22d6bfa0bd
The TPIU supports serializing the data stream both using an UART-like NRZ protocol as well as using Manchester encoding. Using Manchester encoding has the advantage that it enables receivers that support it to recover the clock from the SWO signal itself. This is particularly useful in situations where the clock rate changes dynamically or is unknown (for example when debugging the clock tree setup or working with a device with a misbehaving main oscillator). Add a Kconfig choice to switch the protocol, keeping the current default of using the NRZ encoding. Signed-off-by: Florian Larysch <larysch@fixme.gmbh>
147 lines
4.5 KiB
C
147 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 TPIU encoding protocol */
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TPI->SPPR = IS_ENABLED(CONFIG_LOG_BACKEND_SWO_PROTOCOL_NRZ) ? 2 : 1;
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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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