From owner-svn-src-head@FreeBSD.ORG Sun Oct 12 17:56:03 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 859C8CA4; Sun, 12 Oct 2014 17:56:03 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 71BC0351; Sun, 12 Oct 2014 17:56:03 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id s9CHu3Vc082787; Sun, 12 Oct 2014 17:56:03 GMT (envelope-from ian@FreeBSD.org) Received: (from ian@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id s9CHu3Hp082786; Sun, 12 Oct 2014 17:56:03 GMT (envelope-from ian@FreeBSD.org) Message-Id: <201410121756.s9CHu3Hp082786@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: ian set sender to ian@FreeBSD.org using -f From: Ian Lepore Date: Sun, 12 Oct 2014 17:56:03 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r273004 - head/sys/dev/uart X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Oct 2014 17:56:03 -0000 Author: ian Date: Sun Oct 12 17:56:02 2014 New Revision: 273004 URL: https://svnweb.freebsd.org/changeset/base/273004 Log: Use the FIFOs in the imx5/imx6 uart hardware instead of interrupting on each byte sent or received. Modified: head/sys/dev/uart/uart_dev_imx.c Modified: head/sys/dev/uart/uart_dev_imx.c ============================================================================== --- head/sys/dev/uart/uart_dev_imx.c Sun Oct 12 17:50:25 2014 (r273003) +++ head/sys/dev/uart/uart_dev_imx.c Sun Oct 12 17:56:02 2014 (r273004) @@ -49,6 +49,17 @@ __FBSDID("$FreeBSD$"); #include /* + * The hardare FIFOs are 32 bytes. We want an interrupt when there are 24 bytes + * available to read or space for 24 more bytes to write. While 8 bytes of + * slack before over/underrun might seem excessive, the hardware can run at + * 5mbps, which means 2uS per char, so at full speed 8 bytes provides only 16uS + * to get into the interrupt handler and service the fifo. + */ +#define IMX_FIFOSZ 32 +#define IMX_RXFIFO_LEVEL 24 +#define IMX_TXFIFO_LEVEL 24 + +/* * Low-level UART interface. */ static int imx_uart_probe(struct uart_bas *bas); @@ -187,6 +198,17 @@ imx_uart_init(struct uart_bas *bas, int SETREG(bas, REG(UBIR), 15); SETREG(bas, REG(UBMR), (baseclk / baudrate) - 1); } + + /* + * Program the tx lowater and rx hiwater levels at which fifo-service + * interrupts are signaled. The tx value is interpetted as "when there + * are only this many bytes remaining" (not "this many free"). + */ + reg = GETREG(bas, REG(UFCR)); + reg &= ~(IMXUART_UFCR_TXTL_MASK | IMXUART_UFCR_RXTL_MASK); + reg |= (IMX_FIFOSZ - IMX_TXFIFO_LEVEL) << IMXUART_UFCR_TXTL_SHIFT; + reg |= IMX_RXFIFO_LEVEL << IMXUART_UFCR_RXTL_SHIFT; + SETREG(bas, REG(UFCR), reg); } static void @@ -199,7 +221,7 @@ static void imx_uart_putc(struct uart_bas *bas, int c) { - while (!(IS(bas, USR2, TXFE))) + while (!(IS(bas, USR1, TRDY))) ; SETREG(bas, REG(UTXD), c); } @@ -302,11 +324,15 @@ imx_uart_bus_attach(struct uart_softc *s (void)imx_uart_bus_getsig(sc); - ENA(bas, UCR4, DREN); - DIS(bas, UCR1, RRDYEN); + /* Clear all pending interrupts. */ + SETREG(bas, REG(USR1), 0xffff); + SETREG(bas, REG(USR2), 0xffff); + + DIS(bas, UCR4, DREN); + ENA(bas, UCR1, RRDYEN); DIS(bas, UCR1, IDEN); DIS(bas, UCR3, RXDSEN); - DIS(bas, UCR2, ATEN); + ENA(bas, UCR2, ATEN); DIS(bas, UCR1, TXMPTYEN); DIS(bas, UCR1, TRDYEN); DIS(bas, UCR4, TCEN); @@ -330,9 +356,6 @@ imx_uart_bus_attach(struct uart_softc *s ENA(bas, UCR2, IRTS); ENA(bas, UCR3, RXDMUXSEL); - /* ACK all interrupts */ - SETREG(bas, REG(USR1), 0xffff); - SETREG(bas, REG(USR2), 0xffff); return (0); } @@ -404,7 +427,7 @@ imx_uart_bus_ipend(struct uart_softc *sc struct uart_bas *bas; int ipend; uint32_t usr1, usr2; - uint32_t ucr1, ucr4; + uint32_t ucr1, ucr2, ucr4; bas = &sc->sc_bas; ipend = 0; @@ -419,18 +442,28 @@ imx_uart_bus_ipend(struct