1 files changed, 545 insertions, 134 deletions

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 323c66c5db50..2e50cc0a9291 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -8,10 +8,14 @@
 #include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/preempt.h>
 #include <linux/highmem.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+#include <linux/string.h>
+#include <linux/of.h>
 
 #include "spi-dw.h"
 
@@ -19,13 +23,10 @@
 #include <linux/debugfs.h>
 #endif
 
-/* Slave spi_dev related */
+/* Slave spi_device related */
 struct chip_data {
-	u8 tmode;		/* TR/TO/RO/EEPROM */
-	u8 type;		/* SPI/SSP/MicroWire */
-
-	u16 clk_div;		/* baud rate divider */
-	u32 speed_hz;		/* baud rate */
+	u32 cr0;
+	u32 rx_sample_dly;	/* RX sample delay */
 };
 
 #ifdef CONFIG_DEBUG_FS
@@ -52,6 +53,7 @@ static const struct debugfs_reg32 dw_spi_dbgfs_regs[] = {
 	DW_SPI_DBGFS_REG("DMACR", DW_SPI_DMACR),
 	DW_SPI_DBGFS_REG("DMATDLR", DW_SPI_DMATDLR),
 	DW_SPI_DBGFS_REG("DMARDLR", DW_SPI_DMARDLR),
+	DW_SPI_DBGFS_REG("RX_SAMPLE_DLY", DW_SPI_RX_SAMPLE_DLY),
 };
 
 static int dw_spi_debugfs_init(struct dw_spi *dws)
@@ -101,7 +103,7 @@ void dw_spi_set_cs(struct spi_device *spi, bool enable)
 	 */
 	if (cs_high == enable)
 		dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
-	else if (dws->cs_override)
+	else
 		dw_writel(dws, DW_SPI_SER, 0);
 }
 EXPORT_SYMBOL_GPL(dw_spi_set_cs);
@@ -109,9 +111,8 @@ EXPORT_SYMBOL_GPL(dw_spi_set_cs);
 /* Return the max entries we can fill into tx fifo */
 static inline u32 tx_max(struct dw_spi *dws)
 {
-	u32 tx_left, tx_room, rxtx_gap;
+	u32 tx_room, rxtx_gap;
 
-	tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
 	tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);
 
 	/*
@@ -122,93 +123,124 @@ static inline u32 tx_max(struct dw_spi *dws)
 	 * shift registers. So a control from sw point of
 	 * view is taken.
 	 */
-	rxtx_gap =  ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
-			/ dws->n_bytes;
+	rxtx_gap = dws->fifo_len - (dws->rx_len - dws->tx_len);
 
-	return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
+	return min3((u32)dws->tx_len, tx_room, rxtx_gap);
 }
 
 /* Return the max entries we should read out of rx fifo */
 static inline u32 rx_max(struct dw_spi *dws)
 {
-	u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;
-
-	return min_t(u32, rx_left, dw_readl(dws, DW_SPI_RXFLR));
+	return min_t(u32, dws->rx_len, dw_readl(dws, DW_SPI_RXFLR));
 }
 
 static void dw_writer(struct dw_spi *dws)
 {
-	u32 max;
+	u32 max = tx_max(dws);
 	u16 txw = 0;
 
-	spin_lock(&dws->buf_lock);
-	max = tx_max(dws);
 	while (max--) {
-		/* Set the tx word if the transfer's original "tx" is not null */
-		if (dws->tx_end - dws->len) {
+		if (dws->tx) {
 			if (dws->n_bytes == 1)
 				txw = *(u8 *)(dws->tx);
 			else
 				txw = *(u16 *)(dws->tx);
+
+			dws->tx += dws->n_bytes;
 		}
 		dw_write_io_reg(dws, DW_SPI_DR, txw);
-		dws->tx += dws->n_bytes;
+		--dws->tx_len;
 	}
-	spin_unlock(&dws->buf_lock);
 }
 
 static void dw_reader(struct dw_spi *dws)
 {
-	u32 max;
+	u32 max = rx_max(dws);
 	u16 rxw;
 
-	spin_lock(&dws->buf_lock);
-	max = rx_max(dws);
 	while (max--) {
 		rxw = dw_read_io_reg(dws, DW_SPI_DR);
-		/* Care rx only if the transfer's original "rx" is not null */
-		if (dws->rx_end - dws->len) {
+		if (dws->rx) {
 			if (dws->n_bytes == 1)
 				*(u8 *)(dws->rx) = rxw;
 			else
 				*(u16 *)(dws->rx) = rxw;
+
+			dws->rx += dws->n_bytes;
 		}
-		dws->rx += dws->n_bytes;
+		--dws->rx_len;
 	}
-	spin_unlock(&dws->buf_lock);
 }
 
