Use larger flash erase sizes to speed up programming.

Loading a 600 KB UF2 file onto a Pico from Windows now
takes 3.2 s instead of 4.8 s.

Author: DavidEGrayson

main.cpp

@@ -1838,29 +1838,38 @@ bool load_command::execute(device_map &devices) {
             }
         }
     }
+
     for (auto mem_range : ranges) {
         enum memory_type type = get_memory_type(mem_range.from);
         // new scope for progress bar
         {
             progress_bar bar("Loading into " + memory_names[type] + ": ");
-            uint32_t batch_size = FLASH_SECTOR_ERASE_SIZE;
-            bool ok = true;
             vector<uint8_t> file_buf;
             vector<uint8_t> device_buf;
-            for (uint32_t base = mem_range.from; base < mem_range.to && ok; ) {
+            for (uint32_t base = mem_range.from; base < mem_range.to; ) {
+                uint32_t batch_size = FLASH_SECTOR_ERASE_SIZE;
+                uint8_t block_erase_cmd = 0x20;
+                if (mem_range.to - base >= 0x10000) {
+                    batch_size = 0x10000;
+                    block_erase_cmd = 0xD8;
+                }
+                else if (mem_range.to - base >= 0x8000) {
+                    batch_size = 0x8000;
+                    block_erase_cmd = 0x52;
+                }
                 uint32_t this_batch = std::min(mem_range.to - base, batch_size);
                 if (type == flash) {
                     // we have to erase an entire page, so then fill with zeros
-                    range aligned_range(base & ~(FLASH_SECTOR_ERASE_SIZE - 1), (base & ~(FLASH_SECTOR_ERASE_SIZE - 1)) + FLASH_SECTOR_ERASE_SIZE);
+                    range aligned_range(base & ~(batch_size - 1), (base & ~(batch_size - 1)) + batch_size);
                     range read_range(base, base + this_batch);
                     read_range.intersect(aligned_range);
                     file_access.read_into_vector(read_range.from, read_range.to - read_range.from, file_buf);
-                    // zero padding up to FLASH_SECTOR_ERASE_SIZE
+                    // zero padding up to batch_size
                     file_buf.insert(file_buf.begin(), read_range.from - aligned_range.from, 0);
                     file_buf.insert(file_buf.end(), aligned_range.to - read_range.to, 0);
-                    assert(file_buf.size() == FLASH_SECTOR_ERASE_SIZE);
+                    assert(file_buf.size() == batch_size);
                     con.exit_xip();
-                    con.flash_erase(aligned_range.from, FLASH_SECTOR_ERASE_SIZE);
+                    con.flash_range_erase(aligned_range.from - FLASH_START, batch_size, batch_size, block_erase_cmd);
                     raw_access.write_vector(aligned_range.from, file_buf);
                     base = read_range.to; // about to add batch_size
                 } else {
@@ -1875,7 +1884,7 @@ bool load_command::execute(device_map &devices) {
             bool ok = true;
             {
                 progress_bar bar("Verifying " + memory_names[type] + ":    ");
-                uint32_t batch_size = FLASH_SECTOR_ERASE_SIZE;
+                uint32_t batch_size = 0x8000;
                 vector<uint8_t> file_buf;
                 vector<uint8_t> device_buf;
                 uint32_t pos = mem_range.from;

picoboot_connection/call.s

@@ -0,0 +1,17 @@
+.cpu cortex-m0
+.thumb
+  push {r4, lr}
+  mov r4, #20
+  ldrh r0, [r4]      // r0 = function_table
+  ldrh r1, args
+  ldrh r4, [r4, #4]  // r4 = table_lookup
+  blx r4
+  mov r4, r0
+  ldr r0, args + 4
+  ldr r1, args + 8
+  ldr r2, args + 12
+  ldrb r3, args + 16
+  blx r4
+  pop {r4, pc}
+.balign 4, 0
+args:

picoboot_connection/picoboot_connection.c

@@ -305,6 +305,28 @@ int picoboot_exec(libusb_device_handle *usb_device, uint32_t addr) {
     return picoboot_cmd(usb_device, &cmd, NULL, 0);
 }
 
