probe: correct SWCLK calculations

Use the actual clk_sys frequency and Round divisors up, otherwise high
swclk speeds get significantly overclocked.

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.12)
 
 include(pico_sdk_import.cmake)
 
-set(FREERTOS_KERNEL_PATH "${CMAKE_CURRENT_LIST_DIR}/freertos")
+set(FREERTOS_KERNEL_PATH ${CMAKE_CURRENT_LIST_DIR}/freertos)
 include(FreeRTOS_Kernel_import.cmake)
 
 project(debugprobe)
@@ -40,8 +40,8 @@ target_include_directories(debugprobe PRIVATE
 
 target_compile_options(debugprobe PRIVATE -Wall)
 
-pico_generate_pio_header(debugprobe "${CMAKE_CURRENT_LIST_DIR}/src/probe.pio")
-pico_generate_pio_header(debugprobe "${CMAKE_CURRENT_LIST_DIR}/src/probe_oen.pio")
+pico_generate_pio_header(debugprobe ${CMAKE_CURRENT_LIST_DIR}/src/probe.pio)
+pico_generate_pio_header(debugprobe ${CMAKE_CURRENT_LIST_DIR}/src/probe_oen.pio)
 
 target_include_directories(debugprobe PRIVATE src)
 

FreeRTOS_Kernel_import.cmake

@@ -7,7 +7,7 @@
 # respectively.
 
 if (DEFINED ENV{FREERTOS_KERNEL_PATH} AND (NOT FREERTOS_KERNEL_PATH))
-    set(FREERTOS_KERNEL_PATH "$ENV{FREERTOS_KERNEL_PATH}")
+    set(FREERTOS_KERNEL_PATH $ENV{FREERTOS_KERNEL_PATH})
     message("Using FREERTOS_KERNEL_PATH from environment ('${FREERTOS_KERNEL_PATH}')")
 endif ()
 
@@ -34,18 +34,18 @@ foreach(SEARCH_PASS RANGE 0 1)
 
     if (NOT FREERTOS_KERNEL_PATH)
         # check if we are inside the FreeRTOS kernel tree (i.e. this file has been included directly)
-        get_filename_component(_ACTUAL_PATH "${CMAKE_CURRENT_LIST_DIR}" REALPATH)
-        get_filename_component(_POSSIBLE_PATH "${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}" REALPATH)
+        get_filename_component(_ACTUAL_PATH ${CMAKE_CURRENT_LIST_DIR} REALPATH)
+        get_filename_component(_POSSIBLE_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH} REALPATH)
         if (_ACTUAL_PATH STREQUAL _POSSIBLE_PATH)
-            get_filename_component(FREERTOS_KERNEL_PATH "${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH}" REALPATH)
+            get_filename_component(FREERTOS_KERNEL_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH} REALPATH)
         endif()
         if (_ACTUAL_PATH STREQUAL _POSSIBLE_PATH)
-            get_filename_component(FREERTOS_KERNEL_PATH "${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH}" REALPATH)
-            message("Setting FREERTOS_KERNEL_PATH to '${FREERTOS_KERNEL_PATH}' based on location of FreeRTOS-Kernel-import.cmake")
+            get_filename_component(FREERTOS_KERNEL_PATH ${CMAKE_CURRENT_LIST_DIR}/${FREERTOS_KERNEL_RP2040_BACK_PATH} REALPATH)
+            message("Setting FREERTOS_KERNEL_PATH to ${FREERTOS_KERNEL_PATH} based on location of FreeRTOS-Kernel-import.cmake")
             break()
         elseif (PICO_SDK_PATH AND EXISTS "${PICO_SDK_PATH}/../FreeRTOS-Kernel")
-            set(FREERTOS_KERNEL_PATH "${PICO_SDK_PATH}/../FreeRTOS-Kernel")
-            message("Defaulting FREERTOS_KERNEL_PATH as sibling of PICO_SDK_PATH: '${FREERTOS_KERNEL_PATH}'")
+            set(FREERTOS_KERNEL_PATH ${PICO_SDK_PATH}/../FreeRTOS-Kernel)
+            message("Defaulting FREERTOS_KERNEL_PATH as sibling of PICO_SDK_PATH: ${FREERTOS_KERNEL_PATH}")
             break()
         endif()
     endif ()
@@ -53,10 +53,10 @@ foreach(SEARCH_PASS RANGE 0 1)
     if (NOT FREERTOS_KERNEL_PATH)
         foreach(POSSIBLE_SUFFIX Source FreeRTOS-Kernel FreeRTOS/Source)
             # check if FreeRTOS-Kernel exists under directory that included us
-            set(SEARCH_ROOT "${CMAKE_CURRENT_SOURCE_DIR}")
-            get_filename_component(_POSSIBLE_PATH "${SEARCH_ROOT}/${POSSIBLE_SUFFIX}" REALPATH)
-            if (EXISTS "${_POSSIBLE_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt")
-                get_filename_component(FREERTOS_KERNEL_PATH "${_POSSIBLE_PATH}" REALPATH)
+            set(SEARCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
+            get_filename_component(_POSSIBLE_PATH ${SEARCH_ROOT}/${POSSIBLE_SUFFIX} REALPATH)
+            if (EXISTS ${_POSSIBLE_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt)
+                get_filename_component(FREERTOS_KERNEL_PATH ${_POSSIBLE_PATH} REALPATH)
                 message("Setting FREERTOS_KERNEL_PATH to '${FREERTOS_KERNEL_PATH}' found relative to enclosing project")
                 break()
             endif()
@@ -81,12 +81,12 @@ endif()
 set(FREERTOS_KERNEL_PATH "${FREERTOS_KERNEL_PATH}" CACHE PATH "Path to the FreeRTOS Kernel")
 