-static void int_error_stop(struct dw_spi *dws, const char *msg)
+int dw_spi_check_status(struct dw_spi *dws, bool raw)
 {
-	spi_reset_chip(dws);
+	u32 irq_status;
+	int ret = 0;
+
+	if (raw)
+		irq_status = dw_readl(dws, DW_SPI_RISR);
+	else
+		irq_status = dw_readl(dws, DW_SPI_ISR);
+
+	if (irq_status & SPI_INT_RXOI) {
+		dev_err(&dws->master->dev, "RX FIFO overflow detected\n");
+		ret = -EIO;
+	}
+
+	if (irq_status & SPI_INT_RXUI) {
+		dev_err(&dws->master->dev, "RX FIFO underflow detected\n");
+		ret = -EIO;
+	}
+
+	if (irq_status & SPI_INT_TXOI) {
+		dev_err(&dws->master->dev, "TX FIFO overflow detected\n");
+		ret = -EIO;
+	}
 
-	dev_err(&dws->master->dev, "%s\n", msg);
-	dws->master->cur_msg->status = -EIO;
-	spi_finalize_current_transfer(dws->master);
+	/* Generically handle the erroneous situation */
+	if (ret) {
+		spi_reset_chip(dws);
+		if (dws->master->cur_msg)
+			dws->master->cur_msg->status = ret;
+	}
+
+	return ret;
 }
+EXPORT_SYMBOL_GPL(dw_spi_check_status);
 
-static irqreturn_t interrupt_transfer(struct dw_spi *dws)
+static irqreturn_t dw_spi_transfer_handler(struct dw_spi *dws)
 {
 	u16 irq_status = dw_readl(dws, DW_SPI_ISR);
 
-	/* Error handling */
-	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
-		dw_readl(dws, DW_SPI_ICR);
-		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
+	if (dw_spi_check_status(dws, false)) {
+		spi_finalize_current_transfer(dws->master);
 		return IRQ_HANDLED;
 	}
 
+	/*
+	 * Read data from the Rx FIFO every time we've got a chance executing
+	 * this method. If there is nothing left to receive, terminate the
+	 * procedure. Otherwise adjust the Rx FIFO Threshold level if it's a
+	 * final stage of the transfer. By doing so we'll get the next IRQ
+	 * right when the leftover incoming data is received.
+	 */
 	dw_reader(dws);
-	if (dws->rx_end == dws->rx) {
-		spi_mask_intr(dws, SPI_INT_TXEI);
+	if (!dws->rx_len) {
+		spi_mask_intr(dws, 0xff);
 		spi_finalize_current_transfer(dws->master);
-		return IRQ_HANDLED;
+	} else if (dws->rx_len <= dw_readl(dws, DW_SPI_RXFTLR)) {
+		dw_writel(dws, DW_SPI_RXFTLR, dws->rx_len - 1);
 	}
+
+	/*
+	 * Send data out if Tx FIFO Empty IRQ is received. The IRQ will be
+	 * disabled after the data transmission is finished so not to
+	 * have the TXE IRQ flood at the final stage of the transfer.
+	 */
 	if (irq_status & SPI_INT_TXEI) {
-		spi_mask_intr(dws, SPI_INT_TXEI);
 		dw_writer(dws);
-		/* Enable TX irq always, it will be disabled when RX finished */
-		spi_umask_intr(dws, SPI_INT_TXEI);
+		if (!dws->tx_len)
+			spi_mask_intr(dws, SPI_INT_TXEI);
 	}
 
 	return IRQ_HANDLED;
@@ -224,105 +256,176 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 		return IRQ_NONE;
 
 	if (!master->cur_msg) {
-		spi_mask_intr(dws, SPI_INT_TXEI);
+		spi_mask_intr(dws, 0xff);
 		return IRQ_HANDLED;
 	}
 
