121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
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/* Copyright 2014 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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/* USART driver for Chrome EC */
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#include "clock.h"
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#include "console.h"
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#include "common.h"
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#include "dma.h"
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#include "hooks.h"
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#include "registers.h"
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#include "system.h"
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#include "task.h"
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#include "uart.h"
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#include "util.h"
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#define CPUTS(outstr) cputs(CC_SYSTEM, outstr)
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#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
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#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
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static int ever_sent; /* if we ever sent byte to TXD? */
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static int init_done; /* Initialization done? */
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static int should_stop; /* Last TX control action */
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int uart_init_done(void)
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{
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return init_done;
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}
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void uart_tx_start(void)
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{
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disable_sleep(SLEEP_MASK_UART);
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should_stop = 0;
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NRF51_UART_INTENSET = BIT(NRF55_UART_TXDRDY_BIT);
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task_trigger_irq(NRF51_PERID_USART);
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}
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void uart_tx_stop(void)
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{
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NRF51_UART_INTENCLR = BIT(NRF55_UART_TXDRDY_BIT);
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should_stop = 1;
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enable_sleep(SLEEP_MASK_UART);
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}
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int uart_tx_ready(void)
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{
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/*
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* nRF51 design is NOT tx-empty style. Instead, it is if a byte is
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* ever transmitted from TxD. This means NRF51_UART_TXDRDY is always
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* 0 after reset. So, we use 'ever_sent' to send the first byte.
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*/
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return NRF51_UART_TXDRDY || (!ever_sent);
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}
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int uart_rx_available(void)
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{
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return NRF51_UART_RXDRDY;
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}
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void uart_tx_flush(void)
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{
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while (!uart_tx_ready())
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;
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}
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void uart_write_char(char c)
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{
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ever_sent = 1;
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NRF51_UART_TXDRDY = 0;
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NRF51_UART_TXD = c;
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NRF51_UART_STARTTX = 1;
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}
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int uart_read_char(void)
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{
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NRF51_UART_RXDRDY = 0;
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return NRF51_UART_RXD;
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}
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/* Interrupt handler for console USART */
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void uart_interrupt(void)
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{
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#ifndef CONFIG_UART_RX_DMA
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/*
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* Read input FIFO until empty. DMA-based receive does this from a
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* hook in the UART buffering module.
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*/
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uart_process_input();
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#endif
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/* Fill output FIFO */
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uart_process_output();
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#ifndef CONFIG_UART_TX_DMA
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if (!should_stop)
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NRF51_UART_INTENSET = BIT(NRF55_UART_TXDRDY_BIT);
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#endif /* CONFIG_UART_TX_DMA */
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}
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DECLARE_IRQ(NRF51_PERID_USART, uart_interrupt, 2);
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void uart_init(void)
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{
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NRF51_UART_PSELTXD = NRF51_UART_TX_PIN; /* GPIO Port for Tx */
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NRF51_UART_PSELRXD = NRF51_UART_RX_PIN; /* GPIO Port for Rx */
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NRF51_UART_CONFIG = 0; /* disable HW flow control, no parity bit */
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NRF51_UART_BAUDRATE = 0x01d7e000; /* 115200 */
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NRF51_UART_ENABLE = 0x4; /* Enable UART */
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task_enable_irq(NRF51_PERID_USART);
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NRF51_UART_INTENSET = BIT(NRF55_UART_RXDRDY_BIT);
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NRF51_UART_STARTRX = 1;
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init_done = 1;
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}
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