drivers/video/fbdev/core/fb_chrdev.c

File Facts

System

Linux kernel

Corpus path

drivers/video/fbdev/core/fb_chrdev.c

Extension

.c

Size

9973 bytes

Lines

439

Domain

Driver Families

Bucket

drivers/video

Inferred role

Driver Families: operation-table or driver-model contract

Status

pattern implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

• Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/compat.h
• linux/console.h
• linux/fb.h
• linux/major.h
• fb_internal.h
• fbcon.h

Detected Declarations

• struct fb_fix_screeninfo32
• struct fb_cmap32
• function fb_read
• function fb_write
• function do_fb_ioctl
• function fb_ioctl
• function fb_getput_cmap
• function do_fscreeninfo_to_user
• function fb_get_fscreeninfo
• function fb_compat_ioctl
• function fb_mmap
• function fb_open
• function fb_release
• function get_fb_unmapped_area
• function fb_register_chrdev
• function fb_unregister_chrdev

Annotated Snippet

static const struct file_operations fb_fops = {
	.owner = THIS_MODULE,
	.read = fb_read,
	.write = fb_write,
	.unlocked_ioctl = fb_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = fb_compat_ioctl,
#endif
	.mmap = fb_mmap,
	.open = fb_open,
	.release = fb_release,
#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) || \
	(defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && \
	 !defined(CONFIG_MMU))
	.get_unmapped_area = get_fb_unmapped_area,
#endif
#ifdef CONFIG_FB_DEFERRED_IO
	.fsync = fb_deferred_io_fsync,
#endif
	.llseek = default_llseek,
};

int fb_register_chrdev(void)
{
	int ret;

	ret = register_chrdev(FB_MAJOR, "fb", &fb_fops);
	if (ret) {
		pr_err("Unable to get major %d for fb devs\n", FB_MAJOR);
		return ret;
	}

	return ret;
}

void fb_unregister_chrdev(void)
{
	unregister_chrdev(FB_MAJOR, "fb");
}

Annotation

• Immediate include surface: `linux/compat.h`, `linux/console.h`, `linux/fb.h`, `linux/major.h`, `fb_internal.h`, `fbcon.h`.
• Detected declarations: `struct fb_fix_screeninfo32`, `struct fb_cmap32`, `function fb_read`, `function fb_write`, `function do_fb_ioctl`, `function fb_ioctl`, `function fb_getput_cmap`, `function do_fscreeninfo_to_user`, `function fb_get_fscreeninfo`, `function fb_compat_ioctl`.
• Atlas domain: Driver Families / drivers/video.
• Implementation status: pattern implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.