[PATCH v3 06/19] auxdisplay: Extract character line display core support
From: Geert Uytterhoeven
Date: Wed Jul 14 2021 - 11:12:02 EST
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 <geert@xxxxxxxxxxxxxx>
---
Changes to img-ascii-lcd.c are untested due to lack of hardware.
The backwards compatibility symlink has been tested by adding similar
code to drivers/auxdisplay/ht16k33.c.
v3:
- Use compat_only_sysfs_link_entry_to_kobj() instead of cooking our
own helper on top of kernfs_create_link(),
v2:
- Drop "select LINEDISP" from HT16K33 symbol,
- Add backwards compatibility symlink.
---
drivers/auxdisplay/Kconfig | 7 +
drivers/auxdisplay/Makefile | 1 +
drivers/auxdisplay/img-ascii-lcd.c | 204 ++++---------------------
drivers/auxdisplay/line-display.c | 231 +++++++++++++++++++++++++++++
drivers/auxdisplay/line-display.h | 43 ++++++
5 files changed, 312 insertions(+), 174 deletions(-)
create mode 100644 drivers/auxdisplay/line-display.c
create mode 100644 drivers/auxdisplay/line-display.h
diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index 1509cb74705a30ad..b41fdc5f7bf72a1b 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -25,6 +25,12 @@ config CHARLCD
This is some character LCD core interface that multiple drivers can
use.
+config LINEDISP
+ tristate "Character line display core support" if COMPILE_TEST
+ help
+ This is the core support for single-line character displays, to be
+ selected by drivers that use it.
+
config HD44780_COMMON
tristate "Common functions for HD44780 (and compatibles) LCD displays" if COMPILE_TEST
select CHARLCD
@@ -155,6 +161,7 @@ config IMG_ASCII_LCD
depends on HAS_IOMEM
default y if MIPS_MALTA
select MFD_SYSCON
+ select LINEDISP
help
Enable this to support the simple ASCII LCD displays found on
development boards such as the MIPS Boston, MIPS Malta & MIPS SEAD3
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index 307771027c893a5b..6968ed4d3f0a8930 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_HD44780) += hd44780.o
obj-$(CONFIG_HT16K33) += ht16k33.o
obj-$(CONFIG_PARPORT_PANEL) += panel.o
obj-$(CONFIG_LCD2S) += lcd2s.o
+obj-$(CONFIG_LINEDISP) += line-display.o
diff --git a/drivers/auxdisplay/img-ascii-lcd.c b/drivers/auxdisplay/img-ascii-lcd.c
index 2b5640b638900a90..fa23e415f260ec56 100644
--- a/drivers/auxdisplay/img-ascii-lcd.c
+++ b/drivers/auxdisplay/img-ascii-lcd.c
@@ -4,7 +4,6 @@
* Author: Paul Burton <paul.burton@xxxxxxxx>
*/
-#include <generated/utsrelease.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
@@ -14,7 +13,8 @@
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
-#include <linux/sysfs.h>
+
+#include "line-display.h"
struct img_ascii_lcd_ctx;
@@ -27,36 +27,26 @@ struct img_ascii_lcd_ctx;
struct img_ascii_lcd_config {
unsigned int num_chars;
bool external_regmap;
- void (*update)(struct img_ascii_lcd_ctx *ctx);
+ void (*update)(struct linedisp *linedisp);
};
/**
* struct img_ascii_lcd_ctx - Private data structure
- * @pdev: the ASCII LCD platform device
* @base: the base address of the LCD registers
* @regmap: the regmap through which LCD registers are accessed
* @offset: the offset within regmap to the start of the LCD registers
* @cfg: pointer to the LCD model configuration
- * @message: the full message to display or scroll on the LCD
- * @message_len: the length of the @message string
