Merge remote-tracking branch 'spi/topic/mxs' into spi-next

drivers/spi/spi-mxs.c

@@ -57,31 +57,50 @@
 
 #define SG_MAXLEN		0xff00
 
+/*
+ * Flags for txrx functions.  More efficient that using an argument register for
+ * each one.
+ */
+#define TXRX_WRITE		(1<<0)	/* This is a write */
+#define TXRX_DEASSERT_CS	(1<<1)	/* De-assert CS at end of txrx */
+
 struct mxs_spi {
 	struct mxs_ssp		ssp;
 	struct completion	c;
+	unsigned int		sck;	/* Rate requested (vs actual) */
 };
 
 static int mxs_spi_setup_transfer(struct spi_device *dev,
-				struct spi_transfer *t)
+				  const struct spi_transfer *t)
 {
 	struct mxs_spi *spi = spi_master_get_devdata(dev->master);
 	struct mxs_ssp *ssp = &spi->ssp;
-	uint32_t hz = 0;
+	const unsigned int hz = min(dev->max_speed_hz, t->speed_hz);
 
-	hz = dev->max_speed_hz;
-	if (t && t->speed_hz)
-		hz = min(hz, t->speed_hz);
 	if (hz == 0) {
-		dev_err(&dev->dev, "Cannot continue with zero clock\n");
+		dev_err(&dev->dev, "SPI clock rate of zero not allowed\n");
 		return -EINVAL;
 	}
 
+	if (hz != spi->sck) {
 		mxs_ssp_set_clk_rate(ssp, hz);
+		/*
+		 * Save requested rate, hz, rather than the actual rate,
+		 * ssp->clk_rate.  Otherwise we would set the rate every trasfer
+		 * when the actual rate is not quite the same as requested rate.
+		 */
+		spi->sck = hz;
+		/*
+		 * Perhaps we should return an error if the actual clock is
+		 * nowhere close to what was requested?
+		 */
+	}
+
+	writel(BM_SSP_CTRL0_LOCK_CS,
+		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
 
 	writel(BF_SSP_CTRL1_SSP_MODE(BV_SSP_CTRL1_SSP_MODE__SPI) |
-		     BF_SSP_CTRL1_WORD_LENGTH
-		     (BV_SSP_CTRL1_WORD_LENGTH__EIGHT_BITS) |
+	       BF_SSP_CTRL1_WORD_LENGTH(BV_SSP_CTRL1_WORD_LENGTH__EIGHT_BITS) |
 	       ((dev->mode & SPI_CPOL) ? BM_SSP_CTRL1_POLARITY : 0) |
 	       ((dev->mode & SPI_CPHA) ? BM_SSP_CTRL1_PHASE : 0),
 	       ssp->base + HW_SSP_CTRL1(ssp));
@@ -94,26 +113,15 @@ static int mxs_spi_setup_transfer(struct spi_device *dev,
 
 static int mxs_spi_setup(struct spi_device *dev)
 {
-	int err = 0;
-
 	if (!dev->bits_per_word)
 		dev->bits_per_word = 8;
 
-	if (dev->mode & ~(SPI_CPOL | SPI_CPHA))
-		return -EINVAL;
-
-	err = mxs_spi_setup_transfer(dev, NULL);
-	if (err) {
-		dev_err(&dev->dev,
-			"Failed to setup transfer, error = %d\n", err);
-	}
-
-	return err;
+	return 0;
 }
 
-static uint32_t mxs_spi_cs_to_reg(unsigned cs)
+static u32 mxs_spi_cs_to_reg(unsigned cs)
 {
-	uint32_t select = 0;
+	u32 select = 0;
 
 	/*
 	 * i.MX28 Datasheet: 17.10.1: HW_SSP_CTRL0
@@ -131,43 +139,11 @@ static uint32_t mxs_spi_cs_to_reg(unsigned cs)
 	return select;
 }
 
