Get a good, basic framework for ISRs and properly handle the data sections.

7 files changed, 189 insertions, 182 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 09a39d9..792547f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 
 include(cmake/fiddle.cmake)
 
-project (ch537)
+project (ch537 LANGUAGES C ASM)
 
 # Configure for Bare Metal.
 set(CMAKE_SYSTEM_NAME Generic)
@@ -12,9 +12,11 @@ set(CMAKE_SYSTEM_PROCESSOR riscv32)
 set(TC_PREFIX riscv32-unknown-elf-)
 include_directories(include linker ${CMAKE_BINARY_DIR}/generated/fdl)
 
-file(GLOB SOURCES "src/*.c" "src/*.s")
+file(GLOB_RECURSE SOURCES "src/*.c" "src/*.s")
 file(GLOB LINKER_SCRIPT "linker/*.ld")
 
+message("Sources ${SOURCES}")
+
 file(REAL_PATH "ch-flash/" CH_FLASH_DIR)
 
 # Set compiler and tools
@@ -24,7 +26,8 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 
 # Set compiler and linker flags
-set(CMAKE_C_FLAGS "-ffreestanding -march=rv32imac -mabi=ilp32 -lgcc -static -nostartfiles -O -std=gnu99" CACHE INTERNAL "C Compiler options")
+set(CMAKE_C_FLAGS "-ffreestanding -march=rv32imac_zicsr -mabi=ilp32 -lgcc -static -nostartfiles -O -std=gnu99" CACHE INTERNAL "C Compiler options")
+set(CMAKE_ASM_FLAGS "-ffreestanding -march=rv32imac_zicsr -mabi=ilp32 -lgcc -static -nostartfiles -O -std=gnu99" CACHE INTERNAL "C Compiler options")
 set(CMAKE_EXE_LINKER_FLAGS "--xref -static -T ${LINKER_SCRIPT}" CACHE INTERNAL "Linker options")
 
 # Add executable with custom linking commands
diff --git a/cmake/fiddle.cmake b/cmake/fiddle.cmake
new file mode 100644
index 0000000..6b151a2
--- /dev/null
+++ b/cmake/fiddle.cmake
@@ -0,0 +1,32 @@
+function(add_fiddle_source header_out fdl_file)
+  get_filename_component(dir_path ${fdl_file} DIRECTORY)
+  get_filename_component(file_name_without_extension ${fdl_file} NAME_WE)
+  set(path_without_extension "${dir_path}/${file_name_without_extension}")
+  
+  # Define the output path based on the input `.fdl` file's name
+  set(output_header "${CMAKE_BINARY_DIR}/generated/${path_without_extension}.h")
+  get_filename_component(output_dir ${output_header} DIRECTORY)
+  
+  # Define the custom command to generate the header
+  add_custom_command(
+      OUTPUT ${output_header}
+      DEPENDS ${fdl_file}
+      COMMENT "Fiddle compile ${fdl_file} -> ${output_header}"
+      COMMAND ${CMAKE_COMMAND} -E make_directory "${output_dir}"
+      COMMAND fiddlec -Lc -h ${output_header} -I ${CMAKE_SOURCE_DIR}/fdl/ --intf-dir ${CMAKE_BINARY_DIR}/fdli/ ${CMAKE_SOURCE_DIR}/${fdl_file}
+  )
+  
+  # Make the output header file available as a source file for the target
+  set_source_files_properties(${output_header} PROPERTIES GENERATED TRUE)
+  set(${header_out} ${output_header} PARENT_SCOPE)
+endfunction()
+
+function(fiddle_sources headers_out files)
+  set(headers)
+  foreach (fdl_file ${files})
+    file(RELATIVE_PATH rel_path "${CMAKE_SOURCE_DIR}" "${fdl_file}")
+    add_fiddle_source(header_out ${rel_path})
+    list(APPEND headers "${header_out}")
+  endforeach()
+  set(${headers_out} "${headers}" PARENT_SCOPE)
+endfunction()
diff --git a/include/isr_vector.h b/include/isr_vector.h
index d916db0..bd5786a 100644
--- a/include/isr_vector.h
+++ b/include/isr_vector.h
@@ -2,55 +2,8 @@
 
