/**************************************************************************** * arch/arm/src/lpc31xx/lpc31_lowputc.c * * Copyright (C) 2009-2010, 2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #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(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 }