lack of hardware.
The backwards compatibility symlink has been tested by adding similar
code to drivers/auxdisplay/ht16k33.c.

v2:
  - Drop "select LINEDISP" from HT16K33 symbol,
  - Add backwards compatibility symlink.
---
 drivers/auxdisplay/Kconfig         |   7 +
 drivers/auxdisplay/Makefile        |   1 +
 drivers/auxdisplay/img-ascii-lcd.c | 205 +++++--------------------
 drivers/auxdisplay/line-display.c  | 231 +++++++++++++++++++++++++++++
 drivers/auxdisplay/line-display.h  |  43 ++++++
 5 files changed, 320 insertions(+), 167 deletions(-)
 create mode 100644 drivers/auxdisplay/line-display.c
 create mode 100644 drivers/auxdisplay/line-display.h

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index 1509cb74705a30ad..b41fdc5f7bf72a1b 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -25,6 +25,12 @@ config CHARLCD
 	  This is some character LCD core interface that multiple drivers can
 	  use.
 
+config LINEDISP
+	tristate "Character line display core support" if COMPILE_TEST
+	help
+	  This is the core support for single-line character displays, to be
+	  selected by drivers that use it.
+
 config HD44780_COMMON
 	tristate "Common functions for HD44780 (and compatibles) LCD displays" if COMPILE_TEST
 	select CHARLCD
@@ -155,6 +161,7 @@ config IMG_ASCII_LCD
 	depends on HAS_IOMEM
 	default y if MIPS_MALTA
 	select MFD_SYSCON
+	select LINEDISP
 	help
 	  Enable this to support the simple ASCII LCD displays found on
 	  development boards such as the MIPS Boston, MIPS Malta & MIPS SEAD3
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index 307771027c893a5b..6968ed4d3f0a8930 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_HD44780)		+= hd44780.o
 obj-$(CONFIG_HT16K33)		+= ht16k33.o
 obj-$(CONFIG_PARPORT_PANEL)	+= panel.o
 obj-$(CONFIG_LCD2S)		+= lcd2s.o
+obj-$(CONFIG_LINEDISP)		+= line-display.o
diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index 2b5640b638900a90..b0f78d1768bba897 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -4,7 +4,6 @@
  * Author: Paul Burton <paul.burton@mips.com>
  */
 
-#include <generated/utsrelease.h>
 #include <linux/kernel.h>
 #include <linux/io.h>
 #include <linux/mfd/syscon.h>
@@ -14,7 +13,8 @@
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
-#include <linux/sysfs.h>
+
+#include "line-display.h"
 
 struct img_ascii_lcd_ctx;
 
@@ -27,36 +27,26 @@ struct img_ascii_lcd_ctx;
 struct img_ascii_lcd_config {
 	unsigned int num_chars;
 	bool external_regmap;
-	void (*update)(struct img_ascii_lcd_ctx *ctx);
+	void (*update)(struct linedisp *linedisp);
 };
 
 /**
  * struct img_ascii_lcd_ctx - Private data structure
- * @pdev: the ASCII LCD platform device
  * @base: the base address of the LCD registers
  * @regmap: the regmap through which LCD registers are accessed
  * @offset: the offset within regmap to the start of the LCD registers
  * @cfg: pointer to the LCD model configuration
- * @message: the full message to display or scroll on the LCD
- * @message_len: the length of the @message string
- * @scroll_pos: index of the first character of @message currently displayed
- * @scroll_rate: scroll interval in jiffies
- * @timer: timer used to implement scrolling
+ * @linedisp: line display structure
  * @curr: the string currently displayed on the LCD
  */
 struct img_ascii_lcd_ctx {
-	struct platform_device *pdev;
 	union {
 		void __iomem *base;
 		struct regmap *regmap;
 	};
 	u32 offset;
 	const struct img_ascii_lcd_config *cfg;
-	char *message;
-	unsigned int message_len;
-	unsigned int scroll_pos;
-	unsigned int scroll_rate;
-	struct timer_list timer;
+	struct linedisp linedisp;
 	char curr[] __aligned(8);
 };
 
@@ -64,8 +54,10 @@ struct img_ascii_lcd_ctx {
  * MIPS Boston development board
  */
 
-static void boston_update(struct img_ascii_lcd_ctx *ctx)
+static void boston_update(struct linedisp *linedisp)
 {
+	struct img_ascii_lcd_ctx *ctx =
+		container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
 	ulong val;
 
 #if BITS_PER_LONG == 64
@@ -90,12 +82,14 @@ static struct img_ascii_lcd_config boston_config = {
  * MIPS Malta development board
  */
 
-static void malta_update(struct img_ascii_lcd_ctx *ctx)
+static void malta_update(struct linedisp *linedisp)
 {
+	struct img_ascii_lcd_ctx *ctx =
+		container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
 	unsigned int i;
 	int err = 0;
 
-	for (i = 0; i < ctx->cfg->num_chars; i++) {
+	for (i = 0; i < linedisp->num_chars; i++) {
 		err = regmap_write(ctx->regmap,
 				   ctx->offset + (i * 8), ctx->curr[i]);
 		if (err)
@@ -173,12 +167,14 @@ static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
 	return 0;
 }
 
-static void sead3_update(struct img_ascii_lcd_ctx *ctx)
+static void sead3_update(struct linedisp *linedisp)
 {
+	struct img_ascii_lcd_ctx *ctx =
+		container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
 	unsigned int i;
 	int err = 0;
 
-	for (i = 0; i < ctx->cfg->num_chars; i++) {
+	for (i = 0; i < linedisp->num_chars; i++) {
 		err = sead3_wait_lcd_idle(ctx);
 		if (err)
 			break;
@@ -218,140 +214,22 @@ static const struct of_device_id img_ascii_lcd_matches[] = {
 };
 MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
 
-/**
- * img_ascii_lcd_scroll() - scroll the display by a character
- * @t: really a pointer to the private data structure
- *
- * Scroll the current message along the LCD by one character, rearming the
- * timer if required.
- */
-static void img_ascii_lcd_scroll(struct timer_list *t)
+static int sysfs_create_file_link(struct kobject *parent,
+				  struct kobject *target, const char *name)
 {
-	struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer);
-	unsigned int i, ch = ctx->scroll_pos;
-	unsigned int num_chars = ctx->cfg->num_chars;
-
-	/* update the current message string */
-	for (i = 0; i < num_chars;) {
-		/* copy as many characters from the string as possible */
-		for (; i < num_chars && ch < ctx->message_len; i++, ch++)
-			ctx->curr[i] = ctx->message[ch];
-
-		/* wrap around to the start of the string */
-		ch = 0;
-	}
-
-	/* update the LCD */
-	ctx->cfg->update(ctx);
+	struct kernfs_node *kn;
 
-	/* move on to the next character */
-	ctx->scroll_pos++;
-	ctx->scroll_pos %= ctx->message_len;
+	kn = kernfs_find_and_get(target->sd, "message");
+	if (!kn)
+		return -ENOENT;
 
-	/* rearm the timer */
-	if (ctx->message_len > ctx->cfg->num_chars)
-		mod_timer(&ctx->timer, jiffies + ctx->scroll_rate);
-}
-
-/**
- * img_ascii_lcd_display() - set the message to be displayed
- * @ctx: pointer to the private data structure
- * @msg: the message to display
- * @count: length of msg, or -1
- *
- * Display a new message @msg on the LCD. @msg can be longer than the number of
- * characters the LCD can display, in which case it will begin scrolling across
- * the LCD display.
- *
- * Return: 0 on success, -ENOMEM on memory allocation failure
- */
-static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
-			     const char *msg, ssize_t count)
-{
-	char *new_msg;
-
-	/* stop the scroll timer */
-	del_timer_sync(&ctx->timer);
-
-	if (count == -1)
-		count = strlen(msg);
-
-	/* if the string ends with a newline, trim it */
-	if (msg[count - 1] == '\n')
-		count--;
-
-	if (!count) {
-		/* clear the LCD */
-		devm_kfree(&ctx->pdev->dev, ctx->message);
-		ctx->message = NULL;
-		ctx->message_len = 0;
-		memset(ctx->curr, ' ', ctx->cfg->num_chars);
-		ctx->cfg->update(ctx);
-		return 0;
-	}
-
-	new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
-	if (!new_msg)
-		return -ENOMEM;
-
-	memcpy(new_msg, msg, count);
-	new_msg[count] = 0;
-
-	if (ctx->message)
-		devm_kfree(&ctx->pdev->dev, ctx->message);
-
-	ctx->message = new_msg;
-	ctx->message_len = count;
-	ctx->scroll_pos = 0;
-
-	/* update the LCD */
-	img_ascii_lcd_scroll(&ctx->timer);
+	kn = kernfs_create_link(parent->sd, "message", kn);
+	if (!kn)
+		return -ENOENT;
 
 	return 0;
 }
 
-/**
- * message_show() - read message via sysfs
- * @dev: the LCD device
- * @attr: the LCD message attribute
- * @buf: the buffer to read the message into
- *
- * Read the current message being displayed or scrolled across the LCD display
- * into @buf, for reads from sysfs.
- *
- * Return: the number of characters written to @buf
- */
-static ssize_t message_show(struct device *dev, struct device_attribute *attr,
-			    char *buf)
-{
-	struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
-
-	return sysfs_emit(buf, "%s\n", ctx->message);
-}
-
-/**
- * message_store() - write a new message via sysfs
- * @dev: the LCD device
- * @attr: the LCD message attribute
- * @buf: the buffer containing the new message
- * @count: the size of the message in @buf
- *
- * Write a new message to display or scroll across the LCD display from sysfs.
- *
- * Return: the size of the message on success, else -ERRNO
- */
-static ssize_t message_store(struct device *dev, struct device_attribute *attr,
-			     const char *buf, size_t count)
-{
-	struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
-	int err;
-
-	err = img_ascii_lcd_display(ctx, buf, count);
-	return err ?: count;
-}
-
-static DEVICE_ATTR_RW(message);
-
 /**
  * img_ascii_lcd_probe() - probe an LCD display device
  * @pdev: the LCD platform device
@@ -391,29 +269,22 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
 			return PTR_ERR(ctx->base);
 	}
 
