in spi-pxa2xx.c [944:1124]
static int pxa2xx_spi_transfer_one(struct spi_controller *controller,
struct spi_device *spi,
struct spi_transfer *transfer)
{
struct driver_data *drv_data = spi_controller_get_devdata(controller);
struct spi_message *message = controller->cur_msg;
struct chip_data *chip = spi_get_ctldata(spi);
u32 dma_thresh = chip->dma_threshold;
u32 dma_burst = chip->dma_burst_size;
u32 change_mask = pxa2xx_spi_get_ssrc1_change_mask(drv_data);
u32 clk_div;
u8 bits;
u32 speed;
u32 cr0;
u32 cr1;
int err;
int dma_mapped;
/* Check if we can DMA this transfer */
if (transfer->len > MAX_DMA_LEN && chip->enable_dma) {
/* Reject already-mapped transfers; PIO won't always work */
if (message->is_dma_mapped
|| transfer->rx_dma || transfer->tx_dma) {
dev_err(&spi->dev,
"Mapped transfer length of %u is greater than %d\n",
transfer->len, MAX_DMA_LEN);
return -EINVAL;
}
/* Warn ... we force this to PIO mode */
dev_warn_ratelimited(&spi->dev,
"DMA disabled for transfer length %u greater than %d\n",
transfer->len, MAX_DMA_LEN);
}
/* Setup the transfer state based on the type of transfer */
if (pxa2xx_spi_flush(drv_data) == 0) {
dev_err(&spi->dev, "Flush failed\n");
return -EIO;
}
drv_data->tx = (void *)transfer->tx_buf;
drv_data->tx_end = drv_data->tx + transfer->len;
drv_data->rx = transfer->rx_buf;
drv_data->rx_end = drv_data->rx + transfer->len;
/* Change speed and bit per word on a per transfer */
bits = transfer->bits_per_word;
speed = transfer->speed_hz;
clk_div = pxa2xx_ssp_get_clk_div(drv_data, speed);
if (bits <= 8) {
drv_data->n_bytes = 1;
drv_data->read = drv_data->rx ? u8_reader : null_reader;
drv_data->write = drv_data->tx ? u8_writer : null_writer;
} else if (bits <= 16) {
drv_data->n_bytes = 2;
drv_data->read = drv_data->rx ? u16_reader : null_reader;
drv_data->write = drv_data->tx ? u16_writer : null_writer;
} else if (bits <= 32) {
drv_data->n_bytes = 4;
drv_data->read = drv_data->rx ? u32_reader : null_reader;
drv_data->write = drv_data->tx ? u32_writer : null_writer;
}
/*
* If bits per word is changed in DMA mode, then must check
* the thresholds and burst also.
*/
if (chip->enable_dma) {
if (pxa2xx_spi_set_dma_burst_and_threshold(chip,
spi,
bits, &dma_burst,
&dma_thresh))
dev_warn_ratelimited(&spi->dev,
"DMA burst size reduced to match bits_per_word\n");
}
dma_mapped = controller->can_dma &&
controller->can_dma(controller, spi, transfer) &&
controller->cur_msg_mapped;
if (dma_mapped) {
/* Ensure we have the correct interrupt handler */
drv_data->transfer_handler = pxa2xx_spi_dma_transfer;
err = pxa2xx_spi_dma_prepare(drv_data, transfer);
if (err)
return err;
/* Clear status and start DMA engine */
cr1 = chip->cr1 | dma_thresh | drv_data->dma_cr1;
pxa2xx_spi_write(drv_data, SSSR, drv_data->clear_sr);
pxa2xx_spi_dma_start(drv_data);
} else {
/* Ensure we have the correct interrupt handler */
drv_data->transfer_handler = interrupt_transfer;
/* Clear status */
cr1 = chip->cr1 | chip->threshold | drv_data->int_cr1;
write_SSSR_CS(drv_data, drv_data->clear_sr);
}
/* NOTE: PXA25x_SSP _could_ use external clocking ... */
cr0 = pxa2xx_configure_sscr0(drv_data, clk_div, bits);
if (!pxa25x_ssp_comp(drv_data))
dev_dbg(&spi->dev, "%u Hz actual, %s\n",
controller->max_speed_hz
/ (1 + ((cr0 & SSCR0_SCR(0xfff)) >> 8)),
dma_mapped ? "DMA" : "PIO");
else
dev_dbg(&spi->dev, "%u Hz actual, %s\n",
controller->max_speed_hz / 2
/ (1 + ((cr0 & SSCR0_SCR(0x0ff)) >> 8)),
dma_mapped ? "DMA" : "PIO");
if (is_lpss_ssp(drv_data)) {
pxa2xx_spi_update(drv_data, SSIRF, GENMASK(7, 0), chip->lpss_rx_threshold);
pxa2xx_spi_update(drv_data, SSITF, GENMASK(15, 0), chip->lpss_tx_threshold);
}
if (is_mrfld_ssp(drv_data)) {
u32 mask = SFIFOTT_RFT | SFIFOTT_TFT;
u32 thresh = 0;
thresh |= SFIFOTT_RxThresh(chip->lpss_rx_threshold);
thresh |= SFIFOTT_TxThresh(chip->lpss_tx_threshold);
pxa2xx_spi_update(drv_data, SFIFOTT, mask, thresh);
}
if (is_quark_x1000_ssp(drv_data))
pxa2xx_spi_update(drv_data, DDS_RATE, GENMASK(23, 0), chip->dds_rate);
/* Stop the SSP */
if (!is_mmp2_ssp(drv_data))
pxa_ssp_disable(drv_data->ssp);
if (!pxa25x_ssp_comp(drv_data))
pxa2xx_spi_write(drv_data, SSTO, chip->timeout);
/* First set CR1 without interrupt and service enables */
pxa2xx_spi_update(drv_data, SSCR1, change_mask, cr1);
/* See if we need to reload the configuration registers */
pxa2xx_spi_update(drv_data, SSCR0, GENMASK(31, 0), cr0);
/* Restart the SSP */
pxa_ssp_enable(drv_data->ssp);
if (is_mmp2_ssp(drv_data)) {
u8 tx_level = read_SSSR_bits(drv_data, SSSR_TFL_MASK) >> 8;
if (tx_level) {
/* On MMP2, flipping SSE doesn't to empty Tx FIFO. */
dev_warn(&spi->dev, "%u bytes of garbage in Tx FIFO!\n", tx_level);
if (tx_level > transfer->len)
tx_level = transfer->len;
drv_data->tx += tx_level;
}
}
if (spi_controller_is_slave(controller)) {
while (drv_data->write(drv_data))
;
if (drv_data->gpiod_ready) {
gpiod_set_value(drv_data->gpiod_ready, 1);
udelay(1);
gpiod_set_value(drv_data->gpiod_ready, 0);
}
}
/*
* Release the data by enabling service requests and interrupts,
* without changing any mode bits.
*/
pxa2xx_spi_write(drv_data, SSCR1, cr1);
return 1;
}