contiki/cpu/cc2538/dev/uart.c

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/*
* Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
* All rights reserved.
*
* 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 of the copyright holder 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 HOLDER 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.
*/
/**
* \addtogroup cc2538-uart
* @{
*
* \file
* Implementation of the cc2538 UART driver
*/
#include "contiki.h"
#include "sys/energest.h"
#include "dev/sys-ctrl.h"
#include "dev/ioc.h"
#include "dev/gpio.h"
#include "dev/uart.h"
#include "lpm.h"
#include "reg.h"
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
static int (* input_handler)(unsigned char c);
/*---------------------------------------------------------------------------*/
/*
* Once we know what UART we're on, configure correct values to be written to
* the correct registers
*/
#if UART_BASE==UART_1_BASE
/* Running, in sleep, in deep sleep, enable the clock for the correct UART */
#define SYS_CTRL_RCGCUART_UART SYS_CTRL_RCGCUART_UART1
#define SYS_CTRL_SCGCUART_UART SYS_CTRL_SCGCUART_UART1
#define SYS_CTRL_DCGCUART_UART SYS_CTRL_DCGCUART_UART1
#define NVIC_INT_UART NVIC_INT_UART1
#define IOC_PXX_SEL_UART_TXD IOC_PXX_SEL_UART1_TXD
#define IOC_UARTRXD_UART IOC_UARTRXD_UART1
#else /* Defaults for UART0 */
#define SYS_CTRL_RCGCUART_UART SYS_CTRL_RCGCUART_UART0
#define SYS_CTRL_SCGCUART_UART SYS_CTRL_SCGCUART_UART0
#define SYS_CTRL_DCGCUART_UART SYS_CTRL_DCGCUART_UART0
#define NVIC_INT_UART NVIC_INT_UART0
#define IOC_PXX_SEL_UART_TXD IOC_PXX_SEL_UART0_TXD
#define IOC_UARTRXD_UART IOC_UARTRXD_UART0
#endif
/*---------------------------------------------------------------------------*/
static void
reset(void)
{
uint32_t lchr;
/* Make sure the UART is disabled before trying to configure it */
REG(UART_BASE | UART_CTL) = UART_CTL_TXE | UART_CTL_RXE;
/* Clear error status */
REG(UART_BASE | UART_ECR) = 0xFF;
/* Store LCHR configuration */
lchr = REG(UART_BASE | UART_LCRH);
/* Flush FIFOs by clearing LCHR.FEN */
REG(UART_BASE | UART_LCRH) = 0;
/* Restore LCHR configuration */
REG(UART_BASE | UART_LCRH) = lchr;
/* UART Enable */
REG(UART_BASE | UART_CTL) |= UART_CTL_UARTEN;
}
/*---------------------------------------------------------------------------*/
static bool
permit_pm1(void)
{
/* Note: UART_FR.TXFE reads 0 if the UART clock is gated. */
return (REG(SYS_CTRL_RCGCUART) & SYS_CTRL_RCGCUART_UART) == 0 ||
(REG(UART_BASE | UART_FR) & UART_FR_TXFE) != 0;
}
/*---------------------------------------------------------------------------*/
void
uart_init(void)
{
lpm_register_peripheral(permit_pm1);
/* Enable clock for the UART while Running, in Sleep and Deep Sleep */
REG(SYS_CTRL_RCGCUART) |= SYS_CTRL_RCGCUART_UART;
REG(SYS_CTRL_SCGCUART) |= SYS_CTRL_SCGCUART_UART;
REG(SYS_CTRL_DCGCUART) |= SYS_CTRL_DCGCUART_UART;
/* Run on SYS_DIV */
REG(UART_BASE | UART_CC) = 0;
/*
* Select the UARTx RX pin by writing to the IOC_UARTRXD_UARTn register
*
* The value to be written will be on of the IOC_INPUT_SEL_Pxn defines from
* ioc.h. The value can also be calculated as:
*
* (port << 3) + pin
*/
REG(IOC_UARTRXD_UART) = (UART_RX_PORT << 3) + UART_RX_PIN;
/*
* Pad Control for the TX pin:
* - Set function to UART0 TX
* - Output Enable
*/
ioc_set_sel(UART_TX_PORT, UART_TX_PIN, IOC_PXX_SEL_UART_TXD);
ioc_set_over(UART_TX_PORT, UART_TX_PIN, IOC_OVERRIDE_OE);
/* Set RX and TX pins to peripheral mode */
GPIO_PERIPHERAL_CONTROL(GPIO_PORT_TO_BASE(UART_TX_PORT), GPIO_PIN_MASK(UART_TX_PIN));
GPIO_PERIPHERAL_CONTROL(GPIO_PORT_TO_BASE(UART_RX_PORT), GPIO_PIN_MASK(UART_RX_PIN));
/*
* UART Interrupt Masks:
* Acknowledge RX and RX Timeout
* Acknowledge Framing, Overrun and Break Errors
*/
REG(UART_BASE | UART_IM) = UART_IM_RXIM | UART_IM_RTIM;
REG(UART_BASE | UART_IM) |= UART_IM_OEIM | UART_IM_BEIM | UART_IM_FEIM;
REG(UART_BASE | UART_IFLS) =
UART_IFLS_RXIFLSEL_1_8 | UART_IFLS_TXIFLSEL_1_2;
/* Make sure the UART is disabled before trying to configure it */
REG(UART_BASE | UART_CTL) = UART_CTL_TXE | UART_CTL_RXE;
/* Baud Rate Generation */
REG(UART_BASE | UART_IBRD) = UART_CONF_IBRD;
REG(UART_BASE | UART_FBRD) = UART_CONF_FBRD;
/* UART Control: 8N1 with FIFOs */
REG(UART_BASE | UART_LCRH) = UART_LCRH_WLEN_8 | UART_LCRH_FEN;
/* UART Enable */
REG(UART_BASE | UART_CTL) |= UART_CTL_UARTEN;
/* Enable UART0 Interrupts */
nvic_interrupt_enable(NVIC_INT_UART);
}
/*---------------------------------------------------------------------------*/
void
uart_set_input(int (* input)(unsigned char c))
{
input_handler = input;
}
/*---------------------------------------------------------------------------*/
void
uart_write_byte(uint8_t b)
{
/* Block if the TX FIFO is full */
while(REG(UART_BASE | UART_FR) & UART_FR_TXFF);
REG(UART_BASE | UART_DR) = b;
}
/*---------------------------------------------------------------------------*/
void
uart_isr(void)
{
uint16_t mis;
ENERGEST_ON(ENERGEST_TYPE_IRQ);
/* Store the current MIS and clear all flags early, except the RTM flag.
* This will clear itself when we read out the entire FIFO contents */
mis = REG(UART_BASE | UART_MIS) & 0x0000FFFF;
REG(UART_BASE | UART_ICR) = 0x0000FFBF;
if(mis & (UART_MIS_RXMIS | UART_MIS_RTMIS)) {
while(!(REG(UART_BASE | UART_FR) & UART_FR_RXFE)) {
if(input_handler != NULL) {
input_handler((unsigned char)(REG(UART_BASE | UART_DR) & 0xFF));
} else {
/* To prevent an Overrun Error, we need to flush the FIFO even if we
* don't have an input_handler. Use mis as a data trash can */
mis = REG(UART_BASE | UART_DR);
}
}
} else if(mis & (UART_MIS_OEMIS | UART_MIS_BEMIS | UART_MIS_FEMIS)) {
/* ISR triggered due to some error condition */
reset();
}
ENERGEST_OFF(ENERGEST_TYPE_IRQ);
}
/** @} */