move fb to psram to save 200KB for user apps

kernel/src/display.rs

@@ -1,6 +1,5 @@
 use crate::framebuffer::{self, AtomicFrameBuffer, FB_PAUSED};
-use alloc::vec;
-use core::sync::atomic::{AtomicBool, Ordering};
+use core::sync::atomic::Ordering;
 use embassy_rp::{
     Peri,
     gpio::{Level, Output},
@@ -9,9 +8,16 @@ use embassy_rp::{
 };
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
-use once_cell::unsync::Lazy;
 use st7365p_lcd::ST7365P;
 
+#[cfg(feature = "pimoroni2w")]
+use core::alloc::{GlobalAlloc, Layout};
+#[cfg(feature = "pimoroni2w")]
+use embedded_graphics::{
+    pixelcolor::Rgb565,
+    prelude::{DrawTarget, RgbColor},
+};
+
 type DISPLAY = ST7365P<
     ExclusiveDevice<Spi<'static, SPI1, Async>, Output<'static>, Delay>,
     Output<'static>,
@@ -22,10 +28,24 @@ type DISPLAY = ST7365P<
 pub const SCREEN_WIDTH: usize = 320;
 pub const SCREEN_HEIGHT: usize = 320;
 
-pub static mut FRAMEBUFFER: Lazy<AtomicFrameBuffer> = Lazy::new(|| {
-    static mut BUF: [u16; framebuffer::SIZE] = [0; framebuffer::SIZE];
-    AtomicFrameBuffer::new(unsafe { &mut BUF })
-});
+pub static mut FRAMEBUFFER: Option<AtomicFrameBuffer> = None;
+
+fn init_fb() {
+    unsafe {
+        FRAMEBUFFER = Some(if cfg!(not(feature = "pimoroni2w")) {
+            static mut BUF: [u16; framebuffer::SIZE] = [0; framebuffer::SIZE];
+            AtomicFrameBuffer::new(&mut BUF)
+        } else {
+            let slab = crate::heap::HEAP.alloc(Layout::array::<u16>(framebuffer::SIZE).unwrap())
+                as *mut u16;
+            let buf = core::slice::from_raw_parts_mut(slab, framebuffer::SIZE);
+
+            let mut fb = AtomicFrameBuffer::new(buf);
+            fb.clear(Rgb565::BLACK).unwrap();
+            fb
+        });
+    }
+}
 
 pub async fn init_display(
     spi: Spi<'static, SPI1, Async>,
@@ -33,6 +53,8 @@ pub async fn init_display(
     data: Peri<'static, PIN_14>,
     reset: Peri<'static, PIN_15>,
 ) -> DISPLAY {
+    init_fb();
+
     let spi_device = ExclusiveDevice::new(spi, Output::new(cs, Level::Low), Delay).unwrap();
     let mut display = ST7365P::new(
         spi_device,
@@ -44,7 +66,14 @@ pub async fn init_display(
     );
     display.init().await.unwrap();
     display.set_custom_orientation(0x40).await.unwrap();
-    unsafe { FRAMEBUFFER.draw(&mut display).await.unwrap() }
+    unsafe {
+        FRAMEBUFFER
+            .as_mut()
+            .unwrap()
+            .draw(&mut display)
+            .await
+            .unwrap()
+    }
     display.set_on().await.unwrap();
 
     display
@@ -54,7 +83,14 @@ pub async fn init_display(
 pub async fn display_handler(mut display: DISPLAY) {
     loop {
         if !FB_PAUSED.load(Ordering::Acquire) {
-            unsafe { FRAMEBUFFER.safe_draw(&mut display).await.unwrap() };
+            unsafe {
+                FRAMEBUFFER
+                    .as_mut()
+                    .unwrap()
+                    .safe_draw(&mut display)
+                    .await
+                    .unwrap()
+            };
         }
 
         // small yield to allow other tasks to run