 	return dws->transfer_handler(dws);
 }
 
-/* Configure CTRLR0 for DW_apb_ssi */
-u32 dw_spi_update_cr0(struct spi_controller *master, struct spi_device *spi,
-		      struct spi_transfer *transfer)
+static u32 dw_spi_prepare_cr0(struct dw_spi *dws, struct spi_device *spi)
 {
-	struct chip_data *chip = spi_get_ctldata(spi);
-	u32 cr0;
-
-	/* Default SPI mode is SCPOL = 0, SCPH = 0 */
-	cr0 = (transfer->bits_per_word - 1)
-		| (chip->type << SPI_FRF_OFFSET)
-		| ((((spi->mode & SPI_CPOL) ? 1 : 0) << SPI_SCOL_OFFSET) |
-		   (((spi->mode & SPI_CPHA) ? 1 : 0) << SPI_SCPH_OFFSET) |
-		   (((spi->mode & SPI_LOOP) ? 1 : 0) << SPI_SRL_OFFSET))
-		| (chip->tmode << SPI_TMOD_OFFSET);
+	u32 cr0 = 0;
+
+	if (!(dws->caps & DW_SPI_CAP_DWC_SSI)) {
+		/* CTRLR0[ 5: 4] Frame Format */
+		cr0 |= SSI_MOTO_SPI << SPI_FRF_OFFSET;
+
+		/*
+		 * SPI mode (SCPOL|SCPH)
+		 * CTRLR0[ 6] Serial Clock Phase
+		 * CTRLR0[ 7] Serial Clock Polarity
+		 */
+		cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << SPI_SCOL_OFFSET;
+		cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << SPI_SCPH_OFFSET;
+
+		/* CTRLR0[11] Shift Register Loop */
+		cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << SPI_SRL_OFFSET;
+	} else {
+		/* CTRLR0[ 7: 6] Frame Format */
+		cr0 |= SSI_MOTO_SPI << DWC_SSI_CTRLR0_FRF_OFFSET;
+
+		/*
+		 * SPI mode (SCPOL|SCPH)
+		 * CTRLR0[ 8] Serial Clock Phase
+		 * CTRLR0[ 9] Serial Clock Polarity
+		 */
+		cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << DWC_SSI_CTRLR0_SCPOL_OFFSET;
+		cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << DWC_SSI_CTRLR0_SCPH_OFFSET;
+
+		/* CTRLR0[13] Shift Register Loop */
+		cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << DWC_SSI_CTRLR0_SRL_OFFSET;
+
+		if (dws->caps & DW_SPI_CAP_KEEMBAY_MST)
+			cr0 |= DWC_SSI_CTRLR0_KEEMBAY_MST;
+	}
 
 	return cr0;
 }
-EXPORT_SYMBOL_GPL(dw_spi_update_cr0);
 
-/* Configure CTRLR0 for DWC_ssi */
-u32 dw_spi_update_cr0_v1_01a(struct spi_controller *master,
-			     struct spi_device *spi,
-			     struct spi_transfer *transfer)
+void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
+			  struct dw_spi_cfg *cfg)
 {
 	struct chip_data *chip = spi_get_ctldata(spi);
-	u32 cr0;
+	u32 cr0 = chip->cr0;
+	u32 speed_hz;
+	u16 clk_div;
+
+	/* CTRLR0[ 4/3: 0] Data Frame Size */
+	cr0 |= (cfg->dfs - 1);
+
+	if (!(dws->caps & DW_SPI_CAP_DWC_SSI))
+		/* CTRLR0[ 9:8] Transfer Mode */
+		cr0 |= cfg->tmode << SPI_TMOD_OFFSET;
+	else
+		/* CTRLR0[11:10] Transfer Mode */
+		cr0 |= cfg->tmode << DWC_SSI_CTRLR0_TMOD_OFFSET;
+
+	dw_writel(dws, DW_SPI_CTRLR0, cr0);
+
+	if (cfg->tmode == SPI_TMOD_EPROMREAD || cfg->tmode == SPI_TMOD_RO)
+		dw_writel(dws, DW_SPI_CTRLR1, cfg->ndf ? cfg->ndf - 1 : 0);
+
+	/* Note DW APB SSI clock divider doesn't support odd numbers */
+	clk_div = (DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1) & 0xfffe;
+	speed_hz = dws->max_freq / clk_div;
+
+	if (dws->current_freq != speed_hz) {
+		spi_set_clk(dws, clk_div);
+		dws->current_freq = speed_hz;
+	}
 
