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From: Chris Packham <chris.packham@alliedtelesis.co.nz>
To: andy@kernel.org,
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Cc: linux-leds@vger.kernel.org,
	devicetree@vger.kernel.org,
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	Chris Packham <chris.packham@alliedtelesis.co.nz>
Subject: [PATCH v6 1/3] auxdisplay: Add 7-segment LED display driver
Date: Fri,  8 Mar 2024 08:50:51 +1300
Message-ID: <20240307195053.1320538-2-chris.packham@alliedtelesis.co.nz>
In-Reply-To: <20240307195053.1320538-1-chris.packham@alliedtelesis.co.nz>
References: <20240307195053.1320538-1-chris.packham@alliedtelesis.co.nz>
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Add a driver for a 7-segment LED display. At the moment only one
character is supported but it should be possible to expand this to
support more characters and/or 14-segment displays in the future.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v6:
    - Enforce maximum number of GPIOs
    - Drop unnecessary 0 in initialiser
    Changes in v5:
    - Add depends on GPIOLIB || COMPILE_TEST
    - Validate that we get enough GPIOs
    Changes in v4:
    - Fix one more usage of 7 segment
    - Move ASCII art diagram to DT binding
    - Include map_to_7segment.h for map_to_seg7()
    - Use initialiser for values in seg_led_update
    Changes in v3:
    - "7 segment" -> "7-Segment" in Kconfig help text
    - Update after feedback from Andy
    - Use compatible =3D "gpio-7-segment" as suggested by Rob
    Changes in v2:
    - Rebased on top of auxdisplay/for-next dropping unnecessary code for=
 7
      segment maps.
    - Update for new linedisp_register() API
    - Include headers based on actual usage
    - Allow building as module
    - Use compatible =3D "generic-gpio-7seg" to keep checkpatch.pl happy

 drivers/auxdisplay/Kconfig        |  11 +++
 drivers/auxdisplay/Makefile       |   1 +
 drivers/auxdisplay/seg-led-gpio.c | 112 ++++++++++++++++++++++++++++++
 3 files changed, 124 insertions(+)
 create mode 100644 drivers/auxdisplay/seg-led-gpio.c

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index d4be0a3695ce..151d95f96b11 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -211,6 +211,17 @@ config ARM_CHARLCD
 	  line and the Linux version on the second line, but that's
 	  still useful.
=20
+config SEG_LED_GPIO
+	tristate "Generic 7-segment LED display"
+	depends on GPIOLIB || COMPILE_TEST
+	select LINEDISP
+	help
+	  This driver supports a generic 7-segment LED display made up
+	  of GPIO pins connected to the individual segments.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called seg-led-gpio.
+
 menuconfig PARPORT_PANEL
 	tristate "Parallel port LCD/Keypad Panel support"
 	depends on PARPORT
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index a725010ca651..4a8ea41b0550 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_PARPORT_PANEL)	+=3D panel.o
 obj-$(CONFIG_LCD2S)		+=3D lcd2s.o
 obj-$(CONFIG_LINEDISP)		+=3D line-display.o
 obj-$(CONFIG_MAX6959)		+=3D max6959.o
+obj-$(CONFIG_SEG_LED_GPIO)	+=3D seg-led-gpio.o
diff --git a/drivers/auxdisplay/seg-led-gpio.c b/drivers/auxdisplay/seg-l=
ed-gpio.c
new file mode 100644
index 000000000000..5dc2a006cac5
--- /dev/null
+++ b/drivers/auxdisplay/seg-led-gpio.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for a 7-segment LED display
+ *
+ * The decimal point LED present on some devices is currently not
+ * supported.
+ *
+ * Copyright (C) Allied Telesis Labs
+ */
+
+#include <linux/bitmap.h>
+#include <linux/container_of.h>
+#include <linux/errno.h>
+#include <linux/gpio/consumer.h>
+#include <linux/map_to_7segment.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include "line-display.h"
+
+struct seg_led_priv {
+	struct linedisp linedisp;
+	struct delayed_work work;
+	struct gpio_descs *segment_gpios;
+};
+
+static void seg_led_update(struct work_struct *work)
+{
+	struct seg_led_priv *priv =3D container_of(work, struct seg_led_priv, w=
ork.work);
+	struct linedisp *linedisp =3D &priv->linedisp;
+	struct linedisp_map *map =3D linedisp->map;
+	DECLARE_BITMAP(values, 8) =3D { };
+
+	bitmap_set_value8(values, map_to_seg7(&map->map.seg7, linedisp->buf[0])=
, 0);
+
+	gpiod_set_array_value_cansleep(priv->segment_gpios->ndescs, priv->segme=
nt_gpios->desc,
+				       priv->segment_gpios->info, values);
+}
+
+static int seg_led_linedisp_get_map_type(struct linedisp *linedisp)
+{
+	struct seg_led_priv *priv =3D container_of(linedisp, struct seg_led_pri=
v, linedisp);
+
+	INIT_DELAYED_WORK(&priv->work, seg_led_update);
+	return LINEDISP_MAP_SEG7;
+}
+
+static void seg_led_linedisp_update(struct linedisp *linedisp)
+{
+	struct seg_led_priv *priv =3D container_of(linedisp, struct seg_led_pri=
v, linedisp);
+
+	schedule_delayed_work(&priv->work, 0);
+}
+
+static const struct linedisp_ops seg_led_linedisp_ops =3D {
+	.get_map_type =3D seg_led_linedisp_get_map_type,
+	.update =3D seg_led_linedisp_update,
+};
+
+static int seg_led_probe(struct platform_device *pdev)
+{
+	struct seg_led_priv *priv;
+	struct device *dev =3D &pdev->dev;
+
+	priv =3D devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->segment_gpios =3D devm_gpiod_get_array(dev, "segment", GPIOD_OUT_=
LOW);
+	if (IS_ERR(priv->segment_gpios))
+		return PTR_ERR(priv->segment_gpios);
+
+	if (priv->segment_gpios->ndescs < 7 || priv->segment_gpios->ndescs > 8)
+		return -EINVAL;
+
+	return linedisp_register(&priv->linedisp, dev, 1, &seg_led_linedisp_ops=
);
+}
+
+static int seg_led_remove(struct platform_device *pdev)
+{
+	struct seg_led_priv *priv =3D platform_get_drvdata(pdev);
+
+	cancel_delayed_work_sync(&priv->work);
+	linedisp_unregister(&priv->linedisp);
+
+	return 0;
+}
+
+static const struct of_device_id seg_led_of_match[] =3D {
+	{ .compatible =3D "gpio-7-segment"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, seg_led_of_match);
+
+static struct platform_driver seg_led_driver =3D {
+	.probe =3D seg_led_probe,
+	.remove =3D seg_led_remove,
+	.driver =3D {
+		.name =3D "seg-led-gpio",
+		.of_match_table =3D seg_led_of_match,
+	},
+};
+module_platform_driver(seg_led_driver);
+
+MODULE_AUTHOR("Chris Packham <chris.packham@alliedtelesis.co.nz>");
+MODULE_DESCRIPTION("7 segment LED driver");
+MODULE_LICENSE("GPL");
--=20
2.43.2