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From: Chris Packham <chris.packham@alliedtelesis.co.nz>
To: ojeda@kernel.org,
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	conor+dt@kernel.org,
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Cc: devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-leds@vger.kernel.org,
	Chris Packham <chris.packham@alliedtelesis.co.nz>
Subject: [PATCH 1/3] auxdisplay: Add 7 segment LED display driver
Date: Mon, 26 Feb 2024 10:34:21 +1300
Message-ID: <20240225213423.690561-2-chris.packham@alliedtelesis.co.nz>
In-Reply-To: <20240225213423.690561-1-chris.packham@alliedtelesis.co.nz>
References: <20240225213423.690561-1-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>
---
 drivers/auxdisplay/Kconfig   |   7 ++
 drivers/auxdisplay/Makefile  |   1 +
 drivers/auxdisplay/seg-led.c | 152 +++++++++++++++++++++++++++++++++++
 3 files changed, 160 insertions(+)
 create mode 100644 drivers/auxdisplay/seg-led.c

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index d944d5298eca..e826b5b15881 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -197,6 +197,13 @@ config ARM_CHARLCD
 	  line and the Linux version on the second line, but that's
 	  still useful.
=20
+config SEG_LED
+	bool "Generic 7 segment LED display"
+	select LINEDISP
+	help
+	  This driver supports a generic 7 segment LED display made up
+	  of GPIO pins connected to the individual segments.
+
 menuconfig PARPORT_PANEL
 	tristate "Parallel port LCD/Keypad Panel support"
 	depends on PARPORT
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index 6968ed4d3f0a..808fdf156bd5 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -14,3 +14,4 @@ obj-$(CONFIG_HT16K33)		+=3D ht16k33.o
 obj-$(CONFIG_PARPORT_PANEL)	+=3D panel.o
 obj-$(CONFIG_LCD2S)		+=3D lcd2s.o
 obj-$(CONFIG_LINEDISP)		+=3D line-display.o
+obj-$(CONFIG_SEG_LED)		+=3D seg-led.o
diff --git a/drivers/auxdisplay/seg-led.c b/drivers/auxdisplay/seg-led.c
new file mode 100644
index 000000000000..c0b302a09cbb
--- /dev/null
+++ b/drivers/auxdisplay/seg-led.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for a 7 segment LED display
+ *
+ * The GPIOs are wired to the 7 segments in a clock wise fashion startin=
g from
+ * the top.
+ *
+ *      -a-
+ *     |   |
+ *     f   b
+ *     |   |
+ *      -g-
+ *     |   |
+ *     e   c
+ *     |   |
+ *      -d-
+ *
+ * The decimal point LED presnet on some devices is currently not
+ * supported.
+ *
+ * Copyright (C) Allied Telesis Labs
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/map_to_7segment.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include "line-display.h"
+
+struct seg_led_priv {
+	struct gpio_descs *segment_gpios;
+	struct delayed_work work;
+	struct linedisp linedisp;
+	struct seg7_conversion_map seg7;
+	unsigned int map_size;
+	size_t num_char;
+	char curr[];
+};
+
+static const SEG7_DEFAULT_MAP(initial_map_seg7);
+
+static ssize_t map_seg7_show(struct device *dev, struct device_attribute=
 *attr,
+			     char *buf)
+{
+	struct seg_led_priv *priv =3D dev_get_drvdata(dev);
+
+	memcpy(buf, &priv->seg7, priv->map_size);
+	return priv->map_size;
+}
+
+static ssize_t map_seg7_store(struct device *dev, struct device_attribut=
e *attr,
+			      const char *buf, size_t cnt)
+{
+	struct seg_led_priv *priv =3D dev_get_drvdata(dev);
+
+	if (cnt !=3D priv->map_size)
+		return -EINVAL;
+
+	memcpy(&priv->seg7, buf, cnt);
+	return cnt;
+}
+
+static DEVICE_ATTR_RW(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 void seg_led_update(struct work_struct *work)
+{
+	struct seg_led_priv *priv =3D container_of(work, struct seg_led_priv, w=
ork.work);
+	DECLARE_BITMAP(values, 8);
+
+	values[0] =3D map_to_seg7(&priv->seg7, priv->curr[0]);
+
+	gpiod_set_array_value_cansleep(priv->segment_gpios->ndescs, priv->segme=
nt_gpios->desc,
+				       priv->segment_gpios->info, values);
+}
+
+static const struct of_device_id seg_led_of_match[] =3D {
+	{ .compatible =3D "generic,gpio-7seg"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, seg_led_of_match);
+
+static int seg_led_probe(struct platform_device *pdev)
+{
+	struct seg_led_priv *priv;
+	int err;
+
+	priv =3D devm_kzalloc(&pdev->dev, struct_size(priv, curr, 1), GFP_KERNE=
L);
+	if (!priv)
+		return -ENOMEM;
+	priv->num_char =3D 1;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->segment_gpios =3D devm_gpiod_get_array(&pdev->dev, "segment", GPI=
OD_OUT_LOW);
+	if (IS_ERR(priv->segment_gpios))
+		return PTR_ERR(priv->segment_gpios);
+
+	priv->seg7 =3D initial_map_seg7;
+	priv->map_size =3D sizeof(priv->seg7);
+
+	err =3D device_create_file(&pdev->dev, &dev_attr_map_seg7);
+	if (err)
+		return err;
+
+	INIT_DELAYED_WORK(&priv->work, seg_led_update);
+
+	err =3D linedisp_register(&priv->linedisp, &pdev->dev, 1, priv->curr,
+				seg_led_linedisp_update);
+	if (err) {
+		device_remove_file(&pdev->dev, &dev_attr_map_seg7);
+		return err;
+	}
+
+	return 0;
+}
+
+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);
+	device_remove_file(&pdev->dev, &dev_attr_map_seg7);
+
+	return 0;
+}
+
+static struct platform_driver seg_led_driver =3D {
+	.probe =3D seg_led_probe,
+	.remove =3D seg_led_remove,
+	.driver =3D {
+		.name =3D "seg-led",
+		.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