148 lines
4.5 KiB
C
148 lines
4.5 KiB
C
/*
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* Copyright (c) 2018 Piotr Mienkowski
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/** @file
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* @brief Serial Wire Output (SWO) backend implementation.
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*
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* SWO/SWV has been developed by ARM. The following code works only on ARM
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* architecture.
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*
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* An SWO viewer program will typically set-up the SWO port including its
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* frequency when connected to the debug probe. Such configuration can persist
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* only until the MCU reset. The SWO backend initialization function will
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* re-configure the SWO port upon boot and set the frequency as specified by
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* the LOG_BACKEND_SWO_FREQ_HZ Kconfig option. To ensure flawless operation
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* this frequency should much the one set by the SWO viewer program.
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*
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* The initialization code assumes that SWO core frequency is equal to HCLK
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* as defined by the clock-frequency property in the CPU node. This may require
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* additional, vendor specific configuration.
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*/
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#include <zephyr/logging/log_backend.h>
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#include <zephyr/logging/log_core.h>
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#include <zephyr/logging/log_output.h>
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#include <zephyr/logging/log_backend_std.h>
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#include <zephyr/drivers/pinctrl.h>
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#include <soc.h>
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/** The stimulus port from which SWO data is received and displayed */
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#define ITM_PORT_LOGGER 0
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/* If ITM has pin control properties, apply them for SWO pins */
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#if DT_NODE_HAS_PROP(DT_NODELABEL(itm), pinctrl_0)
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PINCTRL_DT_DEFINE(DT_NODELABEL(itm));
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#endif
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/* Set TPIU prescaler for the current debug trace clock frequency. */
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#if CONFIG_LOG_BACKEND_SWO_FREQ_HZ == 0
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#define SWO_FREQ_DIV 1
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#else
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#if CONFIG_LOG_BACKEND_SWO_REF_FREQ_HZ == 0
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#error "SWO reference frequency is not configured"
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#endif
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#define SWO_FREQ_DIV \
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((CONFIG_LOG_BACKEND_SWO_REF_FREQ_HZ + (CONFIG_LOG_BACKEND_SWO_FREQ_HZ / 2)) / \
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CONFIG_LOG_BACKEND_SWO_FREQ_HZ)
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#if SWO_FREQ_DIV > 0xFFFF
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#error CONFIG_LOG_BACKEND_SWO_FREQ_HZ is too low. SWO clock divider is 16-bit. \
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Minimum supported SWO clock frequency is \
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[Reference Clock Frequency]/2^16.
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#endif
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#endif
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static uint8_t buf[1];
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static uint32_t log_format_current = CONFIG_LOG_BACKEND_SWO_OUTPUT_DEFAULT;
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static int char_out(uint8_t *data, size_t length, void *ctx)
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{
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ARG_UNUSED(ctx);
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for (size_t i = 0; i < length; i++) {
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ITM_SendChar(data[i]);
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}
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return length;
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}
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LOG_OUTPUT_DEFINE(log_output_swo, char_out, buf, sizeof(buf));
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static void log_backend_swo_process(const struct log_backend *const backend,
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union log_msg_generic *msg)
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{
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uint32_t flags = log_backend_std_get_flags();
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log_format_func_t log_output_func = log_format_func_t_get(log_format_current);
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log_output_func(&log_output_swo, &msg->log, flags);
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}
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static int format_set(const struct log_backend *const backend, uint32_t log_type)
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{
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log_format_current = log_type;
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return 0;
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}
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static void log_backend_swo_init(struct log_backend const *const backend)
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{
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/* Enable DWT and ITM units */
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CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
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/* Enable access to ITM registers */
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ITM->LAR = 0xC5ACCE55;
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/* Disable stimulus ports ITM_STIM0-ITM_STIM31 */
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ITM->TER = 0x0;
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/* Disable ITM */
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ITM->TCR = 0x0;
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/* Select NRZ (UART) encoding protocol */
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TPI->SPPR = 2;
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/* Set SWO baud rate prescaler value: SWO_clk = ref_clock/(ACPR + 1) */
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TPI->ACPR = SWO_FREQ_DIV - 1;
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/* Enable unprivileged access to ITM stimulus ports */
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ITM->TPR = 0x0;
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/* Configure Debug Watchpoint and Trace */
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DWT->CTRL &= (DWT_CTRL_POSTPRESET_Msk | DWT_CTRL_POSTINIT_Msk | DWT_CTRL_CYCCNTENA_Msk);
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DWT->CTRL |= (DWT_CTRL_POSTPRESET_Msk | DWT_CTRL_POSTINIT_Msk);
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/* Configure Formatter and Flush Control Register */
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TPI->FFCR = 0x00000100;
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/* Enable ITM, set TraceBusID=1, no local timestamp generation */
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ITM->TCR = 0x0001000D;
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/* Enable stimulus port used by the logger */
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ITM->TER = 1 << ITM_PORT_LOGGER;
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/* Initialize pin control settings, if any are defined */
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#if DT_NODE_HAS_PROP(DT_NODELABEL(itm), pinctrl_0)
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const struct pinctrl_dev_config *pincfg =
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PINCTRL_DT_DEV_CONFIG_GET(DT_NODELABEL(itm));
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pinctrl_apply_state(pincfg, PINCTRL_STATE_DEFAULT);
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#endif
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}
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static void log_backend_swo_panic(struct log_backend const *const backend)
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{
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}
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static void dropped(const struct log_backend *const backend, uint32_t cnt)
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{
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ARG_UNUSED(backend);
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log_backend_std_dropped(&log_output_swo, cnt);
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}
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const struct log_backend_api log_backend_swo_api = {
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.process = log_backend_swo_process,
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.panic = log_backend_swo_panic,
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.init = log_backend_swo_init,
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.dropped = IS_ENABLED(CONFIG_LOG_MODE_IMMEDIATE) ? NULL : dropped,
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.format_set = format_set,
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};
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LOG_BACKEND_DEFINE(log_backend_swo, log_backend_swo_api, true);
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