drivers/usb/misc/usb4604.c

Source file repositories/reference/linux-study-clean/drivers/usb/misc/usb4604.c

File Facts

System
Linux kernel
Corpus path
drivers/usb/misc/usb4604.c
Extension
.c
Size
3436 bytes
Lines
164
Domain
Driver Families
Bucket
drivers/usb
Inferred role
Driver Families: implementation source
Status
source 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

struct usb4604 {
	enum usb4604_mode	mode;
	struct device		*dev;
	struct gpio_desc	*gpio_reset;
};

static void usb4604_reset(struct usb4604 *hub, int state)
{
	gpiod_set_value_cansleep(hub->gpio_reset, state);

	/* Wait for i2c logic to come up */
	if (state)
		msleep(250);
}

static int usb4604_connect(struct usb4604 *hub)
{
	struct device *dev = hub->dev;
	struct i2c_client *client = to_i2c_client(dev);
	int err;
	u8 connect_cmd[] = { 0xaa, 0x55, 0x00 };

	usb4604_reset(hub, 1);

	err = i2c_master_send(client, connect_cmd, ARRAY_SIZE(connect_cmd));
	if (err < 0) {
		usb4604_reset(hub, 0);
		return err;
	}

	hub->mode = USB4604_MODE_HUB;
	dev_dbg(dev, "switched to HUB mode\n");

	return 0;
}

static int usb4604_switch_mode(struct usb4604 *hub, enum usb4604_mode mode)
{
	struct device *dev = hub->dev;
	int err = 0;

	switch (mode) {
	case USB4604_MODE_HUB:
		err = usb4604_connect(hub);
		break;

	case USB4604_MODE_STANDBY:
		usb4604_reset(hub, 0);
		dev_dbg(dev, "switched to STANDBY mode\n");
		break;

	default:
		dev_err(dev, "unknown mode is requested\n");
		err = -EINVAL;
		break;
	}

	return err;
}

static int usb4604_probe(struct usb4604 *hub)
{
	struct device *dev = hub->dev;
	struct device_node *np = dev->of_node;
	struct gpio_desc *gpio;
	u32 mode = USB4604_MODE_HUB;

	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
	if (IS_ERR(gpio))
		return PTR_ERR(gpio);
	hub->gpio_reset = gpio;

	if (of_property_read_u32(np, "initial-mode", &hub->mode))
		hub->mode = mode;

	return usb4604_switch_mode(hub, hub->mode);
}

static int usb4604_i2c_probe(struct i2c_client *i2c)
{
	struct usb4604 *hub;

	hub = devm_kzalloc(&i2c->dev, sizeof(*hub), GFP_KERNEL);
	if (!hub)
		return -ENOMEM;

	i2c_set_clientdata(i2c, hub);
	hub->dev = &i2c->dev;

	return usb4604_probe(hub);

Annotation

Implementation Notes