-	/* CTRLR0[ 4: 0] Data Frame Size */
-	cr0 = (transfer->bits_per_word - 1);
+	/* Update RX sample delay if required */
+	if (dws->cur_rx_sample_dly != chip->rx_sample_dly) {
+		dw_writel(dws, DW_SPI_RX_SAMPLE_DLY, chip->rx_sample_dly);
+		dws->cur_rx_sample_dly = chip->rx_sample_dly;
+	}
+}
+EXPORT_SYMBOL_GPL(dw_spi_update_config);
 
-	/* CTRLR0[ 7: 6] Frame Format */
-	cr0 |= chip->type << DWC_SSI_CTRLR0_FRF_OFFSET;
+static void dw_spi_irq_setup(struct dw_spi *dws)
+{
+	u16 level;
+	u8 imask;
 
 	/*
-	 * SPI mode (SCPOL|SCPH)
-	 * CTRLR0[ 8] Serial Clock Phase
-	 * CTRLR0[ 9] Serial Clock Polarity
+	 * Originally Tx and Rx data lengths match. Rx FIFO Threshold level
+	 * will be adjusted at the final stage of the IRQ-based SPI transfer
+	 * execution so not to lose the leftover of the incoming data.
 	 */
-	cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << DWC_SSI_CTRLR0_SCPOL_OFFSET;
-	cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << DWC_SSI_CTRLR0_SCPH_OFFSET;
+	level = min_t(u16, dws->fifo_len / 2, dws->tx_len);
+	dw_writel(dws, DW_SPI_TXFTLR, level);
+	dw_writel(dws, DW_SPI_RXFTLR, level - 1);
 
-	/* CTRLR0[11:10] Transfer Mode */
-	cr0 |= chip->tmode << DWC_SSI_CTRLR0_TMOD_OFFSET;
+	imask = SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI |
+		SPI_INT_RXFI;
+	spi_umask_intr(dws, imask);
 
-	/* CTRLR0[13] Shift Register Loop */
-	cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << DWC_SSI_CTRLR0_SRL_OFFSET;
+	dws->transfer_handler = dw_spi_transfer_handler;
+}
 
-	return cr0;
+/*
+ * The iterative procedure of the poll-based transfer is simple: write as much
+ * as possible to the Tx FIFO, wait until the pending to receive data is ready
+ * to be read, read it from the Rx FIFO and check whether the performed
+ * procedure has been successful.
+ *
+ * Note this method the same way as the IRQ-based transfer won't work well for
+ * the SPI devices connected to the controller with native CS due to the
+ * automatic CS assertion/de-assertion.
+ */
+static int dw_spi_poll_transfer(struct dw_spi *dws,
+				struct spi_transfer *transfer)
+{
+	struct spi_delay delay;
+	u16 nbits;
+	int ret;
+
+	delay.unit = SPI_DELAY_UNIT_SCK;
+	nbits = dws->n_bytes * BITS_PER_BYTE;
+
+	do {
+		dw_writer(dws);
+
+		delay.value = nbits * (dws->rx_len - dws->tx_len);
+		spi_delay_exec(&delay, transfer);
+
+		dw_reader(dws);
+
+		ret = dw_spi_check_status(dws, true);
+		if (ret)
+			return ret;
+	} while (dws->rx_len);
+
+	return 0;
 }
-EXPORT_SYMBOL_GPL(dw_spi_update_cr0_v1_01a);
 
 static int dw_spi_transfer_one(struct spi_controller *master,
 		struct spi_device *spi, struct spi_transfer *transfer)
 {
 	struct dw_spi *dws = spi_controller_get_devdata(master);
-	struct chip_data *chip = spi_get_ctldata(spi);
-	unsigned long flags;
-	u8 imask = 0;
-	u16 txlevel = 0;
-	u32 cr0;
+	struct dw_spi_cfg cfg = {
+		.tmode = SPI_TMOD_TR,
+		.dfs = transfer->bits_per_word,
+		.freq = transfer->speed_hz,
+	};
 	int ret;
 
 	dws->dma_mapped = 0;
-	spin_lock_irqsave(&dws->buf_lock, flags);
+	dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
 	dws->tx = (void *)transfer->tx_buf;
-	dws->tx_end = dws->tx + transfer->len;
+	dws->tx_len = transfer->len / dws->n_bytes;
 	dws->rx = transfer->rx_buf;
-	dws->rx_end = dws->rx + transfer->len;
-	dws->len = transfer->len;
-	spin_unlock_irqrestore(&dws->buf_lock, flags);
+	dws->rx_len = dws->tx_len;
 
