fusee: Complete re-write of the hardware initialization code:

- Updated code to match hekate's;
- Improved nxboot (now boots firmwares 2.x successfully);
- Temporarily disabled built-in boot system module support;
- Fixed multiple bugs.

fusee/fusee-primary/src/btn.c

@@ -0,0 +1,64 @@
+#include <stdint.h>
+
+#include "btn.h"
+#include "i2c.h"
+#include "gpio.h"
+#include "timers.h"
+
+uint32_t btn_read()
+{
+    uint32_t res = 0;
+    
+    if (!gpio_read(GPIO_BUTTON_VOL_DOWN))
+        res |= BTN_VOL_DOWN;
+    
+    if (!gpio_read(GPIO_BUTTON_VOL_UP))
+        res |= BTN_VOL_UP;
+    
+    uint32_t val = 0;
+    if (i2c_query(4, 0x3C, 0x15, &val, 1))
+    {
+        if (val & 0x4)
+            res |= BTN_POWER;
+    }
+    
+    return res;
+}
+
+uint32_t btn_wait()
+{
+    uint32_t res = 0, btn = btn_read();
+    int pwr = 0;
+
+    if (btn & BTN_POWER)
+    {
+        pwr = 1;
+        btn &= ~BTN_POWER;
+    }
+
+    do
+    {
+        res = btn_read();
+
+        if (!(res & BTN_POWER) && pwr)
+            pwr = 0;
+        else if (pwr)
+            res &= ~BTN_POWER;
+    } while (btn == res);
+
+    return res;
+}
+
+uint32_t btn_wait_timeout(uint32_t time_ms, uint32_t mask)
+{
+    uint32_t timeout = get_time_ms() + time_ms;
+    uint32_t res = btn_read() & mask;
+
+    do
+    {
+        if (!(res & mask))
+            res = btn_read() & mask;
+    } while (get_time_ms() < timeout);
+
+    return res;
+}