如何解决裸机树莓派帧缓冲不工作
我一直致力于为 raspBerry pi 3B 1.2 编写裸机程序
我在汇编程序中编写了一个可以调用 rust 函数的启动函数。我目前正在尝试初始化并将单一颜色绘制到帧缓冲区。当我尝试这个并在我的 pi 上运行时，默认渐变停止显示并且屏幕变黑。但是，没有其他显示。这种情况有什么原因吗？
这是我的启动函数：
pub extern "C" fn start() {
let fb = gpu::init();
if let Ok(fbi) = fb {
fbi.draw();
}
}
这是我的 gpu.rs 文件：
//! This module provides an interface to the raspBerry pi's built in gpu
use super::mmio;
const MBox_BASE_OFFSET: usize = 0x0000b880;
pub fn init() -> Result<FBInfo,()>{
let fb_info = FBInfo {
width: 1920,height: 1080,v_width: 1920,v_height: 1080,pitch: 0,bit_depth: 16,x_offset: 0,y_offset: 0,ptr: 0,size: 0,};
let gpu_channel = Channel::new(0).unwrap();
unsafe {
let fbi_ptr = &fb_info as *const FBInfo;
gpu_channel.write(fbi_ptr as u32 + 0x40000000)
}
if gpu_channel.read() == 0 {Ok(fb_info)} else {Err(())}
}
fn wait_util_ready() {
loop {
//wait until mailBox is ready
let status = MailBoxRegister::Status.read();
if status & 0x80000000 == 0 {
break;
}
}
}
pub struct Channel{
number: u32,}
impl Channel {
const CHANNELS: u32 = 7;
pub fn new(number: u32) -> Result<Self,()> {
if number < Channel::CHANNELS {Ok(Channel { number: number} )} else { Err(()) }
}
pub fn read(&self) -> u32 {
loop {
wait_util_ready();
let value = mmio::read_at_offset(MBox_BASE_OFFSET + MailBoxRegister::Read as usize);
if value & 0b1111 == self.number {
return value;
}
}
}
pub fn write(&self,value: u32) {
wait_util_ready();
mmio::write_at_offset(value + self.number,MBox_BASE_OFFSET + MailBoxRegister::Write as usize)
}
}
pub enum MailBoxRegister {
Read = 0,Poll= 16,Sender = 20,Status = 24,Configuration = 28,Write = 32
}
impl MailBoxRegister {
pub fn read(self) -> u32 {
mmio::read_at_offset(MBox_BASE_OFFSET + self as usize)
}
}
#[repr(align(4))]
pub struct FBInfo {
width: u32,height: u32,v_width: u32,v_height: u32,pitch: u32,bit_depth: u32,x_offset: u32,y_offset: u32,ptr: u32,size: u32,}
impl FBInfo {
pub fn draw(&self) {
let color: u16 = 0xff;
loop {
let mut current_pxl = self.ptr;
for y in 0..self.v_height {
for x in 0..self.v_width {
unsafe {
core::ptr::write_volatile((current_pxl as *mut u16),color);
}
current_pxl += 2
}
}
}
}
}
这是我的 mmio.rs 文件：
pub const MMIO_START: usize = 0x3F000000;
pub fn write_at_offset(data: u32,offset: usize) {
unsafe {
core::ptr::write_volatile((MMIO_START + offset) as *mut u32,data);
}
}
pub fn read_at_offset(offset: usize) -> u32 {
unsafe {
core::ptr::read_volatile((MMIO_START + offset) as *const u32)
}
}
将不胜感激任何帮助。
编辑：这里是编译程序的反汇编：
disassembly of section .rodata.cst16:
0000000000000000 <.rodata.cst16>:
0: 00000780 udf #1920
4: 00000438 udf #1080
8: 00000780 udf #1920
c: 00000438 udf #1080
disassembly of section .rodata.cst8:
0000000000000010 <.rodata.cst8>:
10: 00000000 udf #0
14: 00000010 udf #16
disassembly of section .text.boot:
0000000000000018 <_start>:
18: d53800a0 mrs x0,mpidr_el1
1c: 92401c00 and x0,x0,#0xff
20: b4000040 cbz x0,28 <master>
24: 1400000b b 50 <hang>
0000000000000028 <master>:
28: 58000180 ldr x0,58 <hang+0x8>
2c: 580001a1 ldr x1,60 <hang+0x10>
30: 14000001 b 34 <bss_init>
0000000000000034 <bss_init>:
34: eb01001f cmp x0,x1
