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remove ASF calls for TRNG

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This commit is contained in:
joeycastillo 2024-09-18 17:09:20 -04:00
parent 7ee3eeac49
commit 2bbd78a99d
1 changed files with 14 additions and 15 deletions
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29
watch-library/hardware/watch/watch_private.c
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@ -91,7 +91,15 @@ void _watch_init(void) {
} }
static inline void _watch_wait_for_entropy() { static inline void _watch_wait_for_entropy() {
while (!hri_trng_get_INTFLAG_reg(TRNG, TRNG_INTFLAG_DATARDY)); while (!TRNG->INTFLAG.bit.DATARDY);
}
void watch_disable_TRNG(void) {
// per Microchip datasheet clarification DS80000782,
// silicon erratum 1.16.1 indicates that the TRNG may leave internal components powered after being disabled.
// the workaround is to disable the TRNG by clearing the control register, twice.
TRNG->CTRLA.bit.ENABLE = 0;
TRNG->CTRLA.bit.ENABLE = 0;
} }
// this function is called by arc4random to get entropy for random number generation. // this function is called by arc4random to get entropy for random number generation.
@ -99,40 +107,31 @@ int getentropy(void *buf, size_t buflen);
// let's use the SAM L22's true random number generator to seed the PRNG! // let's use the SAM L22's true random number generator to seed the PRNG!
int getentropy(void *buf, size_t buflen) { int getentropy(void *buf, size_t buflen) {
hri_mclk_set_APBCMASK_TRNG_bit(MCLK); MCLK->APBCMASK.bit.TRNG_ = 1;
hri_trng_set_CTRLA_ENABLE_bit(TRNG); TRNG->CTRLA.bit.ENABLE = 1;
size_t i = 0; size_t i = 0;
while(i < buflen / 4) { while(i < buflen / 4) {
_watch_wait_for_entropy(); _watch_wait_for_entropy();
((uint32_t *)buf)[i++] = hri_trng_read_DATA_reg(TRNG); ((uint32_t *)buf)[i++] = TRNG->DATA.reg;
} }
// but what if they asked for an awkward number of bytes? // but what if they asked for an awkward number of bytes?
if (buflen % 4) { if (buflen % 4) {
// all good: let's fill in one, two or three bytes at the end of the buffer. // all good: let's fill in one, two or three bytes at the end of the buffer.
_watch_wait_for_entropy(); _watch_wait_for_entropy();
uint32_t last_little_bit = hri_trng_read_DATA_reg(TRNG); uint32_t last_little_bit = TRNG->DATA.reg;
for(size_t j = 0; j <= (buflen % 4); j++) { for(size_t j = 0; j <= (buflen % 4); j++) {
((uint8_t *)buf)[i * 4 + j] = (last_little_bit >> (j * 8)) & 0xFF; ((uint8_t *)buf)[i * 4 + j] = (last_little_bit >> (j * 8)) & 0xFF;
} }
} }
watch_disable_TRNG(); watch_disable_TRNG();
hri_mclk_clear_APBCMASK_TRNG_bit(MCLK); MCLK->APBCMASK.bit.TRNG_ = 0;
return 0; return 0;
} }
void watch_disable_TRNG(void);
void watch_disable_TRNG(void) {
// per Microchip datasheet clarification DS80000782,
// silicon erratum 1.16.1 indicates that the TRNG may leave internal components powered after being disabled.
// the workaround is to disable the TRNG by clearing the control register, twice.
hri_trng_write_CTRLA_reg(TRNG, 0);
hri_trng_write_CTRLA_reg(TRNG, 0);
}
void _watch_enable_tc0(void) { void _watch_enable_tc0(void) {
// before we init TinyUSB, we are going to need a periodic callback to handle TinyUSB tasks. // before we init TinyUSB, we are going to need a periodic callback to handle TinyUSB tasks.
// TC2 and TC3 are reserved for devices on the 9-pin connector, so let's use TC0. // TC2 and TC3 are reserved for devices on the 9-pin connector, so let's use TC0.