-	/* Ensure dw->rx and dw->rx_end are visible */
+	/* Ensure the data above is visible for all CPUs */
 	smp_mb();
 
 	spi_enable_chip(dws, 0);
 
-	/* Handle per transfer options for bpw and speed */
-	if (transfer->speed_hz != dws->current_freq) {
-		if (transfer->speed_hz != chip->speed_hz) {
-			/* clk_div doesn't support odd number */
-			chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe;
-			chip->speed_hz = transfer->speed_hz;
-		}
-		dws->current_freq = transfer->speed_hz;
-		spi_set_clk(dws, chip->clk_div);
-	}
-
-	transfer->effective_speed_hz = dws->max_freq / chip->clk_div;
-	dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
+	dw_spi_update_config(dws, spi, &cfg);
 
-	cr0 = dws->update_cr0(master, spi, transfer);
-	dw_writel(dws, DW_SPI_CTRLR0, cr0);
+	transfer->effective_speed_hz = dws->current_freq;
 
 	/* Check if current transfer is a DMA transaction */
 	if (master->can_dma && master->can_dma(master, spi, transfer))
@@ -331,32 +434,20 @@ static int dw_spi_transfer_one(struct spi_controller *master,
 	/* For poll mode just disable all interrupts */
 	spi_mask_intr(dws, 0xff);
 
-	/*
-	 * Interrupt mode
-	 * we only need set the TXEI IRQ, as TX/RX always happen syncronizely
-	 */
 	if (dws->dma_mapped) {
 		ret = dws->dma_ops->dma_setup(dws, transfer);
-		if (ret < 0) {
-			spi_enable_chip(dws, 1);
+		if (ret)
 			return ret;
-		}
-	} else {
-		txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
-		dw_writel(dws, DW_SPI_TXFTLR, txlevel);
-
-		/* Set the interrupt mask */
-		imask |= SPI_INT_TXEI | SPI_INT_TXOI |
-			 SPI_INT_RXUI | SPI_INT_RXOI;
-		spi_umask_intr(dws, imask);
-
-		dws->transfer_handler = interrupt_transfer;
 	}
 
 	spi_enable_chip(dws, 1);
 
 	if (dws->dma_mapped)
 		return dws->dma_ops->dma_transfer(dws, transfer);
+	else if (dws->irq == IRQ_NOTCONNECTED)
+		return dw_spi_poll_transfer(dws, transfer);
+
+	dw_spi_irq_setup(dws);
 
 	return 1;
 }
@@ -372,21 +463,336 @@ static void dw_spi_handle_err(struct spi_controller *master,
 	spi_reset_chip(dws);
 }
 
