/************************************************************************** * arch/arm/src/lm3s/lm3s_lowputc.c * * Copyright (C) 2009 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 "up_internal.h" #include "up_arch.h" #include "chip.h" #include "lm3s_internal.h" /************************************************************************** * Private Definitions **************************************************************************/ /* Configuration **********************************************************/ /* Is there a serial console? */ #if defined(CONFIG_UART0_SERIAL_CONSOLE) && !defined(CONFIG_UART0_DISABLE) # undef CONFIG_UART1_SERIAL_CONSOLE # define HAVE_CONSOLE 1 #elif defined(CONFIG_UART1_SERIAL_CONSOLE) && !defined(CONFIG_UART1_DISABLE) # undef CONFIG_UART0_SERIAL_CONSOLE # define HAVE_CONSOLE 1 #else # undef CONFIG_UART0_SERIAL_CONSOLE # undef CONFIG_UART1_SERIAL_CONSOLE # undef HAVE_CONSOLE #endif /* Select UART parameters for the selected console */ #if defined(CONFIG_UART0_SERIAL_CONSOLE) # define LM3S_CONSOLE_BASE LM3S_UART0_BASE # define LM3S_CONSOLE_BAUD CONFIG_UART0_BAUD # define LM3S_CONSOLE_BITS CONFIG_UART0_BITS # define LM3S_CONSOLE_PARITY CONFIG_UART0_PARITY # define LM3S_CONSOLE_2STOP CONFIG_UART0_2STOP #elif defined(CONFIG_UART1_SERIAL_CONSOLE) # define LM3S_CONSOLE_BASE LM3S_UART1_BASE # define LM3S_CONSOLE_BAUD CONFIG_UART1_BAUD # define LM3S_CONSOLE_BITS CONFIG_UART1_BITS # define LM3S_CONSOLE_PARITY CONFIG_UART1_PARITY # define LM3S_CONSOLE_2STOP CONFIG_UART1_2STOP #else # error "No CONFIG_UARTn_SERIAL_CONSOLE Setting" #endif /* Get LCRH settings */ #if LM3S_CONSOLE_BITS == 5 # define UART_LCRH_NBITS UART_LCRH_WLEN_5BITS #elif LM3S_CONSOLE_BITS == 6 # define UART_LCRH_NBITS UART_LCRH_WLEN_6BITS #elif LM3S_CONSOLE_BITS == 7 # define UART_LCRH_NBITS UART_LCRH_WLEN_7BITS #elif LM3S_CONSOLE_BITS == 8 # define UART_LCRH_NBITS UART_LCRH_WLEN_8BITS #else # error "Number of bits not supported" #endif #if LM3S_CONSOLE_PARITY == 0 # define UART_LCRH_PARITY (0) #elif LM3S_CONSOLE_PARITY == 1 # define UART_LCRH_PARITY UART_LCRH_PEN #elif LM3S_CONSOLE_PARITY == 2 # define UART_LCRH_PARITY (UART_LCRH_PEN|UART_LCRH_EPS) #else # error "Invalid parity selection" #endif #if LM3S_CONSOLE_2STOP != 0 # define UART_LCRH_NSTOP UART_LCRH_STP2 #else # define UART_LCRH_NSTOP (0) #endif #define UART_LCRH_VALUE (UART_LCRH_NBITS|UART_LCRH_PARITY|UART_LCRH_NSTOP|UART_LCRH_FEN) /* Calculate BAUD rate from the SYS clock: * * "The baud-rate divisor is a 22-bit number consisting of a 16-bit integer and a 6-bit * fractional part. The number formed by these two values is used by the baud-rate generator * to determine the bit period. Having a fractional baud-rate divider allows the UART to * generate all the standard baud rates. * * "The 16-bit integer is loaded through the UART Integer Baud-Rate Divisor (UARTIBRD) * register ... and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate * Divisor (UARTFBRD) register... The baud-rate divisor (BRD) has the following relationship * to the system clock (where BRDI is the integer part of the BRD and BRDF is the fractional * part, separated by a decimal place.): * * "BRD = BRDI + BRDF = UARTSysClk / (16 * Baud Rate) * * "where UARTSysClk is the system clock connected to the UART. The 6-bit fractional number * (that is to be loaded into the DIVFRAC bit field in the UARTFBRD register) can be calculated * by taking the fractional part of the baud-rate divisor, multiplying it by 64, and adding 0.5 * to account for rounding errors: * * "UARTFBRD[DIVFRAC] = integer(BRDF * 64 + 0.5) * * "The UART generates an internal baud-rate reference clock at 16x the baud-rate (referred * to as Baud16). This reference clock is divided by 16 to generate the transmit clock, and is * used for error detection during receive operations. * * "Along with the UART Line Control, High Byte (UARTLCRH) register ..., the UARTIBRD and * UARTFBRD registers form an internal 30-bit register. This internal register is