1732dcb90c
In some cases it may be useful to be able to bitbang a UART, such as during early bring-up when a driver for the actual controller isn't available yet. On some platforms we may even want to use this permanently, such as on the SDM845 where the hardware UART controller needs to have firmware loaded and is thus unavailable for most of the bootblock. This patch adds some helper code that makes it easy to implement this on a platform, you just have to pass it a function to control the Tx pin state and it will do the rest. It relies on the mono_time API and is thus bound to microsecond timing granularity, but that seems to be barely good enough for 115200 baud if the bit times are calculated carefully. Change-Id: If7dcecc7b8a95ec15f456efd2ec1f1e0dde239b4 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/25812 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
106 lines
3 KiB
C
106 lines
3 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2012 The ChromiumOS Authors. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef CONSOLE_UART_H
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#define CONSOLE_UART_H
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#include <rules.h>
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#include <stdint.h>
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/* Return the clock frequency UART uses as reference clock for
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* baudrate generator. */
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unsigned int uart_platform_refclk(void);
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#if IS_ENABLED(CONFIG_UART_OVERRIDE_BAUDRATE)
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/* Return the baudrate, define this in your platform when using the above
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configuration. */
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unsigned int get_uart_baudrate(void);
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#else
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static inline unsigned int get_uart_baudrate(void)
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{
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return CONFIG_TTYS0_BAUD;
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}
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#endif
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/* Returns the divisor value for a given baudrate.
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* The formula to satisfy is:
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* refclk / divisor = baudrate * oversample
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*/
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unsigned int uart_baudrate_divisor(unsigned int baudrate,
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unsigned int refclk, unsigned int oversample);
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/* Returns the oversample divisor multiplied by any other divisors that act
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* on the input clock
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*/
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unsigned int uart_input_clock_divider(void);
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/* Bitbang out one byte on an 8n1 UART through the output function set_tx(). */
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void uart_bitbang_tx_byte(unsigned char data, void (*set_tx)(int line_state));
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void uart_init(int idx);
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void uart_tx_byte(int idx, unsigned char data);
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void uart_tx_flush(int idx);
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unsigned char uart_rx_byte(int idx);
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uintptr_t uart_platform_base(int idx);
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#if !defined(__ROMCC__)
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static inline void *uart_platform_baseptr(int idx)
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{
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return (void *)uart_platform_base(idx);
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}
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void oxford_remap(unsigned int new_base);
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#define __CONSOLE_SERIAL_ENABLE__ (IS_ENABLED(CONFIG_CONSOLE_SERIAL) && \
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(ENV_BOOTBLOCK || ENV_ROMSTAGE || ENV_RAMSTAGE || ENV_VERSTAGE || \
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ENV_POSTCAR || (ENV_SMM && IS_ENABLED(CONFIG_DEBUG_SMI))))
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#if __CONSOLE_SERIAL_ENABLE__
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static inline void __uart_init(void)
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{
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uart_init(CONFIG_UART_FOR_CONSOLE);
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}
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static inline void __uart_tx_byte(u8 data)
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{
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uart_tx_byte(CONFIG_UART_FOR_CONSOLE, data);
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}
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static inline void __uart_tx_flush(void)
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{
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uart_tx_flush(CONFIG_UART_FOR_CONSOLE);
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}
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#else
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static inline void __uart_init(void) {}
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static inline void __uart_tx_byte(u8 data) {}
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static inline void __uart_tx_flush(void) {}
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#endif
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#if IS_ENABLED(CONFIG_GDB_STUB) && (ENV_ROMSTAGE || ENV_RAMSTAGE)
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#define CONFIG_UART_FOR_GDB CONFIG_UART_FOR_CONSOLE
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static inline void __gdb_hw_init(void) { uart_init(CONFIG_UART_FOR_GDB); }
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static inline void __gdb_tx_byte(u8 data)
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{
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uart_tx_byte(CONFIG_UART_FOR_GDB, data);
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}
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static inline void __gdb_tx_flush(void) { uart_tx_flush(CONFIG_UART_FOR_GDB); }
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static inline u8 __gdb_rx_byte(void)
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{
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return uart_rx_byte(CONFIG_UART_FOR_GDB);
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}
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#endif
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#endif /* __ROMCC__ */
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#endif /* CONSOLE_UART_H */
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