-	ctx->pdev = pdev;
-	ctx->cfg = cfg;
-	ctx->message = NULL;
-	ctx->scroll_pos = 0;
-	ctx->scroll_rate = HZ / 2;
-
-	/* initialise a timer for scrolling the message */
-	timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
-
-	platform_set_drvdata(pdev, ctx);
-
-	/* display a default message */
-	err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE "       ", -1);
+	err = linedisp_register(&ctx->linedisp, dev, cfg->num_chars, ctx->curr,
+				cfg->update);
 	if (err)
-		goto out_del_timer;
+		return err;
 
-	err = device_create_file(dev, &dev_attr_message);
+	/* for backwards compatibility */
+	err = sysfs_create_file_link(&dev->kobj, &ctx->linedisp.dev.kobj,
+				     "message");
 	if (err)
-		goto out_del_timer;
+		goto err_unregister;
 
+	platform_set_drvdata(pdev, ctx);
 	return 0;
-out_del_timer:
-	del_timer_sync(&ctx->timer);
+
+err_unregister:
+	linedisp_unregister(&ctx->linedisp);
 	return err;
 }
 
@@ -430,8 +301,8 @@ static int img_ascii_lcd_remove(struct platform_device *pdev)
 {
 	struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
 
-	device_remove_file(&pdev->dev, &dev_attr_message);
-	del_timer_sync(&ctx->timer);
+	sysfs_remove_link(&pdev->dev.kobj, "message");
+	linedisp_unregister(&ctx->linedisp);
 	return 0;
 }
 
diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c
new file mode 100644
index 0000000000000000..4b97c20ac0b381ee
--- /dev/null
+++ b/drivers/auxdisplay/line-display.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Character line display core support
+ *
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.com>
+ *
+ * Copyright (C) 2021 Glider bv
+ */
+
+#include <generated/utsrelease.h>
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/timer.h>
+
+#include "line-display.h"
+
+/**
+ * linedisp_scroll() - scroll the display by a character
+ * @t: really a pointer to the private data structure
+ *
+ * Scroll the current message along the display by one character, rearming the
+ * timer if required.
+ */
+static void linedisp_scroll(struct timer_list *t)
+{
+	struct linedisp *linedisp = from_timer(linedisp, t, timer);
+	unsigned int i, ch = linedisp->scroll_pos;
+	unsigned int num_chars = linedisp->num_chars;
+
+	/* update the current message string */
+	for (i = 0; i < num_chars;) {
+		/* copy as many characters from the string as possible */
+		for (; i < num_chars && ch < linedisp->message_len; i++, ch++)
+			linedisp->buf[i] = linedisp->message[ch];
+
+		/* wrap around to the start of the string */
+		ch = 0;
+	}
+
+	/* update the display */
+	linedisp->update(linedisp);
+
+	/* move on to the next character */
+	linedisp->scroll_pos++;
+	linedisp->scroll_pos %= linedisp->message_len;
+
+	/* rearm the timer */
+	if (linedisp->message_len > num_chars)
+		mod_timer(&linedisp->timer, jiffies + linedisp->scroll_rate);
+}
+
+/**
+ * linedisp_display() - set the message to be displayed
+ * @linedisp: pointer to the private data structure
+ * @msg: the message to display
+ * @count: length of msg, or -1
+ *
+ * Display a new message @msg on the display. @msg can be longer than the
+ * number of characters the display can display, in which case it will begin
+ * scrolling across the display.
+ *
+ * Return: 0 on success, -ENOMEM on memory allocation failure
+ */
+static int linedisp_display(struct linedisp *linedisp, const char *msg,
+			    ssize_t count)
+{
+	char *new_msg;
+
+	/* stop the scroll timer */
+	del_timer_sync(&linedisp->timer);
+
+	if (count == -1)
+		count = strlen(msg);
+
+	/* if the string ends with a newline, trim it */
+	if (msg[count - 1] == '\n')
+		count--;
+
+	if (!count) {
+		/* Clear the display */
+		kfree(linedisp->message);
+		linedisp->message = NULL;
+		linedisp->message_len = 0;
+		memset(linedisp->buf, ' ', linedisp->num_chars);
+		linedisp->update(linedisp);
+		return 0;
+	}
+
+	new_msg = kmalloc(count + 1, GFP_KERNEL);
+	if (!new_msg)
+		return -ENOMEM;
+
+	memcpy(new_msg, msg, count);
+	new_msg[count] = 0;
+
+	kfree(linedisp->message);
+
+	linedisp->message = new_msg;
+	linedisp->message_len = count;
+	linedisp->scroll_pos = 0;
+
+	/* update the display */
+	linedisp_scroll(&linedisp->timer);
+
+	return 0;
+}
+
+/**
+ * message_show() - read message via sysfs
+ * @dev: the display device
+ * @attr: the display message attribute
+ * @buf: the buffer to read the message into
+ *
+ * Read the current message being displayed or scrolled across the display into
+ * @buf, for reads from sysfs.
+ *
+ * Return: the number of characters written to @buf
+ */
+static ssize_t message_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+
+	return sysfs_emit(buf, "%s\n", linedisp->message);
+}
+
+/**
+ * message_store() - write a new message via sysfs
+ * @dev: the display device
+ * @attr: the display message attribute
+ * @buf: the buffer containing the new message
+ * @count: the size of the message in @buf
+ *
+ * Write a new message to display or scroll across the display from sysfs.
+ *
+ * Return: the size of the message on success, else -ERRNO
+ */
+static ssize_t message_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+	int err;
+
+	err = linedisp_display(linedisp, buf, count);
+	return err ?: count;
+}
+
+static DEVICE_ATTR_RW(message);
+
+static struct attribute *linedisp_attrs[] = {
+	&dev_attr_message.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(linedisp);
+
+static const struct device_type linedisp_type = {
+	.groups	= linedisp_groups,
+};
+
+/**
+ * linedisp_register - register a character line display
+ * @linedisp: pointer to character line display structure
+ * @parent: parent device
+ * @num_chars: the number of characters that can be displayed
+ * @buf: pointer to a buffer that can hold @num_chars characters
+ * @update: Function called to update the display.  This must not sleep!
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int linedisp_register(struct linedisp *linedisp, struct device *parent,
+		      unsigned int num_chars, char *buf,
+		      void (*update)(struct linedisp *linedisp))
+{
+	static atomic_t linedisp_id = ATOMIC_INIT(-1);
+	int err;
+
+	memset(linedisp, 0, sizeof(*linedisp));
+	linedisp->dev.parent = parent;
+	linedisp->dev.type = &linedisp_type;
+	linedisp->update = update;
+	linedisp->buf = buf;
+	linedisp->num_chars = num_chars;
+	linedisp->scroll_rate = HZ / 2;
+
+	device_initialize(&linedisp->dev);
+	dev_set_name(&linedisp->dev, "linedisp.%lu",
+		     (unsigned long)atomic_inc_return(&linedisp_id));
+
+	/* initialise a timer for scrolling the message */
+	timer_setup(&linedisp->timer, linedisp_scroll, 0);
+
+	err = device_add(&linedisp->dev);
+	if (err)
+		goto out_del_timer;
+
+	/* display a default message */
+	err = linedisp_display(linedisp, "Linux " UTS_RELEASE "       ", -1);
+	if (err)
+		goto out_del_dev;
+
+	return 0;
+
+out_del_dev:
+	device_del(&linedisp->dev);
+out_del_timer:
+	del_timer_sync(&linedisp->timer);
+	put_device(&linedisp->dev);
+	return err;
+}
+EXPORT_SYMBOL_GPL(linedisp_register);
+
+/**
+ * linedisp_unregister - unregister a character line display
+ * @linedisp: pointer to character line display structure registered previously
+ *	      with linedisp_register()
+ */
+void linedisp_unregister(struct linedisp *linedisp)
+{
+	device_del(&linedisp->dev);
+	del_timer_sync(&linedisp->timer);
+	kfree(linedisp->message);
+	put_device(&linedisp->dev);
+}
+EXPORT_SYMBOL_GPL(linedisp_unregister);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/auxdisplay/line-display.h b/drivers/auxdisplay/line-display.h
new file mode 100644
index 0000000000000000..0f5891d34c485871
--- /dev/null
+++ b/drivers/auxdisplay/line-display.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Character line display core support
+ *
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.com>
+ *
+ * Copyright (C) 2021 Glider bv
+ */
+
+#ifndef _LINEDISP_H
+#define _LINEDISP_H
+
+/**
+ * struct linedisp - character line display private data structure
+ * @dev: the line display device
+ * @timer: timer used to implement scrolling
+ * @update: function called to update the display
+ * @buf: pointer to the buffer for the string currently displayed
+ * @message: the full message to display or scroll on the display
+ * @num_chars: the number of characters that can be displayed
+ * @message_len: the length of the @message string
+ * @scroll_pos: index of the first character of @message currently displayed
+ * @scroll_rate: scroll interval in jiffies
+ */
+struct linedisp {
+	struct device dev;
+	struct timer_list timer;
+	void (*update)(struct linedisp *linedisp);
+	char *buf;
+	char *message;
+	unsigned int num_chars;
+	unsigned int message_len;
+	unsigned int scroll_pos;
+	unsigned int scroll_rate;
+};
+
+int linedisp_register(struct linedisp *linedisp, struct device *parent,
+		      unsigned int num_chars, char *buf,
+		      void (*update)(struct linedisp *linedisp));
+void linedisp_unregister(struct linedisp *linedisp);
+
+#endif /* LINEDISP_H */
-- 
2.25.1

Re: [PATCH v2 06/18] auxdisplay: Extract character line display core support

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 1719 bytes --]

Hi Geert,

I love your patch! Yet something to improve:

[auto build test ERROR on robh/for-next]
[also build test ERROR on staging/staging-testing linus/master v5.13-rc7 next-20210625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
config: powerpc-allmodconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/5505aedee505055e2fe16a718203e24fd8519e2a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
        git checkout 5505aedee505055e2fe16a718203e24fd8519e2a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: ".kernfs_create_link" [drivers/auxdisplay/img-ascii-lcd.ko] undefined!

