From 7e76aece6f036cb7ada4858d6aa73825bfe22983 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Tue, 19 Oct 2021 16:45:05 +0200 Subject: auxdisplay: Extract character line display core support Extract the character line display core support from the simple ASCII LCD driver for the MIPS Boston, Malta & SEAD3 development boards into its own subdriver, so it can be reused for other displays. As this moves the "message" device attribute in sysfs in a "linedisp.N" subdirectory, a symlink is added to preserve backwards compatibility. Signed-off-by: Geert Uytterhoeven Signed-off-by: Miguel Ojeda --- drivers/auxdisplay/line-display.c | 231 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) create mode 100644 drivers/auxdisplay/line-display.c (limited to 'drivers/auxdisplay/line-display.c') diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c new file mode 100644 index 000000000000..4b97c20ac0b3 --- /dev/null +++ b/drivers/auxdisplay/line-display.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Character line display core support + * + * Copyright (C) 2016 Imagination Technologies + * Author: Paul Burton + * + * Copyright (C) 2021 Glider bv + */ + +#include + +#include +#include +#include +#include +#include +#include + +#include "line-display.h" + +/** + * 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 = from_timer(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->update(linedisp); + + /* move on to the next character */ + linedisp->scroll_pos++; + linedisp->scroll_pos %= linedisp->message_len; + + /* rearm the timer */ + if (linedisp->message_len > num_chars) + 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 */ + del_timer_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->update(linedisp); + return 0; + } + + new_msg = kmalloc(count + 1, GFP_KERNEL); + if (!new_msg) + return -ENOMEM; + + memcpy(new_msg, msg, count); + new_msg[count] = 0; + + kfree(linedisp->message); + + linedisp->message = new_msg; + linedisp->message_len = count; + linedisp->scroll_pos = 0; + + /* update the display */ + linedisp_scroll(&linedisp->timer); + + 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 = container_of(dev, struct 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 = container_of(dev, struct linedisp, dev); + int err; + + err = linedisp_display(linedisp, buf, count); + return err ?: count; +} + +static DEVICE_ATTR_RW(message); + +static struct attribute *linedisp_attrs[] = { + &dev_attr_message.attr, + NULL, +}; +ATTRIBUTE_GROUPS(linedisp); + +static const struct device_type linedisp_type = { + .groups = linedisp_groups, +}; + +/** + * 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 + * @buf: pointer to a buffer that can hold @num_chars characters + * @update: Function called to update the display. This must not sleep! + * + * Return: zero on success, else a negative error code. + */ +int linedisp_register(struct linedisp *linedisp, struct device *parent, + unsigned int num_chars, char *buf, + void (*update)(struct linedisp *linedisp)) +{ + static atomic_t linedisp_id = ATOMIC_INIT(-1); + int err; + + memset(linedisp, 0, sizeof(*linedisp)); + linedisp->dev.parent = parent; + linedisp->dev.type = &linedisp_type; + linedisp->update = update; + linedisp->buf = buf; + linedisp->num_chars = num_chars; + linedisp->scroll_rate = HZ / 2; + + device_initialize(&linedisp->dev); + dev_set_name(&linedisp->dev, "linedisp.%lu", + (unsigned long)atomic_inc_return(&linedisp_id)); + + /* initialise a timer for scrolling the message */ + timer_setup(&linedisp->timer, linedisp_scroll, 0); + + err = device_add(&linedisp->dev); + if (err) + goto out_del_timer; + + /* display a default message */ + err = linedisp_display(linedisp, "Linux " UTS_RELEASE " ", -1); + if (err) + goto out_del_dev; + + return 0; + +out_del_dev: + device_del(&linedisp->dev); +out_del_timer: + del_timer_sync(&linedisp->timer); + put_device(&linedisp->dev); + return err; +} +EXPORT_SYMBOL_GPL(linedisp_register); + +/** + * 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); + del_timer_sync(&linedisp->timer); + kfree(linedisp->message); + put_device(&linedisp->dev); +} +EXPORT_SYMBOL_GPL(linedisp_unregister); + +MODULE_LICENSE("GPL"); -- cgit v1.2.3