fbdev: Handle video= parameter in video/cmdline.c

Handle the command-line parameter video= in video/cmdline.c. Implement
the fbdev helper fb_get_options() on top. Will allows to handle the
kernel parameter in DRM without fbdev dependencies.

Note that __video_get_options() has the meaning of its return value
inverted compared to fb_get_options(). The new helper returns true if
the adapter has been enabled, and false otherwise.

There is the ofonly parameter, which disables output for non-OF-based
framebuffers. It is only for offb and looks like a workaround. The actual
purpose it not clear to me. Use 'video=off' or 'nomodeset' instead.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230209135509.7786-9-tzimmermann@suse.de

2 files changed, 13 insertions, 83 deletions

diff --git a/drivers/video/fbdev/core/Makefile b/drivers/video/fbdev/core/Makefile
index 26cbc965497c..08fabce76b74 100644
--- a/drivers/video/fbdev/core/Makefile
+++ b/drivers/video/fbdev/core/Makefile
@@ -1,9 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_FB_CMDLINE)          += fb_cmdline.o
 obj-$(CONFIG_FB_NOTIFY)           += fb_notify.o
 obj-$(CONFIG_FB)                  += fb.o
 fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o \
-                                     modedb.o fbcvt.o
+                                     modedb.o fbcvt.o fb_cmdline.o
 fb-$(CONFIG_FB_DEFERRED_IO)       += fb_defio.o
 
 ifeq ($(CONFIG_FRAMEBUFFER_CONSOLE),y)
diff --git a/drivers/video/fbdev/core/fb_cmdline.c b/drivers/video/fbdev/core/fb_cmdline.c
index f811c7b679e1..4d1634c492ec 100644
--- a/drivers/video/fbdev/core/fb_cmdline.c
+++ b/drivers/video/fbdev/core/fb_cmdline.c
@@ -14,42 +14,12 @@
  * Authors:
  *    Daniel Vetter <daniel.vetter@ffwll.ch>
  */
-#include <linux/init.h>
-#include <linux/fb.h>
-
-static char *video_options[FB_MAX] __read_mostly;
-static const char *fb_mode_option __read_mostly;
-static int ofonly __read_mostly;
-
-static const char *__fb_get_options(const char *name)
-{
-	const char *options = NULL;
-	size_t name_len = 0;
-
-	if (name)
-		name_len = strlen(name);
 
-	if (name_len) {
-		unsigned int i;
-		const char *opt;
-
-		for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
-			if (!video_options[i])
-				continue;
-			if (video_options[i][0] == '\0')
-				continue;
-			opt = video_options[i];
-			if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
-				options = opt + name_len + 1;
-		}
-	}
+#include <linux/export.h>
+#include <linux/fb.h>
+#include <linux/string.h>
 
-	/* No match, return global options */
-	if (!options)
-		options = fb_mode_option;
-
-	return options;
-}
+#include <video/cmdline.h>
 
 /**
  * fb_get_options - get kernel boot parameters
@@ -65,17 +35,18 @@ static const char *__fb_get_options(const char *name)
  */
 int fb_get_options(const char *name, char **option)
 {
-	int retval = 0;
-	const char *options;
+	const char *options = NULL;
+	bool is_of = false;
+	bool enabled;
 
-	if (name && ofonly && strncmp(name, "offb", 4))
-		retval = 1;
+	if (name)
+		is_of = strncmp(name, "offb", 4);
 
-	options = __fb_get_options(name);
+	enabled = __video_get_options(name, &options, is_of);
 
 	if (options) {
 		if (!strncmp(options, "off", 3))
-			retval = 1;
+			enabled = false;
 	}
 
 	if (option) {
@@ -85,46 +56,6 @@ int fb_get_options(const char *name, char **option)
 			*option = NULL;
 	}
 
-	return retval;
+	return enabled ? 0 : 1; // 0 on success, 1 otherwise
 }
 EXPORT_SYMBOL(fb_get_options);
-
-/**
- *	video_setup - process command line options
- *	@options: string of options
- *
- *	Process command line options for frame buffer subsystem.
- *
- *	NOTE: This function is a __setup and __init function.
- *            It only stores the options.  Drivers have to call
- *            fb_get_options() as necessary.
- */
-static int __init video_setup(char *options)
-{
-	if (!options || !*options)
-		goto out;
-
-	if (!strncmp(options, "ofonly", 6)) {
-		ofonly = 1;
-		goto out;
-	}
-
-	if (strchr(options, ':')) {
-		/* named */
-		int i;
-
-		for (i = 0; i < FB_MAX; i++) {
-			if (video_options[i] == NULL) {
-				video_options[i] = options;
-				break;
-			}
-		}
-	} else {
-		/* global */
-		fb_mode_option = options;
-	}
-
-out:
-	return 1;
-}
-__setup("video=", video_setup);