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machine/samd21: write to flash memory in 64 byte long chunks

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This commit is contained in:
Mateusz Nowak
2025-05-22 23:59:05 +02:00
committed by Ron Evans
parent cb5f7ad3fd
commit 3eeffca841
1 changed files with 6 additions and 4 deletions
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src/machine/machine_atsamd21.go
+6 -4
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@@ -1904,7 +1904,7 @@ func (f flashBlockDevice) ReadAt(p []byte, off int64) (n int, err error) {
} }
// WriteAt writes the given number of bytes to the block device. // WriteAt writes the given number of bytes to the block device.
// Only word (32 bits) length data can be programmed. // Data is written to the page buffer in 4-byte chunks, then saved to flash memory.
// See Atmel-42181G–SAM-D21_Datasheet–09/2015 page 359. // See Atmel-42181G–SAM-D21_Datasheet–09/2015 page 359.
// If the length of p is not long enough it will be padded with 0xFF bytes. // If the length of p is not long enough it will be padded with 0xFF bytes.
// This method assumes that the destination is already erased. // This method assumes that the destination is already erased.
@@ -1921,8 +1921,10 @@ func (f flashBlockDevice) WriteAt(p []byte, off int64) (n int, err error) {
waitWhileFlashBusy() waitWhileFlashBusy()
for j := 0; j < len(padded); j += int(f.WriteBlockSize()) { for j := 0; j < len(padded); j += int(f.WriteBlockSize()) {
// write word // page buffer is 64 bytes long, but only 4 bytes can be written at once
*(*uint32)(unsafe.Pointer(address)) = binary.LittleEndian.Uint32(padded[j : j+int(f.WriteBlockSize())]) for k := 0; k < int(f.WriteBlockSize()); k += 4 {
*(*uint32)(unsafe.Pointer(address + uintptr(k))) = binary.LittleEndian.Uint32(padded[j+k : j+k+4])
}
sam.NVMCTRL.SetADDR(uint32(address >> 1)) sam.NVMCTRL.SetADDR(uint32(address >> 1))
sam.NVMCTRL.CTRLA.Set(sam.NVMCTRL_CTRLA_CMD_WP | (sam.NVMCTRL_CTRLA_CMDEX_KEY << sam.NVMCTRL_CTRLA_CMDEX_Pos)) sam.NVMCTRL.CTRLA.Set(sam.NVMCTRL_CTRLA_CMD_WP | (sam.NVMCTRL_CTRLA_CMDEX_KEY << sam.NVMCTRL_CTRLA_CMDEX_Pos))
@@ -1944,7 +1946,7 @@ func (f flashBlockDevice) Size() int64 {
return int64(FlashDataEnd() - FlashDataStart()) return int64(FlashDataEnd() - FlashDataStart())
} }
const writeBlockSize = 4 const writeBlockSize = 64
// WriteBlockSize returns the block size in which data can be written to // WriteBlockSize returns the block size in which data can be written to
// memory. It can be used by a client to optimize writes, non-aligned writes // memory. It can be used by a client to optimize writes, non-aligned writes