drivers/usb/serial/mct_u232.c

Source file repositories/reference/linux-study-clean/drivers/usb/serial/mct_u232.c

File Facts

System
Linux kernel
Corpus path
drivers/usb/serial/mct_u232.c
Extension
.c
Size
22248 bytes
Lines
783
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 mct_u232_private {
	struct urb *read_urb;
	spinlock_t lock;
	unsigned int	     control_state; /* Modem Line Setting (TIOCM) */
	unsigned char        last_lcr;      /* Line Control Register */
	unsigned char	     last_lsr;      /* Line Status Register */
	unsigned char	     last_msr;      /* Modem Status Register */
	unsigned int	     rx_flags;      /* Throttling flags */
};

#define THROTTLED		0x01

/*
 * Handle vendor specific USB requests
 */

#define WDR_TIMEOUT 5000 /* default urb timeout */

/*
 * Later day 2.6.0-test kernels have new baud rates like B230400 which
 * we do not know how to support. We ignore them for the moment.
 */
static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
					speed_t value, speed_t *result)
{
	*result = value;

	if (le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_SITECOM_PID
		|| le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_BELKIN_F5U109_PID) {
		switch (value) {
		case 300:
			return 0x01;
		case 600:
			return 0x02; /* this one not tested */
		case 1200:
			return 0x03;
		case 2400:
			return 0x04;
		case 4800:
			return 0x06;
		case 9600:
			return 0x08;
		case 19200:
			return 0x09;
		case 38400:
			return 0x0a;
		case 57600:
			return 0x0b;
		case 115200:
			return 0x0c;
		default:
			*result = 9600;
			return 0x08;
		}
	} else {
		/* FIXME: Can we use any divider - should we do
		   divider = 115200/value;
		   real baud = 115200/divider */
		switch (value) {
		case 300: break;
		case 600: break;
		case 1200: break;
		case 2400: break;
		case 4800: break;
		case 9600: break;
		case 19200: break;
		case 38400: break;
		case 57600: break;
		case 115200: break;
		default:
			value = 9600;
			*result = 9600;
		}
		return 115200/value;
	}
}

static int mct_u232_set_baud_rate(struct tty_struct *tty,
	struct usb_serial *serial, struct usb_serial_port *port, speed_t value)
{
	unsigned int divisor;
	int rc;
	unsigned char *buf;
	unsigned char cts_enable_byte = 0;
	speed_t speed;

	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
	if (buf == NULL)
		return -ENOMEM;

Annotation

Implementation Notes