uart_softc *sc SETREG(bas, REG(USR2), usr2); ucr1 = GETREG(bas, REG(UCR1)); + ucr2 = GETREG(bas, REG(UCR2)); ucr4 = GETREG(bas, REG(UCR4)); - if ((usr2 & FLD(USR2, TXFE)) && (ucr1 & FLD(UCR1, TXMPTYEN))) { - DIS(bas, UCR1, TXMPTYEN); - /* Continue TXing */ + /* If we have reached tx low-water, we can tx some more now. */ + if ((usr1 & FLD(USR1, TRDY)) && (ucr1 & FLD(UCR1, TRDYEN))) { + DIS(bas, UCR1, TRDYEN); ipend |= SER_INT_TXIDLE; } - if ((usr2 & FLD(USR2, RDR)) && (ucr4 & FLD(UCR4, DREN))) { - DIS(bas, UCR4, DREN); - /* Wow, new char on input */ + + /* + * If we have reached the rx high-water, or if there are bytes in the rx + * fifo and no new data has arrived for 8 character periods (aging + * timer), we have input data to process. + */ + if (((usr1 & FLD(USR1, RRDY)) && (ucr1 & FLD(UCR1, RRDYEN))) || + ((usr1 & FLD(USR1, AGTIM)) && (ucr2 & FLD(UCR2, ATEN)))) { + DIS(bas, UCR1, RRDYEN); + DIS(bas, UCR2, ATEN); ipend |= SER_INT_RXREADY; } + + /* A break can come in at any time, it never gets disabled. */ if ((usr2 & FLD(USR2, BRCD)) && (ucr4 & FLD(UCR4, BKEN))) ipend |= SER_INT_BREAK; @@ -459,8 +492,14 @@ imx_uart_bus_probe(struct uart_softc *sc if (error) return (error); - sc->sc_rxfifosz = 1; - sc->sc_txfifosz = 1; + /* + * On input we can read up to the full fifo size at once. On output, we + * want to write only as much as the programmed tx low water level, + * because that's all we can be certain we have room for in the fifo + * when we get a tx-ready interrupt. + */ + sc->sc_rxfifosz = IMX_FIFOSZ; + sc->sc_txfifosz = IMX_TXFIFO_LEVEL; device_set_desc(sc->sc_dev, "Freescale i.MX UART"); return (0); @@ -475,20 +514,20 @@ imx_uart_bus_receive(struct uart_softc * bas = &sc->sc_bas; uart_lock(sc->sc_hwmtx); - /* Read while we have anything in FIFO */ + /* + * Empty the rx fifo. We get the RRDY interrupt when IMX_RXFIFO_LEVEL + * (the rx high-water level) is reached, but we set sc_rxfifosz to the + * full hardware fifo size, so we can safely process however much is + * there, not just the highwater size. + */ while (IS(bas, USR2, RDR)) { if (uart_rx_full(sc)) { /* No space left in input buffer */ sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN; break; } - out = 0; xc = GETREG(bas, REG(URXD)); - - /* We have valid char */ - if (xc & FLD(URXD, CHARRDY)) - out = xc & 0x000000ff; - + out = xc & 0x000000ff; if (xc & FLD(URXD, FRMERR)) out |= UART_STAT_FRAMERR; if (xc & FLD(URXD, PRERR)) @@ -500,8 +539,8 @@ imx_uart_bus_receive(struct uart_softc * uart_rx_put(sc, out); } - /* Reenable Data Ready interrupt */ - ENA(bas, UCR4, DREN); + ENA(bas, UCR1, RRDYEN); + ENA(bas, UCR2, ATEN); uart_unlock(sc->sc_hwmtx); return (0); @@ -523,14 +562,17 @@ imx_uart_bus_transmit(struct uart_softc bas = &sc->sc_bas; uart_lock(sc->sc_hwmtx); - /* Fill TX FIFO */ + /* + * Fill the tx fifo. The uart core puts at most IMX_TXFIFO_LEVEL bytes + * into the txbuf (because that's what sc_txfifosz is set to), and + * because we got the TRDY (low-water reached) interrupt we know at + * least that much space is available in the fifo. + */ for (i = 0; i < sc->sc_txdatasz; i++) { SETREG(bas, REG(UTXD), sc->sc_txbuf[i] & 0xff); } - sc->sc_txbusy = 1; - /* Call me when ready */ - ENA(bas, UCR1, TXMPTYEN); + ENA(bas, UCR1, TRDYEN); uart_unlock(sc->sc_hwmtx); @@ -544,7 +586,8 @@ imx_uart_bus_grab(struct uart_softc *sc) bas = &sc->sc_bas; uart_lock(sc->sc_hwmtx); - DIS(bas, UCR4, DREN); + DIS(bas, UCR1, RRDYEN); + DIS(bas, UCR2, ATEN); uart_unlock(sc->sc_hwmtx); } @@ -555,6 +598,7 @@ imx_uart_bus_ungrab(struct uart_softc *s bas = &sc->sc_bas; uart_lock(sc->sc_hwmtx); - ENA(bas, UCR4, DREN); + ENA(bas, UCR1, RRDYEN); + ENA(bas, UCR2, ATEN); uart_unlock(sc->sc_hwmtx); }