auxdisplay: linedisp: Add support for overriding character mapping

There is already the driver using character mapping table for
7 or 14 segment display. It is possible to override it. Make
the similar in the line display library to allow other drivers
to utilise the same functionality.
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/auxdisplay/line-display.c

@@ -22,6 +22,9 @@
 #include <linux/sysfs.h>
 #include <linux/timer.h>
 
+#include <linux/map_to_7segment.h>
+#include <linux/map_to_14segment.h>
+
 #include "line-display.h"
 
 #define DEFAULT_SCROLL_RATE	(HZ / 2)
@@ -188,12 +191,71 @@ static ssize_t scroll_step_ms_store(struct device *dev,
 
 static DEVICE_ATTR_RW(scroll_step_ms);
 
+static ssize_t map_seg_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+	struct linedisp_map *map = linedisp->map;
+
+	memcpy(buf, &map->map, map->size);
+	return map->size;
+}
+
+static ssize_t map_seg_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+	struct linedisp_map *map = linedisp->map;
+
+	if (count != map->size)
+		return -EINVAL;
+
+	memcpy(&map->map, buf, count);
+	return count;
+}
+
+static const SEG7_DEFAULT_MAP(initial_map_seg7);
+static DEVICE_ATTR(map_seg7, 0644, map_seg_show, map_seg_store);
+
+static const SEG14_DEFAULT_MAP(initial_map_seg14);
+static DEVICE_ATTR(map_seg14, 0644, map_seg_show, map_seg_store);
+
 static struct attribute *linedisp_attrs[] = {
 	&dev_attr_message.attr,
 	&dev_attr_scroll_step_ms.attr,
-	NULL,
+	&dev_attr_map_seg7.attr,
+	&dev_attr_map_seg14.attr,
+	NULL
+};
+
+static umode_t linedisp_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
+	struct linedisp_map *map = linedisp->map;
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_map_seg7.attr) {
+		if (!map)
+			return 0;
+		if (map->type != LINEDISP_MAP_SEG7)
+			return 0;
+	}
+
+	if (attr == &dev_attr_map_seg14.attr) {
+		if (!map)
+			return 0;
+		if (map->type != LINEDISP_MAP_SEG14)
+			return 0;
+	}
+
+	return mode;
+};
+
+static const struct attribute_group linedisp_group = {
+	.is_visible	= linedisp_attr_is_visible,
+	.attrs		= linedisp_attrs,
 };
-ATTRIBUTE_GROUPS(linedisp);
+__ATTRIBUTE_GROUPS(linedisp);
 
 static DEFINE_IDA(linedisp_id);
 
@@ -201,6 +263,7 @@ static void linedisp_release(struct device *dev)
 {
 	struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
 
+	kfree(linedisp->map);
 	kfree(linedisp->message);
 	ida_free(&linedisp_id, linedisp->id);
 }
@@ -210,6 +273,44 @@ static const struct device_type linedisp_type = {
 	.release = linedisp_release,
 };
 
+static int linedisp_init_map(struct linedisp *linedisp)
+{
+	struct linedisp_map *map;
+	int err;
+
+	if (!linedisp->ops->get_map_type)
+		return 0;
+
+	err = linedisp->ops->get_map_type(linedisp);
+	if (err < 0)
+		return err;
+
+	map = kmalloc(sizeof(*map), GFP_KERNEL);
+	if (!map)
+		return -ENOMEM;
+
+	map->type = err;
+
+	/* assign initial mapping */
+	switch (map->type) {
+	case LINEDISP_MAP_SEG7:
+		map->map.seg7 = initial_map_seg7;
+		map->size = sizeof(map->map.seg7);
+		break;
+	case LINEDISP_MAP_SEG14:
+		map->map.seg14 = initial_map_seg14;
+		map->size = sizeof(map->map.seg14);
+		break;
+	default:
+		kfree(map);
+		return -EINVAL;
+	}
+
+	linedisp->map = map;
+
+	return 0;
+}
+
 /**
  * linedisp_register - register a character line display
  * @linedisp: pointer to character line display structure
@@ -242,6 +343,11 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent,
 	device_initialize(&linedisp->dev);
 	dev_set_name(&linedisp->dev, "linedisp.%u", linedisp->id);
 
+	/* initialise a character mapping, if required */
+	err = linedisp_init_map(linedisp);
+	if (err)
+		goto out_put_device;
+
 	/* initialise a timer for scrolling the message */
 	timer_setup(&linedisp->timer, linedisp_scroll, 0);
 
@@ -260,6 +366,7 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent,
 	device_del(&linedisp->dev);
 out_del_timer:
 	del_timer_sync(&linedisp->timer);
+out_put_device:
 	put_device(&linedisp->dev);
 	return err;
 }

drivers/auxdisplay/line-display.h

@@ -14,13 +14,43 @@
 #include <linux/device.h>
 #include <linux/timer_types.h>
 
+#include <linux/map_to_7segment.h>
+#include <linux/map_to_14segment.h>
+
 struct linedisp;
 
+/**
+ * enum linedisp_map_type - type of the character mapping
+ * @LINEDISP_MAP_SEG7: Map characters to 7 segment display
+ * @LINEDISP_MAP_SEG14: Map characters to 14 segment display
+ */
+enum linedisp_map_type {
+	LINEDISP_MAP_SEG7,
+	LINEDISP_MAP_SEG14,
+};
+
+/**
+ * struct linedisp_map - character mapping
+ * @type: type of the character mapping
+ * @map: conversion character mapping
+ * @size: size of the @map
+ */
+struct linedisp_map {
+	enum linedisp_map_type type;
+	union {
+		struct seg7_conversion_map seg7;
+		struct seg14_conversion_map seg14;
+	} map;
+	unsigned int size;
+};
+
 /**
  * struct linedisp_ops - character line display operations
+ * @get_map_type: Function called to get the character mapping, if required
  * @update: Function called to update the display. This must not sleep!
  */
 struct linedisp_ops {
+	int (*get_map_type)(struct linedisp *linedisp);
 	void (*update)(struct linedisp *linedisp);
 };
 
@@ -41,6 +71,7 @@ struct linedisp {
 	struct device dev;
 	struct timer_list timer;
 	const struct linedisp_ops *ops;
+	struct linedisp_map *map;
 	char *buf;
 	char *message;
 	unsigned int num_chars;