detect USB console / add timeouts

debug.asm

@@ -49,7 +49,9 @@ Drive64Write:
     sw      t3, PI_RD_LEN(t5)  // "read" from DRAM to cart
 //  PI_WAIT() // if we always wait before doing operations, this shouldn't be necessary
 
-Drive64WriteDirect: // TODO: rewrite so this takes a0, a1 instead of a2, a3
+Drive64WriteDirect: // TODO: rewrite so this takes a0,a1 instead of a2,a3
+    lli     v0, 0
+
     lui     at, 0x0100      // set printf channel
     or      a3, a3, at
     lli     t1, 0x08        // WRITE mode
@@ -61,14 +63,17 @@ Drive64WriteDirect: // TODO: rewrite so this takes a0, a1 instead of a2, a3
     lui     t9, K_BASE
     lw      t9, K_CI_BASE(t9)
 
-    CI_USB_WRITE_WAIT() // clobbers t0, requires t9
+    CI_USB_WRITE_WAIT(0x10000) // clobbers t0,v0, requires t9
+    bnez    v0, Drive64WriteExit
+    nop
+
     sw      a2, CI_USB_PARAM_RESULT_0(t9)
     PI_WAIT() // yes, these waits seem to be necessary
     sw      a3, CI_USB_PARAM_RESULT_1(t9)
     PI_WAIT()
     sw      t1, CI_USB_COMMAND_STATUS(t9)
-// if we always wait before doing operations, this shouldn't be necessary:
-//  CI_USB_WRITE_WAIT()
+
+    CI_USB_WRITE_WAIT(0x10000) // clobbers t0,v0, requires t9
 
 Drive64WriteExit:
     jr      ra
@@ -102,7 +107,7 @@ DumpAndWrite:
     bnez    v0, DumpAndWriteExit
 
     lui     t0, K_BASE // delay slot
-    lw      t1, K_64DRIVE_MAGIC(t0)
+    lw      t1, K_CONSOLE_AVAILABLE(t0)
     beqz    t1, DumpAndWriteExit
 
     ori     a0, s0, r0 // delay slot

inc/64drive.inc

@@ -42,11 +42,30 @@ macro CI_WAIT() {
     nop
 }
 
-macro CI_USB_WRITE_WAIT() {
+macro CI_USB_WRITE_WAIT(timeout) {
     PI_WAIT()
--
+
+    if {timeout} > 0 {
+        li      v0, {timeout}
+    -
+        lw      t0, CI_USB_COMMAND_STATUS(t9)
+        beqz    v0,+ // die
+        srl     t0, t0, 4 // shift out ARM status, leaving WRITE status
+        bnez    t0,-
+        subiu   v0, v0, 1
+        b       ++ // exit normally
+        or      v0, r0, r0
+    +
+        li      t0, 0xF
+        sw      t0, CI_USB_COMMAND_STATUS(t9) // force disarm
+        lli     v0, 0xDEAD // return error code
+    +
+
+    } else {
+    -
         lw      t0, CI_USB_COMMAND_STATUS(t9)
         srl     t0, t0, 4 // shift out ARM status, leaving WRITE status
         bnez    t0,-
         nop
+    }
 }

inc/main.inc

@@ -21,6 +21,7 @@ constant K_BADVADDR(0x0618)
 
 constant K_64DRIVE_MAGIC(0x0700)
 constant K_CI_BASE(0x0704)
+constant K_CONSOLE_AVAILABLE(0x0708)
 
 constant K_STACK(0x0C00 - 0x10)
 constant K_XXD(0x0C00) // size: 0x400 (any larger and you overwrite kernel code)

kernel.asm

@@ -82,6 +82,17 @@ Drive64Confirmed:
     sw      t1, CI_COMMAND(t9)
     CI_WAIT() // clobbers t0, requires t9
 
+Drive64CheckConsole:
+    // NOTE: we only check at boot, so disconnecting the console
+    //       while running will cause a ton of lag (timeouts) until reset.
+    sw      r0, K_CONSOLE_AVAILABLE(k0)
+    la      a2, KConsoleConfirmed
+    jal     Drive64WriteDirect
+    lli     a3, KConsoleConfirmedX - KConsoleConfirmed
+    lli     t0, 1
+    beqzl   v0, Drive64Done
+    sw      t0, K_CONSOLE_AVAILABLE(k0)
+
 Drive64Done:
 
     // delay to empty pipeline?
@@ -258,7 +269,7 @@ if K_DEBUG {
 
 IHMain: // free to modify any GPR from here to IHExit
 macro KDumpString(str) {
-    lw      t1, K_64DRIVE_MAGIC(k0)
+    lw      t1, K_CONSOLE_AVAILABLE(k0)
     beqz    t1,+
     la      a2, {str}
     jal     Drive64WriteDirect
@@ -372,18 +383,24 @@ ReturnFromInterrupt:
 
 include "debug.asm"
 
-align(4)
+align(8)
 KString0:
     db " ~~ Interrupt Handled ~~", 10, 0
 
-align(4)
+align(8)
 KString1:
     db "    Interrupt States:", 10, 0
 
-align(4)
+align(8)
 KNewline:
     db 10, 0, 0, 0
     dw 0, 0, 0
 
+align(8)
+KConsoleConfirmed:
+    db "USB debug console detected", 10, 0
+align(16)
+KConsoleConfirmedX:
+
 align(4)
     nops((K_BASE << 16) + 0x10000)