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7dab0e853c
The UART block on the g chip has no functionality to adjust the parity. Unfortunately, this feature is needed for certain applications. This commit adds a UART bit bang driver with support for configuring the baud rate and parity. It currently only supports 8 data bits. BUG=b:35648297 BRANCH=cr50 TEST=make -j buildall TEST=With some other patches, successfully flash rowan EC at 9600 baud. Change-Id: I86a160c0960e46b3a8bb1057518f625aefb7d81f Signed-off-by: Aseda Aboagye <aaboagye@google.com> Reviewed-on: https://chromium-review.googlesource.com/503473 Commit-Ready: Aseda Aboagye <aaboagye@chromium.org> Tested-by: Aseda Aboagye <aaboagye@chromium.org> Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
113 lines
3.0 KiB
C
113 lines
3.0 KiB
C
/* Copyright 2017 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef __CROS_EC_CHIP_G_UART_BITBANG_H
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#define __CROS_EC_CHIP_G_UART_BITBANG_H
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/* UART Bit Banging */
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#include "common.h"
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#include "gpio.h"
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/* These are functions that we'll have to replace. */
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struct uartn_function_ptrs {
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int (*_rx_available)(int uart);
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void (*_write_char)(int uart, char c);
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int (*_read_char)(int uart);
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};
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/*
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* And these are the function definitions. The functions live in
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* chip/g/uartn.c.
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*/
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extern int _uartn_rx_available(int uart);
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extern void _uartn_write_char(int uart, char c);
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extern int _uartn_read_char(int uart);
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extern int _uart_bitbang_rx_available(int uart);
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extern void _uart_bitbang_write_char(int uart, char c);
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extern int _uart_bitbang_read_char(int uart);
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extern struct uartn_function_ptrs uartn_funcs[];
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struct uart_bitbang_properties {
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enum gpio_signal tx_gpio;
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enum gpio_signal rx_gpio;
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uint32_t tx_pinmux_reg;
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uint32_t tx_pinmux_regval;
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uint32_t rx_pinmux_reg;
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uint32_t rx_pinmux_regval;
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int baud_rate;
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uint8_t uart;
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struct {
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unsigned int head : 3;
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unsigned int tail : 3;
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unsigned int parity : 2;
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} htp __packed;
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};
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/* In order to bitbang a UART, a board must define a bitbang_config. */
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extern struct uart_bitbang_properties bitbang_config;
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/**
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* Enable bit banging mode for a UART.
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*
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* @param uart: Index of UART to enable bit banging mode.
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* @param baud_rate: desired baud rate.
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* @param parity: 0: no parity, 1: odd parity, 2: even parity.
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*
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* @returns EC_SUCCESS on success, otherwise an error.
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*/
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int uart_bitbang_enable(int uart, int baud_rate, int parity);
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/**
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* Disable bit banging mode for a UART.
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*
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* @param uart: Index of UART to disable bit banging mode.
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*/
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int uart_bitbang_disable(int uart);
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/**
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* Returns 1 if bit banging mode is enabled for the UART.
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*
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* @param uart: Index of UART to query.
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*/
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int uart_bitbang_is_enabled(int uart);
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/**
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* TX a character on a UART configured for bit banging mode.
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*
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* @param uart: Index of UART to use.
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* @param c: Character to send out.
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*/
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void uart_bitbang_write_char(int uart, char c);
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/**
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* Sample the RX line on a UART configured for bit banging mode.
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*
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* This is called when a falling edge is seen on the RX line and will attempt to
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* receive a character. Incoming data with framing errors or parity errors will
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* be discarded.
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*
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* @param uart: Index of UART to use.
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* @returns EC_SUCCESS if a character was successfully received, EC_ERROR_CRC if
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* there was a framing or parity issue.
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*/
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int uart_bitbang_receive_char(int uart);
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/**
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* Returns 1 if there are characters available for consumption, otherwise 0.
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*
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* @param uart: Index of UART to check.
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*/
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int uart_bitbang_is_char_available(int uart);
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/**
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* Retrieve a character from the bit bang RX buffer.
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*
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* @param uart: Index of UART to use.
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*/
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int uart_bitbang_read_char(int uart);
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#endif /* __CROS_EC_CHIP_G_UART_BITBANG_H */
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