- * @scroll_pos: index of the first character of @message currently displayed
- * @scroll_rate: scroll interval in jiffies
- * @timer: timer used to implement scrolling
+ * @linedisp: line display structure
* @curr: the string currently displayed on the LCD
*/
struct img_ascii_lcd_ctx {
- struct platform_device *pdev;
union {
void __iomem *base;
struct regmap *regmap;
};
u32 offset;
const struct img_ascii_lcd_config *cfg;
- char *message;
- unsigned int message_len;
- unsigned int scroll_pos;
- unsigned int scroll_rate;
- struct timer_list timer;
+ struct linedisp linedisp;
char curr[] __aligned(8);
};
@@ -64,8 +54,10 @@ struct img_ascii_lcd_ctx {
* MIPS Boston development board
*/
-static void boston_update(struct img_ascii_lcd_ctx *ctx)
+static void boston_update(struct linedisp *linedisp)
{
+ struct img_ascii_lcd_ctx *ctx =
+ container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
ulong val;
#if BITS_PER_LONG == 64
@@ -90,12 +82,14 @@ static struct img_ascii_lcd_config boston_config = {
* MIPS Malta development board
*/
-static void malta_update(struct img_ascii_lcd_ctx *ctx)
+static void malta_update(struct linedisp *linedisp)
{
+ struct img_ascii_lcd_ctx *ctx =
+ container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
unsigned int i;
int err = 0;
- for (i = 0; i < ctx->cfg->num_chars; i++) {
+ for (i = 0; i < linedisp->num_chars; i++) {
err = regmap_write(ctx->regmap,
ctx->offset + (i * 8), ctx->curr[i]);
if (err)
@@ -173,12 +167,14 @@ static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
return 0;
}
-static void sead3_update(struct img_ascii_lcd_ctx *ctx)
+static void sead3_update(struct linedisp *linedisp)
{
+ struct img_ascii_lcd_ctx *ctx =
+ container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
unsigned int i;
int err = 0;
- for (i = 0; i < ctx->cfg->num_chars; i++) {
+ for (i = 0; i < linedisp->num_chars; i++) {
err = sead3_wait_lcd_idle(ctx);
if (err)
break;
@@ -218,140 +214,6 @@ static const struct of_device_id img_ascii_lcd_matches[] = {
};
MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
-/**
- * img_ascii_lcd_scroll() - scroll the display by a character
- * @t: really a pointer to the private data structure
- *
- * Scroll the current message along the LCD by one character, rearming the
- * timer if required.
- */
-static void img_ascii_lcd_scroll(struct timer_list *t)
-{
- struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer);
- unsigned int i, ch = ctx->scroll_pos;
- unsigned int num_chars = ctx->cfg->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 < ctx->message_len; i++, ch++)
- ctx->curr[i] = ctx->message[ch];
-
- /* wrap around to the start of the string */
- ch = 0;
- }
-
- /* update the LCD */
- ctx->cfg->update(ctx);
-
- /* move on to the next character */
- ctx->scroll_pos++;
- ctx->scroll_pos %= ctx->message_len;
-
- /* rearm the timer */
- if (ctx->message_len > ctx->cfg->num_chars)
- mod_timer(&ctx->timer, jiffies + ctx->scroll_rate);
-}
-
-/**
- * img_ascii_lcd_display() - set the message to be displayed
- * @ctx: pointer to the private data structure
- * @msg: the message to display
- * @count: length of msg, or -1
- *
- * Display a new message @msg on the LCD. @msg can be longer than the number of
- * characters the LCD can display, in which case it will begin scrolling across
- * the LCD display.