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 73351 bytes --]

Re: [PATCH v2 06/18] auxdisplay: Extract character line display core support

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 1755 bytes --]

Hi Geert,

I love your patch! Yet something to improve:

[auto build test ERROR on robh/for-next]
[also build test ERROR on staging/staging-testing linus/master v5.13-rc7 next-20210625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
config: powerpc-allmodconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/5505aedee505055e2fe16a718203e24fd8519e2a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
        git checkout 5505aedee505055e2fe16a718203e24fd8519e2a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: ".kernfs_create_link" [drivers/auxdisplay/img-ascii-lcd.ko] undefined!

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 73351 bytes --]

Re: [PATCH v2 06/18] auxdisplay: Extract character line display core support

[Geert Uytterhoeven]

Hi Kernel Test Robot,

On Sat, Jun 26, 2021 at 1:36 AM kernel test robot <lkp@intel.com> wrote:
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on robh/for-next]
> [also build test ERROR on staging/staging-testing linus/master v5.13-rc7 next-20210625]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url:    https://github.com/0day-ci/linux/commits/Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
> config: powerpc-allmodconfig (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/0day-ci/linux/commit/5505aedee505055e2fe16a718203e24fd8519e2a
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
>         git checkout 5505aedee505055e2fe16a718203e24fd8519e2a
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>, old ones prefixed by <<):
>
> >> ERROR: modpost: ".kernfs_create_link" [drivers/auxdisplay/img-ascii-lcd.ko] undefined!

Thanks a lot!

This helped me finding compat_only_sysfs_link_entry_to_kobj(), which
I hadn't found before, and which does an even better job than my custom
sysfs_create_file_link() implementation.

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

Re: [PATCH v2 06/18] auxdisplay: Extract character line display core support

[Geert Uytterhoeven]

[-- Attachment #1: Type: text/plain, Size: 2330 bytes --]

Hi Kernel Test Robot,

On Sat, Jun 26, 2021 at 1:36 AM kernel test robot <lkp@intel.com> wrote:
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on robh/for-next]
> [also build test ERROR on staging/staging-testing linus/master v5.13-rc7 next-20210625]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url:    https://github.com/0day-ci/linux/commits/Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
> config: powerpc-allmodconfig (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/0day-ci/linux/commit/5505aedee505055e2fe16a718203e24fd8519e2a
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Geert-Uytterhoeven/auxdisplay-ht16k33-Add-character-display-support/20210625-210014
>         git checkout 5505aedee505055e2fe16a718203e24fd8519e2a
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>, old ones prefixed by <<):
>
> >> ERROR: modpost: ".kernfs_create_link" [drivers/auxdisplay/img-ascii-lcd.ko] undefined!

Thanks a lot!

This helped me finding compat_only_sysfs_link_entry_to_kobj(), which
I hadn't found before, and which does an even better job than my custom
sysfs_create_file_link() implementation.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert(a)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

[PATCH v2 07/18] auxdisplay: linedisp: Use kmemdup_nul() helper

[Geert Uytterhoeven]

Use the existing kmemdup_nul() helper instead of open-coding the same
operation.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/line-display.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c
index 4b97c20ac0b381ee..3f35199bc39f511f 100644
--- a/drivers/auxdisplay/line-display.c
+++ b/drivers/auxdisplay/line-display.c
@@ -91,13 +91,10 @@ static int linedisp_display(struct linedisp *linedisp, const char *msg,
 		return 0;
 	}
 
-	new_msg = kmalloc(count + 1, GFP_KERNEL);
+	new_msg = kmemdup_nul(msg, count, GFP_KERNEL);
 	if (!new_msg)
 		return -ENOMEM;
 
-	memcpy(new_msg, msg, count);
-	new_msg[count] = 0;
-
 	kfree(linedisp->message);
 
 	linedisp->message = new_msg;
-- 
2.25.1

[PATCH v2 08/18] auxdisplay: linedisp: Add support for changing scroll rate

[Geert Uytterhoeven]

If the message to display is longer than the number of characters that
the display can show, the message will be scrolled.  Currently the
scroll rate is fixed, moving every 500 ms.

Add support for changing the scroll rate through a "scroll_step_ms"
device attribute in sysfs.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/line-display.c | 37 +++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c
index 3f35199bc39f511f..03e7f104aa1add32 100644
--- a/drivers/auxdisplay/line-display.c
+++ b/drivers/auxdisplay/line-display.c
@@ -19,6 +19,8 @@
 
 #include "line-display.h"
 
+#define DEFAULT_SCROLL_RATE	(HZ / 2)
+
 /**
  * linedisp_scroll() - scroll the display by a character
  * @t: really a pointer to the private data structure
@@ -50,7 +52,7 @@ static void linedisp_scroll(struct timer_list *t)
 	linedisp->scroll_pos %= linedisp->message_len;
 
 	/* rearm the timer */
-	if (linedisp->message_len > num_chars)
+	if (linedisp->message_len > num_chars && linedisp->scroll_rate)
 		mod_timer(&linedisp->timer, jiffies + linedisp->scroll_rate);
 }
 
@@ -149,8 +151,39 @@ static ssize_t message_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR_RW(message);
 
+static ssize_t scroll_step_ms_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+
+	return sysfs_emit(buf, "%u\n", jiffies_to_msecs(linedisp->scroll_rate));
+}
+
+static ssize_t scroll_step_ms_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+	unsigned int ms;
+
+	if (kstrtouint(buf, 10, &ms) != 0)
+		return -EINVAL;
+
+	linedisp->scroll_rate = msecs_to_jiffies(ms);
+	if (linedisp->message && linedisp->message_len > linedisp->num_chars) {
+		del_timer_sync(&linedisp->timer);
+		if (linedisp->scroll_rate)
+			linedisp_scroll(&linedisp->timer);
+	}
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(scroll_step_ms);
+
 static struct attribute *linedisp_attrs[] = {
 	&dev_attr_message.attr,
+	&dev_attr_scroll_step_ms.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(linedisp);
@@ -182,7 +215,7 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent,
 	linedisp->update = update;
 	linedisp->buf = buf;
 	linedisp->num_chars = num_chars;
-	linedisp->scroll_rate = HZ / 2;
+	linedisp->scroll_rate = DEFAULT_SCROLL_RATE;
 
 	device_initialize(&linedisp->dev);
 	dev_set_name(&linedisp->dev, "linedisp.%lu",
-- 
2.25.1

[PATCH v2 09/18] auxdisplay: ht16k33: Connect backlight to fbdev

[Geert Uytterhoeven]

Currently /sys/class/graphics/fb0/bl_curve is not accessible (-ENODEV),
as the driver does not connect the backlight to the frame buffer device.
Fix this moving backlight initialization up, and filling in
fb_info.bl_dev.

Fixes: 8992da44c6805d53 ("auxdisplay: ht16k33: Driver for LED controller")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - New.
---
 drivers/auxdisplay/ht16k33.c | 56 ++++++++++++++++++------------------
 1 file changed, 28 insertions(+), 28 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 1e69cc6d21a0dca2..2b630e194570f6e5 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -413,6 +413,33 @@ static int ht16k33_probe(struct i2c_client *client,
 	if (err)
 		return err;
 
+	/* Backlight */
+	memset(&bl_props, 0, sizeof(struct backlight_properties));
+	bl_props.type = BACKLIGHT_RAW;
+	bl_props.max_brightness = MAX_BRIGHTNESS;
+
+	bl = devm_backlight_device_register(&client->dev, DRIVER_NAME"-bl",
+					    &client->dev, priv,
+					    &ht16k33_bl_ops, &bl_props);
+	if (IS_ERR(bl)) {
+		dev_err(&client->dev, "failed to register backlight\n");
+		return PTR_ERR(bl);
+	}
+
+	err = of_property_read_u32(node, "default-brightness-level",
+				   &dft_brightness);
+	if (err) {
+		dft_brightness = MAX_BRIGHTNESS;
+	} else if (dft_brightness > MAX_BRIGHTNESS) {
+		dev_warn(&client->dev,
+			 "invalid default brightness level: %u, using %u\n",
+			 dft_brightness, MAX_BRIGHTNESS);
+		dft_brightness = MAX_BRIGHTNESS;
+	}
+
+	bl->props.brightness = dft_brightness;
+	ht16k33_bl_update_status(bl);
+
 	/* Framebuffer (2 bytes per column) */
 	BUILD_BUG_ON(PAGE_SIZE < HT16K33_FB_SIZE);
 	fbdev->buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
@@ -445,6 +472,7 @@ static int ht16k33_probe(struct i2c_client *client,
 	fbdev->info->screen_size = HT16K33_FB_SIZE;
 	fbdev->info->fix = ht16k33_fb_fix;
 	fbdev->info->var = ht16k33_fb_var;
+	fbdev->info->bl_dev = bl;
 	fbdev->info->pseudo_palette = NULL;
 	fbdev->info->flags = FBINFO_FLAG_DEFAULT;
 	fbdev->info->par = priv;
@@ -460,34 +488,6 @@ static int ht16k33_probe(struct i2c_client *client,
 			goto err_fbdev_unregister;
 	}
 
