Author: ian Date: Sun Feb 5 15:45:31 2017 New Revision: 313287 URL: https://svnweb.freebsd.org/changeset/base/313287
Log: Add tsw_busy support to usb_serial (ucom). The tty layer uses tsw_busy to poll for busy/idle status of the transmitter hardware during close() and tcdrain(). The ucom layer defines ULSR_TXRDY and ULSR_TSRE bits for the line status register; when both are set, the transmitter is idle. Not all chip drivers maintain those bits in the sc_lsr field, and if the bits never get set the transmitter will always appear busy, causing hangs in tcdrain(). These changes add a new sc_flag bit, UCOM_FLAG_LSRTXIDLE. When this flag is set, ucom_busy() uses the lsr bits to return busy vs. idle state, otherwise it always returns idle (which is effectively what happened before this change because tsw_busy wasn't implemented). For the uftdi chip driver, these changes stop masking out the tx idle bits when processing the status register (because now they're useful), and it calls ucom_use_lsr_txbits() to indicate the bits are maintained by the driver and can be used by ucom_busy(). Differential Revision: https://reviews.freebsd.org/D9183 Modified: head/sys/dev/usb/serial/uftdi.c head/sys/dev/usb/serial/usb_serial.c head/sys/dev/usb/serial/usb_serial.h Modified: head/sys/dev/usb/serial/uftdi.c ============================================================================== --- head/sys/dev/usb/serial/uftdi.c Sun Feb 5 14:25:31 2017 (r313286) +++ head/sys/dev/usb/serial/uftdi.c Sun Feb 5 15:45:31 2017 (r313287) @@ -1123,6 +1123,9 @@ uftdi_attach(device_t dev) FTDI_SIO_SET_DATA_PARITY_NONE | FTDI_SIO_SET_DATA_BITS(8)); + /* Indicate tx bits in sc_lsr can be used to determine busy vs idle. */ + ucom_use_lsr_txbits(&sc->sc_ucom); + error = ucom_attach(&sc->sc_super_ucom, &sc->sc_ucom, 1, sc, &uftdi_callback, &sc->sc_mtx); if (error) { @@ -1279,16 +1282,20 @@ uftdi_read_callback(struct usb_xfer *xfe offset = 0; /* * Extract packet headers and payload bytes from the buffer. - * Feed payload bytes to ucom/tty layer; OR-accumulate header - * status bits which are transient and could toggle with each - * packet. After processing all packets in the buffer, process - * the accumulated transient MSR and LSR values along with the + * Feed payload bytes to ucom/tty layer; OR-accumulate the + * receiver-related header status bits which are transient and + * could toggle with each packet, but for transmitter-related + * bits keep only the ones from the last packet. + * + * After processing all packets in the buffer, process the + * accumulated transient MSR and LSR values along with the * non-transient bits from the last packet header. */ while (buflen >= UFTDI_IHDRSIZE) { usbd_copy_out(pc, offset, buf, UFTDI_IHDRSIZE); offset += UFTDI_IHDRSIZE; buflen -= UFTDI_IHDRSIZE; + lsr &= ~(ULSR_TXRDY | ULSR_TSRE); lsr |= FTDI_GET_LSR(buf); if (FTDI_GET_MSR(buf) & FTDI_SIO_RI_MASK) msr |= SER_RI; @@ -1311,8 +1318,7 @@ uftdi_read_callback(struct usb_xfer *xfe if (ftdi_msr & FTDI_SIO_RLSD_MASK) msr |= SER_DCD; - if ((sc->sc_msr != msr) || - ((sc->sc_lsr & FTDI_LSR_MASK) != (lsr & FTDI_LSR_MASK))) { + if (sc->sc_msr != msr || sc->sc_lsr != lsr) { DPRINTF("status change msr=0x%02x (0x%02x) " "lsr=0x%02x (0x%02x)\n", msr, sc->sc_msr, lsr, sc->sc_lsr); Modified: head/sys/dev/usb/serial/usb_serial.c ============================================================================== --- head/sys/dev/usb/serial/usb_serial.c Sun Feb 5 14:25:31 2017 (r313286) +++ head/sys/dev/usb/serial/usb_serial.c Sun Feb 5 15:45:31 2017 (r313287) @@ -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 * Modified: head/sys/dev/usb/serial/usb_serial.h ============================================================================== --- head/sys/dev/usb/serial/usb_serial.h Sun Feb 5 14:25:31 2017 (r313286) +++ head/sys/dev/usb/serial/usb_serial.h Sun Feb 5 15:45:31 2017 (r313287) @@ -180,6 +180,7 @@ struct ucom_softc { #define UCOM_FLAG_WAIT_REFS 0x0100 /* set if we must wait for refs */ #define UCOM_FLAG_FREE_UNIT 0x0200 /* set if we must free the unit */ #define UCOM_FLAG_INWAKEUP 0x0400 /* set if we are in the tsw_inwakeup callback */ +#define UCOM_FLAG_LSRTXIDLE 0x0800 /* set if sc_lsr bits ULSR_TSRE+TXRDY work */ uint8_t sc_lsr; uint8_t sc_msr; uint8_t sc_mcr; @@ -218,4 +219,12 @@ void ucom_drain(struct ucom_super_softc void ucom_drain_all(void *); void ucom_ref(struct ucom_super_softc *); int ucom_unref(struct ucom_super_softc *); + +static inline void +ucom_use_lsr_txbits(struct ucom_softc *sc) +{ + + sc->sc_flag |= UCOM_FLAG_LSRTXIDLE; +} + #endif /* _USB_SERIAL_H_ */ _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
