93 lines
2.1 KiB
C
93 lines
2.1 KiB
C
/* rtt_console.c - Console messages to a RAM buffer that is then read by
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* the Segger J-Link debugger
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*/
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/*
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* Copyright (c) 2016 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/sys/printk.h>
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#include <zephyr/device.h>
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#include <zephyr/init.h>
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#include <SEGGER_RTT.h>
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extern void __printk_hook_install(int (*fn)(int));
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extern void __stdout_hook_install(int (*fn)(int));
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static bool host_present;
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/** @brief Wait for fixed period.
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*
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*/
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static void wait(void)
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{
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if (!IS_ENABLED(CONFIG_MULTITHREADING) || k_is_in_isr()) {
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if (IS_ENABLED(CONFIG_RTT_TX_RETRY_IN_INTERRUPT)) {
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k_busy_wait(1000*CONFIG_RTT_TX_RETRY_DELAY_MS);
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}
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} else {
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k_msleep(CONFIG_RTT_TX_RETRY_DELAY_MS);
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}
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}
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static int rtt_console_out(int character)
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{
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char c = (char)character;
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unsigned int cnt;
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int max_cnt = CONFIG_RTT_TX_RETRY_CNT;
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do {
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SEGGER_RTT_LOCK();
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cnt = SEGGER_RTT_WriteNoLock(0, &c, 1);
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SEGGER_RTT_UNLOCK();
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/* There are two possible reasons for not writing any data to
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* RTT:
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* - The host is not connected and not reading the data.
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* - The buffer got full and will be read by the host.
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* These two situations are distinguished using the following
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* algorithm:
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* At the beginning, the module assumes that the host is active,
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* so when no data is read, it busy waits and retries.
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* If, after retrying, the host reads the data, the module
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* assumes that the host is active. If it fails, the module
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* assumes that the host is inactive and stores that
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* information. On next call, only one attempt takes place.
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* The host is marked as active if the attempt is successful.
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*/
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if (cnt) {
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/* byte processed - host is present. */
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host_present = true;
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} else if (host_present) {
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if (max_cnt) {
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wait();
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max_cnt--;
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continue;
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} else {
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host_present = false;
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}
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}
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break;
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} while (1);
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return character;
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}
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static int rtt_console_init(void)
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{
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#ifdef CONFIG_PRINTK
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__printk_hook_install(rtt_console_out);
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#endif
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__stdout_hook_install(rtt_console_out);
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return 0;
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}
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SYS_INIT(rtt_console_init, PRE_KERNEL_1, CONFIG_CONSOLE_INIT_PRIORITY);
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