-	/* Backlight */
-	memset(&bl_props, 0, sizeof(struct backlight_properties));
-	bl_props.type = BACKLIGHT_RAW;
-	bl_props.max_brightness = MAX_BRIGHTNESS;
-
-	bl = devm_backlight_device_register(&client->dev, DRIVER_NAME"-bl",
-					    &client->dev, priv,
-					    &ht16k33_bl_ops, &bl_props);
-	if (IS_ERR(bl)) {
-		dev_err(&client->dev, "failed to register backlight\n");
-		err = PTR_ERR(bl);
-		goto err_fbdev_unregister;
-	}
-
-	err = of_property_read_u32(node, "default-brightness-level",
-				   &dft_brightness);
-	if (err) {
-		dft_brightness = MAX_BRIGHTNESS;
-	} else if (dft_brightness > MAX_BRIGHTNESS) {
-		dev_warn(&client->dev,
-			 "invalid default brightness level: %u, using %u\n",
-			 dft_brightness, MAX_BRIGHTNESS);
-		dft_brightness = MAX_BRIGHTNESS;
-	}
-
-	bl->props.brightness = dft_brightness;
-	ht16k33_bl_update_status(bl);
-
 	ht16k33_fb_queue(priv);
 	return 0;
 
-- 
2.25.1

[PATCH v2 10/18] auxdisplay: ht16k33: Use HT16K33_FB_SIZE in ht16k33_initialize()

[Geert Uytterhoeven]

Use the existing HT16K33_FB_SIZE definition instead of open-coding the
same calculation using an hardcoded value.
While at it, restore reverse Christmas tree variable declaration order.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
---
v2:
  - Add Acked-by.
---
 drivers/auxdisplay/ht16k33.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 2b630e194570f6e5..99daf1974980b435 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -168,9 +168,9 @@ static void ht16k33_fb_update(struct work_struct *work)
 
 static int ht16k33_initialize(struct ht16k33_priv *priv)
 {
+	uint8_t data[HT16K33_FB_SIZE];
 	uint8_t byte;
 	int err;
-	uint8_t data[HT16K33_MATRIX_LED_MAX_COLS * 2];
 
 	/* Clear RAM (8 * 16 bits) */
 	memset(data, 0, sizeof(data));
-- 
2.25.1

[PATCH v2 11/18] auxdisplay: ht16k33: Remove unneeded error check in keypad probe()

[Geert Uytterhoeven]

There is no need to check the return code of input_register_device(),
just propagate it to the caller.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
---
v2:
  - Add Acked-by.
---
 drivers/auxdisplay/ht16k33.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 99daf1974980b435..8c9acc4800bc94e0 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -378,11 +378,7 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 
 	ht16k33_keypad_stop(keypad->dev);
 
-	err = input_register_device(keypad->dev);
-	if (err)
-		return err;
-
-	return 0;
+	return input_register_device(keypad->dev);
 }
 
 static int ht16k33_probe(struct i2c_client *client,
-- 
2.25.1

[PATCH v2 12/18] auxdisplay: ht16k33: Convert to simple i2c probe function

[Geert Uytterhoeven]

ht16k33_probe() does not use the passed i2c_device_id, so the driver can
be converted trivially to the new-style of i2c probing.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
---
v2:
  - Add Acked-by.
---
 drivers/auxdisplay/ht16k33.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 8c9acc4800bc94e0..8c1689b77db95676 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -381,8 +381,7 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 	return input_register_device(keypad->dev);
 }
 
-static int ht16k33_probe(struct i2c_client *client,
-				  const struct i2c_device_id *id)
+static int ht16k33_probe(struct i2c_client *client)
 {
 	int err;
 	uint32_t dft_brightness;
@@ -523,7 +522,7 @@ static const struct of_device_id ht16k33_of_match[] = {
 MODULE_DEVICE_TABLE(of, ht16k33_of_match);
 
 static struct i2c_driver ht16k33_driver = {
-	.probe		= ht16k33_probe,
+	.probe_new	= ht16k33_probe,
 	.remove		= ht16k33_remove,
 	.driver		= {
 		.name		= DRIVER_NAME,
-- 
2.25.1

[PATCH v2 13/18] auxdisplay: ht16k33: Add helper variable dev

[Geert Uytterhoeven]

This driver has many users of "client->dev".  Add shorthands to simplify
the code.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
---
v2:
  - Add Acked-by,
  - Rebased.
---
 drivers/auxdisplay/ht16k33.c | 43 ++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 8c1689b77db95676..75d326a823543898 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -316,7 +316,8 @@ static void ht16k33_keypad_stop(struct input_dev *dev)
 static int ht16k33_keypad_probe(struct i2c_client *client,
 				struct ht16k33_keypad *keypad)
 {
-	struct device_node *node = client->dev.of_node;
+	struct device *dev = &client->dev;
+	struct device_node *node = dev->of_node;
 	u32 rows = HT16K33_MATRIX_KEYPAD_MAX_ROWS;
 	u32 cols = HT16K33_MATRIX_KEYPAD_MAX_COLS;
 	int err;
@@ -324,7 +325,7 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 	keypad->client = client;
 	init_waitqueue_head(&keypad->wait);
 
-	keypad->dev = devm_input_allocate_device(&client->dev);
+	keypad->dev = devm_input_allocate_device(dev);
 	if (!keypad->dev)
 		return -ENOMEM;
 
@@ -341,17 +342,17 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 	err = of_property_read_u32(node, "debounce-delay-ms",
 				   &keypad->debounce_ms);
 	if (err) {
-		dev_err(&client->dev, "key debounce delay not specified\n");
+		dev_err(dev, "key debounce delay not specified\n");
 		return err;
 	}
 
-	err = matrix_keypad_parse_of_params(&client->dev, &rows, &cols);
+	err = matrix_keypad_parse_of_params(dev, &rows, &cols);
 	if (err)
 		return err;
 	if (rows > HT16K33_MATRIX_KEYPAD_MAX_ROWS ||
 	    cols > HT16K33_MATRIX_KEYPAD_MAX_COLS) {
-		dev_err(&client->dev, "%u rows or %u cols out of range in DT\n",
-			rows, cols);
+		dev_err(dev, "%u rows or %u cols out of range in DT\n", rows,
+			cols);
 		return -ERANGE;
 	}
 
@@ -362,17 +363,17 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 	err = matrix_keypad_build_keymap(NULL, NULL, rows, cols, NULL,
 					 keypad->dev);
 	if (err) {
-		dev_err(&client->dev, "failed to build keymap\n");
+		dev_err(dev, "failed to build keymap\n");
 		return err;
 	}
 
-	err = devm_request_threaded_irq(&client->dev, client->irq,
-					NULL, ht16k33_keypad_irq_thread,
+	err = devm_request_threaded_irq(dev, client->irq, NULL,
+					ht16k33_keypad_irq_thread,
 					IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 					DRIVER_NAME, keypad);
 	if (err) {
-		dev_err(&client->dev, "irq request failed %d, error %d\n",
-			client->irq, err);
+		dev_err(dev, "irq request failed %d, error %d\n", client->irq,
+			err);
 		return err;
 	}
 
@@ -389,14 +390,15 @@ static int ht16k33_probe(struct i2c_client *client)
 	struct backlight_properties bl_props;
 	struct ht16k33_priv *priv;
 	struct ht16k33_fbdev *fbdev;
-	struct device_node *node = client->dev.of_node;
+	struct device *dev = &client->dev;
+	struct device_node *node = dev->of_node;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
-		dev_err(&client->dev, "i2c_check_functionality error\n");
+		dev_err(dev, "i2c_check_functionality error\n");
 		return -EIO;
 	}
 
-	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
@@ -413,11 +415,10 @@ static int ht16k33_probe(struct i2c_client *client)
 	bl_props.type = BACKLIGHT_RAW;
 	bl_props.max_brightness = MAX_BRIGHTNESS;
 
-	bl = devm_backlight_device_register(&client->dev, DRIVER_NAME"-bl",
-					    &client->dev, priv,
+	bl = devm_backlight_device_register(dev, DRIVER_NAME"-bl", dev, priv,
 					    &ht16k33_bl_ops, &bl_props);
 	if (IS_ERR(bl)) {
-		dev_err(&client->dev, "failed to register backlight\n");
+		dev_err(dev, "failed to register backlight\n");
 		return PTR_ERR(bl);
 	}
 
@@ -426,7 +427,7 @@ static int ht16k33_probe(struct i2c_client *client)
 	if (err) {
 		dft_brightness = MAX_BRIGHTNESS;
 	} else if (dft_brightness > MAX_BRIGHTNESS) {
-		dev_warn(&client->dev,
+		dev_warn(dev,
 			 "invalid default brightness level: %u, using %u\n",
 			 dft_brightness, MAX_BRIGHTNESS);
 		dft_brightness = MAX_BRIGHTNESS;
@@ -441,13 +442,13 @@ static int ht16k33_probe(struct i2c_client *client)
 	if (!fbdev->buffer)
 		return -ENOMEM;
 
