diff options
Diffstat (limited to 'sys/dev/usb/serial/usb_serial.c')
| -rw-r--r-- | sys/dev/usb/serial/usb_serial.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/sys/dev/usb/serial/usb_serial.c b/sys/dev/usb/serial/usb_serial.c index 23ee3305a181..c5fc14b41b4d 100644 --- a/sys/dev/usb/serial/usb_serial.c +++ b/sys/dev/usb/serial/usb_serial.c @@ -161,6 +161,7 @@ static tsw_param_t ucom_param; static tsw_outwakeup_t ucom_outwakeup; static tsw_inwakeup_t ucom_inwakeup; static tsw_free_t ucom_free; +static tsw_busy_t ucom_busy; static struct ttydevsw ucom_class = { .tsw_flags = TF_INITLOCK | TF_CALLOUT, @@ -172,6 +173,7 @@ static struct ttydevsw ucom_class = { .tsw_param = ucom_param, .tsw_modem = ucom_modem, .tsw_free = ucom_free, + .tsw_busy = ucom_busy, }; MODULE_DEPEND(ucom, usb, 1, 1, 1); @@ -1294,6 +1296,27 @@ ucom_outwakeup(struct tty *tp) ucom_start_transfers(sc); } +static bool +ucom_busy(struct tty *tp) +{ + struct ucom_softc *sc = tty_softc(tp); + const uint8_t txidle = ULSR_TXRDY | ULSR_TSRE; + + UCOM_MTX_ASSERT(sc, MA_OWNED); + + DPRINTFN(3, "sc = %p lsr 0x%02x\n", sc, sc->sc_lsr); + + /* + * If the driver maintains the txidle bits in LSR, we can use them to + * determine whether the transmitter is busy or idle. Otherwise we have + * to assume it is idle to avoid hanging forever on tcdrain(3). + */ + if (sc->sc_flag & UCOM_FLAG_LSRTXIDLE) + return ((sc->sc_lsr & txidle) != txidle); + else + return (false); +} + /*------------------------------------------------------------------------* * ucom_get_data * |