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cpu/cc2538: spi: unify spi_transfer_bytes()

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Use a common helper function to read/write the data register.
This commit is contained in:
Benjamin Valentin 2020-03-09 16:30:43 +01:00
parent 68b2c57d2d
commit 80392dc644
1 changed files with 14 additions and 22 deletions
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36
cpu/cc2538/periph/spi.c
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@ -121,6 +121,14 @@ void spi_release(spi_t bus)
mutex_unlock(&locks[bus]);
}
static uint8_t _trx(cc2538_ssi_t *dev, uint8_t in)
{
while (!(dev->SR & SSI_SR_TNF)) {}
dev->DR = in;
while (!(dev->SR & SSI_SR_RNE)) {}
return dev->DR;
}
void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
const void *out, void *in, size_t len)
{
@ -136,35 +144,19 @@ void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
}
if (!in_buf) {
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = out_buf[i];
while (!(dev(bus)->SR & SSI_SR_RNE)) {}
dev(bus)->DR;
for (const void *end = out_buf + len; out_buf != end; ++out_buf) {
_trx(dev(bus), *out_buf);
}
}
else if (!out_buf) {
size_t in_cnt = 0;
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = 0;
while (!(dev(bus)->SR & SSI_SR_RNE)) {}
in_buf[in_cnt++] = dev(bus)->DR;
}
/* get remaining bytes */
while (dev(bus)->SR & SSI_SR_RNE) {
in_buf[in_cnt++] = dev(bus)->DR;
for (void *end = in_buf + len; in_buf != end; ++in_buf) {
*in_buf = _trx(dev(bus), 0);
}
}
else {
for (size_t i = 0; i < len; i++) {
while (!(dev(bus)->SR & SSI_SR_TNF)) {}
dev(bus)->DR = out_buf[i];
while (!(dev(bus)->SR & SSI_SR_RNE)) {}
in_buf[i] = dev(bus)->DR;
for (void *end = in_buf + len; in_buf != end; ++in_buf, ++out_buf) {
*in_buf = _trx(dev(bus), *out_buf);
}
/* wait until no more busy */
while ((dev(bus)->SR & SSI_SR_BSY)) {}
}
if ((!cont) && (cs != SPI_CS_UNDEF)) {