esp32c3 flashless target (#627)

Author: tact1m4n3

examples/espressif/esp/README.md

@@ -19,3 +19,9 @@ NOTE: you have to provide a [bootloader](https://docs.espressif.com/projects/esp
 esptool.py --chip esp32c3 --baud 460800 --before default_reset --after hard_reset write_flash 0x0 \
     zig-out/firmware/esp32_c3_direct_boot_blinky.bin
 ```
+
+- flashless image
+
+```sh
+esptool.py --chip esp32c3 --baud 460800 --no-stub load_ram zig-out/firmware/esp32_c3_flashless_blinky.bin
+```

examples/espressif/esp/build.zig

@@ -15,6 +15,7 @@ pub fn build(b: *std.Build) void {
     const targets = [_]TargetDescription{
         .{ .prefix = "esp32_c3", .target = mb.ports.esp.chips.esp32_c3 },
         .{ .prefix = "esp32_c3_direct_boot", .target = mb.ports.esp.chips.esp32_c3_direct_boot },
+        .{ .prefix = "esp32_c3_flashless", .target = mb.ports.esp.chips.esp32_c3_flashless },
     };
 
     const available_examples = [_]Example{

examples/espressif/esp/src/custom_clock_config.zig

@@ -5,7 +5,6 @@ const clocks = hal.clocks;
 const usb_serial_jtag = hal.usb_serial_jtag;
 
 pub const microzig_options: microzig.Options = .{
-    .log_level = .debug,
     .logFn = usb_serial_jtag.logger.log,
 };
 

examples/espressif/esp/src/systimer.zig

@@ -7,7 +7,6 @@ const systimer = hal.systimer;
 const usb_serial_jtag = hal.usb_serial_jtag;
 
 pub const microzig_options: microzig.Options = .{
-    .log_level = .debug,
     .logFn = usb_serial_jtag.logger.log,
     .interrupts = .{
         .interrupt1 = timer_interrupt,

examples/espressif/esp/src/ws2812_blinky.zig

@@ -6,7 +6,7 @@ const hal = microzig.hal;
 const gpio = hal.gpio;
 
 pub const microzig_options: microzig.Options = .{
-    .log_level = .debug,
+    .logFn = hal.usb_serial_jtag.logger.log,
 };
 
 pub fn main() !void {

port/espressif/esp/build.zig

@@ -7,6 +7,7 @@ const Self = @This();
 chips: struct {
     esp32_c3: *const microzig.Target,
     esp32_c3_direct_boot: *const microzig.Target,
+    esp32_c3_flashless: *const microzig.Target,
 },
 
 boards: struct {},
@@ -106,6 +107,18 @@ pub fn init(dep: *std.Build.Dependency) Self {
                     ),
                 },
             }),
+            .esp32_c3_flashless = chip_esp32_c3.derive(.{
+                .ram_image = true,
+                .linker_script = .{
+                    .generate = .memory_regions,
+                    .file = generate_linker_script(
+                        dep,
+                        "final.ld",
+                        b.path("ld/esp32_c3/flashless_sections.ld"),
+                        b.path("ld/esp32_c3/rom_functions.ld"),
+                    ),
+                },
+            }),
         },
         .boards = .{},
     };

port/espressif/esp/ld/esp32_c3/flashless_sections.ld

@@ -0,0 +1,34 @@
+SECTIONS
+{
+  .ram_text ORIGIN(IRAM) : AT(0)
+  {
+    microzig_ram_text_start = .;
+
+    KEEP(*(microzig_ram_start))
+    *(.text*)
+    KEEP(*(.ram_text))
+
+  } > IRAM
+
+  . = ALIGN(8);
+  _iram_size = . - microzig_ram_text_start;
+
+  _dram_start = ORIGIN(DRAM) + _iram_size;
+  .data _dram_start : AT(_iram_size)
+  {
+    microzig_data_start = .;
+    *(.sdata*)
+    *(.data*)
+    *(.rodata*)
+  } > DRAM
+
+  .bss (NOLOAD) :
+  {
+    microzig_bss_start = .;
+    *(.bss*)
+    *(.sbss*)
+    microzig_bss_end = .;
+  } > DRAM
+
+  PROVIDE(__global_pointer$ = microzig_data_start + 0x800);
+}