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spi: rzv2h-rspi: add support for DMA mode
The DMA controller can be used to transfer data to and from the SPI controller without involving the CPU for each word of a SPI transfer. Add support for DMA mode. Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com> Link: https://patch.msgid.link/20251201134229.600817-12-cosmin-gabriel.tanislav.xa@renesas.com Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Cosmin Tanislav
Mark Brown
parent
163345e356
commit
fa08b56686
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@ -9,6 +9,7 @@
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#include <linux/bitops.h>
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#include <linux/bits.h>
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#include <linux/clk.h>
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#include <linux/dmaengine.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/limits.h>
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@ -21,6 +22,8 @@
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#include <linux/spi/spi.h>
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#include <linux/wait.h>
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#include "internals.h"
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/* Registers */
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#define RSPI_SPDR 0x00
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#define RSPI_SPCR 0x08
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@ -96,6 +99,7 @@ struct rzv2h_rspi_info {
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struct rzv2h_rspi_priv {
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struct spi_controller *controller;
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const struct rzv2h_rspi_info *info;
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struct platform_device *pdev;
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void __iomem *base;
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struct clk *tclk;
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struct clk *pclk;
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@ -108,6 +112,7 @@ struct rzv2h_rspi_priv {
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u8 spr;
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u8 brdv;
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bool use_pclk;
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bool dma_callbacked;
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};
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#define RZV2H_RSPI_TX(func, type) \
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@ -219,6 +224,20 @@ static int rzv2h_rspi_receive(struct rzv2h_rspi_priv *rspi, void *rxbuf,
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return 0;
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}
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static bool rzv2h_rspi_can_dma(struct spi_controller *ctlr, struct spi_device *spi,
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struct spi_transfer *xfer)
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{
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struct rzv2h_rspi_priv *rspi = spi_controller_get_devdata(ctlr);
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if (ctlr->fallback)
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return false;
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if (!ctlr->dma_tx || !ctlr->dma_rx)
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return false;
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return xfer->len > rspi->info->fifo_size;
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}
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static int rzv2h_rspi_transfer_pio(struct rzv2h_rspi_priv *rspi,
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struct spi_device *spi,
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struct spi_transfer *transfer,
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@ -240,21 +259,149 @@ static int rzv2h_rspi_transfer_pio(struct rzv2h_rspi_priv *rspi,
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return ret;
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}
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static void rzv2h_rspi_dma_complete(void *arg)
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{
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struct rzv2h_rspi_priv *rspi = arg;
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rspi->dma_callbacked = 1;
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wake_up_interruptible(&rspi->wait);
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}
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static struct dma_async_tx_descriptor *
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rzv2h_rspi_setup_dma_channel(struct rzv2h_rspi_priv *rspi,
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struct dma_chan *chan, struct sg_table *sg,
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enum dma_slave_buswidth width,
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enum dma_transfer_direction direction)
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{
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struct dma_slave_config config = {
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.dst_addr = rspi->pdev->resource->start + RSPI_SPDR,
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.src_addr = rspi->pdev->resource->start + RSPI_SPDR,
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.dst_addr_width = width,
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.src_addr_width = width,
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.direction = direction,
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};
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struct dma_async_tx_descriptor *desc;
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int ret;
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ret = dmaengine_slave_config(chan, &config);
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if (ret)
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return ERR_PTR(ret);
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desc = dmaengine_prep_slave_sg(chan, sg->sgl, sg->nents, direction,
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DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
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if (!desc)
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return ERR_PTR(-EAGAIN);
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if (direction == DMA_DEV_TO_MEM) {
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desc->callback = rzv2h_rspi_dma_complete;
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desc->callback_param = rspi;
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}
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return desc;
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}
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static enum dma_slave_buswidth
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rzv2h_rspi_dma_width(struct rzv2h_rspi_priv *rspi)
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{
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switch (rspi->bytes_per_word) {
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case 4:
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return DMA_SLAVE_BUSWIDTH_4_BYTES;
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case 2:
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return DMA_SLAVE_BUSWIDTH_2_BYTES;
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case 1:
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return DMA_SLAVE_BUSWIDTH_1_BYTE;
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default:
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return DMA_SLAVE_BUSWIDTH_UNDEFINED;
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}
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}
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static int rzv2h_rspi_transfer_dma(struct rzv2h_rspi_priv *rspi,
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struct spi_device *spi,
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struct spi_transfer *transfer,
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unsigned int words_to_transfer)
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{
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struct dma_async_tx_descriptor *tx_desc = NULL, *rx_desc = NULL;
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enum dma_slave_buswidth width;
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dma_cookie_t cookie;
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int ret;
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width = rzv2h_rspi_dma_width(rspi);
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if (width == DMA_SLAVE_BUSWIDTH_UNDEFINED)
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return -EINVAL;
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rx_desc = rzv2h_rspi_setup_dma_channel(rspi, rspi->controller->dma_rx,
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&transfer->rx_sg, width,
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DMA_DEV_TO_MEM);
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if (IS_ERR(rx_desc))
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return PTR_ERR(rx_desc);
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tx_desc = rzv2h_rspi_setup_dma_channel(rspi, rspi->controller->dma_tx,
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&transfer->tx_sg, width,
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DMA_MEM_TO_DEV);
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if (IS_ERR(tx_desc))
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return PTR_ERR(tx_desc);
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cookie = dmaengine_submit(rx_desc);
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if (dma_submit_error(cookie))
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return cookie;
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cookie = dmaengine_submit(tx_desc);
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if (dma_submit_error(cookie)) {
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dmaengine_terminate_sync(rspi->controller->dma_rx);
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return cookie;
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}
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/*
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* DMA transfer does not need IRQs to be enabled.
