1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/spi/spi-pxa2xx-dma.c b/drivers/spi/spi-pxa2xx-dma.c
new file mode 100644
index 000000000..be563f0dd
--- /dev/null
+++ b/drivers/spi/spi-pxa2xx-dma.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PXA2xx SPI DMA engine support.
+ *
+ * Copyright (C) 2013, 2021 Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/scatterlist.h>
+#include <linux/sizes.h>
+
+#include <linux/spi/pxa2xx_spi.h>
+#include <linux/spi/spi.h>
+
+#include "spi-pxa2xx.h"
+
+static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
+					     bool error)
+{
+	struct spi_message *msg = drv_data->controller->cur_msg;
+
+	/*
+	 * It is possible that one CPU is handling ROR interrupt and other
+	 * just gets DMA completion. Calling pump_transfers() twice for the
+	 * same transfer leads to problems thus we prevent concurrent calls
+	 * by using dma_running.
+	 */
+	if (atomic_dec_and_test(&drv_data->dma_running)) {
+		/*
+		 * If the other CPU is still handling the ROR interrupt we
+		 * might not know about the error yet. So we re-check the
+		 * ROR bit here before we clear the status register.
+		 */
+		if (!error)
+			error = read_SSSR_bits(drv_data, drv_data->mask_sr) & SSSR_ROR;
+
+		/* Clear status & disable interrupts */
+		clear_SSCR1_bits(drv_data, drv_data->dma_cr1);
+		write_SSSR_CS(drv_data, drv_data->clear_sr);
+		if (!pxa25x_ssp_comp(drv_data))
+			pxa2xx_spi_write(drv_data, SSTO, 0);
+
+		if (error) {
+			/* In case we got an error we disable the SSP now */
+			pxa_ssp_disable(drv_data->ssp);
+			msg->status = -EIO;
+		}
+
+		spi_finalize_current_transfer(drv_data->controller);
+	}
+}
+
+static void pxa2xx_spi_dma_callback(void *data)
+{
+	pxa2xx_spi_dma_transfer_complete(data, false);
+}
+
+static struct dma_async_tx_descriptor *
+pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
+			   enum dma_transfer_direction dir,
+			   struct spi_transfer *xfer)
+{
+	struct chip_data *chip =
+		spi_get_ctldata(drv_data->controller->cur_msg->spi);
+	enum dma_slave_buswidth width;
+	struct dma_slave_config cfg;
+	struct dma_chan *chan;
+	struct sg_table *sgt;
+	int ret;
+
+	switch (drv_data->n_bytes) {
+	case 1:
+		width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+		break;
+	case 2:
+		width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+		break;
+	default:
+		width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		break;
+	}
+
+	memset(&cfg, 0, sizeof(cfg));
+	cfg.direction = dir;
+
+	if (dir == DMA_MEM_TO_DEV) {
+		cfg.dst_addr = drv_data->ssp->phys_base + SSDR;
+		cfg.dst_addr_width = width;
+		cfg.dst_maxburst = chip->dma_burst_size;
+
+		sgt = &xfer->tx_sg;
+		chan = drv_data->controller->dma_tx;
+	} else {
+		cfg.src_addr = drv_data->ssp->phys_base + SSDR;
+		cfg.src_addr_width = width;
+		cfg.src_maxburst = chip->dma_burst_size;
+
+		sgt = &xfer->rx_sg;
+		chan = drv_data->controller->dma_rx;
+	}
+
+	ret = dmaengine_slave_config(chan, &cfg);
+	if (ret) {
+		dev_warn(drv_data->ssp->dev, "DMA slave config failed\n");
+		return NULL;
+	}
+
+	return dmaengine_prep_slave_sg(chan, sgt->sgl, sgt->nents, dir,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+}
+
+irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
+{
+	u32 status;
+
+	status = read_SSSR_bits(drv_data, drv_data->mask_sr);
+	if (status & SSSR_ROR) {
+		dev_err(drv_data->ssp->dev, "FIFO overrun\n");
+
