83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
/* or1k_uart.c -- UART implementation for OpenRISC 1000.
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*
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*Copyright (c) 2014 Authors
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*
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* Contributor Stefan Wallentowitz <stefan.wallentowitz@tum.de>
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*
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* The authors hereby grant permission to use, copy, modify, distribute,
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* and license this software and its documentation for any purpose, provided
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* that existing copyright notices are retained in all copies and that this
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* notice is included verbatim in any distributions. No written agreement,
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* license, or royalty fee is required for any of the authorized uses.
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* Modifications to this software may be copyrighted by their authors
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* and need not follow the licensing terms described here, provided that
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* the new terms are clearly indicated on the first page of each file where
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* they apply.
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*/
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#include "include/or1k-support.h"
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#include "or1k_uart.h"
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#include <stdint.h>
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void (*_or1k_uart_read_cb)(char c);
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void _or1k_uart_interrupt_handler(uint32_t data)
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{
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_or1k_uart_read_cb(REG8(RB));
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}
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int _or1k_uart_init(void)
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{
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uint16_t divisor;
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// Is uart present?
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if (!_or1k_board_uart_base) {
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return -1;
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}
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// Reset the callback function
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_or1k_uart_read_cb = 0;
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// Calculate and set divisor
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divisor = _or1k_board_clk_freq / (_or1k_board_uart_baud * 16);
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REG8(LCR) = LCR_DLA;
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REG8(DLB1) = divisor & 0xff;
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REG8(DLB2) = divisor >> 8;
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// Set line control register:
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// - 8 bits per character
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// - 1 stop bit
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// - No parity
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// - Break disabled
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// - Disallow access to divisor latch
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REG8(LCR) = LCR_BPC_8;
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// Reset FIFOs and set trigger level to 14 bytes
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REG8(FCR) = FCR_CLRRECV | FCR_CLRTMIT | FCR_TRIG_14;
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// Disable all interrupts
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REG8(IER) = 0;
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return 0;
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}
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void _or1k_uart_write(char c)
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{
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while (!REG8(LSR) & LSR_TFE) {}
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REG8(THR) = c;
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}
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void or1k_uart_set_read_cb(void (*cb)(char c))
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{
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_or1k_uart_read_cb = cb;
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// Enable interrupt
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REG8(IER) = 1 << IER_RDAI;
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or1k_interrupt_handler_add(_or1k_board_uart_IRQ,
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_or1k_uart_interrupt_handler, 0);
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or1k_interrupt_enable(_or1k_board_uart_IRQ);
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}
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