 #include <stdint.h>
 
-/* Type def to a void function to make things mor ereadable. */
-typedef void (*isr_routine)(void);
-
-typedef struct {
-  // What NULL points to. nothing useful.
-  uint32_t reserved__;
-  // Called when the device boots or reset is pressed.
-  isr_routine reset_cb;
-  isr_routine nmi_cb;
-  isr_routine exc_cb;
-
-  uint32_t _reserved_1[8];
-
-  isr_routine systick_cb;
-
-  uint32_t _reserved_2;
-
-  isr_routine swi_cb;
-
-  uint32_t _reserved_3;
-
-  isr_routine tmr0_cb;
-  isr_routine gpio_a_cb;
-  isr_routine gpio_b_cb;
-  isr_routine spi0_cb;
-  isr_routine blel_cb;
-  isr_routine bleb_cb;
-  isr_routine usb_cb;
-
-  uint32_t _reserved_4;
-
-  isr_routine tmr1_cb;
-  isr_routine tmr2_cb;
-  isr_routine uart0_cb;
-  isr_routine uart1_cb;
-  isr_routine rtc_cb;
-  isr_routine adc_cb;
-
-  uint32_t _reserved_5;
-
-  isr_routine pwmx_cb;
-  isr_routine tmr3_cb;
-  isr_routine uart2_cb;
-  isr_routine uart3_cb;
-  isr_routine wdog_bat_cb;
-} isr_vector_t;
-
 /** Reference to the global ISR vector. */
-extern isr_vector_t isr_vector;
+extern char isr_vector;
 
 /** Default IRQ handler. This is weakly defined and can be overridden. */
 void default_irq_handler(void);
@@ -79,3 +32,5 @@ void irq_on_tmr3(void);
 void irq_on_uart2(void);
 void irq_on_uart3(void);
 void irq_on_wdog_bat(void);
+
+#define IRQ(name) void __attribute__((__section__(".isr_vector"))) name(void)
diff --git a/linker/ls.ld b/linker/ls.ld
index e4cc0af..18ee181 100644
--- a/linker/ls.ld
+++ b/linker/ls.ld
@@ -7,22 +7,36 @@ MEMORY
 SECTIONS
 {
   . = ORIGIN(flash);
+
   .text : ALIGN(0x04) {
-    *(.isr_vector);
-    . = ALIGN(0x100);
+    *(.sinit);
+
+    /* The ch573 starts execution at address 0x0000, so we have to make sure the
+     * on_reset function is put at the beginning of the flash. */
+    *(.isr_routines.on_reset);
+
+    /* The rest of the code. */
     *(.text);
   } >flash AT>flash
 
-  DATA_VALUES_IN_FLASH = LOADADDR(.data);
+  ISR_VECTOR_IN_FLASH = LOADADDR(.isr_vector);
+  .isr_vector : ALIGN(0x04) {
+    ISR_VECTOR_START = .;
+    *(.isr_vector);
+    ISR_VECTOR_STOP = .;
+  } >sram AT>flash
 
+  DATA_VALUES_IN_FLASH = LOADADDR(.data);
   .data : ALIGN(0x04) {
     . = ALIGN(0x04);
     DATA_SEGMENT_START = .;
     *(.data);
     *(.data.*);
+    *(.sdata);
     *(.rodata.*);
-    DATA_SEGMENT_STOP = .;
+    *(.srodata.*);
     . = ALIGN(0x04);
+    DATA_SEGMENT_STOP = .;
   } >sram AT>flash
 
