1 files changed, 86 insertions, 17 deletions

diff --git a/src/host.rs b/src/host.rs
index eb10b22..e8325a7 100644
--- a/src/host.rs
+++ b/src/host.rs
@@ -127,9 +127,26 @@ fn region_alias(output: &mut dyn Write, name: &str, placement: Memory) -> io::Re
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct FlashOpts {
     size: usize,
+    offset: u32,
     flexspi: FlexSpi,
 }
 
+impl FlashOpts {
+    /// Produce the flash address of the image within
+    /// FlexSPI memory.
+    fn flash_origin(&self, family: Family) -> Option<u32> {
+        self.flexspi
+            .start_address(family)
+            .map(|start_address| start_address + self.offset)
+    }
+
+    /// A bootable image (with the boot header) isn't offset
+    /// in flash.
+    fn is_boot_image(&self) -> bool {
+        self.offset == 0
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct EnvOverride {
     default: usize,
@@ -342,6 +359,43 @@ impl RuntimeBuilder {
             heap_size: EnvOverride::new(0),
             flash_opts: Some(FlashOpts {
                 size: flash_size,
+                offset: 0,
+                flexspi: FlexSpi::family_default(family),
+            }),
+            linker_script_name: DEFAULT_LINKER_SCRIPT_NAME.into(),
+        }
+    }
+
+    /// Allocate a flash partition for this program to be booted by your software.
+    ///
+    /// `partition_size` is the size of the flash allocation, in bytes, for this
+    /// program. `partition_offset` describes the byte offset where the partition
+    /// starts. The offset is from the start of the FlexSPI memory region.
+    ///
+    /// The program constructed at this flash location cannot be booted by NXP's boot
+    /// ROM. You should bring your own software to execute this program. Note that
+    /// [the runtime behaviors](RuntimeBuilder) ensure that the vector table is placed
+    /// in flash at the given `partition_offset`.
+    ///
+    /// To compute a partition offset from two absolute flash addresses, use
+    /// [`Family::flexspi_start_addr`] to learn the FlexSPI starting address.
+    pub fn in_flash(family: Family, partition_size: usize, partition_offset: u32) -> Self {
+        Self {
+            family,
+            flexram_banks: family.default_flexram_banks(),
+            text: Memory::Itcm,
+            rodata: Memory::Ocram,
+            data: Memory::Ocram,
+            vectors: Memory::Dtcm,
+            bss: Memory::Ocram,
+            uninit: Memory::Ocram,
+            stack: Memory::Dtcm,
+            stack_size: EnvOverride::new(8 * 1024),
+            heap: Memory::Dtcm,
+            heap_size: EnvOverride::new(0),
+            flash_opts: Some(FlashOpts {
+                size: partition_size,
+                offset: partition_offset,
                 flexspi: FlexSpi::family_default(family),
             }),
             linker_script_name: DEFAULT_LINKER_SCRIPT_NAME.into(),
@@ -508,19 +562,21 @@ impl RuntimeBuilder {
         if let Some(flash_opts) = &self.flash_opts {
             write_flash_memory_map(writer, self.family, flash_opts, &self.flexram_banks)?;
 
-            let boot_header_x = match self.family {
-                Family::Imxrt1010
-                | Family::Imxrt1015
-                | Family::Imxrt1020
-                | Family::Imxrt1040
-                | Family::Imxrt1050
-                | Family::Imxrt1060
-                | Family::Imxrt1064
-                | Family::Imxrt1160
-                | Family::Imxrt1170 => include_bytes!("host/imxrt-boot-header.x").as_slice(),
-                Family::Imxrt1180 => include_bytes!("host/imxrt-boot-header-1180.x").as_slice(),
-            };
-            writer.write_all(boot_header_x)?;
+            if flash_opts.is_boot_image() {
+                let boot_header_x = match self.family {
+                    Family::Imxrt1010
+                    | Family::Imxrt1015
+                    | Family::Imxrt1020
+                    | Family::Imxrt1040
+                    | Family::Imxrt1050
+                    | Family::Imxrt1060
+                    | Family::Imxrt1064
+                    | Family::Imxrt1160
+                    | Family::Imxrt1170 => include_bytes!("host/imxrt-boot-header.x").as_slice(),
+                    Family::Imxrt1180 => include_bytes!("host/imxrt-boot-header-1180.x").as_slice(),
+                };
+                writer.write_all(boot_header_x)?;
+            }
         } else {
             write_ram_memory_map(writer, self.family, &self.flexram_banks)?;
         }
@@ -695,10 +751,7 @@ fn write_flash_memory_map(
     writeln!(
         output,
         "FLASH (RX) : ORIGIN = {:#X}, LENGTH = {:#X}",
-        flash_opts
-            .flexspi
-            .start_address(family)
-            .expect("Already checked"),
+        flash_opts.flash_origin(family).expect("Already checked"),
         flash_opts.size
     )?;
     write_flexram_memories(output, family, flexram_banks)?;
@@ -901,6 +954,22 @@ impl Family {
             },
         }
     }
+
+    /// Returns the starting address for the given `flexspi` instance.
+    ///
+    /// If a FlexSPI instance isn't available for this family, the return
+    /// is `None`. Otherwise, the return is the starting address in the
+    /// MCU's memory map.
+    ///
+    /// ```
+    /// use imxrt_rt::{Family::*, FlexSpi::*};
+    ///
+    /// assert_eq!(Imxrt1060.flexspi_start_addr(FlexSpi1), Some(0x6000_0000));
+    /// assert!(Imxrt1010.flexspi_start_addr(FlexSpi2).is_none());
+    /// ```
+    pub fn flexspi_start_addr(self, flexspi: FlexSpi) -> Option<u32> {
+        flexspi.start_address(self)
+    }
 }
 
 /// FlexRAM bank allocations.