+		dmaengine_terminate_async(drv_data->controller->dma_rx);
+		dmaengine_terminate_async(drv_data->controller->dma_tx);
+
+		pxa2xx_spi_dma_transfer_complete(drv_data, true);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+int pxa2xx_spi_dma_prepare(struct driver_data *drv_data,
+			   struct spi_transfer *xfer)
+{
+	struct dma_async_tx_descriptor *tx_desc, *rx_desc;
+	int err;
+
+	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV, xfer);
+	if (!tx_desc) {
+		dev_err(drv_data->ssp->dev, "failed to get DMA TX descriptor\n");
+		err = -EBUSY;
+		goto err_tx;
+	}
+
+	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM, xfer);
+	if (!rx_desc) {
+		dev_err(drv_data->ssp->dev, "failed to get DMA RX descriptor\n");
+		err = -EBUSY;
+		goto err_rx;
+	}
+
+	/* We are ready when RX completes */
+	rx_desc->callback = pxa2xx_spi_dma_callback;
+	rx_desc->callback_param = drv_data;
+
+	dmaengine_submit(rx_desc);
+	dmaengine_submit(tx_desc);
+	return 0;
+
+err_rx:
+	dmaengine_terminate_async(drv_data->controller->dma_tx);
+err_tx:
+	return err;
+}
+
+void pxa2xx_spi_dma_start(struct driver_data *drv_data)
+{
+	dma_async_issue_pending(drv_data->controller->dma_rx);
+	dma_async_issue_pending(drv_data->controller->dma_tx);
+
+	atomic_set(&drv_data->dma_running, 1);
+}
+
+void pxa2xx_spi_dma_stop(struct driver_data *drv_data)
+{
+	atomic_set(&drv_data->dma_running, 0);
+	dmaengine_terminate_sync(drv_data->controller->dma_rx);
+	dmaengine_terminate_sync(drv_data->controller->dma_tx);
+}
+
+int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
+{
+	struct pxa2xx_spi_controller *pdata = drv_data->controller_info;
+	struct spi_controller *controller = drv_data->controller;
+	struct device *dev = drv_data->ssp->dev;
+	dma_cap_mask_t mask;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	controller->dma_tx = dma_request_slave_channel_compat(mask,
+				pdata->dma_filter, pdata->tx_param, dev, "tx");
+	if (!controller->dma_tx)
+		return -ENODEV;
+
+	controller->dma_rx = dma_request_slave_channel_compat(mask,
+				pdata->dma_filter, pdata->rx_param, dev, "rx");
+	if (!controller->dma_rx) {
+		dma_release_channel(controller->dma_tx);
+		controller->dma_tx = NULL;
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+void pxa2xx_spi_dma_release(struct driver_data *drv_data)
+{
+	struct spi_controller *controller = drv_data->controller;
+
+	if (controller->dma_rx) {
+		dmaengine_terminate_sync(controller->dma_rx);
+		dma_release_channel(controller->dma_rx);
+		controller->dma_rx = NULL;
+	}
+	if (controller->dma_tx) {
+		dmaengine_terminate_sync(controller->dma_tx);
+		dma_release_channel(controller->dma_tx);
+		controller->dma_tx = NULL;
+	}
+}
+
+int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
+					   struct spi_device *spi,
+					   u8 bits_per_word, u32 *burst_code,
+					   u32 *threshold)
+{
+	struct pxa2xx_spi_chip *chip_info = spi->controller_data;
+	struct driver_data *drv_data = spi_controller_get_devdata(spi->controller);
+	u32 dma_burst_size = drv_data->controller_info->dma_burst_size;
+
+	/*
+	 * If the DMA burst size is given in chip_info we use that,
+	 * otherwise we use the default. Also we use the default FIFO
+	 * thresholds for now.
+	 */
+	*burst_code = chip_info ? chip_info->dma_burst_size : dma_burst_size;
+	*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
+		   | SSCR1_TxTresh(TX_THRESH_DFLT);
+
+	return 0;
+}