1 files changed, 596 insertions, 0 deletions
diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c
new file mode 100644
index 000000000000..4e22373fcc1a
--- /dev/null
+++ b/drivers/auxdisplay/line-display.c
@@ -0,0 +1,596 @@
+// 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
+ * Copyright (C) 2025 Jean-François Lessard
+ */
+
+#ifndef CONFIG_PANEL_BOOT_MESSAGE
+#include <generated/utsrelease.h>
+#endif
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/idr.h>
+#include <linux/jiffies.h>
+#include <linux/kstrtox.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#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)
+
+/**
+ * struct linedisp_attachment - Holds the device to linedisp mapping
+ * @list: List entry for the linedisp_attachments list
+ * @device: Pointer to the device where linedisp attributes are added
+ * @linedisp: Pointer to the linedisp mapped to the device
+ * @direct: true for directly attached device using linedisp_attach(),
+ *	    false for child registered device using linedisp_register()
+ */
+struct linedisp_attachment {
+	struct list_head list;
+	struct device *device;
+	struct linedisp *linedisp;
+	bool direct;
+};
+
+static LIST_HEAD(linedisp_attachments);
+static DEFINE_SPINLOCK(linedisp_attachments_lock);
+
+static int create_attachment(struct device *dev, struct linedisp *linedisp, bool direct)
+{
+	struct linedisp_attachment *attachment;
+
+	attachment = kzalloc(sizeof(*attachment), GFP_KERNEL);
+	if (!attachment)
+		return -ENOMEM;
+
+	attachment->device = dev;
+	attachment->linedisp = linedisp;
+	attachment->direct = direct;
+
+	guard(spinlock)(&linedisp_attachments_lock);
+	list_add(&attachment->list, &linedisp_attachments);
+
+	return 0;
+}
+
+static struct linedisp *delete_attachment(struct device *dev, bool direct)
+{
+	struct linedisp_attachment *attachment;
+	struct linedisp *linedisp;
+
+	guard(spinlock)(&linedisp_attachments_lock);
+
+	list_for_each_entry(attachment, &linedisp_attachments, list) {
+		if (attachment->device == dev &&
+		    attachment->direct == direct)
+			break;
+	}
+
+	if (list_entry_is_head(attachment, &linedisp_attachments, list))
+		return NULL;
+
+	linedisp = attachment->linedisp;
+	list_del(&attachment->list);
+	kfree(attachment);
+
+	return linedisp;
+}
+
+static struct linedisp *to_linedisp(struct device *dev)
+{
+	struct linedisp_attachment *attachment;
+
+	guard(spinlock)(&linedisp_attachments_lock);
+
+	list_for_each_entry(attachment, &linedisp_attachments, list) {
+		if (attachment->device == dev)
+			break;
+	}
+
+	if (list_entry_is_head(attachment, &linedisp_attachments, list))
+		return NULL;
+
+	return attachment->linedisp;
+}
+
+static inline bool should_scroll(struct linedisp *linedisp)
+{
+	return linedisp->message_len > linedisp->num_chars && linedisp->scroll_rate;
+}
+
+/**
+ * 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 = timer_container_of(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->ops->update(linedisp);
+
+	/* move on to the next character */
+	linedisp->scroll_pos++;
+	linedisp->scroll_pos %= linedisp->message_len;
+
+	/* rearm the timer */
+	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 */
+	timer_delete_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->ops->update(linedisp);
+		return 0;
+	}
+
+	new_msg = kmemdup_nul(msg, count, GFP_KERNEL);
+	if (!new_msg)
+		return -ENOMEM;
+
+	kfree(linedisp->message);
+
+	linedisp->message = new_msg;
+	linedisp->message_len = count;
+	linedisp->scroll_pos = 0;
+
+	if (should_scroll(linedisp)) {
+		/* display scrolling message */
+		linedisp_scroll(&linedisp->timer);
+	} else {
+		/* display static message */
+		memset(linedisp->buf, ' ', linedisp->num_chars);
+		memcpy(linedisp->buf, linedisp->message,
+		       umin(linedisp->num_chars, linedisp->message_len));
+		linedisp->ops->update(linedisp);
+	}
+
+	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 = to_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 = to_linedisp(dev);
+	int err;
+
+	err = linedisp_display(linedisp, buf, count);
+	return err ?: count;
+}
+
+static DEVICE_ATTR_RW(message);
+
+static ssize_t num_chars_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct linedisp *linedisp = to_linedisp(dev);
+
+	return sysfs_emit(buf, "%u\n", linedisp->num_chars);
+}
+
+static DEVICE_ATTR_RO(num_chars);
+
+static ssize_t scroll_step_ms_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct linedisp *linedisp = to_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 = to_linedisp(dev);
+	unsigned int ms;
+	int err;
+
+	err = kstrtouint(buf, 10, &ms);
+	if (err)
+		return err;
+
+	timer_delete_sync(&linedisp->timer);
+
+	linedisp->scroll_rate = msecs_to_jiffies(ms);
+
+	if (should_scroll(linedisp))
+		linedisp_scroll(&linedisp->timer);
+
+	return count;
+}
+
+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 = to_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 = to_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_num_chars.attr,
+	&dev_attr_scroll_step_ms.attr,
+	&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 = to_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);
+
+static DEFINE_IDA(linedisp_id);
+
+static void linedisp_release(struct device *dev)
+{
+	struct linedisp *linedisp = to_linedisp(dev);
+
+	kfree(linedisp->map);
+	kfree(linedisp->message);
+	kfree(linedisp->buf);
+	ida_free(&linedisp_id, linedisp->id);
+}
+
+static const struct device_type linedisp_type = {
+	.groups	= linedisp_groups,
+	.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;
+}
+
+#ifdef CONFIG_PANEL_BOOT_MESSAGE
+#define LINEDISP_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
+#else
+#define LINEDISP_INIT_TEXT "Linux " UTS_RELEASE "       "
+#endif
+
+/**
+ * linedisp_attach - attach a character line display
+ * @linedisp: pointer to character line display structure
+ * @dev: pointer of the device to attach to
+ * @num_chars: the number of characters that can be displayed
+ * @ops: character line display operations
+ *
+ * Directly attach the line-display sysfs attributes to the passed device.
