1 files changed, 66 insertions, 136 deletions

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 871e337..919fa9d 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -58,8 +58,6 @@ struct chip_data {
 	u8 bits_per_word;
 	u16 clk_div;		/* baud rate divider */
 	u32 speed_hz;		/* baud rate */
-	int (*write)(struct dw_spi *dws);
-	int (*read)(struct dw_spi *dws);
 	void (*cs_control)(u32 command);
 };
 
@@ -162,107 +160,70 @@ static inline void mrst_spi_debugfs_remove(struct dw_spi *dws)
 }
 #endif /* CONFIG_DEBUG_FS */
 
-static void wait_till_not_busy(struct dw_spi *dws)
+/* Return the max entries we can fill into tx fifo */
+static inline u32 tx_max(struct dw_spi *dws)
 {
-	unsigned long end = jiffies + 1 + usecs_to_jiffies(5000);
+	u32 tx_left, tx_room, rxtx_gap;
 
-	while (time_before(jiffies, end)) {
-		if (!(dw_readw(dws, sr) & SR_BUSY))
-			return;
-		cpu_relax();
-	}
-	dev_err(&dws->master->dev,
-		"DW SPI: Status keeps busy for 5000us after a read/write!\n");
-}
-
-static void flush(struct dw_spi *dws)
-{
-	while (dw_readw(dws, sr) & SR_RF_NOT_EMPT) {
-		dw_readw(dws, dr);
-		cpu_relax();
-	}
-
-	wait_till_not_busy(dws);
-}
-
-static int null_writer(struct dw_spi *dws)
-{
-	u8 n_bytes = dws->n_bytes;
+	tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
+	tx_room = dws->fifo_len - dw_readw(dws, txflr);
 
-	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
-		|| (dws->tx == dws->tx_end))
-		return 0;
-	dw_writew(dws, dr, 0);
-	dws->tx += n_bytes;
+	/*
+	 * Another concern is about the tx/rx mismatch, we
+	 * though to use (dws->fifo_len - rxflr - txflr) as
+	 * one maximum value for tx, but it doesn't cover the
+	 * data which is out of tx/rx fifo and inside the
+	 * 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;
 
-	wait_till_not_busy(dws);
-	return 1;
+	return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
 }
 
-static int null_reader(struct dw_spi *dws)
+/* Return the max entries we should read out of rx fifo */
+static inline u32 rx_max(struct dw_spi *dws)
 {
-	u8 n_bytes = dws->n_bytes;
+	u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;
 
-	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
-		&& (dws->rx < dws->rx_end)) {
-		dw_readw(dws, dr);
-		dws->rx += n_bytes;
-	}
-	wait_till_not_busy(dws);
-	return dws->rx == dws->rx_end;
+	return min(rx_left, (u32)dw_readw(dws, rxflr));
 }
 
-static int u8_writer(struct dw_spi *dws)
+static void dw_writer(struct dw_spi *dws)
 {
-	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
-		|| (dws->tx == dws->tx_end))
-		return 0;
+	u32 max = tx_max(dws);
+	u16 txw = 0;
 
-	dw_writew(dws, dr, *(u8 *)(dws->tx));
-	++dws->tx;
-
-	wait_till_not_busy(dws);
-	return 1;
-}
-
-static int u8_reader(struct dw_spi *dws)
-{
-	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
-		&& (dws->rx < dws->rx_end)) {
-		*(u8 *)(dws->rx) = dw_readw(dws, dr);
-		++dws->rx;
+	while (max--) {
+		/* Set the tx word if the transfer's original "tx" is not null */
+		if (dws->tx_end - dws->len) {
+			if (dws->n_bytes == 1)
+				txw = *(u8 *)(dws->tx);
+			else
+				txw = *(u16 *)(dws->tx);
+		}
+		dw_writew(dws, dr, txw);
+		dws->tx += dws->n_bytes;
 	}
-
-	wait_till_not_busy(dws);
-	return dws->rx == dws->rx_end;
 }
 
-static int u16_writer(struct dw_spi *dws)
+static void dw_reader(struct dw_spi *dws)
 {
-	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)
-		|| (dws->tx == dws->tx_end))
-		return 0;
+	u32 max = rx_max(dws);
+	u16 rxw;
 
-	dw_writew(dws, dr, *(u16 *)(dws->tx));
-	dws->tx += 2;
-
-	wait_till_not_busy(dws);
-	return 1;
-}
-
-static int u16_reader(struct dw_spi *dws)
-{
-	u16 temp;
-
-	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)
-		&& (dws->rx < dws->rx_end)) {
-		temp = dw_readw(dws, dr);
-		*(u16 *)(dws->rx) = temp;
-		dws->rx += 2;
+	while (max--) {
+		rxw = dw_readw(dws, dr);
+		/* Care rx only if the transfer's original "rx" is not null */
+		if (dws->rx_end - dws->len) {
+			if (dws->n_bytes == 1)
+				*(u8 *)(dws->rx) = rxw;
+			else
+				*(u16 *)(dws->rx) = rxw;
+		}
+		dws->rx += dws->n_bytes;
 	}
-
-	wait_till_not_busy(dws);
-	return dws->rx == dws->rx_end;
 }
 
 static void *next_transfer(struct dw_spi *dws)
@@ -334,8 +295,7 @@ static void giveback(struct dw_spi *dws)
 
 static void int_error_stop(struct dw_spi *dws, const char *msg)
 {
-	/* Stop and reset hw */
-	flush(dws);
+	/* Stop the hw */
 	spi_enable_chip(dws, 0);
 
 	dev_err(&dws->master->dev, "%s\n", msg);
@@ -362,35 +322,28 @@ EXPORT_SYMBOL_GPL(dw_spi_xfer_done);
 
