drivers/macintosh/ans-lcd.c

File Facts

System

Linux kernel

Corpus path

drivers/macintosh/ans-lcd.c

Extension

.c

Size

4108 bytes

Lines

206

Domain

Driver Families

Bucket

drivers/macintosh

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/types.h
• linux/errno.h
• linux/kernel.h
• linux/miscdevice.h
• linux/fcntl.h
• linux/module.h
• linux/delay.h
• linux/fs.h
• linux/of.h
• linux/uaccess.h
• asm/sections.h
• asm/io.h
• ans-lcd.h

Detected Declarations

• function anslcd_write_byte_ctrl
• function anslcd_write_byte_data
• function anslcd_write
• function anslcd_ioctl
• function anslcd_open
• function anslcd_init
• function anslcd_exit
• module init anslcd_init

Annotated Snippet

const struct file_operations anslcd_fops = {
	.write		= anslcd_write,
	.unlocked_ioctl	= anslcd_ioctl,
	.open		= anslcd_open,
	.llseek		= default_llseek,
};

static struct miscdevice anslcd_dev = {
	LCD_MINOR,
	"anslcd",
	&anslcd_fops
};

static const char anslcd_logo[] __initconst =
				"********************"  /* Line #1 */
				"*      LINUX!      *"  /* Line #3 */
				"*    Welcome to    *"  /* Line #2 */
				"********************"; /* Line #4 */

static int __init
anslcd_init(void)
{
	int a;
	int retval;
	struct device_node* node;

	node = of_find_node_by_name(NULL, "lcd");
	if (!node || !of_node_name_eq(node->parent, "gc")) {
		of_node_put(node);
		return -ENODEV;
	}
	of_node_put(node);

	anslcd_ptr = ioremap(ANSLCD_ADDR, 0x20);
	
	retval = misc_register(&anslcd_dev);
	if(retval < 0){
		printk(KERN_INFO "LCD: misc_register failed\n");
		iounmap(anslcd_ptr);
		return retval;
	}

#ifdef DEBUG
	printk(KERN_DEBUG "LCD: init\n");
#endif

	mutex_lock(&anslcd_mutex);
	anslcd_write_byte_ctrl ( 0x38 );
	anslcd_write_byte_ctrl ( 0x0c );
	anslcd_write_byte_ctrl ( 0x06 );
	anslcd_write_byte_ctrl ( 0x01 );
	anslcd_write_byte_ctrl ( 0x02 );
	for(a=0;a<80;a++) {
		anslcd_write_byte_data(anslcd_logo[a]);
	}
	mutex_unlock(&anslcd_mutex);
	return 0;
}

static void __exit
anslcd_exit(void)
{
	misc_deregister(&anslcd_dev);
	iounmap(anslcd_ptr);
}

module_init(anslcd_init);
module_exit(anslcd_exit);
MODULE_LICENSE("GPL v2");

Annotation

• Immediate include surface: `linux/types.h`, `linux/errno.h`, `linux/kernel.h`, `linux/miscdevice.h`, `linux/fcntl.h`, `linux/module.h`, `linux/delay.h`, `linux/fs.h`.
• Detected declarations: `function anslcd_write_byte_ctrl`, `function anslcd_write_byte_data`, `function anslcd_write`, `function anslcd_ioctl`, `function anslcd_open`, `function anslcd_init`, `function anslcd_exit`, `module init anslcd_init`.
• Atlas domain: Driver Families / drivers/macintosh.
• 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.