-	fbdev->cache = devm_kmalloc(&client->dev, HT16K33_FB_SIZE, GFP_KERNEL);
+	fbdev->cache = devm_kmalloc(dev, HT16K33_FB_SIZE, GFP_KERNEL);
 	if (!fbdev->cache) {
 		err = -ENOMEM;
 		goto err_fbdev_buffer;
 	}
 
-	fbdev->info = framebuffer_alloc(0, &client->dev);
+	fbdev->info = framebuffer_alloc(0, dev);
 	if (!fbdev->info) {
 		err = -ENOMEM;
 		goto err_fbdev_buffer;
@@ -456,7 +457,7 @@ static int ht16k33_probe(struct i2c_client *client)
 	err = of_property_read_u32(node, "refresh-rate-hz",
 		&fbdev->refresh_rate);
 	if (err) {
-		dev_err(&client->dev, "refresh rate not specified\n");
+		dev_err(dev, "refresh rate not specified\n");
 		goto err_fbdev_info;
 	}
 	fb_bl_default_curve(fbdev->info, 0, MIN_BRIGHTNESS, MAX_BRIGHTNESS);
-- 
2.25.1

[PATCH v2 14/18] auxdisplay: ht16k33: Move delayed work

[Geert Uytterhoeven]

Move delayed_work from ht16k33_fbdev to ht16k33_priv, as it is not
specific to dot-matrix displays, but common to all display types.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/ht16k33.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 75d326a823543898..c7a3a0e1fbb5d03e 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -65,11 +65,11 @@ struct ht16k33_fbdev {
 	uint32_t refresh_rate;
 	uint8_t *buffer;
 	uint8_t *cache;
-	struct delayed_work work;
 };
 
 struct ht16k33_priv {
 	struct i2c_client *client;
+	struct delayed_work work;
 	struct ht16k33_keypad keypad;
 	struct ht16k33_fbdev fbdev;
 };
@@ -117,7 +117,7 @@ static void ht16k33_fb_queue(struct ht16k33_priv *priv)
 {
 	struct ht16k33_fbdev *fbdev = &priv->fbdev;
 
-	schedule_delayed_work(&fbdev->work, HZ / fbdev->refresh_rate);
+	schedule_delayed_work(&priv->work, HZ / fbdev->refresh_rate);
 }
 
 /*
@@ -125,10 +125,9 @@ static void ht16k33_fb_queue(struct ht16k33_priv *priv)
  */
 static void ht16k33_fb_update(struct work_struct *work)
 {
-	struct ht16k33_fbdev *fbdev =
-		container_of(work, struct ht16k33_fbdev, work.work);
-	struct ht16k33_priv *priv =
-		container_of(fbdev, struct ht16k33_priv, fbdev);
+	struct ht16k33_priv *priv = container_of(work, struct ht16k33_priv,
+						 work.work);
+	struct ht16k33_fbdev *fbdev = &priv->fbdev;
 
 	uint8_t *p1, *p2;
 	int len, pos = 0, first = -1;
@@ -462,7 +461,7 @@ static int ht16k33_probe(struct i2c_client *client)
 	}
 	fb_bl_default_curve(fbdev->info, 0, MIN_BRIGHTNESS, MAX_BRIGHTNESS);
 
-	INIT_DELAYED_WORK(&fbdev->work, ht16k33_fb_update);
+	INIT_DELAYED_WORK(&priv->work, ht16k33_fb_update);
 	fbdev->info->fbops = &ht16k33_fb_ops;
 	fbdev->info->screen_base = (char __iomem *) fbdev->buffer;
 	fbdev->info->screen_size = HT16K33_FB_SIZE;
@@ -502,7 +501,7 @@ static int ht16k33_remove(struct i2c_client *client)
 	struct ht16k33_priv *priv = i2c_get_clientdata(client);
 	struct ht16k33_fbdev *fbdev = &priv->fbdev;
 
-	cancel_delayed_work_sync(&fbdev->work);
+	cancel_delayed_work_sync(&priv->work);
 	unregister_framebuffer(fbdev->info);
 	framebuffer_release(fbdev->info);
 	free_page((unsigned long) fbdev->buffer);
-- 
2.25.1

[PATCH v2 15/18] auxdisplay: ht16k33: Extract ht16k33_brightness_set()

[Geert Uytterhoeven]

Extract brightness handling into a helper function, so it can be called
from multiple places.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - No changes.
---
 drivers/auxdisplay/ht16k33.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index c7a3a0e1fbb5d03e..ed5aab2627e028ed 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -113,6 +113,22 @@ static int ht16k33_display_off(struct ht16k33_priv *priv)
 	return i2c_smbus_write_byte(priv->client, REG_DISPLAY_SETUP);
 }
 
+static int ht16k33_brightness_set(struct ht16k33_priv *priv,
+				  unsigned int brightness)
+{
+	int error;
+
+	if (brightness == 0)
+		return ht16k33_display_off(priv);
+
+	error = ht16k33_display_on(priv);
+	if (error)
+		return error;
+
+	return i2c_smbus_write_byte(priv->client,
+				    REG_BRIGHTNESS | (brightness - 1));
+}
+
 static void ht16k33_fb_queue(struct ht16k33_priv *priv)
 {
 	struct ht16k33_fbdev *fbdev = &priv->fbdev;
@@ -197,13 +213,10 @@ static int ht16k33_bl_update_status(struct backlight_device *bl)
 
 	if (bl->props.power != FB_BLANK_UNBLANK ||
 	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
-	    bl->props.state & BL_CORE_FBBLANK || brightness == 0) {
-		return ht16k33_display_off(priv);
-	}
+	    bl->props.state & BL_CORE_FBBLANK)
+		brightness = 0;
 
-	ht16k33_display_on(priv);
-	return i2c_smbus_write_byte(priv->client,
-				    REG_BRIGHTNESS | (brightness - 1));
+	return ht16k33_brightness_set(priv, brightness);
 }
 
 static int ht16k33_bl_check_fb(struct backlight_device *bl, struct fb_info *fi)
-- 
2.25.1

[PATCH v2 16/18] auxdisplay: ht16k33: Extract frame buffer probing

[Geert Uytterhoeven]

Extract all frame buffer (including backlight) probing into
ht16k33_fbdev_probe().

Call ht16k33_fbdev_probe() after ht16k33_keypad_probe(), as the latter
does not need any manual cleanup in the probe error path.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2:
  - Rebased.
---
 drivers/auxdisplay/ht16k33.c | 98 +++++++++++++++++++-----------------
 1 file changed, 53 insertions(+), 45 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index ed5aab2627e028ed..af7489acfacbd409 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -394,33 +394,15 @@ static int ht16k33_keypad_probe(struct i2c_client *client,
 	return input_register_device(keypad->dev);
 }
 
-static int ht16k33_probe(struct i2c_client *client)
+static int ht16k33_fbdev_probe(struct i2c_client *client,
+			       struct ht16k33_priv *priv, uint32_t brightness)
 {
-	int err;
-	uint32_t dft_brightness;
-	struct backlight_device *bl;
-	struct backlight_properties bl_props;
-	struct ht16k33_priv *priv;
-	struct ht16k33_fbdev *fbdev;
 	struct device *dev = &client->dev;
+	struct ht16k33_fbdev *fbdev = &priv->fbdev;
 	struct device_node *node = dev->of_node;
-
-	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
-		dev_err(dev, "i2c_check_functionality error\n");
-		return -EIO;
-	}
-
-	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
-
-	priv->client = client;
-	i2c_set_clientdata(client, priv);
-	fbdev = &priv->fbdev;
-
-	err = ht16k33_initialize(priv);
-	if (err)
-		return err;
+	struct backlight_properties bl_props;
+	struct backlight_device *bl;
+	int err;
 
 	/* Backlight */
 	memset(&bl_props, 0, sizeof(struct backlight_properties));
@@ -434,18 +416,7 @@ static int ht16k33_probe(struct i2c_client *client)
 		return PTR_ERR(bl);
 	}
 
-	err = of_property_read_u32(node, "default-brightness-level",
-				   &dft_brightness);
-	if (err) {
-		dft_brightness = MAX_BRIGHTNESS;
-	} else if (dft_brightness > MAX_BRIGHTNESS) {
-		dev_warn(dev,
-			 "invalid default brightness level: %u, using %u\n",
-			 dft_brightness, MAX_BRIGHTNESS);
-		dft_brightness = MAX_BRIGHTNESS;
-	}
-
-	bl->props.brightness = dft_brightness;
+	bl->props.brightness = brightness;
 	ht16k33_bl_update_status(bl);
 
 	/* Framebuffer (2 bytes per column) */
@@ -489,18 +460,9 @@ static int ht16k33_probe(struct i2c_client *client)
 	if (err)
 		goto err_fbdev_info;
 
-	/* Keypad */
-	if (client->irq > 0) {
-		err = ht16k33_keypad_probe(client, &priv->keypad);
-		if (err)
-			goto err_fbdev_unregister;
-	}
-
 	ht16k33_fb_queue(priv);
 	return 0;
 
-err_fbdev_unregister:
-	unregister_framebuffer(fbdev->info);
 err_fbdev_info:
 	framebuffer_release(fbdev->info);
 err_fbdev_buffer:
@@ -509,6 +471,52 @@ static int ht16k33_probe(struct i2c_client *client)
 	return err;
 }
 
+static int ht16k33_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device_node *node = dev->of_node;
+	struct ht16k33_priv *priv;
+	uint32_t dft_brightness;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(dev, "i2c_check_functionality error\n");
+		return -EIO;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	i2c_set_clientdata(client, priv);
+
+	err = ht16k33_initialize(priv);
+	if (err)
+		return err;
+
+	err = of_property_read_u32(node, "default-brightness-level",
+				   &dft_brightness);
+	if (err) {
+		dft_brightness = MAX_BRIGHTNESS;
+	} else if (dft_brightness > MAX_BRIGHTNESS) {
+		dev_warn(dev,
+			 "invalid default brightness level: %u, using %u\n",
+			 dft_brightness, MAX_BRIGHTNESS);
+		dft_brightness = MAX_BRIGHTNESS;
+	}
+
+	/* Keypad */
+	if (client->irq > 0) {
+		err = ht16k33_keypad_probe(client, &priv->keypad);
+		if (err)
+			return err;
+	}
+
+	/* Frame Buffer Display */
+	return ht16k33_fbdev_probe(client, priv, dft_brightness);
+}
+
 static int ht16k33_remove(struct i2c_client *client)
 {
 	struct ht16k33_priv *priv = i2c_get_clientdata(client);
-- 
2.25.1

[PATCH v2 17/18] auxdisplay: ht16k33: Add support for segment displays

[Geert Uytterhoeven]

The Holtek HT16K33 LED controller is not only used for driving
dot-matrix displays, but also for driving segment displays.

