Fix Arduino RP2040 flash size

For RP2040 boards, we now change the default flash size based on
the configured flash. We will still try to read the size from the
flash first.

Fixes micropython#4874

Author: tannewt

ports/raspberrypi/Makefile

@@ -260,6 +260,12 @@ $(BUILD)/stage2.c: stage2.c.jinja gen_stage2.py | $(BUILD)/
 	$(STEPECHO) "GEN $<"
 	$(Q)$(PYTHON3) gen_stage2.py $< $@ $(EXTERNAL_FLASH_DEVICES)
 
+$(HEADER_BUILD)/flash_info.h: flash_info.h.jinja gen_stage2.py | $(HEADER_BUILD)/
+	$(STEPECHO) "GEN $<"
+	$(Q)$(PYTHON3) gen_stage2.py $< $@ $(EXTERNAL_FLASH_DEVICES)
+
+$(BUILD)/supervisor/internal_flash.o: $(HEADER_BUILD)/flash_info.h
+
 $(BUILD)/boot2.elf: $(BUILD)/stage2.c
 	$(STEPECHO) "BOOT $<"
 	$(Q)$(CC) $(CFLAGS) $(BOOT2_S_CFLAGS) -Os -ggdb3 -I. -fPIC --specs=nosys.specs -nostartfiles -Wl,-T,boot_stage2.ld  -Wl,-Map=$@.map -o $@ $<

ports/raspberrypi/flash_info.h.jinja

@@ -0,0 +1,5 @@
+// This file is auto-generated using gen_stage2.py
+
+#pragma once
+
+#define FLASH_DEFAULT_POWER_OF_TWO {{ default_power_of_two }}

ports/raspberrypi/gen_stage2.py

@@ -1,3 +1,4 @@
+import math
 import sys
 import cascadetoml
 import pathlib
@@ -46,6 +47,18 @@ def all_match(nvms, key, default=None):
 
     max_clock_speed_mhz = min((x.get("max_clock_speed_mhz", 1000) for x in flashes["nvm"]))
 
+    default_power_of_two = None
+    for nvm in flashes["nvm"]:
+        capacity = nvm.get("capacity", 0)
+        if not 21 <= capacity < 30:
+            power_of_two = int(math.log2(nvm["total_size"]))
+            if not default_power_of_two:
+                default_power_of_two = power_of_two
+            else:
+                default_power_of_two = min(power_of_two, default_power_of_two)
+    if not default_power_of_two:
+        default_power_of_two = 21
+
     # Check that we have a consistent way to set quad enable.
     if continuous_status_write is None and split_status_write is None:
         print("quad not ok", continuous_status_write, split_status_write)
@@ -71,6 +84,7 @@ def all_match(nvms, key, default=None):
         "clock_divider": clock_divider,
         "read_command": read_command,
         "wait_cycles": wait_cycles,
+        "default_power_of_two": default_power_of_two,
     }
 
     template = Template(input_template.read_text())

ports/raspberrypi/supervisor/internal_flash.c

@@ -32,6 +32,7 @@
 
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
+#include "genhdr/flash_info.h"
 #include "py/mphal.h"
 #include "py/obj.h"
 #include "py/runtime.h"
@@ -68,7 +69,7 @@ void supervisor_flash_init(void) {
     uint8_t cmd[] = {0x9f, 0, 0, 0};
     uint8_t data[4];
     flash_do_cmd(cmd, data, 4);
-    uint8_t power_of_two = 21;
+    uint8_t power_of_two = FLASH_DEFAULT_POWER_OF_TWO;
     // Flash must be at least 2MB (1 << 21) because we use the first 1MB for the
     // CircuitPython core. We validate the range because Adesto Tech flash chips
     // don't return the correct value. So, we default to 2MB which will work for