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 <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>

Author: geertu

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

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

drivers/auxdisplay/img-ascii-lcd.c

@@ -4,7 +4,6 @@
  * Author: Paul Burton <[email protected]>
  */
 
-#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;
 
@@ -27,45 +27,37 @@ 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);
 };
 
 /*
  * 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;
 }