Add support for 4-digit 7-segment and quad 14-segment alphanumeric
displays, like the Adafruit 7-segment and 14-segment display backpack
and FeatherWing expansion boards.  Use the character line display core
support to display a message, which will be scrolled if it doesn't fit.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
The 7-segment support is based on schematics, and untested on actual
hardware.

v2:
  - Move "select LINEDISP" to this patch,
  - Set "err = -EINVAL" in switch() case that cannot happen.
---
 drivers/auxdisplay/Kconfig   |   1 +
 drivers/auxdisplay/ht16k33.c | 199 +++++++++++++++++++++++++++++++++--
 2 files changed, 193 insertions(+), 7 deletions(-)

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index b41fdc5f7bf72a1b..42fc7b155de09dbc 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -176,6 +176,7 @@ config HT16K33
 	select FB_SYS_IMAGEBLIT
 	select INPUT_MATRIXKMAP
 	select FB_BACKLIGHT
+	select LINEDISP
 	help
 	  Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
 	  LED controller driver with keyscan.
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index af7489acfacbd409..28207517a4725250 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -5,6 +5,7 @@
  * Author: Robin van der Gracht <robin@protonic.nl>
  *
  * Copyright: (C) 2016 Protonic Holland.
+ * Copyright (C) 2021 Glider bv
  */
 
 #include <linux/kernel.h>
@@ -17,9 +18,18 @@
 #include <linux/backlight.h>
 #include <linux/input.h>
 #include <linux/input/matrix_keypad.h>
+#include <linux/leds.h>
+#include <linux/of_device.h>
 #include <linux/workqueue.h>
 #include <linux/mm.h>
 
+#include <linux/map_to_7segment.h>
+#include <linux/map_to_14segment.h>
+
+#include <asm/unaligned.h>
+
+#include "line-display.h"
+
 /* Registers */
 #define REG_SYSTEM_SETUP		0x20
 #define REG_SYSTEM_SETUP_OSC_ON		BIT(0)
@@ -47,6 +57,12 @@
 #define BYTES_PER_ROW		(HT16K33_MATRIX_LED_MAX_ROWS / 8)
 #define HT16K33_FB_SIZE		(HT16K33_MATRIX_LED_MAX_COLS * BYTES_PER_ROW)
 
+enum display_type {
+	DISP_MATRIX = 0,
+	DISP_QUAD_7SEG,
+	DISP_QUAD_14SEG,
+};
+
 struct ht16k33_keypad {
 	struct i2c_client *client;
 	struct input_dev *dev;
@@ -67,11 +83,25 @@ struct ht16k33_fbdev {
 	uint8_t *cache;
 };
 
+struct ht16k33_seg {
+	struct linedisp linedisp;
+	union {
+		struct seg7_conversion_map seg7;
+		struct seg14_conversion_map seg14;
+	} map;
+	unsigned int map_size;
+	char curr[4];
+};
+
 struct ht16k33_priv {
 	struct i2c_client *client;
 	struct delayed_work work;
 	struct ht16k33_keypad keypad;
-	struct ht16k33_fbdev fbdev;
+	union {
+		struct ht16k33_fbdev fbdev;
+		struct ht16k33_seg seg;
+	};
+	enum display_type type;
 };
 
 static const struct fb_fix_screeninfo ht16k33_fb_fix = {
@@ -101,6 +131,33 @@ static const struct fb_var_screeninfo ht16k33_fb_var = {
 	.vmode = FB_VMODE_NONINTERLACED,
 };
 
+static const SEG7_DEFAULT_MAP(initial_map_seg7);
+static const SEG14_DEFAULT_MAP(initial_map_seg14);
+
+static ssize_t map_seg_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct ht16k33_priv *priv = dev_get_drvdata(dev);
+
+	memcpy(buf, &priv->seg.map, priv->seg.map_size);
+	return priv->seg.map_size;
+}
+
+static ssize_t map_seg_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t cnt)
+{
+	struct ht16k33_priv *priv = dev_get_drvdata(dev);
+
+	if (cnt != priv->seg.map_size)
+		return -EINVAL;
+
+	memcpy(&priv->seg.map, buf, cnt);
+	return cnt;
+}
+
+static DEVICE_ATTR(map_seg7, 0644, map_seg_show, map_seg_store);
+static DEVICE_ATTR(map_seg14, 0644, map_seg_show, map_seg_store);
+
 static int ht16k33_display_on(struct ht16k33_priv *priv)
 {
 	uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON;
@@ -325,6 +382,51 @@ static void ht16k33_keypad_stop(struct input_dev *dev)
 	disable_irq(keypad->client->irq);
 }
 
+static void ht16k33_linedisp_update(struct linedisp *linedisp)
+{
+	struct ht16k33_priv *priv = container_of(linedisp, struct ht16k33_priv,
+						 seg.linedisp);
+
+	schedule_delayed_work(&priv->work, 0);
+}
+
+static void ht16k33_seg7_update(struct work_struct *work)
+{
+	struct ht16k33_priv *priv = container_of(work, struct ht16k33_priv,
+						 work.work);
+	struct ht16k33_seg *seg = &priv->seg;
+	char *s = seg->curr;
+	uint8_t buf[9];
+
+	buf[0] = map_to_seg7(&seg->map.seg7, *s++);
+	buf[1] = 0;
+	buf[2] = map_to_seg7(&seg->map.seg7, *s++);
+	buf[3] = 0;
+	buf[4] = 0;
+	buf[5] = 0;
+	buf[6] = map_to_seg7(&seg->map.seg7, *s++);
+	buf[7] = 0;
+	buf[8] = map_to_seg7(&seg->map.seg7, *s++);
+
+	i2c_smbus_write_i2c_block_data(priv->client, 0, ARRAY_SIZE(buf), buf);
+}
+
+static void ht16k33_seg14_update(struct work_struct *work)
+{
+	struct ht16k33_priv *priv = container_of(work, struct ht16k33_priv,
+						 work.work);
+	struct ht16k33_seg *seg = &priv->seg;
+	char *s = seg->curr;
+	uint8_t buf[8];
+
+	put_unaligned_le16(map_to_seg14(&seg->map.seg14, *s++), buf);
+	put_unaligned_le16(map_to_seg14(&seg->map.seg14, *s++), buf + 2);
+	put_unaligned_le16(map_to_seg14(&seg->map.seg14, *s++), buf + 4);
+	put_unaligned_le16(map_to_seg14(&seg->map.seg14, *s++), buf + 6);
+
+	i2c_smbus_write_i2c_block_data(priv->client, 0, ARRAY_SIZE(buf), buf);
+}
+
 static int ht16k33_keypad_probe(struct i2c_client *client,
 				struct ht16k33_keypad *keypad)
 {
@@ -471,10 +573,58 @@ static int ht16k33_fbdev_probe(struct i2c_client *client,
 	return err;
 }
 
+static int ht16k33_seg_probe(struct i2c_client *client,
+			     struct ht16k33_priv *priv, uint32_t brightness)
+{
+	struct ht16k33_seg *seg = &priv->seg;
+	struct device *dev = &client->dev;
+	int err;
+
+	err = ht16k33_brightness_set(priv, MAX_BRIGHTNESS);
+	if (err)
+		return err;
+
+	switch (priv->type) {
+	case DISP_MATRIX:
+		/* not handled here */
+		err = -EINVAL;
+		break;
+
+	case DISP_QUAD_7SEG:
+		INIT_DELAYED_WORK(&priv->work, ht16k33_seg7_update);
+		seg->map.seg7 = initial_map_seg7;
+		seg->map_size = sizeof(seg->map.seg7);
+		err = device_create_file(dev, &dev_attr_map_seg7);
+		break;
+
+	case DISP_QUAD_14SEG:
+		INIT_DELAYED_WORK(&priv->work, ht16k33_seg14_update);
+		seg->map.seg14 = initial_map_seg14;
+		seg->map_size = sizeof(seg->map.seg14);
+		err = device_create_file(dev, &dev_attr_map_seg14);
+		break;
+	}
+	if (err)
+		return err;
+
+	err = linedisp_register(&seg->linedisp, dev, 4, seg->curr,
+				ht16k33_linedisp_update);
+	if (err)
+		goto err_remove_map_file;
+
+	return 0;
+
+err_remove_map_file:
+	device_remove_file(dev, &dev_attr_map_seg7);
+	device_remove_file(dev, &dev_attr_map_seg14);
+	return err;
+}
+
 static int ht16k33_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct device_node *node = dev->of_node;
+	const struct of_device_id *id;
 	struct ht16k33_priv *priv;
 	uint32_t dft_brightness;
 	int err;
@@ -489,6 +639,9 @@ static int ht16k33_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	priv->client = client;
+	id = i2c_of_match_device(dev->driver->of_match_table, client);
+	if (id)
+		priv->type = (uintptr_t)id->data;
 	i2c_set_clientdata(client, priv);
 
 	err = ht16k33_initialize(priv);
@@ -513,8 +666,19 @@ static int ht16k33_probe(struct i2c_client *client)
 			return err;
 	}
 