 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
-	u16 irq_status, irq_mask = 0x3f;
-	u32 int_level = dws->fifo_len / 2;
-	u32 left;
+	u16 irq_status = dw_readw(dws, isr);
 
-	irq_status = dw_readw(dws, isr) & irq_mask;
 	/* Error handling */
 	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
 		dw_readw(dws, txoicr);
 		dw_readw(dws, rxoicr);
 		dw_readw(dws, rxuicr);
-		int_error_stop(dws, "interrupt_transfer: fifo overrun");
+		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
 		return IRQ_HANDLED;
 	}
 
+	dw_reader(dws);
+	if (dws->rx_end == dws->rx) {
+		spi_mask_intr(dws, SPI_INT_TXEI);
+		dw_spi_xfer_done(dws);
+		return IRQ_HANDLED;
+	}
 	if (irq_status & SPI_INT_TXEI) {
 		spi_mask_intr(dws, SPI_INT_TXEI);
-
-		left = (dws->tx_end - dws->tx) / dws->n_bytes;
-		left = (left > int_level) ? int_level : left;
-
-		while (left--)
-			dws->write(dws);
-		dws->read(dws);
-
-		/* Re-enable the IRQ if there is still data left to tx */
-		if (dws->tx_end > dws->tx)
-			spi_umask_intr(dws, SPI_INT_TXEI);
-		else
-			dw_spi_xfer_done(dws);
+		dw_writer(dws);
+		/* Enable TX irq always, it will be disabled when RX finished */
+		spi_umask_intr(dws, SPI_INT_TXEI);
 	}
 
 	return IRQ_HANDLED;
@@ -399,15 +352,13 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
 	struct dw_spi *dws = dev_id;
-	u16 irq_status, irq_mask = 0x3f;
+	u16 irq_status = dw_readw(dws, isr) & 0x3f;
 
-	irq_status = dw_readw(dws, isr) & irq_mask;
 	if (!irq_status)
 		return IRQ_NONE;
 
 	if (!dws->cur_msg) {
 		spi_mask_intr(dws, SPI_INT_TXEI);
-		/* Never fail */
 		return IRQ_HANDLED;
 	}
 
@@ -417,13 +368,11 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 /* Must be called inside pump_transfers() */
 static void poll_transfer(struct dw_spi *dws)
 {
-	while (dws->write(dws))
-		dws->read(dws);
-	/*
-	 * There is a possibility that the last word of a transaction
-	 * will be lost if data is not ready. Re-read to solve this issue.
-	 */
-	dws->read(dws);
+	do {
+		dw_writer(dws);
+		dw_reader(dws);
+		cpu_relax();
+	} while (dws->rx_end > dws->rx);
 
 	dw_spi_xfer_done(dws);
 }
@@ -483,8 +432,6 @@ static void pump_transfers(unsigned long data)
 	dws->tx_end = dws->tx + transfer->len;
 	dws->rx = transfer->rx_buf;
 	dws->rx_end = dws->rx + transfer->len;
-	dws->write = dws->tx ? chip->write : null_writer;
-	dws->read = dws->rx ? chip->read : null_reader;
 	dws->cs_change = transfer->cs_change;
 	dws->len = dws->cur_transfer->len;
 	if (chip != dws->prev_chip)
@@ -518,20 +465,8 @@ static void pump_transfers(unsigned long data)
 
 		switch (bits) {
 		case 8:
-			dws->n_bytes = 1;
-			dws->dma_width = 1;
-			dws->read = (dws->read != null_reader) ?
-					u8_reader : null_reader;
-			dws->write = (dws->write != null_writer) ?
-					u8_writer : null_writer;
-			break;
 		case 16:
-			dws->n_bytes = 2;
-			dws->dma_width = 2;
-			dws->read = (dws->read != null_reader) ?
-					u16_reader : null_reader;
-			dws->write = (dws->write != null_writer) ?
-					u16_writer : null_writer;
+			dws->n_bytes = dws->dma_width = bits >> 3;
 			break;
 		default:
 			printk(KERN_ERR "MRST SPI0: unsupported bits:"
@@ -575,7 +510,7 @@ static void pump_transfers(unsigned long data)
 		txint_level = dws->fifo_len / 2;
 		txint_level = (templen > txint_level) ? txint_level : templen;
 
-		imask |= SPI_INT_TXEI;
+		imask |= SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI;
 		dws->transfer_handler = interrupt_transfer;
 	}
 
@@ -733,13 +668,9 @@ static int dw_spi_setup(struct spi_device *spi)
 	if (spi->bits_per_word <= 8) {
 		chip->n_bytes = 1;
 		chip->dma_width = 1;
-		chip->read = u8_reader;
-		chip->write = u8_writer;
 	} else if (spi->bits_per_word <= 16) {
 		chip->n_bytes = 2;
 		chip->dma_width = 2;
-		chip->read = u16_reader;
-		chip->write = u16_writer;
 	} else {
 		/* Never take >16b case for MRST SPIC */
 		dev_err(&spi->dev, "invalid wordsize\n");
@@ -851,7 +782,6 @@ static void spi_hw_init(struct dw_spi *dws)
 	spi_enable_chip(dws, 0);
 	spi_mask_intr(dws, 0xff);
 	spi_enable_chip(dws, 1);
-	flush(dws);
 
 	/*
 	 * Try to detect the FIFO depth if not set by interface driver,