-static void mxs_spi_set_cs(struct mxs_spi *spi, unsigned cs)
-{
-	const uint32_t mask =
-		BM_SSP_CTRL0_WAIT_FOR_CMD | BM_SSP_CTRL0_WAIT_FOR_IRQ;
-	uint32_t select;
-	struct mxs_ssp *ssp = &spi->ssp;
-
-	writel(mask, ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
-	select = mxs_spi_cs_to_reg(cs);
-	writel(select, ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
-}
-
-static inline void mxs_spi_enable(struct mxs_spi *spi)
-{
-	struct mxs_ssp *ssp = &spi->ssp;
-
-	writel(BM_SSP_CTRL0_LOCK_CS,
-		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
-	writel(BM_SSP_CTRL0_IGNORE_CRC,
-		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
-}
-
-static inline void mxs_spi_disable(struct mxs_spi *spi)
-{
-	struct mxs_ssp *ssp = &spi->ssp;
-
-	writel(BM_SSP_CTRL0_LOCK_CS,
-		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
-	writel(BM_SSP_CTRL0_IGNORE_CRC,
-		ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
-}
-
 static int mxs_ssp_wait(struct mxs_spi *spi, int offset, int mask, bool set)
 {
 	const unsigned long timeout = jiffies + msecs_to_jiffies(SSP_TIMEOUT);
 	struct mxs_ssp *ssp = &spi->ssp;
-	uint32_t reg;
+	u32 reg;
 
 	do {
 		reg = readl_relaxed(ssp->base + offset);
@@ -200,9 +176,9 @@ static irqreturn_t mxs_ssp_irq_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
+static int mxs_spi_txrx_dma(struct mxs_spi *spi,
 			    unsigned char *buf, int len,
-			    int *first, int *last, int write)
+			    unsigned int flags)
 {
 	struct mxs_ssp *ssp = &spi->ssp;
 	struct dma_async_tx_descriptor *desc = NULL;
@@ -211,11 +187,11 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 	const int sgs = DIV_ROUND_UP(len, desc_len);
 	int sg_count;
 	int min, ret;
-	uint32_t ctrl0;
+	u32 ctrl0;
 	struct page *vm_page;
 	void *sg_buf;
 	struct {
-		uint32_t		pio[4];
+		u32			pio[4];
 		struct scatterlist	sg;
 	} *dma_xfer;
 
@@ -228,21 +204,25 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 
 	INIT_COMPLETION(spi->c);
 
+	/* Chip select was already programmed into CTRL0 */
 	ctrl0 = readl(ssp->base + HW_SSP_CTRL0);
-	ctrl0 &= ~BM_SSP_CTRL0_XFER_COUNT;
-	ctrl0 |= BM_SSP_CTRL0_DATA_XFER | mxs_spi_cs_to_reg(cs);
+	ctrl0 &= ~(BM_SSP_CTRL0_XFER_COUNT | BM_SSP_CTRL0_IGNORE_CRC |
+		 BM_SSP_CTRL0_READ);
+	ctrl0 |= BM_SSP_CTRL0_DATA_XFER;
 
-	if (*first)
-		ctrl0 |= BM_SSP_CTRL0_LOCK_CS;
-	if (!write)
+	if (!(flags & TXRX_WRITE))
 		ctrl0 |= BM_SSP_CTRL0_READ;
 
 	/* Queue the DMA data transfer. */
 	for (sg_count = 0; sg_count < sgs; sg_count++) {
+		/* Prepare the transfer descriptor. */
 		min = min(len, desc_len);
 
-		/* Prepare the transfer descriptor. */
-		if ((sg_count + 1 == sgs) && *last)
+		/*
+		 * De-assert CS on last segment if flag is set (i.e., no more
+		 * transfers will follow)
+		 */
+		if ((sg_count + 1 == sgs) && (flags & TXRX_DEASSERT_CS))
 			ctrl0 |= BM_SSP_CTRL0_IGNORE_CRC;
 
 		if (ssp->devid == IMX23_SSP) {
@@ -267,7 +247,7 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 
 		sg_init_one(&dma_xfer[sg_count].sg, sg_buf, min);
 		ret = dma_map_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
-			write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+			(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 
 		len -= min;
 		buf += min;
@@ -287,7 +267,7 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 
 		desc = dmaengine_prep_slave_sg(ssp->dmach,
 				&dma_xfer[sg_count].sg, 1,
-				write ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
+				(flags & TXRX_WRITE) ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
 				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
 		if (!desc) {
@@ -324,7 +304,7 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 	while (--sg_count >= 0) {
 err_mapped:
 		dma_unmap_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
-			write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+			(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 	}
 
 	kfree(dma_xfer);
@@ -332,20 +312,19 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
 	return ret;
 }
 