-	/* Frame Buffer Display */
-	return ht16k33_fbdev_probe(client, priv, dft_brightness);
+	switch (priv->type) {
+	case DISP_MATRIX:
+		/* Frame Buffer Display */
+		err = ht16k33_fbdev_probe(client, priv, dft_brightness);
+		break;
+
+	case DISP_QUAD_7SEG:
+	case DISP_QUAD_14SEG:
+		/* Segment Display */
+		err = ht16k33_seg_probe(client, priv, dft_brightness);
+		break;
+	}
+	return err;
 }
 
 static int ht16k33_remove(struct i2c_client *client)
@@ -523,9 +687,21 @@ static int ht16k33_remove(struct i2c_client *client)
 	struct ht16k33_fbdev *fbdev = &priv->fbdev;
 
 	cancel_delayed_work_sync(&priv->work);
-	unregister_framebuffer(fbdev->info);
-	framebuffer_release(fbdev->info);
-	free_page((unsigned long) fbdev->buffer);
+
+	switch (priv->type) {
+	case DISP_MATRIX:
+		unregister_framebuffer(fbdev->info);
+		framebuffer_release(fbdev->info);
+		free_page((unsigned long)fbdev->buffer);
+		break;
+
+	case DISP_QUAD_7SEG:
+	case DISP_QUAD_14SEG:
+		linedisp_unregister(&priv->seg.linedisp);
+		device_remove_file(&client->dev, &dev_attr_map_seg7);
+		device_remove_file(&client->dev, &dev_attr_map_seg14);
+		break;
+	}
 
 	return 0;
 }
@@ -537,7 +713,16 @@ static const struct i2c_device_id ht16k33_i2c_match[] = {
 MODULE_DEVICE_TABLE(i2c, ht16k33_i2c_match);
 
 static const struct of_device_id ht16k33_of_match[] = {
-	{ .compatible = "holtek,ht16k33", },
+	{
+		/* 0.56" 4-Digit 7-Segment FeatherWing Display (Red) */
+		.compatible = "adafruit,3108", .data = (void *)DISP_QUAD_7SEG,
+	}, {
+		/* 0.54" Quad Alphanumeric FeatherWing Display (Red) */
+		.compatible = "adafruit,3130", .data = (void *)DISP_QUAD_14SEG,
+	}, {
+		/* Generic, assumed Dot-Matrix Display */
+		.compatible = "holtek,ht16k33", .data = (void *)DISP_MATRIX,
+	},
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ht16k33_of_match);
-- 
2.25.1

[PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Geert Uytterhoeven]

Instantiate a single LED for a segment display.  This allows the user to
control display brightness and blinking through the LED class API and
triggers, and exposes the display color.
The LED will be named "auxdisplay:<color>:backlight".

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
For setting display brightness, this could use the existing backlight
support for frame buffer devices instantiated for dot-matrix displays.
However, using the leds subsystem instead has the advantage that the
driver can make use of the HT16K33's hardware blinking support, and can
expose the display color.  It can still be used with ledtrig-backlight.
Using "led-backlight", the backlight can no longer be controlled from
sysfs, precluding the use of other triggers incl. hardware blinking.

v2:
  - Use "auxdisplay" instead of DRIVER_NAME in LED name.
---
 drivers/auxdisplay/ht16k33.c | 81 ++++++++++++++++++++++++++++++++++--
 1 file changed, 77 insertions(+), 4 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 28207517a4725250..cd88c7bcb1d713bf 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -29,6 +29,7 @@
 #include <asm/unaligned.h>
 
 #include "line-display.h"
+#include "../leds/leds.h"		/* for led_colors[] */
 
 /* Registers */
 #define REG_SYSTEM_SETUP		0x20
@@ -36,6 +37,10 @@
 
 #define REG_DISPLAY_SETUP		0x80
 #define REG_DISPLAY_SETUP_ON		BIT(0)
+#define REG_DISPLAY_SETUP_BLINK_OFF	(0 << 1)
+#define REG_DISPLAY_SETUP_BLINK_2HZ	(1 << 1)
+#define REG_DISPLAY_SETUP_BLINK_1HZ	(2 << 1)
+#define REG_DISPLAY_SETUP_BLINK_0HZ5	(3 << 1)
 
 #define REG_ROWINT_SET			0xA0
 #define REG_ROWINT_SET_INT_EN		BIT(0)
@@ -57,6 +62,8 @@
 #define BYTES_PER_ROW		(HT16K33_MATRIX_LED_MAX_ROWS / 8)
 #define HT16K33_FB_SIZE		(HT16K33_MATRIX_LED_MAX_COLS * BYTES_PER_ROW)
 
+#define COLOR_DEFAULT		LED_COLOR_ID_RED
+
 enum display_type {
 	DISP_MATRIX = 0,
 	DISP_QUAD_7SEG,
@@ -85,6 +92,7 @@ struct ht16k33_fbdev {
 
 struct ht16k33_seg {
 	struct linedisp linedisp;
+	struct led_classdev led;
 	union {
 		struct seg7_conversion_map seg7;
 		struct seg14_conversion_map seg14;
@@ -102,6 +110,7 @@ struct ht16k33_priv {
 		struct ht16k33_seg seg;
 	};
 	enum display_type type;
+	uint8_t blink;
 };
 
 static const struct fb_fix_screeninfo ht16k33_fb_fix = {
@@ -160,7 +169,7 @@ static DEVICE_ATTR(map_seg14, 0644, map_seg_show, map_seg_store);
 
 static int ht16k33_display_on(struct ht16k33_priv *priv)
 {
-	uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON;
+	uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON | priv->blink;
 
 	return i2c_smbus_write_byte(priv->client, data);
 }
@@ -175,8 +184,11 @@ static int ht16k33_brightness_set(struct ht16k33_priv *priv,
 {
 	int error;
 
-	if (brightness == 0)
+	if (brightness == 0) {
+		// Disable blink mode
+		priv->blink = REG_DISPLAY_SETUP_BLINK_OFF;
 		return ht16k33_display_off(priv);
+	}
 
 	error = ht16k33_display_on(priv);
 	if (error)
@@ -186,6 +198,49 @@ static int ht16k33_brightness_set(struct ht16k33_priv *priv,
 				    REG_BRIGHTNESS | (brightness - 1));
 }
 
+static int ht16k33_brightness_set_blocking(struct led_classdev *led_cdev,
+					   enum led_brightness brightness)
+{
+	struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
+						 seg.led);
+
+	return ht16k33_brightness_set(priv, brightness);
+}
+
+static int ht16k33_blink_set(struct led_classdev *led_cdev,
+			     unsigned long *delay_on, unsigned long *delay_off)
+{
+	struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
+						 seg.led);
+	unsigned int delay;
+	uint8_t blink;
+	int error;
+
+	if (!*delay_on && !*delay_off) {
+		blink = REG_DISPLAY_SETUP_BLINK_1HZ;
+		delay = 1000;
+	} else if (*delay_on <= 750) {
+		blink = REG_DISPLAY_SETUP_BLINK_2HZ;
+		delay = 500;
+	} else if (*delay_on <= 1500) {
+		blink = REG_DISPLAY_SETUP_BLINK_1HZ;
+		delay = 1000;
+	} else {
+		blink = REG_DISPLAY_SETUP_BLINK_0HZ5;
+		delay = 2000;
+	}
+
+	error = i2c_smbus_write_byte(priv->client,
+				     REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON |
+				     blink);
+	if (error)
+		return error;
+
+	priv->blink = blink;
+	*delay_on = *delay_off = delay;
+	return 0;
+}
+
 static void ht16k33_fb_queue(struct ht16k33_priv *priv)
 {
 	struct ht16k33_fbdev *fbdev = &priv->fbdev;
@@ -576,11 +631,29 @@ static int ht16k33_fbdev_probe(struct i2c_client *client,
 static int ht16k33_seg_probe(struct i2c_client *client,
 			     struct ht16k33_priv *priv, uint32_t brightness)
 {
-	struct ht16k33_seg *seg = &priv->seg;
 	struct device *dev = &client->dev;
+	struct device_node *node = dev->of_node;
+	struct ht16k33_seg *seg = &priv->seg;
+	u32 color = COLOR_DEFAULT;
 	int err;
 
-	err = ht16k33_brightness_set(priv, MAX_BRIGHTNESS);
+	of_property_read_u32(node, "color", &color);
+	seg->led.name = devm_kasprintf(dev, GFP_KERNEL,
+			"auxdisplay:%s:" LED_FUNCTION_BACKLIGHT,
+			color < LED_COLOR_ID_MAX ? led_colors[color] : "");
+	seg->led.brightness_set_blocking = ht16k33_brightness_set_blocking;
+	seg->led.blink_set = ht16k33_blink_set;
+	seg->led.flags = LED_CORE_SUSPENDRESUME;
+	seg->led.brightness = brightness;
+	seg->led.max_brightness = MAX_BRIGHTNESS;
+
+	err = devm_led_classdev_register(dev, &seg->led);
+	if (err) {
+		dev_err(dev, "Failed to register LED\n");
+		return err;
+	}
+
+	err = ht16k33_brightness_set(priv, seg->led.brightness);
 	if (err)
 		return err;
 
-- 
2.25.1

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Marek Behun]

On Fri, 25 Jun 2021 14:59:02 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Instantiate a single LED for a segment display.  This allows the user to
> control display brightness and blinking through the LED class API and
> triggers, and exposes the display color.
> The LED will be named "auxdisplay:<color>:backlight".