38: 54000060 b.eq 44 <enter_rust> // b.none
3c: f900001f str xzr,[x0]
40: 91002000 add x0,#0x8
0000000000000044 <enter_rust>:
44: 5800013e ldr x30,68 <hang+0x18>
48: 910003df mov sp,x30
4c: 94001020 bl 40cc <start>
0000000000000050 <hang>:
50: 14000000 b 50 <hang>
54: d503201f nop
58: 00000070 udf #112
5c: 00000000 udf #0
60: 00000070 udf #112
64: 00000000 udf #0
68: 00004070 udf #16496
6c: 00000000 udf #0
disassembly of section .text._ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E:
0000000000004070 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E>:
4070: b9400c09 ldr w9,[x0,#12]
4074: 34000069 cbz w9,4080 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x10>
4078: 52801fe8 mov w8,#0xff // #255
407c: 14000003 b 4088 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x18>
4080: 14000000 b 4080 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x10>
4084: b9400c09 ldr w9,#12]
4088: b940080b ldr w11,#8]
408c: 34ffffe9 cbz w9,4088 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x18>
4090: 34ffffeb cbz w11,408c <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x1c>
4094: b940200a ldr w10,#32]
4098: 2a1f03ec mov w12,wzr
409c: 340000cb cbz w11,40b4 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x44>
40a0: 2a0a03ed mov w13,w10
40a4: 7100056b subs w11,w11,#0x1
40a8: 1100094a add w10,w10,#0x2
40ac: 790001a8 strh w8,[x13]
40b0: 54ffff81 b.ne 40a0 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x30> // b.any
40b4: 1100058c add w12,w12,#0x1
40b8: 6b09019f cmp w12,w9
40bc: 54fffe40 b.eq 4084 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x14> // b.none
40c0: b940080b ldr w11,#8]
40c4: 35fffeeb cbnz w11,40a0 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x30>
40c8: 17fffffb b 40b4 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E+0x44>
disassembly of section .text.start:
00000000000040cc <start>:
40cc: d10183ff sub sp,sp,#0x60
40d0: 90ffffe8 adrp x8,0 <_start-0x18>
40d4: 90ffffe9 adrp x9,0 <_start-0x18>
40d8: 3dc00100 ldr q0,[x8]
40dc: fd400921 ldr d1,[x9,#16]
40e0: 52971308 mov w8,#0xb898 // #47256
40e4: 72a7e008 movk w8,#0x3f00,lsl #16
40e8: 3d800fe0 str q0,[sp,#48]
40ec: fd0023e1 str d1,#64]
40f0: a904ffff stp xzr,xzr,#72]
40f4: b9400109 ldr w9,[x8]
40f8: 37ffffe9 tbnz w9,#31,40f4 <start+0x28>
40fc: 9100c3e9 add x9,#0x30
4100: 52a8000a mov w10,#0x40000000 // #1073741824
4104: 0b0a0129 add w9,w9,w10
4108: b9000909 str w9,[x8,#8]
410c: b9400109 ldr w9,[x8]
4110: 37ffffe9 tbnz w9,410c <start+0x40>
4114: b85e8109 ldur w9,#-24]
4118: 72000d3f tst w9,#0xf
411c: 54ffff81 b.ne 410c <start+0x40> // b.any
4120: 34000069 cbz w9,412c <start+0x60>
4124: 910183ff add sp,#0x60
4128: d65f03c0 ret
412c: ad4187e0 ldp q0,q1,#48]
4130: f9402be8 ldr x8,#80]
4134: 9100c3e0 add x0,#0x30
4138: ad0007e0 stp q0,[sp]
413c: f90013e8 str x8,#32]
4140: ad0187e0 stp q0,#48]
4144: f9002be8 str x8,#80]
4148: 97ffffca bl 4070 <_ZN8graph_os8platform6raspi33gpu6FBInfo4draw17h1a3de04fef86caf4E>
414c: d4200020 brk #0x1
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 dio@foxmail.com 举报，一经查实，本站将立刻删除。
