auxdisplay: Add 7-segment LED display driver

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>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index d4be0a3..151d95f 100644 (file)
--- 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.
 
+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 a725010..4a8ea41 100644 (file)
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_PARPORT_PANEL)   += panel.o
 obj-$(CONFIG_LCD2S)            += lcd2s.o
 obj-$(CONFIG_LINEDISP)         += line-display.o
 obj-$(CONFIG_MAX6959)          += max6959.o
+obj-$(CONFIG_SEG_LED_GPIO)     += seg-led-gpio.o

diff --git a/drivers/auxdisplay/seg-led-gpio.c b/drivers/auxdisplay/seg-led-gpio.c
new file mode 100644 (file)
index 0000000..5dc2a00
--- /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 = container_of(work, struct seg_led_priv, work.work);
+       struct linedisp *linedisp = &priv->linedisp;
+       struct linedisp_map *map = linedisp->map;
+       DECLARE_BITMAP(values, 8) = { };
+
+       bitmap_set_value8(values, map_to_seg7(&map->map.seg7, linedisp->buf[0]), 0);
+
+       gpiod_set_array_value_cansleep(priv->segment_gpios->ndescs, priv->segment_gpios->desc,
+                                      priv->segment_gpios->info, values);
+}
+
+static int seg_led_linedisp_get_map_type(struct linedisp *linedisp)
+{
+       struct seg_led_priv *priv = container_of(linedisp, struct seg_led_priv, 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 = container_of(linedisp, struct seg_led_priv, linedisp);
+
+       schedule_delayed_work(&priv->work, 0);
+}
+
+static const struct linedisp_ops seg_led_linedisp_ops = {
+       .get_map_type = seg_led_linedisp_get_map_type,
+       .update = seg_led_linedisp_update,
+};
+
+static int seg_led_probe(struct platform_device *pdev)
+{
+       struct seg_led_priv *priv;
+       struct device *dev = &pdev->dev;
+
+       priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       platform_set_drvdata(pdev, priv);
+
+       priv->segment_gpios = 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 = 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[] = {
+       { .compatible = "gpio-7-segment"},
+       {}
+};
+MODULE_DEVICE_TABLE(of, seg_led_of_match);
+
+static struct platform_driver seg_led_driver = {
+       .probe = seg_led_probe,
+       .remove = seg_led_remove,
+       .driver = {
+               .name = "seg-led-gpio",
+               .of_match_table = 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");