   .bss : ALIGN(0x04) {
diff --git a/src/blinky.c b/src/blinky.c
index d8a29bd..9f89238 100644
--- a/src/blinky.c
+++ b/src/blinky.c
@@ -1,50 +1,19 @@
 #include <stdint.h>
 
+#include "isr_vector.h"
 #include "ch573/gpio.h"
 
 #define GPIO_PORT_A ch573_gpio__gpio_port_a
 #define GPIO_PORT CH573_GPIO__GPIO_PORT_T_INTF
 
-static void start(void);
-
-/*
- * Function (or really pointer to code) for the reset interrupt handler.
- */
-void on_reset(void);
-
 /*
  * Function which delays for a bit.
  */
 void delay(void);
 
-/* Type def to a void function to make things mor ereadable. */
-typedef void (*isr_routine)(void);
-
-/** The ISR Vector structure. This is linked to starting at address 0. */
-// __attribute((__section__(".isr_vector"))) volatile struct {
-//   // What NULL points to. nothing useful.
-//   uint32_t reserved__;
-//   // Called when the device boots or reset is pressed.
-//   isr_routine reset_cb;
-//   isr_routine nmi_cb;
-//   isr_routine exc_cb;
-// } isr_vectors = {.reset_cb = on_reset};
-
-/*
- * The reset callback.This has to be a naked function because the stack pointer
- * may not be initialized!!.
- */
-__attribute((naked)) void on_reset(void)
-{
-  // Set up the stack pointer to point to the end of SRAM.
-  asm volatile(
-      "li	sp,0x20008000\n"
-      "addi	sp,sp,-4\n"
-      "jalr %0\n"
-      "spin:\n"
-      "j spin\n"
-      :
-      : "r"(start));
+void main(void);
+IRQ(irq_on_systick) {
+  main();
 }
 
 uint32_t collatz(uint32_t n)
@@ -77,38 +46,35 @@ void blink_n(int n)
 
 void delay(void)
 {
-  for (volatile uint32_t i = 0; i < 10000; ++i);
+  for (volatile uint32_t i = 0; i < 10000; ++i) {
+    asm volatile("");
+  }
 }
 
+volatile uint32_t deadbeef = 0xdeadbeef;
+
+// Memory-mapped address of the data values in flash.
+extern uint32_t DATA_VALUES_IN_FLASH;
+
+// Where the data is located in sram.
+extern uint32_t DATA_SEGMENT_START;
+extern uint32_t DATA_SEGMENT_STOP;
+
 /* Main routine. This is called on_reset once everything else has been set up.
  */
-static void start(void)
+void main(void)
 {
   GPIO_PORT.dir.set(GPIO_PORT_A, DIR_OUT, 8);
   GPIO_PORT.pd_drv.set(GPIO_PORT_A, PD_DRV_OPEN_DRAIN, 8);
 
   for (;;) {
-    GPIO_PORT.out.set(GPIO_PORT_A, ON, 8);
+    if (deadbeef == 0xdeadbeef) {
+      GPIO_PORT.out.set(GPIO_PORT_A, ON, 8);
+    }
     delay();
     delay();
     delay();
     GPIO_PORT.out.set(GPIO_PORT_A, OFF, 8);
     delay();
   }
-
-  // uint32_t i;
-  // for (i = 1;; ++i) {
-  //   uint32_t c = collatz(i);
-  //   blink_n(c);
-
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  //   delay();
-  // }
 }
diff --git a/src/init.c b/src/init.c
index 8d895f5..a81ce1d 100644
--- a/src/init.c
+++ b/src/init.c
@@ -2,34 +2,19 @@
 #include <stdint.h>
 
