drivers/watchdog/pika_wdt.c

Source file repositories/reference/linux-study-clean/drivers/watchdog/pika_wdt.c

File Facts

System
Linux kernel
Corpus path
drivers/watchdog/pika_wdt.c
Extension
.c
Size
6936 bytes
Lines
303
Domain
Driver Families
Bucket
drivers/watchdog
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.

Dependency Surface

Detected Declarations

Annotated Snippet

static const struct file_operations pikawdt_fops = {
	.owner		= THIS_MODULE,
	.open		= pikawdt_open,
	.release	= pikawdt_release,
	.write		= pikawdt_write,
	.unlocked_ioctl	= pikawdt_ioctl,
	.compat_ioctl	= compat_ptr_ioctl,
};

static struct miscdevice pikawdt_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &pikawdt_fops,
};

static int __init pikawdt_init(void)
{
	struct device_node *np;
	void __iomem *fpga;
	u32 post1;
	int ret;

	np = of_find_compatible_node(NULL, NULL, "pika,fpga");
	if (np == NULL) {
		pr_err("Unable to find fpga\n");
		return -ENOENT;
	}

	pikawdt_private.fpga = of_iomap(np, 0);
	of_node_put(np);
	if (pikawdt_private.fpga == NULL) {
		pr_err("Unable to map fpga\n");
		return -ENOMEM;
	}

	ident.firmware_version = in_be32(pikawdt_private.fpga + 0x1c) & 0xffff;

	/* POST information is in the sd area. */
	np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");
	if (np == NULL) {
		pr_err("Unable to find fpga-sd\n");
		ret = -ENOENT;
		goto out;
	}

	fpga = of_iomap(np, 0);
	of_node_put(np);
	if (fpga == NULL) {
		pr_err("Unable to map fpga-sd\n");
		ret = -ENOMEM;
		goto out;
	}

	/* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --
	 * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog
	 *           timeout.
	 */
	post1 = in_be32(fpga + 0x40);
	if (post1 & 0x80000000)
		pikawdt_private.bootstatus = WDIOF_CARDRESET;

	iounmap(fpga);

	timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);

	ret = misc_register(&pikawdt_miscdev);
	if (ret) {
		pr_err("Unable to register miscdev\n");
		goto out;
	}

	pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
		heartbeat, nowayout);
	return 0;

out:
	iounmap(pikawdt_private.fpga);
	return ret;
}

static void __exit pikawdt_exit(void)
{
	misc_deregister(&pikawdt_miscdev);

	iounmap(pikawdt_private.fpga);
}

module_init(pikawdt_init);
module_exit(pikawdt_exit);

Annotation

Implementation Notes