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128 lines
3.1 KiB
C
128 lines
3.1 KiB
C
/*
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* PL011 UART driver
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*
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* Copyright (C) 2009 B Labs Ltd.
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*/
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#include <libdev/uart.h>
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#include <libdev/io.h>
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#include "uart.h"
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/* Error status bits in receive status register */
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#define PL011_FE (1 << 0)
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#define PL011_PE (1 << 1)
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#define PL011_BE (1 << 2)
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#define PL011_OE (1 << 3)
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/* Status bits in flag register */
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#define PL011_TXFE (1 << 7)
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#define PL011_RXFF (1 << 6)
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#define PL011_TXFF (1 << 5)
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#define PL011_RXFE (1 << 4)
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#define PL011_BUSY (1 << 3)
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#define PL011_DCD (1 << 2)
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#define PL011_DSR (1 << 1)
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#define PL011_CTS (1 << 0)
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void uart_tx_char(unsigned long base, char c)
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{
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unsigned int val = 0;
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do {
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val = read((base + PL011_UARTFR));
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} while (val & PL011_TXFF); /* TX FIFO FULL */
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write(c, (base + PL011_UARTDR));
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}
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char uart_rx_char(unsigned long base)
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{
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unsigned int val = 0;
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do {
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val = read(base + PL011_UARTFR);
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} while (val & PL011_RXFE); /* RX FIFO Empty */
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return (char)read((base + PL011_UARTDR));
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}
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/*
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* Sets the baud rate in kbps. It is recommended to use
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* standard rates such as: 1200, 2400, 3600, 4800, 7200,
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* 9600, 14400, 19200, 28800, 38400, 57600 76800, 115200.
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*/
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void pl011_set_baudrate(unsigned long base, unsigned int baud,
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unsigned int clkrate)
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{
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const unsigned int uartclk = 24000000; /* 24Mhz clock fixed on pb926 */
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unsigned int val = 0, ipart = 0, fpart = 0;
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/* Use default pb926 rate if no rate is supplied */
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if (clkrate == 0)
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clkrate = uartclk;
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if (baud > 115200 || baud < 1200)
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baud = 38400; /* Default rate. */
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/* 24000000 / (38400 * 16) */
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ipart = 39;
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write(ipart, base + PL011_UARTIBRD);
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write(fpart, base + PL011_UARTFBRD);
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/*
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* For the IBAUD and FBAUD to update, we need to
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* write to UARTLCR_H because the 3 registers are
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* actually part of a single register in hardware
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* which only updates by a write to UARTLCR_H
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*/
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val = read(base + PL011_UARTLCR_H);
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write(val, base + PL011_UARTLCR_H);
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}
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void uart_init(unsigned long uart_base)
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{
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/* Initialise data register for 8 bit data read/writes */
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pl011_set_word_width(uart_base, 8);
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/*
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* Fifos are disabled because by default it is assumed the port
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* will be used as a user terminal, and in that case the typed
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* characters will only show up when fifos are flushed, rather than
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* when each character is typed. We avoid this by not using fifos.
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*/
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pl011_disable_fifos(uart_base);
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/* Set default baud rate of 38400 */
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pl011_set_baudrate(uart_base, 38400, 24000000);
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/* Set default settings of 1 stop bit, no parity, no hw flow ctrl */
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pl011_set_stopbits(uart_base, 1);
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pl011_parity_disable(uart_base);
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/* Enable rx, tx, and uart chip */
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pl011_tx_enable(uart_base);
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pl011_rx_enable(uart_base);
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pl011_uart_enable(uart_base);
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}
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unsigned long uart_print_base;
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void platform_init(void)
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{
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uart_print_base = PL011_BASE;
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/*
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* We dont need to initialize uart here for variant-userspace,
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* as this is the same uart as used by kernel and hence
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* already initialized, we just need
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* a uart struct instance with proper base address.
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*
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* But in case of baremetal like loader, no one has done
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* initialization, so we need to do it.
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*/
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#if defined(VARIANT_BAREMETAL)
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uart_init(uart_print_base);
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#endif
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}
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