+ * The caller is responsible for calling linedisp_detach() to release resources
+ * after use.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int linedisp_attach(struct linedisp *linedisp, struct device *dev,
+		    unsigned int num_chars, const struct linedisp_ops *ops)
+{
+	int err;
+
+	memset(linedisp, 0, sizeof(*linedisp));
+	linedisp->ops = ops;
+	linedisp->num_chars = num_chars;
+	linedisp->scroll_rate = DEFAULT_SCROLL_RATE;
+
+	linedisp->buf = kzalloc(linedisp->num_chars, GFP_KERNEL);
+	if (!linedisp->buf)
+		return -ENOMEM;
+
+	/* initialise a character mapping, if required */
+	err = linedisp_init_map(linedisp);
+	if (err)
+		goto out_free_buf;
+
+	/* initialise a timer for scrolling the message */
+	timer_setup(&linedisp->timer, linedisp_scroll, 0);
+
+	err = create_attachment(dev, linedisp, true);
+	if (err)
+		goto out_del_timer;
+
+	/* display a default message */
+	err = linedisp_display(linedisp, LINEDISP_INIT_TEXT, -1);
+	if (err)
+		goto out_del_attach;
+
+	/* add attribute groups to target device */
+	err = device_add_groups(dev, linedisp_groups);
+	if (err)
+		goto out_del_attach;
+
+	return 0;
+
+out_del_attach:
+	delete_attachment(dev, true);
+out_del_timer:
+	timer_delete_sync(&linedisp->timer);
+out_free_buf:
+	kfree(linedisp->buf);
+	return err;
+}
+EXPORT_SYMBOL_NS_GPL(linedisp_attach, "LINEDISP");
+
+/**
+ * linedisp_detach - detach a character line display
+ * @dev: pointer of the device to detach from, that was previously
+ *	 attached with linedisp_attach()
+ */
+void linedisp_detach(struct device *dev)
+{
+	struct linedisp *linedisp;
+
+	linedisp = delete_attachment(dev, true);
+	if (!linedisp)
+		return;
+
+	timer_delete_sync(&linedisp->timer);
+
+	device_remove_groups(dev, linedisp_groups);
+
+	kfree(linedisp->map);
+	kfree(linedisp->message);
+	kfree(linedisp->buf);
+}
+EXPORT_SYMBOL_NS_GPL(linedisp_detach, "LINEDISP");
+
+/**
+ * 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
+ * @ops: character line display operations
+ *
+ * Register the line-display sysfs attributes to a new device named
+ * "linedisp.N" added to the passed parent device.
+ * The caller is responsible for calling linedisp_unregister() to release
+ * resources after use.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int linedisp_register(struct linedisp *linedisp, struct device *parent,
+		      unsigned int num_chars, const struct linedisp_ops *ops)
+{
+	int err;
+
+	memset(linedisp, 0, sizeof(*linedisp));
+	linedisp->dev.parent = parent;
+	linedisp->dev.type = &linedisp_type;
+	linedisp->ops = ops;
+	linedisp->num_chars = num_chars;
+	linedisp->scroll_rate = DEFAULT_SCROLL_RATE;
+
+	err = ida_alloc(&linedisp_id, GFP_KERNEL);
+	if (err < 0)
+		return err;
+	linedisp->id = err;
+
+	device_initialize(&linedisp->dev);
+	dev_set_name(&linedisp->dev, "linedisp.%u", linedisp->id);
+
+	err = -ENOMEM;
+	linedisp->buf = kzalloc(linedisp->num_chars, GFP_KERNEL);
+	if (!linedisp->buf)
+		goto out_put_device;
+
+	/* 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);
+
+	err = create_attachment(&linedisp->dev, linedisp, false);
+	if (err)
+		goto out_del_timer;
+
+	/* display a default message */
+	err = linedisp_display(linedisp, LINEDISP_INIT_TEXT, -1);
+	if (err)
+		goto out_del_attach;
+
+	err = device_add(&linedisp->dev);
+	if (err)
+		goto out_del_attach;
+
+	return 0;
+
+out_del_attach:
+	delete_attachment(&linedisp->dev, false);
+out_del_timer:
+	timer_delete_sync(&linedisp->timer);
+out_put_device:
+	put_device(&linedisp->dev);
+	return err;
+}
+EXPORT_SYMBOL_NS_GPL(linedisp_register, "LINEDISP");
+
+/**
+ * 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);
+	delete_attachment(&linedisp->dev, false);
+	timer_delete_sync(&linedisp->timer);
+	put_device(&linedisp->dev);
+}
+EXPORT_SYMBOL_NS_GPL(linedisp_unregister, "LINEDISP");
+
+MODULE_DESCRIPTION("Character line display core support");
+MODULE_LICENSE("GPL");