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Merged
merged 1 commit into from
Sep 17, 2020
Merged

Add non-DMA SPI support. #3393

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41 changes: 29 additions & 12 deletions ports/esp32s2/common-hal/busio/SPI.c
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Original file line number Diff line number Diff line change
Expand Up @@ -183,9 +183,6 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,

// spi_hal_init clears the given hal context so set everything after.
spi_hal_init(hal, host_id);
hal->dmadesc_tx = &self->tx_dma;
hal->dmadesc_rx = &self->rx_dma;
hal->dmadesc_n = 1;

// We don't use native CS.
// hal->cs_setup = 0;
Expand All @@ -196,7 +193,6 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
hal->half_duplex = 0;
// hal->tx_lsbfirst = 0;
// hal->rx_lsbfirst = 0;
hal->dma_enabled = 1;
hal->no_compensate = 1;
// Ignore CS bits

Expand Down Expand Up @@ -315,16 +311,34 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, const uint8_t *data_ou
hal->rcv_buffer = NULL;
// Reset timing_conf in case we've moved since the last time we used it.
hal->timing_conf = &self->timing_conf;
lldesc_t tx_dma __attribute__((aligned(16)));
lldesc_t rx_dma __attribute__((aligned(16)));
hal->dmadesc_tx = &tx_dma;
hal->dmadesc_rx = &rx_dma;
hal->dmadesc_n = 1;

size_t burst_length;
// If both of the incoming pointers are DMA capable then use DMA. Otherwise, do
// bursts the size of the SPI data buffer without DMA.
if ((data_out == NULL || esp_ptr_dma_capable(data_out)) &&
(data_in == NULL || esp_ptr_dma_capable(data_out))) {
hal->dma_enabled = 1;
burst_length = LLDESC_MAX_NUM_PER_DESC;
} else {
hal->dma_enabled = 0;
burst_length = sizeof(hal->hw->data_buf);
}

// This rounds up.
size_t dma_count = (len + LLDESC_MAX_NUM_PER_DESC - 1) / LLDESC_MAX_NUM_PER_DESC;
for (size_t i = 0; i < dma_count; i++) {
size_t offset = LLDESC_MAX_NUM_PER_DESC * i;
size_t dma_len = len - offset;
if (dma_len > LLDESC_MAX_NUM_PER_DESC) {
dma_len = LLDESC_MAX_NUM_PER_DESC;
size_t burst_count = (len + burst_length - 1) / burst_length;
for (size_t i = 0; i < burst_count; i++) {
size_t offset = burst_length * i;
size_t this_length = len - offset;
if (this_length > burst_length) {
this_length = burst_length;
}
hal->tx_bitlen = dma_len * self->bits;
hal->rx_bitlen = dma_len * self->bits;
hal->tx_bitlen = this_length * self->bits;
hal->rx_bitlen = this_length * self->bits;
if (data_out != NULL) {
hal->send_buffer = (uint8_t*) data_out + offset;
}
Expand All @@ -341,6 +355,9 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, const uint8_t *data_ou
}
spi_hal_fetch_result(hal);
}
hal->dmadesc_tx = NULL;
hal->dmadesc_rx = NULL;
hal->dmadesc_n = 0;

return true;
}
Expand Down
4 changes: 0 additions & 4 deletions ports/esp32s2/common-hal/busio/SPI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,6 @@ typedef struct {
spi_hal_context_t hal_context;
spi_hal_timing_conf_t timing_conf;
intr_handle_t interrupt;
// IDF allocates these in DMA accessible memory so they may need to move when
// we use external RAM for CircuitPython.
lldesc_t tx_dma;
lldesc_t rx_dma;
uint32_t target_frequency;
int32_t real_frequency;
uint8_t polarity;
Expand Down