diff options
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/serial/ch341.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index c5ecdcd51ffc..f2b93f4554a7 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -87,6 +87,7 @@ struct ch341_private { u8 mcr; u8 msr; u8 lcr; + unsigned long quirks; }; static void ch341_set_termios(struct tty_struct *tty, @@ -308,6 +309,53 @@ out: kfree(buffer); return r; } +static int ch341_detect_quirks(struct usb_serial_port *port) +{ + struct ch341_private *priv = usb_get_serial_port_data(port); + struct usb_device *udev = port->serial->dev; + const unsigned int size = 2; + unsigned long quirks = 0; + char *buffer; + int r; + + buffer = kmalloc(size, GFP_KERNEL); + if (!buffer) + return -ENOMEM; + + /* + * A subset of CH34x devices does not support all features. The + * prescaler is limited and there is no support for sending a RS232 + * break condition. A read failure when trying to set up the latter is + * used to detect these devices. + */ + r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG, + USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, + CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT); + if (r == -EPIPE) { + dev_dbg(&port->dev, "break control not supported\n"); + r = 0; + goto out; + } + + if (r != size) { + if (r >= 0) + r = -EIO; + dev_err(&port->dev, "failed to read break control: %d\n", r); + goto out; + } + + r = 0; +out: + kfree(buffer); + + if (quirks) { + dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks); + priv->quirks |= quirks; + } + + return r; +} + static int ch341_port_probe(struct usb_serial_port *port) { struct ch341_private *priv; @@ -330,6 +378,11 @@ static int ch341_port_probe(struct usb_serial_port *port) goto error; usb_set_serial_port_data(port, priv); + + r = ch341_detect_quirks(port); + if (r < 0) + goto error; + return 0; error: kfree(priv); |