only * updated when a write operation to UARTLCRH is performed, so any changes to the baud-rate * divisor must be followed by a write to the UARTLCRH register for the changes to take effect. ..." */ #define LM3S_BRDDEN (16 * LM3S_CONSOLE_BAUD) #define LM3S_BRDI (SYSCLK_FREQUENCY / LM3S_BRDDEN) #define LM3S_REMAINDER (SYSCLK_FREQUENCY - LM3S_BRDDEN * LM3S_BRDI) #define LM3S_DIVFRAC ((LM3S_REMAINDER * 64 + (LM3S_BRDDEN/2)) / LM3S_BRDDEN) /* For example: LM3S_CONSOLE_BAUD = 115,200, SYSCLK_FREQUENCY = 50,000,000: * * LM3S_BRDDEN = (16 * 115,200) = 1,843,200 * LM3S_BRDI = 50,000,000 / 1,843,200 = 27 * LM3S_REMAINDER = 50,000,000 - 1,843,200 * 27 = 233,600 * LM3S_DIVFRAC = (233,600 * 64 + 921,600) / 1,843,200 = 8 * * Which should yied BAUD = 50,000,000 / (16 * (27 + 8/64)) = 115207.37 */ /************************************************************************** * Private Types **************************************************************************/ /************************************************************************** * Private Function Prototypes **************************************************************************/ /************************************************************************** * Global Variables **************************************************************************/ /************************************************************************** * Private Variables **************************************************************************/ /************************************************************************** * Private Functions **************************************************************************/ /************************************************************************** * Public Functions **************************************************************************/ /************************************************************************** * Name: up_lowputc * * Description: * Output one byte on the serial console * **************************************************************************/ void up_lowputc(char ch) { #ifdef HAVE_CONSOLE /* Wait until the TX FIFO is not full */ while ((getreg32(LM3S_CONSOLE_BASE+LM3S_UART_FR_OFFSET) & UART_FR_TXFF) != 0); /* Then send the character */ putreg32((uint32)ch, LM3S_CONSOLE_BASE+LM3S_UART_DR_OFFSET); #endif } /************************************************************************** * Name: up_lowsetup * * Description: * This performs basic initialization of the UART used for the serial * console. Its purpose is to get the console output availabe as soon * as possible. * **************************************************************************/ void up_lowsetup(void) { #if defined(HAVE_CONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG) uint32 ctl; /* Enable the selected console device */ /* 1. Disable the UART by clearing the UARTEN bit in the UART CTL register */ ctl = getreg32(LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET); ctl &= ~UART_CTL_UARTEN; putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET); /* 2. Write the integer portion of the BRD to the UART IBRD register */ putreg32(LM3S_BRDI, LM3S_CONSOLE_BASE+LM3S_UART_IBRD_OFFSET); /* 3. Write the fractional portion of the BRD to the UART FBRD register */ putreg32(LM3S_DIVFRAC, LM3S_CONSOLE_BASE+LM3S_UART_FBRD_OFFSET); /* 4. Write the desired serial parameters to the UART LCRH register */ putreg32(UART_LCRH_VALUE, LM3S_CONSOLE_BASE+LM3S_UART_LCRH_OFFSET); /* 5. Enable the UART by setting the UARTEN bit in the UART CTL register */ ctl |= (UART_CTL_UARTEN|UART_CTL_TXE|UART_CTL_RXE); putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET); #endif /* Then configure GPIO pins to enable the selected UARTs. NOTE: The * serial driver later depends on this pin configuration. */ #ifndef CONFIG_UART0_DISABLE lm3s_configgpio(GPIO_UART0_RX); lm3s_configgpio(GPIO_UART0_TX); #endif #ifndef CONFIG_UART1_DISABLE lm3s_configgpio(GPIO_UART1_RX); lm3s_configgpio(GPIO_UART1_TX); #endif }