 #include "isr_vector.h"
-#include "ch573/gpio.h"
-
-_Static_assert(offsetof(typeof(isr_vector_t), nmi_cb) == 0x8, "Offset wrong");
-
-_Static_assert(
-    offsetof(typeof(isr_vector_t), systick_cb) == 0x30, "Offset wrong ");
-
-_Static_assert(
-    offsetof(typeof(isr_vector_t), tmr0_cb) == 0x40, "Offset wrong ");
-
-_Static_assert(
-    offsetof(typeof(isr_vector_t), tmr1_cb) == 0x60, "Offset wrong ");
-
-_Static_assert(
-    offsetof(typeof(isr_vector_t), pwmx_cb) == 0x7c, "Offset wrong ");
-
-_Static_assert(
-    offsetof(typeof(isr_vector_t), wdog_bat_cb) == 0x8c, "Offset wrong ");
 
 void on_reset(void);
 
-void __attribute__((weak, interrupt)) default_irq_handler(void)
+void __attribute__((weak, interrupt, __section__(".isr_vector")))
+default_irq_handler(void)
 {
   return;
 }
 
-#define WEAK_IRQ(irq) \
-  void __attribute__((weak, alias("default_irq_handler"))) irq(void)
+#define WEAK_IRQ(irq)                                                  \
+  void __attribute__((                                                 \
+      weak, alias("default_irq_handler"), __section__(".isr_vector"))) \
+  irq(void)
 
 WEAK_IRQ(irq_on_nmi);
 WEAK_IRQ(irq_on_exc);
@@ -54,43 +39,28 @@ WEAK_IRQ(irq_on_uart2);
 WEAK_IRQ(irq_on_uart3);
 WEAK_IRQ(irq_on_wdog_bat);
 
-/** The ISR Vector structure. This is linked to starting at address 0. */
-__attribute((__section__(".isr_vector"))) volatile isr_vector_t isr_vectors = {
-    .reset_cb = on_reset,
-    .nmi_cb = irq_on_nmi,
-    .exc_cb = irq_on_exc,
-    .systick_cb = irq_on_systick,
-    .swi_cb = irq_on_swi,
-    .tmr0_cb = irq_on_tmr0,
-    .gpio_a_cb = irq_on_gpio_a,
-    .gpio_b_cb = irq_on_gpio_b,
-    .spi0_cb = irq_on_spi0,
-    .blel_cb = irq_on_blel,
-    .bleb_cb = irq_on_bleb,
-    .usb_cb = irq_on_usb,
-    .tmr1_cb = irq_on_tmr1,
-    .tmr2_cb = irq_on_tmr2,
-    .uart0_cb = irq_on_uart0,
-    .uart1_cb = irq_on_uart1,
-    .rtc_cb = irq_on_rtc,
-    .adc_cb = irq_on_adc,
-    .pwmx_cb = irq_on_pwmx,
-    .tmr3_cb = irq_on_tmr3,
-    .uart2_cb = irq_on_uart2,
-    .uart3_cb = irq_on_uart3,
-    .wdog_bat_cb = irq_on_wdog_bat,
-};
+// Memory-mapped address of the data values in flash.
+extern uint32_t ISR_VECTOR_IN_FLASH;
+
+// Where the data is located in sram.
+extern uint32_t ISR_VECTOR_START;
+extern uint32_t ISR_VECTOR_STOP;
 
 // Memory-mapped address of the data values in flash.
-extern uint32_t* DATA_VALUES_IN_FLASH;
+extern uint32_t DATA_VALUES_IN_FLASH;
 
 // Where the data is located in sram.
-extern uint32_t* DATA_SEGMENT_START;
-extern uint32_t* DATA_SEGMENT_STOP;
+extern uint32_t DATA_SEGMENT_START;
+extern uint32_t DATA_SEGMENT_STOP;
 
 // Where 0-initialized data is in sram.
-extern uint32_t* BSS_START;
-extern uint32_t* BSS_STOP;
+extern uint32_t BSS_START;
+extern uint32_t BSS_STOP;
+
+static inline void set_mtvec(void* vector_table)
+{
+  asm volatile("csrw mtvec, %0" : : "r"(vector_table));
+}
 
