more clean up

config.txt

@@ -1,3 +1,4 @@
 kernel=kernel8.img
 arm_64bit=1
 enable_uart=1
+program_usb_boot_mode=1

src/gpio.rs

@@ -3,17 +3,18 @@ use crate::uart::{self};
 const GPFSEL_BASE: u32 = 0x3F20_0000;
 const GPSET_BASE: u32 = 0x3F20_001C;
 const GPCLR_BASE: u32 = 0x3F20_0028;
+const GPLEV_BASE: u32 = 0x3F20_0034;
 
 #[repr(u32)]
 pub enum GPIOState {
-    input = 0b000,
+    Input = 0b000,
-    output = 0b001,
+    Output = 0b001,
-    alternative0 = 0b100,
+    Alternative0 = 0b100,
-    alternative1 = 0b101,
+    Alternative1 = 0b101,
-    alternative2 = 0b110,
+    Alternative2 = 0b110,
-    alternative3 = 0b111,
+    Alternative3 = 0b111,
-    alternative4 = 0b011,
+    Alternative4 = 0b011,
-    alternative5 = 0b010,
+    Alternative5 = 0b010,
 }
 
 pub unsafe fn set_gpio_state(gpio: u8, state: GPIOState) -> Result<(), &'static str> {
@@ -61,3 +62,14 @@ pub fn gpio_low(gpio: u8) -> Result<(), &'static str> {
     }
     Ok(())
 }
+
+pub fn gpio_get_state(gpio: u8) -> u8 {
+    unsafe {
+        let register_index = gpio / 32;
+        let register_offset = gpio % 32;
+        let register_addr = GPLEV_BASE + (register_index as u32 * 4);
+
+        let state = core::ptr::read_volatile(register_addr as *mut u32);
+        return ((state >> register_offset) & 0b1) as u8;
+    }
+}

src/main.rs

@@ -27,7 +27,7 @@ pub unsafe extern "C" fn _start() {
 extern "C" fn main() {
     uart::configure_uart();
     unsafe {
-        let _ = set_gpio_state(29, gpio::GPIOState::output);
+        let _ = set_gpio_state(29, gpio::GPIOState::Output);
     }
 
     // Delay so clock speed can stabilize