Add new system for startup.

Now instead of init() and main() being responsible for all
initialization, individual modules can link in their own
initialization routines.

There are 7 levels for these initializiation routines.

So far these are how the levels are defined

level 0 - Here the world is dark. Nothing is initialized.
          This level is responsible for initializing the
          system clock.

level 1 - The system clock has been configured, but nothing else. Not
          even global variables. This level is responsible for loading
          the data sections from flash and clearing the .bss section.

level 2 - USART2 is enabled and set to be the main kernel logging
          vehicle. From this point on klogf(...) can be used.

level 3 - The NVIC is reset to point to the flash. From this point
          on interrupts can be received. I expect this is where
          most core initialization routines will take place

levels 4 to 7 - User initializiation levels.

main - main() is called after all 8 initialization levels have executed,
       so in a sense main() is like a 9th initialization level, except
       that there is can be only one main() routine whereas there can be
       multiple initalization routines per level.

1 files changed, 7 insertions, 102 deletions

diff --git a/02-usart/src/kern/main.c b/02-usart/src/kern/main.c
index 32166bc..ebb2164 100644
--- a/02-usart/src/kern/main.c
+++ b/02-usart/src/kern/main.c
@@ -1,67 +1,12 @@
-
 #include "arch.h"
+#include "kern/log.h"
 
-#include "arch/stm32l4xxx/peripherals/clock.h"
-#include "arch/stm32l4xxx/peripherals/dma.h"
-#include "arch/stm32l4xxx/peripherals/gpio.h"
 #include "arch/stm32l4xxx/peripherals/system.h"
-#include "arch/stm32l4xxx/peripherals/usart.h"
-#include "arch/stm32l4xxx/peripherals/nvic.h"
-#include "arch/stm32l4xxx/peripherals/irq.h"
-
-#include "kern/dma/dma_manager.h"
-#include "kern/gpio/gpio_manager.h"
-#include "kern/gpio/sysled.h"
-
-#include "kern/delay.h"
-#include "kern/mem.h"
-#include "kern/string.h"
-
-/** Overrides the default systick irq handler. */
-void on_systick()
-{
-  static int is_on = 0;
-  gpio_reserved_pin_t sysled = get_sysled();
-
-  if (is_on) {
-    set_gpio_pin_low(sysled);
-  } else {
-    set_gpio_pin_high(sysled);
-  }
-
-  is_on = ! is_on;
-}
+#include "arch/stm32l4xxx/peripherals/clock.h"
 
-void setup_usart2(uint32_t baud_rate)
+void on_systick() /* Overrides weak-symbol on_systick. */
 {
-  enable_hsi(&RCC, true);
-
-  int ec = 0;
-  gpio_enable_alternate_function(
-      GPIO_ALTERNATE_FUNCTION_USART2_TX, GPIO_PIN_PA2, &ec);
-
-  if (ec) {
-    unhandled_isr(ec & 0xff);
-  }
-
-  gpio_enable_alternate_function(
-      GPIO_ALTERNATE_FUNCTION_USART2_RX, GPIO_PIN_PA15, &ec);
-
-  if (ec) {
-    unhandled_isr(ec & 0xff);
-  }
-
-  set_usart2_clock_src(&RCC, USART_CLK_SRC_HSI16);
-  set_usart2_clock_enabled(&RCC, USART_CLK_SRC_HSI16);
-
-  /* De-assert reset of USART2 */
-  regset(RCC.apb1rst1_r, rcc_usart2rst, 0);
-
-  USART2.c_r1 = 0;
-  USART2.c_r2 = 0;
-  USART2.c_r3 = 0;
-
-  usart_set_divisor(&USART2, 16000000 / baud_rate);
+  klogf("Systick\n");
 }
 
 #ifdef ARCH_STM32L4
@@ -69,56 +14,16 @@ void setup_usart2(uint32_t baud_rate)
 /* Main function. This gets executed from the interrupt vector defined above. */
 int main()
 {
-  /* Enable a higher clock frequency. */
-  set_system_clock_MHz(80);
-
-  setup_usart2(115200);
-  regset(USART2.c_r1, usart_txeie, 1);
-  regset(USART2.c_r1, usart_rxneie, 1);
-  usart_enable_dma(&USART2, USART_ENABLE_TX);
-  usart_set_enabled(&USART2, USART_ENABLE_TX | USART_ENABLE_RX);
-
-
-  dma_opts_t opts = DEFAULT_DMA_OPTS;
-  opts.transfer_complete_interrupt_enable = 1;
-  int ec = 0;
-  dma_mem2p_channel_t dma_chan =
-    select_dma_channel_mem2p(DMA1_PERIPH_USART2_TX, &opts, &ec);
-  enable_interrupt(dma_channel_get_interrupt(dma_chan.c_));
+  klogf("Hello, World! Clock Mhz: %d\n", (uint32_t) get_clock_mhz());
 
-  if (ec) {
-    usart_printf(&USART2, "Select DMA channel failed :( %d\n", ec);
-    for (;;);
-  }
-
-  // const char* thing = "Good Thing This Works!";
-
-  char* str = halloc(128);
-  kstrcpy(str, "Hello, Heap!");
-
-  usart_printf(&USART2, "DATA_SEGMENT_START %p\n", &DATA_SEGMENT_START);
-  usart_printf(&USART2, "DATA_SEGMENT_STOP: %p\n", &DATA_SEGMENT_STOP);
-  usart_printf(&USART2, "str at: %p\n", str);
-  usart_printf(&USART2, "str: %s\n", str);
-  // usart_printf(&USART2, "%s\n", thing);
-  // regset(USART2.ic_r, usart_tccf, 1);
-  // dma_mem2p_initiate_transfer(dma_chan, thing, strlen(thing));
-
-  gpio_reserved_pin_t sysled = get_sysled();
-  set_gpio_pin_high(sysled);
-
-  // usart_printf(&USART2, "Start Configuring Countdown!\n");
-
-  /* Set the countdown to start from 1,000,0000. */
-  SCB.strv_r = 1000000;
+  /* Set the countdown to start from 10,000,0000. */
+  SCB.strv_r = 10000000;
 
   /* Enable interrupts. */
   regset(SCB.stcs_r, scb_tickint, 1);
 
   /* Start the systick. */
   regset(SCB.stcs_r, scb_enable, 1);
-
-  // usart_printf(&USART2, "Start Countdown Started!\n");
 }
 
 #endif