drivers/char/nwflash.c

File Facts

System

Linux kernel

Corpus path

drivers/char/nwflash.c

Extension

.c

Size

13145 bytes

Lines

628

Domain

Driver Families

Bucket

drivers/char

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/module.h
• linux/types.h
• linux/fs.h
• linux/errno.h
• linux/mm.h
• linux/delay.h
• linux/proc_fs.h
• linux/miscdevice.h
• linux/spinlock.h
• linux/rwsem.h
• linux/init.h
• linux/mutex.h
• linux/jiffies.h
• asm/hardware/dec21285.h
• asm/io.h
• asm/mach-types.h
• linux/uaccess.h
• asm/nwflash.h

Detected Declarations

• function get_flash_id
• function flash_ioctl
• function flash_read
• function flash_write
• function flash_llseek
• function erase_block
• function write_block
• function kick_open
• function nwflash_init
• function nwflash_exit
• module init nwflash_init

Annotated Snippet

static const struct file_operations flash_fops =
{
	.owner		= THIS_MODULE,
	.llseek		= flash_llseek,
	.read		= flash_read,
	.write		= flash_write,
	.unlocked_ioctl	= flash_ioctl,
};

static struct miscdevice flash_miscdev =
{
	NWFLASH_MINOR,
	"nwflash",
	&flash_fops
};

static int __init nwflash_init(void)
{
	int ret = -ENODEV;

	if (machine_is_netwinder()) {
		int id;

		FLASH_BASE = ioremap(DC21285_FLASH, KFLASH_SIZE4);
		if (!FLASH_BASE)
			goto out;

		id = get_flash_id();
		if ((id != KFLASH_ID) && (id != KFLASH_ID4)) {
			ret = -ENXIO;
			iounmap((void *)FLASH_BASE);
			printk("Flash: incorrect ID 0x%04X.\n", id);
			goto out;
		}

		printk("Flash ROM driver v.%s, flash device ID 0x%04X, size %d Mb.\n",
		       NWFLASH_VERSION, id, gbFlashSize / (1024 * 1024));

		ret = misc_register(&flash_miscdev);
		if (ret < 0) {
			iounmap((void *)FLASH_BASE);
		}
	}
out:
	return ret;
}

static void __exit nwflash_exit(void)
{
	misc_deregister(&flash_miscdev);
	iounmap((void *)FLASH_BASE);
}

MODULE_DESCRIPTION("NetWinder flash memory driver");
MODULE_LICENSE("GPL");

module_param(flashdebug, bool, 0644);

module_init(nwflash_init);
module_exit(nwflash_exit);

Annotation

• Immediate include surface: `linux/module.h`, `linux/types.h`, `linux/fs.h`, `linux/errno.h`, `linux/mm.h`, `linux/delay.h`, `linux/proc_fs.h`, `linux/miscdevice.h`.
• Detected declarations: `function get_flash_id`, `function flash_ioctl`, `function flash_read`, `function flash_write`, `function flash_llseek`, `function erase_block`, `function write_block`, `function kick_open`, `function nwflash_init`, `function nwflash_exit`.
• Atlas domain: Driver Families / drivers/char.
• 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.