- *
- * Return: 0 on success, -ENOMEM on memory allocation failure
- */
-static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
- const char *msg, ssize_t count)
-{
- char *new_msg;
-
- /* stop the scroll timer */
- del_timer_sync(&ctx->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 LCD */
- devm_kfree(&ctx->pdev->dev, ctx->message);
- ctx->message = NULL;
- ctx->message_len = 0;
- memset(ctx->curr, ' ', ctx->cfg->num_chars);
- ctx->cfg->update(ctx);
- return 0;
- }
-
- new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
- if (!new_msg)
- return -ENOMEM;
-
- memcpy(new_msg, msg, count);
- new_msg[count] = 0;
-
- if (ctx->message)
- devm_kfree(&ctx->pdev->dev, ctx->message);
-
- ctx->message = new_msg;
- ctx->message_len = count;
- ctx->scroll_pos = 0;
-
- /* update the LCD */
- img_ascii_lcd_scroll(&ctx->timer);
-
- return 0;
-}
-
-/**
- * message_show() - read message via sysfs
- * @dev: the LCD device
- * @attr: the LCD message attribute
- * @buf: the buffer to read the message into
- *
- * Read the current message being displayed or scrolled across the LCD 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 img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
-
- return sysfs_emit(buf, "%s\n", ctx->message);
-}
-
-/**
- * message_store() - write a new message via sysfs
- * @dev: the LCD device
- * @attr: the LCD 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 LCD 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 img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
- int err;
-
- err = img_ascii_lcd_display(ctx, buf, count);
- return err ?: count;
-}
-
-static DEVICE_ATTR_RW(message);
-
/**
* img_ascii_lcd_probe() - probe an LCD display device
* @pdev: the LCD platform device
@@ -391,29 +253,23 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
return PTR_ERR(ctx->base);
}
- ctx->pdev = pdev;
- ctx->cfg = cfg;
- ctx->message = NULL;
- ctx->scroll_pos = 0;
- ctx->scroll_rate = HZ / 2;
-
- /* initialise a timer for scrolling the message */
- timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
-
- platform_set_drvdata(pdev, ctx);
-
- /* display a default message */
- err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1);
+ err = linedisp_register(&ctx->linedisp, dev, cfg->num_chars, ctx->curr,
+ cfg->update);
if (err)
- goto out_del_timer;
+ return err;
- err = device_create_file(dev, &dev_attr_message);
+ /* for backwards compatibility */
+ err = compat_only_sysfs_link_entry_to_kobj(&dev->kobj,
+ &ctx->linedisp.dev.kobj,
+ "message", NULL);
if (err)
- goto out_del_timer;
+ goto err_unregister;
+ platform_set_drvdata(pdev, ctx);
return 0;
-out_del_timer:
- del_timer_sync(&ctx->timer);
+
+err_unregister:
+ linedisp_unregister(&ctx->linedisp);
return err;
}
@@ -430,8 +286,8 @@ static int img_ascii_lcd_remove(struct platform_device *pdev)
{
struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
- device_remove_file(&pdev->dev, &dev_attr_message);
- del_timer_sync(&ctx->timer);
+ sysfs_remove_link(&pdev->dev.kobj, "message");
+ linedisp_unregister(&ctx->linedisp);
return 0;
}
diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c
new file mode 100644
index 0000000000000000..4b97c20ac0b381ee
--- /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 <paul.burton@xxxxxxxx>
+ *
+ * Copyright (C) 2021 Glider bv
+ */
+
+#include <generated/utsrelease.h>
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/timer.h>
+
+#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");
diff --git a/drivers/auxdisplay/line-display.h b/drivers/auxdisplay/line-display.h
new file mode 100644
index 0000000000000000..0f5891d34c485871
--- /dev/null
+++ b/drivers/auxdisplay/line-display.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Character line display core support
+ *
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@xxxxxxxx>
+ *
+ * Copyright (C) 2021 Glider bv
+ */
+
+#ifndef _LINEDISP_H
+#define _LINEDISP_H
+
+/**
+ * struct linedisp - character line display private data structure
+ * @dev: the line display device
+ * @timer: timer used to implement scrolling
+ * @update: function called to update the display
+ * @buf: pointer to the buffer for the string currently displayed
+ * @message: the full message to display or scroll on the display
+ * @num_chars: the number of characters that can be displayed
+ * @message_len: the length of the @message string
+ * @scroll_pos: index of the first character of @message currently displayed
+ * @scroll_rate: scroll interval in jiffies
+ */
+struct linedisp {
+ struct device dev;
+ struct timer_list timer;
+ void (*update)(struct linedisp *linedisp);
+ char *buf;
+ char *message;
+ unsigned int num_chars;
+ unsigned int message_len;
+ unsigned int scroll_pos;
+ unsigned int scroll_rate;
+};
+
+int linedisp_register(struct linedisp *linedisp, struct device *parent,
+ unsigned int num_chars, char *buf,
+ void (*update)(struct linedisp *linedisp));
+void linedisp_unregister(struct linedisp *linedisp);
+
+#endif /* LINEDISP_H */
--
2.25.1