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author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2009-05-11 22:54:50 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2009-05-11 22:54:50 +0000 |
commit | 653293320a64e69454ee832e23bd2d9203580f92 (patch) | |
tree | a9312cdc29992361f51cbf4684cc651eca19716d /nuttx/arch/arm/src/lm3s/lm3s_lowputc.c | |
parent | 00bbb58c99ff728e82d633acd3b7059233801674 (diff) | |
download | px4-nuttx-653293320a64e69454ee832e23bd2d9203580f92.tar.gz px4-nuttx-653293320a64e69454ee832e23bd2d9203580f92.tar.bz2 px4-nuttx-653293320a64e69454ee832e23bd2d9203580f92.zip |
Add low-level console support for LM3S3918
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1770 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/arch/arm/src/lm3s/lm3s_lowputc.c')
-rw-r--r-- | nuttx/arch/arm/src/lm3s/lm3s_lowputc.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/lm3s/lm3s_lowputc.c b/nuttx/arch/arm/src/lm3s/lm3s_lowputc.c new file mode 100644 index 000000000..554e57f7f --- /dev/null +++ b/nuttx/arch/arm/src/lm3s/lm3s_lowputc.c @@ -0,0 +1,265 @@ +/************************************************************************** + * arch/arm/src/lm3s/lm3s_lowputc.c + * + * Copyright (C) 2009 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 "up_internal.h" +#include "up_arch.h" + +#include "chip.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 PCLK1: + * + * "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 = 20,000,000: + * + * LM3S_BRDDEN = (16 * 115,200) = 1,843,200 + * LM3S_BRDI = 20,000,000 / 1,843,200 = 10 + * LM3S_REMAINDER = 20,000,000 - 1,843,200 * 10 = 1,568,000 + * LM3S_DIVFRAC = (1,568,000 * 64 + 921,600) / 1,843,200 = 54 + * + * Which should yied BAUD = 20,000,000 / (16 * (10 + 54/64)) = 115273.8 + */ + +/************************************************************************** + * 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) +{ +#ifdef HAVE_CONSOLE + uint16 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; + putreg32(ctl, LM3S_CONSOLE_BASE+LM3S_UART_CTL_OFFSET); +#endif + + /* Configure GPIO pins to enable all UARTs in the configuration + * (the serial driver later depends on this configuration) + */ + +#ifndef CONFIG_UART0_DISABLE + lm3x_configgpio(GPIO_UART0_RX); + lm3x_configgpio(GPIO_UART0_TX); +#endif + +#ifndef CONFIG_UART1_DISABLE + lm3x_configgpio(GPIO_UART1_RX); + lm3x_configgpio(GPIO_UART1_TX); +#endif +} + + |