What if there are multiple "auxdisplay"s ?
Doesn't this subsystem have IDs? So that you can use auxdisplayN for
device name, for example?


> +	of_property_read_u32(node, "color", &color);
> +	seg->led.name = devm_kasprintf(dev, GFP_KERNEL,
> +			"auxdisplay:%s:" LED_FUNCTION_BACKLIGHT,
> +			color < LED_COLOR_ID_MAX ? led_colors[color] : "");

If you use devm_led_classdev_register_ext and pass struct
led_init_data, LED core will generate name of the LED itself.

Marek

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Marek Behun]

On Fri, 25 Jun 2021 22:39:16 +0200
Marek Behun <marek.behun@nic.cz> wrote:

> On Fri, 25 Jun 2021 14:59:02 +0200
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> 
> > Instantiate a single LED for a segment display.  This allows the user to
> > control display brightness and blinking through the LED class API and
> > triggers, and exposes the display color.
> > The LED will be named "auxdisplay:<color>:backlight".  
> 
> What if there are multiple "auxdisplay"s ?
> Doesn't this subsystem have IDs? So that you can use auxdisplayN for
> device name, for example?

Or if this driver creates a fbdev, maybe "fb<N>" for devicename?

Marek

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Geert Uytterhoeven]

Hi Marek,

On Fri, Jun 25, 2021 at 10:40 PM Marek Behun <marek.behun@nic.cz> wrote:
> On Fri, 25 Jun 2021 22:39:16 +0200
> Marek Behun <marek.behun@nic.cz> wrote:
> > On Fri, 25 Jun 2021 14:59:02 +0200
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > Instantiate a single LED for a segment display.  This allows the user to
> > > control display brightness and blinking through the LED class API and
> > > triggers, and exposes the display color.
> > > The LED will be named "auxdisplay:<color>:backlight".
> >
> > What if there are multiple "auxdisplay"s ?
> > Doesn't this subsystem have IDs? So that you can use auxdisplayN for
> > device name, for example?
>
> Or if this driver creates a fbdev, maybe "fb<N>" for devicename?

This LED device is only registered when using the HT16K33 to drive
segment displays.
When driving a dot matrix display, the driver still use fbdev and
devm_backlight_device_register(), for backwards compatibility.

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

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Geert Uytterhoeven]

Hi Marek,

On Fri, Jun 25, 2021 at 10:39 PM Marek Behun <marek.behun@nic.cz> wrote:
> On Fri, 25 Jun 2021 14:59:02 +0200
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> > Instantiate a single LED for a segment display.  This allows the user to
> > control display brightness and blinking through the LED class API and
> > triggers, and exposes the display color.
> > The LED will be named "auxdisplay:<color>:backlight".
>
> What if there are multiple "auxdisplay"s ?

I understand the LED core will just add a suffix on a name collision.

> Doesn't this subsystem have IDs? So that you can use auxdisplayN for
> device name, for example?

Auxdisplay does not have IDs, as there is no subsystem to register
with.  It's just a collection of drivers for auxiliary displays with
no common API.  Some drivers use fbdev, others use a chardev, or an
attribute file in sysfs.

BTW, I just followed Pavel's advice in naming.

> > +     of_property_read_u32(node, "color", &color);
> > +     seg->led.name = devm_kasprintf(dev, GFP_KERNEL,
> > +                     "auxdisplay:%s:" LED_FUNCTION_BACKLIGHT,
> > +                     color < LED_COLOR_ID_MAX ? led_colors[color] : "");
>
> If you use devm_led_classdev_register_ext and pass struct
> led_init_data, LED core will generate name of the LED itself.

Will that make any difference, except for adding more code?
Looking at the implementation, I still have to use devm_kasprintf()
to combine color and function for led_init_data.default_label?

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

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Marek Behun]

On Mon, 28 Jun 2021 11:21:04 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Hi Marek,
> 
> On Fri, Jun 25, 2021 at 10:39 PM Marek Behun <marek.behun@nic.cz> wrote:
> > On Fri, 25 Jun 2021 14:59:02 +0200
> > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >  
> > > Instantiate a single LED for a segment display.  This allows the user to
> > > control display brightness and blinking through the LED class API and
> > > triggers, and exposes the display color.
> > > The LED will be named "auxdisplay:<color>:backlight".  
> >
> > What if there are multiple "auxdisplay"s ?  
> 
> I understand the LED core will just add a suffix on a name collision.
> 
> > Doesn't this subsystem have IDs? So that you can use auxdisplayN for
> > device name, for example?  
> 
> Auxdisplay does not have IDs, as there is no subsystem to register
> with.  It's just a collection of drivers for auxiliary displays with
> no common API.  Some drivers use fbdev, others use a chardev, or an
> attribute file in sysfs.
> 
> BTW, I just followed Pavel's advice in naming.

Very well.

> > > +     of_property_read_u32(node, "color", &color);
> > > +     seg->led.name = devm_kasprintf(dev, GFP_KERNEL,
> > > +                     "auxdisplay:%s:" LED_FUNCTION_BACKLIGHT,
> > > +                     color < LED_COLOR_ID_MAX ? led_colors[color] : "");  
> >
> > If you use devm_led_classdev_register_ext and pass struct
> > led_init_data, LED core will generate name of the LED itself.  
> 
> Will that make any difference, except for adding more code?

You are hardcoding the backlight function. Using the _ext() registering
function will make it so that the function and color are parsed from
fwnode by LED core. I understand that the function will always be
"backlight" in this case, but this should be specified in the
device-tree anyway, so why not use it?

> Looking at the implementation, I still have to use devm_kasprintf()
> to combine color and function for led_init_data.default_label?

AFAIK you don't have to fill in default_label. (If the needed OF
properties are not present so that default_label is tried, it means the
device-tree does not correctly specify the device. In that case I don't
think it is a problem if the default_label is not present and LED
core will use the OF node name as the LED name.)

The code could look like this

  struct led_init_data init_data = {};

  init_data.fwnode = of_fwnode_handle(node);
  init_data.devicename = "auxdisplay";
  init_data.devname_mandatory = true;

  ...register_ext();

But if you still don't want to do this then ignore me :)

Marek

Re: [PATCH v2 18/18] auxdisplay: ht16k33: Add segment display LED support

[Geert Uytterhoeven]

Hi Marek,

On Mon, Jun 28, 2021 at 12:15 PM Marek Behun <marek.behun@nic.cz> wrote:
> On Mon, 28 Jun 2021 11:21:04 +0200
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Fri, Jun 25, 2021 at 10:39 PM Marek Behun <marek.behun@nic.cz> wrote:
> > > On Fri, 25 Jun 2021 14:59:02 +0200
> > > Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > >
> > > > Instantiate a single LED for a segment display.  This allows the user to
> > > > control display brightness and blinking through the LED class API and
> > > > triggers, and exposes the display color.
> > > > The LED will be named "auxdisplay:<color>:backlight".
> > >
> > > What if there are multiple "auxdisplay"s ?
> >
> > I understand the LED core will just add a suffix on a name collision.
> >
> > > Doesn't this subsystem have IDs? So that you can use auxdisplayN for
> > > device name, for example?
> >
> > Auxdisplay does not have IDs, as there is no subsystem to register
> > with.  It's just a collection of drivers for auxiliary displays with
> > no common API.  Some drivers use fbdev, others use a chardev, or an
> > attribute file in sysfs.
> >
> > BTW, I just followed Pavel's advice in naming.
>
> Very well.
>
> > > > +     of_property_read_u32(node, "color", &color);
> > > > +     seg->led.name = devm_kasprintf(dev, GFP_KERNEL,
> > > > +                     "auxdisplay:%s:" LED_FUNCTION_BACKLIGHT,
> > > > +                     color < LED_COLOR_ID_MAX ? led_colors[color] : "");
> > >
> > > If you use devm_led_classdev_register_ext and pass struct
> > > led_init_data, LED core will generate name of the LED itself.
> >
> > Will that make any difference, except for adding more code?
>
> You are hardcoding the backlight function. Using the _ext() registering
> function will make it so that the function and color are parsed from
> fwnode by LED core. I understand that the function will always be
> "backlight" in this case, but this should be specified in the
> device-tree anyway, so why not use it?
>
> > Looking at the implementation, I still have to use devm_kasprintf()
> > to combine color and function for led_init_data.default_label?
>
> AFAIK you don't have to fill in default_label. (If the needed OF
> properties are not present so that default_label is tried, it means the
> device-tree does not correctly specify the device. In that case I don't
> think it is a problem if the default_label is not present and LED
> core will use the OF node name as the LED name.)
>
> The code could look like this
>
>   struct led_init_data init_data = {};
>
>   init_data.fwnode = of_fwnode_handle(node);
>   init_data.devicename = "auxdisplay";
>   init_data.devname_mandatory = true;
>
>   ...register_ext();
>
> But if you still don't want to do this then ignore me :)

No, thanks a lot!

Your comments made me realize I should put the LED properties in an
"led" subnode, and defer all parsing to the LED core.
This also allows the user to use the more powerful LED mode even in
dot-matrix mode, while falling back to the existing backlight mode if
no "led" subnode is found, and thus preserving backwards compatibility.

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