diff options
Diffstat (limited to 'nuttx/arch/arm/src/lpc31xx/lpc31_lowputc.c')
| -rwxr-xr-x | nuttx/arch/arm/src/lpc31xx/lpc31_lowputc.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/lpc31xx/lpc31_lowputc.c b/nuttx/arch/arm/src/lpc31xx/lpc31_lowputc.c new file mode 100755 index 0000000000..7d8a7cc325 --- /dev/null +++ b/nuttx/arch/arm/src/lpc31xx/lpc31_lowputc.c @@ -0,0 +1,356 @@ +/**************************************************************************** + * arch/arm/src/lpc31xx/lpc31_lowputc.c + * + * Copyright (C) 2009-2010 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <sys/types.h> +#include <stdint.h> +#include <debug.h> + +#include <nuttx/arch.h> + +#include "up_arch.h" +#include "up_internal.h" + +#include "lpc31_cgudrvr.h" +#include "lpc31_uart.h" + +/**************************************************************************** + * Definitions + ****************************************************************************/ + +/* Configuration ************************************************************/ + +/* Is the UART enabled? */ + +#ifdef CONFIG_LPC31_UART +# define HAVE_UART 1 + +/* Is it a serial console? */ + +# ifdef CONFIG_UART_SERIAL_CONSOLE +# define HAVE_CONSOLE 1 + + /* Is initialization performed by up_earlyserialinit()? Or is UART + * initialization suppressed? + */ + +# if defined(CONFIG_USE_EARLYSERIALINIT) || defined(CONFIG_SUPPRESS_LPC31_UART_CONFIG) +# undef NEED_LOWSETUP +# else +# define NEED_LOWSETUP 1 +# endif +# else +# undef HAVE_CONSOLE +# undef NEED_LOWSETUP +# endif + +#else +# undef HAVE_UART +# undef HAVE_CONSOLE +# undef NEED_LOWSETUP +#endif + +/**************************************************************************** + * Private Types + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: up_waittxready + ****************************************************************************/ + +#ifdef HAVE_CONSOLE +static inline void up_waittxready(void) +{ + int tmp; + + /* Limit how long we will wait for the TX available condition */ + + for (tmp = 1000 ; tmp > 0 ; tmp--) + { + /* Check if the tranmitter holding register (THR) is empty */ + + if ((getreg32(LPC31_UART_LSR) & UART_LSR_THRE) != 0) + { + /* The THR is empty, return */ + + break; + } + } +} +#endif + +/**************************************************************************** + * Name: up_configbaud + ****************************************************************************/ + +#ifdef NEED_LOWSETUP +static inline void up_configbaud(void) +{ + /* In a buckled-up, embedded system, there is no reason to constantly + * calculate the following. The calculation can be skipped if the + * MULVAL, DIVADDVAL, and DIVISOR values are provided in the configuration + * file. + */ + +#ifndef CONFIG_LPC31_UART_MULVAL + uint32_t qtrclk; + uint32_t regval; + + /* Test values calculated for every multiplier/divisor combination */ + + uint32_t tdiv; + uint32_t terr; + int tmulval; + int tdivaddval; + + /* Optimal multiplier/divider values */ + + uint32_t div = 0; + uint32_t err = 100000; + int mulval = 1; + int divaddval = 0; + + /* Baud is generated using FDR and DLL-DLM registers + * + * baud = clock * (mulval/(mulval+divaddval) / (16 * div) + * + * Or + * + * div = (clock/16) * (mulval/(mulval+divaddval) / baud + * + * Where mulval = Fractional divider multiplier + * divaddval = Fractional divider pre-scale div + * div = DLL-DLM divisor + */ + + /* Get UART block clock divided by 16 */ + + qtrclk = lpc31_clkfreq(CLKID_UARTUCLK, DOMAINID_UART) >> 4; + + /* Try every valid multiplier, tmulval (or until a perfect + * match is found). + */ + + for (tmulval = 1 ; tmulval <= 15 && err > 0; tmulval++) + { + /* Try every valid pre-scale div, tdivaddval (or until a perfect + * match is found). + */ + + for (tdivaddval = 0 ; tdivaddval <= 15 && err > 0; tdivaddval++) + { + /* Calculate the divisor with these fractional divider settings */ + + uint32_t tmp = (tmulval * qtrclk) / ((tmulval + tdivaddval)); + tdiv = (tmp + (CONFIG_UART_BAUD>>1)) / CONFIG_UART_BAUD; + + /* Check if this candidate divisor is within a valid range */ + + if (tdiv > 2 && tdiv < 0x10000) + { + /* Calculate the actual baud and the error */ + + uint32_t actualbaud = tmp / tdiv; + + if (actualbaud <= CONFIG_UART_BAUD) + { + terr = CONFIG_UART_BAUD - actualbaud; + } + else + { + terr = actualbaud - CONFIG_UART_BAUD; + } + + /* Is this the smallest error we have encountered? */ + + if (terr < err) + { + /* Yes, save these settings as the new, candidate optimal settings */ + + mulval = tmulval ; + divaddval = tdivaddval; + div = tdiv; + err = terr; + } + } + } + } + + /* Set the Divisor Latch Access Bit (DLAB) to enable DLL/DLM access */ + + regval = getreg32(LPC31_UART_LCR); + regval |= UART_LCR_DLAB; + putreg32(regval, LPC31_UART_LCR); + + /* Configure the MS and LS DLAB registers */ + + putreg32(div & UART_DLL_MASK, LPC31_UART_DLL); + putreg32((div >> 8) & UART_DLL_MASK, LPC31_UART_DLM); + + regval &= ~UART_LCR_DLAB; + putreg32(regval, LPC31_UART_LCR); + + /* Configure the Fractional Divider Register (FDR) */ + + putreg32((mulval << UART_FDR_MULVAL_SHIFT) | + (divaddval << UART_FDR_DIVADDVAL_SHIFT), + LPC31_UART_FDR); +#else + /* Set the Divisor Latch Access Bit (DLAB) to enable DLL/DLM access */ + + regval = getreg32(LPC31_UART_LCR); + regval |= UART_LCR_DLAB; + putreg32(regval, LPC31_UART_LCR); + + /* Configure the MS and LS DLAB registers */ + + putreg32(CONFIG_LPC31_UART_DIVISOR & UART_DLL_MASK, LPC31_UART_DLL); + putreg32((CONFIG_LPC31_UART_DIVISOR >> 8) & UART_DLL_MASK, LPC31_UART_DLM); + + regval &= ~UART_LCR_DLAB; + putreg32(regval, LPC31_UART_LCR); + + /* Configure the Fractional Divider Register (FDR) */ + + putreg32((CONFIG_LPC31_UART_MULVAL << UART_FDR_MULVAL_SHIFT) | + (CONFIG_LPC31_UART_DIVADDVAL << UART_FDR_DIVADDVAL_SHIFT), + LPC31_UART_FDR); +#endif +} +#endif + +/**************************************************************************** + * Public Functions + ****************************************************************************/ +/**************************************************************************** + * Name: lpc31_lowsetup + * + * Description: + * Called early in up_boot. Performs chip-common low level initialization. + * + ****************************************************************************/ + +void lpc31_lowsetup(void) +{ +#ifdef NEED_LOWSETUP + uint32_t regval; + + /* Enable UART system clock */ + + lpc31_enableclock(CLKID_UARTAPBCLK); + lpc31_enableclock(CLKID_UARTUCLK); + + /* Clear fifos */ + + putreg32((UART_FCR_RXFIFORST|UART_FCR_TXFIFORST), LPC31_UART_FCR); + + /* Set trigger */ + + putreg32((UART_FCR_FIFOENABLE|UART_FCR_RXTRIGLEVEL_16), LPC31_UART_FCR); + + /* Set up the LCR */ + + regval = 0; + +#if CONFIG_UART_BITS == 5 + regval |= UART_LCR_WDLENSEL_5BITS; +#elif CONFIG_UART_BITS == 6 + regval |= UART_LCR_WDLENSEL_6BITS; +#elif CONFIG_UART_BITS == 7 + regval |= UART_LCR_WDLENSEL_7BITS; +#else + regval |= UART_LCR_WDLENSEL_8BITS; +#endif + +#if CONFIG_UART_2STOP > 0 + regval |= UART_LCR_NSTOPBITS; +#endif + +#if CONFIG_UART_PARITY == 1 + regval |= UART_LCR_PAREN; +#elif CONFIG_UART_PARITY == 2 + regval |= (UART_LCR_PAREVEN|UART_LCR_PAREN); +#endif + putreg32(regval, LPC31_UART_LCR); + + /* Set the BAUD divisor */ + + up_configbaud(); + + /* Configure the FIFOs */ + + putreg32((UART_FCR_RXTRIGLEVEL_16|UART_FCR_TXFIFORST| + UART_FCR_RXFIFORST|UART_FCR_FIFOENABLE), + LPC31_UART_FCR); + + /* The NuttX serial driver waits for the first THRE interrrupt before + * sending serial data... However, it appears that the lpc313x hardware + * does not generate that interrupt until a transition from not-empty + * to empty. So, the current kludge here is to send one NULL at + * startup to kick things off. + */ + + putreg32('\0', LPC31_UART_THR); +#endif +} + +/**************************************************************************** + * Name: up_lowputc + * + * Description: + * Provide priority, low-level access to support OS debug writes + * + ****************************************************************************/ + +void up_lowputc(char ch) +{ +#ifdef HAVE_CONSOLE + up_waittxready(); + putreg32((uint32_t)ch, LPC31_UART_THR); +#endif +} |