 /*
  * Initialize the data segment and the bss segment.
@@ -100,15 +70,23 @@ extern uint32_t* BSS_STOP;
  */
 void init_data_segments(void)
 {
-  uint32_t* src = DATA_VALUES_IN_FLASH;
-  uint32_t* dest = DATA_SEGMENT_START;
+  /* Copy the data from the flash to memory. */
+  uint32_t* src = &DATA_VALUES_IN_FLASH;
+  uint32_t* dest = &DATA_SEGMENT_START;
+  while (dest != &DATA_SEGMENT_STOP) {
+    *(dest++) = *(src++);
+  }
 
-  while (dest != DATA_SEGMENT_STOP) {
+  /* Copy the ISR vector to memory. This makes it possible to still recieve
+   * interrupts even when the flash is powered down. */
+  src = &ISR_VECTOR_IN_FLASH;
+  dest = &ISR_VECTOR_START;
+  while (dest != &ISR_VECTOR_STOP) {
     *(dest++) = *(src++);
   }
 
-  dest = BSS_START;
-  while (dest != BSS_STOP) {
+  dest = &BSS_START;
+  while (dest != &BSS_STOP) {
     *(dest++) = 0;
   }
 }
@@ -118,26 +96,31 @@ void init_data_segments(void)
  */
 extern void main(void);
 
-#define GPIO_PORT_A ch573_gpio__gpio_port_a
-#define GPIO_PORT CH573_GPIO__GPIO_PORT_T_INTF
 /* Start function. Responsible for initializing the system and jumping to the
  * main function. */
-// static void start(void)
-// {
-//   // init_data_segments();
-//   GPIO_PORT.dir.set(GPIO_PORT_A, DIR_OUT, 8);
-//   GPIO_PORT.pd_drv.set(GPIO_PORT_A, PD_DRV_OPEN_DRAIN, 8);
-//   GPIO_PORT.out.set(GPIO_PORT_A, OFF, 8);
-// 
-//   main();
-// }
-
-/*
- * The reset callback.This has to be a naked function because the stack pointer
- * may not be initialized!!.
- */
+static void start(void)
+{
+  /* Initialize the data segments. */
+  init_data_segments();
+  /* Set the mtvec to the isr_vector. */
+  set_mtvec(&isr_vector);
+  /* Jump to main */
+  main();
+}
 
 /*
  * The reset callback.This has to be a naked function because the stack pointer
  * may not be initialized!!.
  */
+__attribute((naked, __section__(".isr_routines.on_reset"))) void on_reset(void)
+{
+  // Set up the stack pointer to point to the end of SRAM.
+  asm volatile(
+      "li	sp,0x20008000\n"
+      "addi	sp,sp,-4\n"
+      "jalr %0\n"
+      "spin:\n"
+      "j spin\n"
+      :
+      : "r"(start));
+}
diff --git a/src/isr.s b/src/isr.s
new file mode 100644
index 0000000..6a9e6cf
--- /dev/null
+++ b/src/isr.s
@@ -0,0 +1,54 @@
+
+.section .sinit
+_start:
+j on_reset /* first instruction. Should jump directly to on_reset */
+
+.section .isr_vector
+.global isr_vector
+isr_vector:
+.align 4
+.word 0
+  j irq_on_nmi
+  j irq_on_exc
+
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+
+  j irq_on_systick
+
+.word 0
+
+  j irq_on_swi
+
+.word 0
+
+  j irq_on_tmr0
+  j irq_on_gpio_a
+  j irq_on_gpio_b
+  j irq_on_spi0
+  j irq_on_blel
+  j irq_on_bleb
+  j irq_on_usb
+
+.word 0
+
+  j irq_on_tmr1
+  j irq_on_tmr2
+  j irq_on_uart0
+  j irq_on_uart1
+  j irq_on_rtc
+  j irq_on_adc
+
+.word 0
+
+  j irq_on_pwmx
+  j irq_on_tmr3
+  j irq_on_uart2
+  j irq_on_uart3
+  j irq_on_wdog_bat