+static int dw_spi_adjust_mem_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
+	if (op->data.dir == SPI_MEM_DATA_IN)
+		op->data.nbytes = clamp_val(op->data.nbytes, 0, SPI_NDF_MASK + 1);
+
+	return 0;
+}
+
+static bool dw_spi_supports_mem_op(struct spi_mem *mem,
+				   const struct spi_mem_op *op)
+{
+	if (op->data.buswidth > 1 || op->addr.buswidth > 1 ||
+	    op->dummy.buswidth > 1 || op->cmd.buswidth > 1)
+		return false;
+
+	return spi_mem_default_supports_op(mem, op);
+}
+
+static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
+{
+	unsigned int i, j, len;
+	u8 *out;
+
+	/*
+	 * Calculate the total length of the EEPROM command transfer and
+	 * either use the pre-allocated buffer or create a temporary one.
+	 */
+	len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
+	if (op->data.dir == SPI_MEM_DATA_OUT)
+		len += op->data.nbytes;
+
+	if (len <= SPI_BUF_SIZE) {
+		out = dws->buf;
+	} else {
+		out = kzalloc(len, GFP_KERNEL);
+		if (!out)
+			return -ENOMEM;
+	}
+
+	/*
+	 * Collect the operation code, address and dummy bytes into the single
+	 * buffer. If it's a transfer with data to be sent, also copy it into the
+	 * single buffer in order to speed the data transmission up.
+	 */
+	for (i = 0; i < op->cmd.nbytes; ++i)
+		out[i] = SPI_GET_BYTE(op->cmd.opcode, op->cmd.nbytes - i - 1);
+	for (j = 0; j < op->addr.nbytes; ++i, ++j)
+		out[i] = SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j - 1);
+	for (j = 0; j < op->dummy.nbytes; ++i, ++j)
+		out[i] = 0x0;
+
+	if (op->data.dir == SPI_MEM_DATA_OUT)
+		memcpy(&out[i], op->data.buf.out, op->data.nbytes);
+
+	dws->n_bytes = 1;
+	dws->tx = out;
+	dws->tx_len = len;
+	if (op->data.dir == SPI_MEM_DATA_IN) {
+		dws->rx = op->data.buf.in;
+		dws->rx_len = op->data.nbytes;
+	} else {
+		dws->rx = NULL;
+		dws->rx_len = 0;
+	}
+
+	return 0;
+}
+
+static void dw_spi_free_mem_buf(struct dw_spi *dws)
+{
+	if (dws->tx != dws->buf)
+		kfree(dws->tx);
+}
+
+static int dw_spi_write_then_read(struct dw_spi *dws, struct spi_device *spi)
+{
+	u32 room, entries, sts;
+	unsigned int len;
+	u8 *buf;
+
+	/*
+	 * At initial stage we just pre-fill the Tx FIFO in with no rush,
+	 * since native CS hasn't been enabled yet and the automatic data
+	 * transmission won't start til we do that.
+	 */
+	len = min(dws->fifo_len, dws->tx_len);
+	buf = dws->tx;
+	while (len--)
+		dw_write_io_reg(dws, DW_SPI_DR, *buf++);
+
+	/*
+	 * After setting any bit in the SER register the transmission will
+	 * start automatically. We have to keep up with that procedure
+	 * otherwise the CS de-assertion will happen whereupon the memory
+	 * operation will be pre-terminated.
+	 */
+	len = dws->tx_len - ((void *)buf - dws->tx);
+	dw_spi_set_cs(spi, false);
+	while (len) {
+		entries = readl_relaxed(dws->regs + DW_SPI_TXFLR);
+		if (!entries) {
+			dev_err(&dws->master->dev, "CS de-assertion on Tx\n");
+			return -EIO;
+		}
+		room = min(dws->fifo_len - entries, len);
+		for (; room; --room, --len)
+			dw_write_io_reg(dws, DW_SPI_DR, *buf++);
+	}
+
+	/*
+	 * Data fetching will start automatically if the EEPROM-read mode is
+	 * activated. We have to keep up with the incoming data pace to
+	 * prevent the Rx FIFO overflow causing the inbound data loss.
+	 */
+	len = dws->rx_len;
+	buf = dws->rx;
+	while (len) {
+		entries = readl_relaxed(dws->regs + DW_SPI_RXFLR);
+		if (!entries) {
+			sts = readl_relaxed(dws->regs + DW_SPI_RISR);
+			if (sts & SPI_INT_RXOI) {
+				dev_err(&dws->master->dev, "FIFO overflow on Rx\n");
+				return -EIO;
+			}
+			continue;
+		}
+		entries = min(entries, len);
+		for (; entries; --entries, --len)
+			*buf++ = dw_read_io_reg(dws, DW_SPI_DR);
+	}
+
+	return 0;
+}
+
+static inline bool dw_spi_ctlr_busy(struct dw_spi *dws)
+{
+	return dw_readl(dws, DW_SPI_SR) & SR_BUSY;
+}
+
+static int dw_spi_wait_mem_op_done(struct dw_spi *dws)
+{
+	int retry = SPI_WAIT_RETRIES;
+	struct spi_delay delay;
+	unsigned long ns, us;
+	u32 nents;
+
+	nents = dw_readl(dws, DW_SPI_TXFLR);
+	ns = NSEC_PER_SEC / dws->current_freq * nents;
+	ns *= dws->n_bytes * BITS_PER_BYTE;
+	if (ns <= NSEC_PER_USEC) {
+		delay.unit = SPI_DELAY_UNIT_NSECS;
+		delay.value = ns;
+	} else {
+		us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
+		delay.unit = SPI_DELAY_UNIT_USECS;
+		delay.value = clamp_val(us, 0, USHRT_MAX);
+	}
+
+	while (dw_spi_ctlr_busy(dws) && retry--)
+		spi_delay_exec(&delay, NULL);
+
+	if (retry < 0) {
+		dev_err(&dws->master->dev, "Mem op hanged up\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void dw_spi_stop_mem_op(struct dw_spi *dws, struct spi_device *spi)
+{
+	spi_enable_chip(dws, 0);
+	dw_spi_set_cs(spi, true);
+	spi_enable_chip(dws, 1);
+}
+
+/*
+ * The SPI memory operation implementation below is the best choice for the