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* For PIO, we only use RX IRQ, so disable that.
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*/
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disable_irq(rspi->irq_rx);
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rspi->dma_callbacked = 0;
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dma_async_issue_pending(rspi->controller->dma_rx);
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dma_async_issue_pending(rspi->controller->dma_tx);
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rzv2h_rspi_clear_all_irqs(rspi);
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ret = wait_event_interruptible_timeout(rspi->wait, rspi->dma_callbacked, HZ);
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if (ret) {
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dmaengine_synchronize(rspi->controller->dma_tx);
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dmaengine_synchronize(rspi->controller->dma_rx);
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ret = 0;
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} else {
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dmaengine_terminate_sync(rspi->controller->dma_tx);
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dmaengine_terminate_sync(rspi->controller->dma_rx);
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ret = -ETIMEDOUT;
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}
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enable_irq(rspi->irq_rx);
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return ret;
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}
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static int rzv2h_rspi_transfer_one(struct spi_controller *controller,
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struct spi_device *spi,
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struct spi_transfer *transfer)
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{
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struct rzv2h_rspi_priv *rspi = spi_controller_get_devdata(controller);
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bool is_dma = spi_xfer_is_dma_mapped(controller, spi, transfer);
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unsigned int words_to_transfer;
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int ret;
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transfer->effective_speed_hz = rspi->freq;
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words_to_transfer = transfer->len / rspi->bytes_per_word;
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ret = rzv2h_rspi_transfer_pio(rspi, spi, transfer, words_to_transfer);
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if (is_dma)
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ret = rzv2h_rspi_transfer_dma(rspi, spi, transfer, words_to_transfer);
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else
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ret = rzv2h_rspi_transfer_pio(rspi, spi, transfer, words_to_transfer);
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rzv2h_rspi_clear_all_irqs(rspi);
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if (is_dma && ret == -EAGAIN)
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/* Retry with PIO */
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transfer->error = SPI_TRANS_FAIL_NO_START;
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return ret;
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}
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@ -557,6 +704,7 @@ static int rzv2h_rspi_probe(struct platform_device *pdev)
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platform_set_drvdata(pdev, rspi);
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rspi->controller = controller;
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rspi->pdev = pdev;
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rspi->info = device_get_match_data(dev);
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@ -613,6 +761,7 @@ static int rzv2h_rspi_probe(struct platform_device *pdev)
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controller->unprepare_message = rzv2h_rspi_unprepare_message;
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controller->num_chipselect = 4;
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controller->transfer_one = rzv2h_rspi_transfer_one;
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controller->can_dma = rzv2h_rspi_can_dma;
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tclk_rate = clk_round_rate(rspi->tclk, 0);
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if (tclk_rate < 0)
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@ -630,6 +779,24 @@ static int rzv2h_rspi_probe(struct platform_device *pdev)
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RSPI_SPBR_SPR_MIN,
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RSPI_SPCMD_BRDV_MIN);
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controller->dma_tx = devm_dma_request_chan(dev, "tx");
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if (IS_ERR(controller->dma_tx)) {
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ret = dev_warn_probe(dev, PTR_ERR(controller->dma_tx),
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"failed to request TX DMA channel\n");
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if (ret == -EPROBE_DEFER)
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return ret;
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controller->dma_tx = NULL;
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}
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controller->dma_rx = devm_dma_request_chan(dev, "rx");
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if (IS_ERR(controller->dma_rx)) {
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ret = dev_warn_probe(dev, PTR_ERR(controller->dma_rx),
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"failed to request RX DMA channel\n");
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if (ret == -EPROBE_DEFER)
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return ret;
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controller->dma_rx = NULL;
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}
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device_set_node(&controller->dev, dev_fwnode(dev));
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ret = devm_spi_register_controller(dev, controller);
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