 get_filename_component(FREERTOS_KERNEL_PATH "${FREERTOS_KERNEL_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
-if (NOT EXISTS "${FREERTOS_KERNEL_PATH}")
+if (NOT EXISTS ${FREERTOS_KERNEL_PATH})
     message(FATAL_ERROR "Directory '${FREERTOS_KERNEL_PATH}' not found")
 endif()
-if (NOT EXISTS "${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt")
-    message(FATAL_ERROR "Directory '${FREERTOS_KERNEL_PATH}' does not contain a '${PICO_PLATFORM}' port here: '${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}'")
+if (NOT EXISTS ${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}/CMakeLists.txt)
+    message(FATAL_ERROR "Directory '${FREERTOS_KERNEL_PATH}' does not contain a '${PICO_PLATFORM}' port here: ${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}")
 endif()
-set(FREERTOS_KERNEL_PATH "${FREERTOS_KERNEL_PATH}" CACHE PATH "Path to the FreeRTOS_KERNEL" FORCE)
+set(FREERTOS_KERNEL_PATH ${FREERTOS_KERNEL_PATH} CACHE PATH "Path to the FreeRTOS_KERNEL" FORCE)
 
-add_subdirectory("${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH}" FREERTOS_KERNEL)
+add_subdirectory(${FREERTOS_KERNEL_PATH}/${FREERTOS_KERNEL_RP2040_RELATIVE_PATH} FREERTOS_KERNEL)

README.md

@@ -9,7 +9,7 @@ Firmware source for the Raspberry Pi Debug Probe SWD/UART accessory. Can also be
 
 # Documentation
 
-Debug Probe documentation can be found in the [Pico Getting Started Guide](https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf). See "Appendix A: Using the Debug Probe".
+Debug Probe documentation can be found at the [Raspberry Pi Microcontroller Documentation portal](https://www.raspberrypi.com/documentation/microcontrollers/debug-probe.html#about-the-debug-probe).
 
 # Hacking
 

blah.patch

@@ -0,0 +1,23 @@
+diff --git a/include/DAP_config.h b/include/DAP_config.h
+index fb02fb1..88c11d9 100755
+--- a/include/DAP_config.h
++++ b/include/DAP_config.h
+@@ -44,6 +44,7 @@ This information includes:
+  - Optional information about a connected Target Device (for Evaluation Boards).
+ */
+ #include <pico/stdlib.h>
++#include <hardware/clocks.h>
+ #include <hardware/gpio.h>
+
+ #include "cmsis_compiler.h"
+@@ -52,8 +53,8 @@ This information includes:
+
+ /// Processor Clock of the Cortex-M MCU used in the Debug Unit.
+ /// This value is used to calculate the SWD/JTAG clock speed.
+-/* Debugprobe actually uses kHz rather than Hz, so just lie about it here */
+-#define CPU_CLOCK               125000000U      ///< Specifies the CPU Clock in Hz.
++/* Debugprobe uses PIO for clock generation, so return the current system clock. */
++#define CPU_CLOCK               clock_get_hz(clk_sys)
+
+ /// Number of processor cycles for I/O Port write operations.
+ /// This value is used to calculate the SWD/JTAG clock speed that is generated with I/O

include/DAP_config.h

@@ -44,6 +44,7 @@ This information includes:
  - Optional information about a connected Target Device (for Evaluation Boards).
 */
 #include <pico/stdlib.h>
+#include <hardware/clocks.h>
 #include <hardware/gpio.h>
 
 #include "cmsis_compiler.h"
@@ -52,8 +53,8 @@ This information includes:
 
 /// Processor Clock of the Cortex-M MCU used in the Debug Unit.
 /// This value is used to calculate the SWD/JTAG clock speed.
-/* Debugprobe actually uses kHz rather than Hz, so just lie about it here */
-#define CPU_CLOCK               125000000U      ///< Specifies the CPU Clock in Hz.
+/* Debugprobe uses PIO for clock generation, so return the current system clock. */
+#define CPU_CLOCK               clock_get_hz(clk_sys)
 