+ * devices, which are selected by the native chip-select lane. It's
+ * specifically developed to workaround the problem with automatic chip-select
+ * lane toggle when there is no data in the Tx FIFO buffer. Luckily the current
+ * SPI-mem core calls exec_op() callback only if the GPIO-based CS is
+ * unavailable.
+ */
+static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+	struct dw_spi *dws = spi_controller_get_devdata(mem->spi->controller);
+	struct dw_spi_cfg cfg;
+	unsigned long flags;
+	int ret;
+
+	/*
+	 * Collect the outbound data into a single buffer to speed the
+	 * transmission up at least on the initial stage.
+	 */
+	ret = dw_spi_init_mem_buf(dws, op);
+	if (ret)
+		return ret;
+
+	/*
+	 * DW SPI EEPROM-read mode is required only for the SPI memory Data-IN
+	 * operation. Transmit-only mode is suitable for the rest of them.
+	 */
+	cfg.dfs = 8;
+	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
+	if (op->data.dir == SPI_MEM_DATA_IN) {
+		cfg.tmode = SPI_TMOD_EPROMREAD;
+		cfg.ndf = op->data.nbytes;
+	} else {
+		cfg.tmode = SPI_TMOD_TO;
+	}
+
+	spi_enable_chip(dws, 0);
+
+	dw_spi_update_config(dws, mem->spi, &cfg);
+
+	spi_mask_intr(dws, 0xff);
+
+	spi_enable_chip(dws, 1);
+
+	/*
+	 * DW APB SSI controller has very nasty peculiarities. First originally
+	 * (without any vendor-specific modifications) it doesn't provide a
+	 * direct way to set and clear the native chip-select signal. Instead
+	 * the controller asserts the CS lane if Tx FIFO isn't empty and a
+	 * transmission is going on, and automatically de-asserts it back to
+	 * the high level if the Tx FIFO doesn't have anything to be pushed
+	 * out. Due to that a multi-tasking or heavy IRQs activity might be
+	 * fatal, since the transfer procedure preemption may cause the Tx FIFO
+	 * getting empty and sudden CS de-assertion, which in the middle of the
+	 * transfer will most likely cause the data loss. Secondly the
+	 * EEPROM-read or Read-only DW SPI transfer modes imply the incoming
+	 * data being automatically pulled in into the Rx FIFO. So if the
+	 * driver software is late in fetching the data from the FIFO before
+	 * it's overflown, new incoming data will be lost. In order to make
+	 * sure the executed memory operations are CS-atomic and to prevent the
+	 * Rx FIFO overflow we have to disable the local interrupts so to block
+	 * any preemption during the subsequent IO operations.
+	 *
+	 * Note. At some circumstances disabling IRQs may not help to prevent
+	 * the problems described above. The CS de-assertion and Rx FIFO
+	 * overflow may still happen due to the relatively slow system bus or
+	 * CPU not working fast enough, so the write-then-read algo implemented
+	 * here just won't keep up with the SPI bus data transfer. Such
+	 * situation is highly platform specific and is supposed to be fixed by
+	 * manually restricting the SPI bus frequency using the
+	 * dws->max_mem_freq parameter.
+	 */
+	local_irq_save(flags);
+	preempt_disable();
+
+	ret = dw_spi_write_then_read(dws, mem->spi);
+
+	local_irq_restore(flags);
+	preempt_enable();
+
+	/*
+	 * Wait for the operation being finished and check the controller
+	 * status only if there hasn't been any run-time error detected. In the
+	 * former case it's just pointless. In the later one to prevent an
+	 * additional error message printing since any hw error flag being set
+	 * would be due to an error detected on the data transfer.
+	 */
+	if (!ret) {
+		ret = dw_spi_wait_mem_op_done(dws);
+		if (!ret)
+			ret = dw_spi_check_status(dws, true);
+	}
+
+	dw_spi_stop_mem_op(dws, mem->spi);
+
+	dw_spi_free_mem_buf(dws);
+
+	return ret;
+}
+
+/*
+ * Initialize the default memory operations if a glue layer hasn't specified
+ * custom ones. Direct mapping operations will be preserved anyway since DW SPI
+ * controller doesn't have an embedded dirmap interface. Note the memory
+ * operations implemented in this driver is the best choice only for the DW APB
+ * SSI controller with standard native CS functionality. If a hardware vendor
+ * has fixed the automatic CS assertion/de-assertion peculiarity, then it will
+ * be safer to use the normal SPI-messages-based transfers implementation.
+ */
+static void dw_spi_init_mem_ops(struct dw_spi *dws)
+{
+	if (!dws->mem_ops.exec_op && !(dws->caps & DW_SPI_CAP_CS_OVERRIDE) &&
+	    !dws->set_cs) {
+		dws->mem_ops.adjust_op_size = dw_spi_adjust_mem_op_size;
+		dws->mem_ops.supports_op = dw_spi_supports_mem_op;
+		dws->mem_ops.exec_op = dw_spi_exec_mem_op;
+		if (!dws->max_mem_freq)
+			dws->max_mem_freq = dws->max_freq;
+	}
+}
+
 /* This may be called twice for each spi dev */
 static int dw_spi_setup(struct spi_device *spi)
 {
+	struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
 	struct chip_data *chip;
 
