From ffb2c4adfb8e65e355b39abd39d994eebc649c98 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
Date: Fri, 3 Jan 2020 04:53:01 +0100
Subject: add (not yet fully working - it can only send through uart now)
 interrupt-driven uart together with "scheduler"

---
 interrupts.c | 93 ++++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 63 insertions(+), 30 deletions(-)

(limited to 'interrupts.c')

diff --git a/interrupts.c b/interrupts.c
index f4192a0..9beee0a 100644
--- a/interrupts.c
+++ b/interrupts.c
@@ -1,6 +1,8 @@
 #include "io.h"
+#include "uart.h"
 #include "svc_interface.h"
 #include "armclock.h"
+#include "scheduler.h"
 
 void __attribute__((noreturn)) setup(void);
 
@@ -14,30 +16,40 @@ void reset_handler(void)
 
 void undefined_instruction_vector(void)
 {
-    puts("Undefined instruction occured");
-    while( 1 )
-    {
-        /* Do Nothing! */
-    }
+  error("Undefined instruction occured");
 }
-
-uint32_t supervisor_call_handler(enum svc_type request, uint32_t arg1,
-				 uint32_t arg2, uint32_t arg3)
+_Bool flag = 0;
+uint32_t supervisor_call_handler(uint32_t regs[14])
 {
-  (void) arg2; (void) arg3; // unused for now
-  
-  switch(request) {
+  switch(regs[0]) {
   case UART_PUTCHAR:
-    putchar(arg1);
+    if (putchar_non_blocking(regs[1]))
+      schedule_wait_for_output(regs, regs[1]);
     break;
   case UART_GETCHAR:
-    return getchar();
+    {
+      int c;
+      if ((c = getchar_non_blocking()) == -1)
+	schedule_wait_for_input(regs);
+      
+      regs[0] = c;
+      break;
+    }
   case UART_WRITE:
-    puts("UART_WRITE not implemented!!!!!");
+    error("UART_WRITE not implemented!!!!!");
     break;
+  case 17:
+    {
+      flag = 1;
+      /* while (1) */
+      /* 	{ */
+      /* 	  printbin(*(uint32_t volatile*) PL011_UART_MIS); puts(""); */
+      /* 	} */
+      break;
+    }
   default:
     // perhaps we should kill the process now?
-    puts("unknown supervisor call type!!!!!");
+    error("unknown supervisor call type!!!!!");
   }
 
   return 0; // a dummy value
@@ -45,36 +57,57 @@ uint32_t supervisor_call_handler(enum svc_type request, uint32_t arg1,
 
 void abort_handler(void)
 {
-  puts("re-entered system");
-
-  while(1);
+  // TODO maybe dump registers here?
+  error("re-entered system due to data/prefetch abort");
 }
 
 void generic_handler(void)
 {
-  puts("something weird happened");
-
-  while(1);
+  error("something weird happened");
 }
 
-void irq_handler(void)
+void irq_handler(uint32_t regs[14])
 {
   if (armclk_irq_pending())
     {
-      puts("<<irq from timer>>");
-      armclk_irq_settimeout(0x00100000);
+      write_SPSR(PL1_PSR);
+      asm volatile("mov r0, %[context]\n\r"
+		   "mov lr, %[return_func]\n\r"
+		   "subs pc, lr, #0" ::
+		   [context]"r" (regs),
+		   [return_func]"r" (schedule_save_context) :
+		   "memory");
     }
-  else
+  else if (uart_irq_pending())
     {
-      puts("unknown irq");
-      while(1);
+      if (uart_recv_irq_pending())
+	{
+	  uart_clear_recv_irq();
+	  scheduler_try_input();
+	}
+      if (uart_send_irq_pending())
+	{
+	  uart_clear_send_irq();
+	  scheduler_try_output();
+	}
+
+      if (read_SPSR().fields.PSR_MODE_4_0 != MODE_USER)
+	{
+	  write_SPSR(PL1_PSR);
+	  asm volatile("mov lr, %0\n\r"
+		       "subs pc, lr, #0" ::
+		       "r" (schedule) : "memory");
+	}
     }
+  else
+    error("unknown irq");
+
+  // important - don't allow this handler to return if irq came from
+  // PL1 (likely supervisor, because we don't really use system) mode
 }
 
 void fiq_handler(void)
 {
-  puts("fiq happened");
-
-  while(1);
+  error("fiq happened");
 }
 
-- 
cgit v1.2.3