+// Calls flash_range_erase in the bootrom.
+int picoboot_flash_range_erase(libusb_device_handle *usb_device,
+  uint32_t addr, uint32_t len, uint32_t block_size, uint8_t block_cmd)
+{
+    // These bytes come from `arm-none-eabi-as -al call.s`, with the function
+    // lookup code and function arguments appended.
+    uint8_t call_asm[] = {
+        0x10, 0xB5, 0x14, 0x24, 0x20, 0x88, 0x05, 0x49,
+        0xA4, 0x88, 0xA0, 0x47, 0x04, 0x1C, 0x04, 0x48,
+        0x04, 0x49, 0x05, 0x4A, 0x05, 0x4B, 0xA0, 0x47,
+        0x10, 0xBD, 0, 0,
+        'R', 'E', 0, 0,
+        addr, addr >> 8, addr >> 16, addr >> 24,
+        len, len >> 8, len >> 16, len >> 24,
+        block_size, block_size >> 8, block_size >> 16, block_size >> 24,
+        block_cmd, 0, 0, 0,
+    };
+    int ret = picoboot_write(usb_device, SRAM_START, call_asm, sizeof(call_asm));
+    if (ret) { return ret; }
+    return picoboot_exec(usb_device, SRAM_START);
+}
+
 int picoboot_flash_erase(libusb_device_handle *usb_device, uint32_t addr, uint32_t len) {
     struct picoboot_cmd cmd;
     if (verbose) output("FLASH_ERASE %08x+%08x\n", (uint) addr, (uint) len);

picoboot_connection/picoboot_connection.h

@@ -39,6 +39,7 @@ int picoboot_enter_cmd_xip(libusb_device_handle *usb_device);
 int picoboot_exit_xip(libusb_device_handle *usb_device);
 int picoboot_reboot(libusb_device_handle *usb_device, uint32_t pc, uint32_t sp, uint32_t delay_ms);
 int picoboot_exec(libusb_device_handle *usb_device, uint32_t addr);
+int picoboot_flash_range_erase(libusb_device_handle *, uint32_t, uint32_t, uint32_t, uint8_t);
 int picoboot_flash_erase(libusb_device_handle *usb_device, uint32_t addr, uint32_t len);
 int picoboot_vector(libusb_device_handle *usb_device, uint32_t addr);
 int picoboot_write(libusb_device_handle *usb_device, uint32_t addr, uint8_t *buffer, uint32_t len);

picoboot_connection/picoboot_connection_cxx.cpp

@@ -81,6 +81,12 @@ void connection::exec(uint32_t addr) {
     wrap_call([&] { return picoboot_exec(device, addr); });
 }
 
+void connection::flash_range_erase(uint32_t addr, uint32_t len,
+    uint32_t block_size, uint8_t block_cmd) {
+    wrap_call([&] { return picoboot_flash_range_erase(device, addr, len,
+      block_size, block_cmd); });
+}
+
 void connection::flash_erase(uint32_t addr, uint32_t len) {
     wrap_call([&] { return picoboot_flash_erase(device, addr, len); });
 }

picoboot_connection/picoboot_connection_cxx.h

@@ -41,6 +41,7 @@ namespace picoboot {
         void exit_xip();
         void reboot(uint32_t pc, uint32_t sp, uint32_t delay_ms);
         void exec(uint32_t addr);
+        void flash_range_erase(uint32_t addr, uint32_t len, uint32_t block_size, uint8_t block_cmd);
         void flash_erase(uint32_t addr, uint32_t len);
         void vector(uint32_t addr);
         void write(uint32_t addr, uint8_t *buffer, uint32_t len);