drivers/char/pc8736x_gpio.c

Source file repositories/reference/linux-study-clean/drivers/char/pc8736x_gpio.c

File Facts

System
Linux kernel
Corpus path
drivers/char/pc8736x_gpio.c
Extension
.c
Size
8996 bytes
Lines
353
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.

Dependency Surface

Detected Declarations

Annotated Snippet

static const struct file_operations pc8736x_gpio_fileops = {
	.owner	= THIS_MODULE,
	.open	= pc8736x_gpio_open,
	.write	= nsc_gpio_write,
	.read	= nsc_gpio_read,
};

static void __init pc8736x_init_shadow(void)
{
	int port;

	/* read the current values driven on the GPIO signals */
	for (port = 0; port < 4; ++port)
		pc8736x_gpio_shadow[port]
		    = inb_p(pc8736x_gpio_base + port_offset[port]
			    + PORT_OUT);

}

static struct cdev pc8736x_gpio_cdev;

static int __init pc8736x_gpio_init(void)
{
	int rc;
	dev_t devid;

	pdev = platform_device_alloc(DEVNAME, 0);
	if (!pdev)
		return -ENOMEM;

	rc = platform_device_add(pdev);
	if (rc) {
		rc = -ENODEV;
		goto undo_platform_dev_alloc;
	}
	dev_info(&pdev->dev, "NatSemi pc8736x GPIO Driver Initializing\n");

	if (!pc8736x_superio_present()) {
		rc = -ENODEV;
		dev_err(&pdev->dev, "no device found\n");
		goto undo_platform_dev_add;
	}
	pc8736x_gpio_ops.dev = &pdev->dev;

	/* Verify that chip and it's GPIO unit are both enabled.
	   My BIOS does this, so I take minimum action here
	 */
	rc = superio_inb(SIO_CF1);
	if (!(rc & 0x01)) {
		rc = -ENODEV;
		dev_err(&pdev->dev, "device not enabled\n");
		goto undo_platform_dev_add;
	}
	device_select(SIO_GPIO_UNIT);
	if (!superio_inb(SIO_UNIT_ACT)) {
		rc = -ENODEV;
		dev_err(&pdev->dev, "GPIO unit not enabled\n");
		goto undo_platform_dev_add;
	}

	/* read the GPIO unit base addr that chip responds to */
	pc8736x_gpio_base = (superio_inb(SIO_BASE_HADDR) << 8
			     | superio_inb(SIO_BASE_LADDR));

	if (!request_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE, DEVNAME)) {
		rc = -ENODEV;
		dev_err(&pdev->dev, "GPIO ioport %x busy\n",
			pc8736x_gpio_base);
		goto undo_platform_dev_add;
	}
	dev_info(&pdev->dev, "GPIO ioport %x reserved\n", pc8736x_gpio_base);

	if (major) {
		devid = MKDEV(major, 0);
		rc = register_chrdev_region(devid, PC8736X_GPIO_CT, DEVNAME);
	} else {
		rc = alloc_chrdev_region(&devid, 0, PC8736X_GPIO_CT, DEVNAME);
		major = MAJOR(devid);
	}

	if (rc < 0) {
		dev_err(&pdev->dev, "register-chrdev failed: %d\n", rc);
		goto undo_request_region;
	}
	if (!major) {
		major = rc;
		dev_dbg(&pdev->dev, "got dynamic major %d\n", major);
	}

	pc8736x_init_shadow();

Annotation

Implementation Notes