nes-proj/cpu/mc1322x/lib/uart.c

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/*
* Copyright (c) 2010, Mariano Alvira <mar@devl.org> and other contributors
* to the MC1322x project (http://mc1322x.devl.org)
* 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 Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of libmc1322x: see http://mc1322x.devl.org
* for details.
*
*
*/
#include <mc1322x.h>
#include <stdint.h>
#define MOD 9999
#define CLK 24000000
#define DIV 16 /* uart->CON.XTIM = 0 is 16x oversample (datasheet is incorrect) */
void uart_setbaud(volatile struct UART_struct * uart, uint32_t baud) {
uint64_t inc;
/* baud rate eqn from reference manual */
/* multiply by an additional 10 to do a fixed point round later */
inc = ((uint64_t) baud * DIV * MOD * 10 / CLK ) - 10 ;
/* add 5 and divide by 10 to get a rounding */
inc = (inc + 5) / 10;
/* UART must be disabled to set the baudrate */
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uart->CONbits.TXE = 0;
uart->CONbits.RXE = 0;
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uart->BR = ( (uint16_t)inc << 16 ) | MOD;
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uart->CONbits.XTIM = 0;
uart->CONbits.TXE = 1;
uart->CONbits.RXE = 1;
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}
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void uart_flowctl(volatile struct UART_struct * uart, uint8_t on) {
if (on) {
if( uart == UART1 ) {
/* CTS and RTS directions */
GPIO->PAD_DIR_SET.U1CTS = 1;
GPIO->PAD_DIR_RESET.U1RTS = 1;
/* function select to uart */
GPIO->FUNC_SEL.U1CTS = 1;
GPIO->FUNC_SEL.U1RTS = 1;
} else {
/* UART 2 */
/* CTS and RTS directions */
GPIO->PAD_DIR_SET.U2CTS = 1;
GPIO->PAD_DIR_RESET.U2RTS = 1;
/* function select to uart */
GPIO->FUNC_SEL.U2CTS = 1;
GPIO->FUNC_SEL.U2RTS = 1;
}
/* enable flow control */
uart->CONbits.FCE = 1;
} else {
/* off */
/* disable flow control */
uart->CONbits.FCE = 0;
if( uart == UART1 ) {
/* CTS and RTS to inputs */
GPIO->PAD_DIR_RESET.U1CTS = 1;
GPIO->PAD_DIR_RESET.U1RTS = 1;
/* function select to gpio */
GPIO->FUNC_SEL.U1CTS = 3;
GPIO->FUNC_SEL.U1RTS = 3;
} else {
/* UART 2 */
/* CTS and RTS to inputs */
GPIO->PAD_DIR_RESET.U2CTS = 1;
GPIO->PAD_DIR_RESET.U2RTS = 1;
/* function select to gpio */
GPIO->FUNC_SEL.U2CTS = 3;
GPIO->FUNC_SEL.U2RTS = 3;
}
}
}
void uart_init(volatile struct UART_struct * uart, uint32_t baud) {
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/* enable the uart so we can set the gpio mode */
/* see Section 11.5.1.2 Alternate Modes */
/* you must enable the peripheral first BEFORE setting the function in GPIO_FUNC_SEL */
/* From the datasheet: "The peripheral function will control operation of the pad IF */
/* THE PERIPHERAL IS ENABLED. */
uart->CONbits = (struct UART_CON) {
.TXE = 1,
.RXE = 1,
};
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/* interrupt when there are this number or more bytes free in the TX buffer*/
uart->TXCON = 16;
if( uart == UART1 ) {
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/* TX and RX directions */
GPIO->PAD_DIR_SET.U1TX = 1;
GPIO->PAD_DIR_RESET.U1RX = 1;
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/* set func sel to UART */
GPIO->FUNC_SEL.U1TX = 1;
GPIO->FUNC_SEL.U1RX = 1;
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#if UART1_RX_BUFFERSIZE > 32
*UART1_UCON = (1 << 0) | (1 << 1) ; /* enable receive, transmit, and both interrupts */
*UART1_URXCON = 30; /* interrupt when fifo is nearly full */
u1_rx_head = 0; u1_rx_tail = 0;
#elif UART1_RX_BUFFERSIZE < 32 /* enable receive, transmit, flow control, disable rx interrupt */
*UART1_UCON = (1 << 0) | (1 << 1) | (1 << 12) | (1 << 14);
*UART1_UCTS = UART1_RX_BUFFERSIZE; /* drop cts when tx buffer at trigger level */
*GPIO_FUNC_SEL1 = ( (0x01 << (0*2)) | (0x01 << (1*2)) ); /* set GPIO17-16 to UART1 CTS and RTS */
#else
*UART1_UCON = (1 << 0) | (1 << 1) | (1 << 14); /* enable receive, transmit, disable rx interrupt */
#endif
u1_tx_head = 0; u1_tx_tail = 0;
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/* tx and rx interrupts are enabled in the UART by default */
/* see status register bits 13 and 14 */
/* enable UART1 interrupts in the interrupt controller */
enable_irq(UART1);
} else {
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/* UART2 */
/* TX and RX directions */
GPIO->PAD_DIR_SET.U2TX = 1;
GPIO->PAD_DIR_RESET.U1RX = 1;
/* set func sel to UART */
GPIO->FUNC_SEL.U2TX = 1;
GPIO->FUNC_SEL.U2RX = 1;
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#if UART2_RX_BUFFERSIZE > 32
*UART2_UCON = (1 << 0) | (1 << 1) ; /* enable receive, transmit, and both interrupts */
*UART2_URXCON = 30; /* interrupt when fifo is nearly full */
u2_rx_head = 0; u2_rx_tail = 0;
#elif UART2_RX_BUFFERSIZE < 32 /* enable receive, transmit, disable flow control, disable rx interrupt */
*UART2_UCON = (1 << 0) | (1 << 1) | (0 << 12) | (1 << 14);
*UART2_UCTS = UART2_RX_BUFFERSIZE; /* drop cts when tx buffer at trigger level */
*GPIO_FUNC_SEL1 = ( (0x01 << (0*2)) | (0x01 << (1*2)) ); /* set GPIO17-16 to UART2 CTS and RTS */
#else
*UART2_UCON = (1 << 0) | (1 << 1) | (1 << 14); /* enable receive, transmit, disable rx interrupt */
#endif
u2_tx_head = 0; u2_tx_tail = 0;
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enable_irq(UART2);
}
uart_setbaud(uart, baud);
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}