auxdisplay: linedisp: Provide struct linedisp_ops for future extension

Currently the line display library doesn't scale in case we want to
provide more operations. Prepare the library to take a newly created
struct linedisp_ops that scales.

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/ht16k33.c

@@ -448,6 +448,10 @@ static void ht16k33_linedisp_update(struct linedisp *linedisp)
 	schedule_delayed_work(&priv->work, 0);
 }
 
+static const struct linedisp_ops ht16k33_linedisp_ops = {
+	.update = ht16k33_linedisp_update,
+};
+
 static void ht16k33_seg7_update(struct work_struct *work)
 {
 	struct ht16k33_priv *priv = container_of(work, struct ht16k33_priv,
@@ -697,7 +701,7 @@ static int ht16k33_seg_probe(struct device *dev, struct ht16k33_priv *priv,
 		return err;
 
 	err = linedisp_register(&seg->linedisp, dev, 4, seg->curr,
-				ht16k33_linedisp_update);
+				&ht16k33_linedisp_ops);
 	if (err)
 		goto err_remove_map_file;
 

drivers/auxdisplay/img-ascii-lcd.c

@@ -22,12 +22,12 @@ struct img_ascii_lcd_ctx;
  * struct img_ascii_lcd_config - Configuration information about an LCD model
  * @num_chars: the number of characters the LCD can display
  * @external_regmap: true if registers are in a system controller, else false
- * @update: function called to update the LCD
+ * @ops: character line display operations
  */
 struct img_ascii_lcd_config {
 	unsigned int num_chars;
 	bool external_regmap;
-	void (*update)(struct linedisp *linedisp);
+	const struct linedisp_ops ops;
 };
 
 /**
@@ -75,7 +75,9 @@ static void boston_update(struct linedisp *linedisp)
 
 static struct img_ascii_lcd_config boston_config = {
 	.num_chars = 8,
-	.update = boston_update,
+	.ops = {
+		.update = boston_update,
+	},
 };
 
 /*
@@ -103,7 +105,9 @@ static void malta_update(struct linedisp *linedisp)
 static struct img_ascii_lcd_config malta_config = {
 	.num_chars = 8,
 	.external_regmap = true,
-	.update = malta_update,
+	.ops = {
+		.update = malta_update,
+	},
 };
 
 /*
@@ -203,7 +207,9 @@ static void sead3_update(struct linedisp *linedisp)
 static struct img_ascii_lcd_config sead3_config = {
 	.num_chars = 16,
 	.external_regmap = true,
-	.update = sead3_update,
+	.ops = {
+		.update = sead3_update,
+	},
 };
 
 static const struct of_device_id img_ascii_lcd_matches[] = {
@@ -248,7 +254,7 @@ static int img_ascii_lcd_probe(struct platform_device *pdev)
 	}
 
 	err = linedisp_register(&ctx->linedisp, dev, cfg->num_chars, ctx->curr,
-				cfg->update);
+				&cfg->ops);
 	if (err)
 		return err;
 

drivers/auxdisplay/line-display.c

@@ -50,7 +50,7 @@ static void linedisp_scroll(struct timer_list *t)
 	}
 
 	/* update the display */
-	linedisp->update(linedisp);
+	linedisp->ops->update(linedisp);
 
 	/* move on to the next character */
 	linedisp->scroll_pos++;
@@ -94,7 +94,7 @@ static int linedisp_display(struct linedisp *linedisp, const char *msg,
 		linedisp->message = NULL;
 		linedisp->message_len = 0;
 		memset(linedisp->buf, ' ', linedisp->num_chars);
-		linedisp->update(linedisp);
+		linedisp->ops->update(linedisp);
 		return 0;
 	}
 
@@ -216,20 +216,20 @@ static const struct device_type linedisp_type = {
  * @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!
+ * @ops: character line display operations
  *
  * 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))
+		      const struct linedisp_ops *ops)
 {
 	int err;
 
 	memset(linedisp, 0, sizeof(*linedisp));
 	linedisp->dev.parent = parent;
 	linedisp->dev.type = &linedisp_type;
-	linedisp->update = update;
+	linedisp->ops = ops;
 	linedisp->buf = buf;
 	linedisp->num_chars = num_chars;
 	linedisp->scroll_rate = DEFAULT_SCROLL_RATE;

drivers/auxdisplay/line-display.h

@@ -14,11 +14,21 @@
 #include <linux/device.h>
 #include <linux/timer_types.h>
 
+struct linedisp;
+
+/**
+ * struct linedisp_ops - character line display operations
+ * @update: Function called to update the display. This must not sleep!
+ */
+struct linedisp_ops {
+	void (*update)(struct linedisp *linedisp);
+};
+
 /**
  * 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
+ * @ops: character line display operations
  * @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
@@ -30,7 +40,7 @@
 struct linedisp {
 	struct device dev;
 	struct timer_list timer;
-	void (*update)(struct linedisp *linedisp);
+	const struct linedisp_ops *ops;
 	char *buf;
 	char *message;
 	unsigned int num_chars;
@@ -42,7 +52,7 @@ struct linedisp {
 
 int linedisp_register(struct linedisp *linedisp, struct device *parent,
 		      unsigned int num_chars, char *buf,
-		      void (*update)(struct linedisp *linedisp));
+		      const struct linedisp_ops *ops);
 void linedisp_unregister(struct linedisp *linedisp);
 
 #endif /* LINEDISP_H */