Hi guys. I'm an intermediate level embedded systems engineer trying to transition a project from STM32F4/7 series over to an NXP I.MX RT 595. So far, I've relied on both the documentation and the provided examples (stellar, kudos NXP - especially for providing CMakes, for use with arm gcc) to breeze my way through porting over 70% in less than a week.
Full disclosure - I'm not that experienced with NXP products or the SDK (touched a development board for the first time about a week ago) and I'm trying to do encryption using HASHCRYPT + DMA.
I'm only going to be encrypting aligned buffers (divisible by 4 words, no more than 8064 words, so as not to exceed the 11-bit MEMCTRL register.
So far, I have the following workflow:
1. I set the appropriate registers (initialization sequence, setting the key, the iv, the length etc.).
2. The actual encryption
// THIS IS BASICALLY COPY - PASTE FROM THE hashcrypt_aes_one_block FUNCTION
HASHCRYPT->MEMADDR = HASHCRYPT_MEMADDR_BASE(plainAes128);
HASHCRYPT->MEMCTRL = HASHCRYPT_MEMCTRL_MASTER(1) |
HASHCRYPT_MEMCTRL_COUNT(size / 16U);
while (size >= HASHCRYPT_AES_BLOCK_SIZE)
{
/* Get result */
while (0U == (HASHCRYPT->STATUS & HASHCRYPT_STATUS_DIGEST_MASK))
{
}
memcpy(outputEncrypted, (uint32_t*)HASHCRYPT->DIGEST0, 16);
idx += HASHCRYPT_AES_BLOCK_SIZE / 4U;
size -= HASHCRYPT_AES_BLOCK_SIZE;
}
HASHCRYPT->CTRL &= ~(HASHCRYPT_CTRL_MODE_MASK);
3. Deinit the module.
From what I imagine, in order to use DMA, I should use a DMA channel that copies data from the peripheral over to the output buffer.
What gives me grief is how I should configure the DMA, exactly. I figure the DMA controller needs to poll for the HASHCRYPT-> STATUS and afterwards to actually copy the data over to the destination.
Any kind of assistance would be greatly appreciated.
Thank you for your time!