 /// Number of processor cycles for I/O Port write operations.
 /// This value is used to calculate the SWD/JTAG clock speed that is generated with I/O

pico_sdk_import.cmake

@@ -5,7 +5,7 @@
 # It should be include()ed prior to project()
 
 if (DEFINED ENV{PICO_SDK_PATH} AND (NOT PICO_SDK_PATH))
-    set(PICO_SDK_PATH "$ENV{PICO_SDK_PATH}")
+    set(PICO_SDK_PATH $ENV{PICO_SDK_PATH})
     message("Using PICO_SDK_PATH from environment ('${PICO_SDK_PATH}')")
 endif ()
 
@@ -15,7 +15,7 @@ if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT} AND (NOT PICO_SDK_FETCH_FROM_GIT))
 endif ()
 
 if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT_PATH} AND (NOT PICO_SDK_FETCH_FROM_GIT_PATH))
-    set(PICO_SDK_FETCH_FROM_GIT_PATH "$ENV{PICO_SDK_FETCH_FROM_GIT_PATH}")
+    set(PICO_SDK_FETCH_FROM_GIT_PATH $ENV{PICO_SDK_FETCH_FROM_GIT_PATH})
     message("Using PICO_SDK_FETCH_FROM_GIT_PATH from environment ('${PICO_SDK_FETCH_FROM_GIT_PATH}')")
 endif ()
 
@@ -26,7 +26,7 @@ set(PICO_SDK_FETCH_FROM_GIT_PATH "${PICO_SDK_FETCH_FROM_GIT_PATH}" CACHE FILEPAT
 if (NOT PICO_SDK_PATH)
     if (PICO_SDK_FETCH_FROM_GIT)
         include(FetchContent)
-        set(FETCHCONTENT_BASE_DIR_SAVE "${FETCHCONTENT_BASE_DIR}")
+        set(FETCHCONTENT_BASE_DIR_SAVE ${FETCHCONTENT_BASE_DIR})
         if (PICO_SDK_FETCH_FROM_GIT_PATH)
             get_filename_component(FETCHCONTENT_BASE_DIR "${PICO_SDK_FETCH_FROM_GIT_PATH}" REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
         endif ()
@@ -49,9 +49,9 @@ if (NOT PICO_SDK_PATH)
         if (NOT pico_sdk)
             message("Downloading Raspberry Pi Pico SDK")
             FetchContent_Populate(pico_sdk)
-            set(PICO_SDK_PATH "${pico_sdk_SOURCE_DIR}")
+            set(PICO_SDK_PATH ${pico_sdk_SOURCE_DIR})
         endif ()
-        set(FETCHCONTENT_BASE_DIR "${FETCHCONTENT_BASE_DIR_SAVE}")
+        set(FETCHCONTENT_BASE_DIR ${FETCHCONTENT_BASE_DIR_SAVE})
     else ()
         message(FATAL_ERROR
                 "SDK location was not specified. Please set PICO_SDK_PATH or set PICO_SDK_FETCH_FROM_GIT to on to fetch from git."
@@ -60,15 +60,15 @@ if (NOT PICO_SDK_PATH)
 endif ()
 
 get_filename_component(PICO_SDK_PATH "${PICO_SDK_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
-if (NOT EXISTS "${PICO_SDK_PATH}")
+if (NOT EXISTS ${PICO_SDK_PATH})
     message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' not found")
 endif ()
 
-set(PICO_SDK_INIT_CMAKE_FILE "${PICO_SDK_PATH}/pico_sdk_init.cmake")
-if (NOT EXISTS "${PICO_SDK_INIT_CMAKE_FILE}")
+set(PICO_SDK_INIT_CMAKE_FILE ${PICO_SDK_PATH}/pico_sdk_init.cmake)
+if (NOT EXISTS ${PICO_SDK_INIT_CMAKE_FILE})
     message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' does not appear to contain the Raspberry Pi Pico SDK")
 endif ()
 
-set(PICO_SDK_PATH "${PICO_SDK_PATH}" CACHE PATH "Path to the Raspberry Pi Pico SDK" FORCE)
+set(PICO_SDK_PATH ${PICO_SDK_PATH} CACHE PATH "Path to the Raspberry Pi Pico SDK" FORCE)
 
-include("${PICO_SDK_INIT_CMAKE_FILE}")
+include(${PICO_SDK_INIT_CMAKE_FILE})

src/probe.c

@@ -61,9 +61,13 @@ static struct _probe probe;
 void probe_set_swclk_freq(uint freq_khz) {
         uint clk_sys_freq_khz = clock_get_hz(clk_sys) / 1000;
         probe_info("Set swclk freq %dKHz sysclk %dkHz\n", freq_khz, clk_sys_freq_khz);
-        uint32_t divider = clk_sys_freq_khz / freq_khz / 4;
+        // Round up (otherwise fast swclks get faster)
+        uint32_t divider = (((clk_sys_freq_khz + freq_khz - 1)/ freq_khz) + 3) / 4;
         if (divider == 0)
             divider = 1;
+        if (divider > 65535)
+            divider = 65535;
+
         pio_sm_set_clkdiv_int_frac(pio0, PROBE_SM, divider, 0);
 }