drm/sysfb: Share helpers for integer validation

Provide sysfb helpers for validating framebuffer integer values
against limits. Update drivers. If a driver did not specify a limit
for a certain value, use INT_MAX.

v2:
- declare module information near EOF (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250410083834.10810-3-tzimmermann@suse.de

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sysfb/drm_sysfb.c b/drivers/gpu/drm/sysfb/drm_sysfb.c
index c083d21fd9ca..308f82153b15 100644
--- a/drivers/gpu/drm/sysfb/drm_sysfb.c
+++ b/drivers/gpu/drm/sysfb/drm_sysfb.c
@@ -1,8 +1,35 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
+#include <linux/export.h>
+#include <linux/limits.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 
+#include <drm/drm_print.h>
+
 #include "drm_sysfb_helper.h"
 
+int drm_sysfb_get_validated_int(struct drm_device *dev, const char *name,
+				u64 value, u32 max)
+{
+	if (value > min(max, INT_MAX)) {
+		drm_warn(dev, "%s of %llu exceeds maximum of %u\n", name, value, max);
+		return -EINVAL;
+	}
+	return value;
+}
+EXPORT_SYMBOL(drm_sysfb_get_validated_int);
+
+int drm_sysfb_get_validated_int0(struct drm_device *dev, const char *name,
+				 u64 value, u32 max)
+{
+	if (!value) {
+		drm_warn(dev, "%s of 0 not allowed\n", name);
+		return -EINVAL;
+	}
+	return drm_sysfb_get_validated_int(dev, name, value, max);
+}
+EXPORT_SYMBOL(drm_sysfb_get_validated_int0);
+
 MODULE_DESCRIPTION("Helpers for DRM sysfb drivers");
 MODULE_LICENSE("GPL");