 	/* Only alloc on first setup */
 	chip = spi_get_ctldata(spi);
 	if (!chip) {
+		struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
+		u32 rx_sample_dly_ns;
+
 		chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
 		if (!chip)
 			return -ENOMEM;
 		spi_set_ctldata(spi, chip);
+		/* Get specific / default rx-sample-delay */
+		if (device_property_read_u32(&spi->dev,
+					     "rx-sample-delay-ns",
+					     &rx_sample_dly_ns) != 0)
+			/* Use default controller value */
+			rx_sample_dly_ns = dws->def_rx_sample_dly_ns;
+		chip->rx_sample_dly = DIV_ROUND_CLOSEST(rx_sample_dly_ns,
+							NSEC_PER_SEC /
+							dws->max_freq);
 	}
 
-	chip->tmode = SPI_TMOD_TR;
+	/*
+	 * Update CR0 data each time the setup callback is invoked since
+	 * the device parameters could have been changed, for instance, by
+	 * the MMC SPI driver or something else.
+	 */
+	chip->cr0 = dw_spi_prepare_cr0(dws, spi);
 
 	return 0;
 }
@@ -423,7 +829,7 @@ static void spi_hw_init(struct device *dev, struct dw_spi *dws)
 	}
 
 	/* enable HW fixup for explicit CS deselect for Amazon's alpine chip */
-	if (dws->cs_override)
+	if (dws->caps & DW_SPI_CAP_CS_OVERRIDE)
 		dw_writel(dws, DW_SPI_CS_OVERRIDE, 0xF);
 }
 
@@ -440,19 +846,22 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 		return -ENOMEM;
 
 	dws->master = master;
-	dws->type = SSI_MOTO_SPI;
 	dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
-	spin_lock_init(&dws->buf_lock);
 
 	spi_controller_set_devdata(master, dws);
 
+	/* Basic HW init */
+	spi_hw_init(dev, dws);
+
 	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
 			  master);
-	if (ret < 0) {
+	if (ret < 0 && ret != -ENOTCONN) {
 		dev_err(dev, "can not get IRQ\n");
 		goto err_free_master;
 	}
 
+	dw_spi_init_mem_ops(dws);
+
 	master->use_gpio_descriptors = true;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
 	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(4, 16);
@@ -460,20 +869,22 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 	master->num_chipselect = dws->num_cs;
 	master->setup = dw_spi_setup;
 	master->cleanup = dw_spi_cleanup;
-	master->set_cs = dw_spi_set_cs;
+	if (dws->set_cs)
+		master->set_cs = dws->set_cs;
+	else
+		master->set_cs = dw_spi_set_cs;
 	master->transfer_one = dw_spi_transfer_one;
 	master->handle_err = dw_spi_handle_err;
+	master->mem_ops = &dws->mem_ops;
 	master->max_speed_hz = dws->max_freq;
 	master->dev.of_node = dev->of_node;
 	master->dev.fwnode = dev->fwnode;
 	master->flags = SPI_MASTER_GPIO_SS;
 	master->auto_runtime_pm = true;
 
-	if (dws->set_cs)
-		master->set_cs = dws->set_cs;
-
-	/* Basic HW init */
-	spi_hw_init(dev, dws);
+	/* Get default rx sample delay */
+	device_property_read_u32(dev, "rx-sample-delay-ns",
+				 &dws->def_rx_sample_dly_ns);
 
 	if (dws->dma_ops && dws->dma_ops->dma_init) {
 		ret = dws->dma_ops->dma_init(dev, dws);