-static int mxs_spi_txrx_pio(struct mxs_spi *spi, int cs,
+static int mxs_spi_txrx_pio(struct mxs_spi *spi,
 			    unsigned char *buf, int len,
-			    int *first, int *last, int write)
+			    unsigned int flags)
 {
 	struct mxs_ssp *ssp = &spi->ssp;
 
-	if (*first)
-		mxs_spi_enable(spi);
-
-	mxs_spi_set_cs(spi, cs);
+	writel(BM_SSP_CTRL0_IGNORE_CRC,
+	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
 
 	while (len--) {
-		if (*last && len == 0)
-			mxs_spi_disable(spi);
+		if (len == 0 && (flags & TXRX_DEASSERT_CS))
+			writel(BM_SSP_CTRL0_IGNORE_CRC,
+			       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
 
 		if (ssp->devid == IMX23_SSP) {
 			writel(BM_SSP_CTRL0_XFER_COUNT,
@@ -356,7 +335,7 @@ static int mxs_spi_txrx_pio(struct mxs_spi *spi, int cs,
 			writel(1, ssp->base + HW_SSP_XFER_SIZE);
 		}
 
-		if (write)
+		if (flags & TXRX_WRITE)
 			writel(BM_SSP_CTRL0_READ,
 				ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
 		else
@@ -369,13 +348,13 @@ static int mxs_spi_txrx_pio(struct mxs_spi *spi, int cs,
 		if (mxs_ssp_wait(spi, HW_SSP_CTRL0, BM_SSP_CTRL0_RUN, 1))
 			return -ETIMEDOUT;
 
-		if (write)
+		if (flags & TXRX_WRITE)
 			writel(*buf, ssp->base + HW_SSP_DATA(ssp));
 
 		writel(BM_SSP_CTRL0_DATA_XFER,
 			     ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
 
-		if (!write) {
+		if (!(flags & TXRX_WRITE)) {
 			if (mxs_ssp_wait(spi, HW_SSP_STATUS(ssp),
 						BM_SSP_STATUS_FIFO_EMPTY, 0))
 				return -ETIMEDOUT;
@@ -400,14 +379,15 @@ static int mxs_spi_transfer_one(struct spi_master *master,
 {
 	struct mxs_spi *spi = spi_master_get_devdata(master);
 	struct mxs_ssp *ssp = &spi->ssp;
-	int first, last;
 	struct spi_transfer *t, *tmp_t;
+	unsigned int flag;
 	int status = 0;
-	int cs;
-
-	first = last = 0;
 
-	cs = m->spi->chip_select;
+	/* Program CS register bits here, it will be used for all transfers. */
+	writel(BM_SSP_CTRL0_WAIT_FOR_CMD | BM_SSP_CTRL0_WAIT_FOR_IRQ,
+	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
+	writel(mxs_spi_cs_to_reg(m->spi->chip_select),
+	       ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
 
 	list_for_each_entry_safe(t, tmp_t, &m->transfers, transfer_list) {
 
@@ -415,16 +395,9 @@ static int mxs_spi_transfer_one(struct spi_master *master,
 		if (status)
 			break;
 
-		if (&t->transfer_list == m->transfers.next)
-			first = 1;
-		if (&t->transfer_list == m->transfers.prev)
-			last = 1;
-		if ((t->rx_buf && t->tx_buf) || (t->rx_dma && t->tx_dma)) {
-			dev_err(ssp->dev,
-				"Cannot send and receive simultaneously\n");
-			status = -EINVAL;
-			break;
-		}
+		/* De-assert on last transfer, inverted by cs_change flag */
+		flag = (&t->transfer_list == m->transfers.prev) ^ t->cs_change ?
+		       TXRX_DEASSERT_CS : 0;
 
 		/*
 		 * Small blocks can be transfered via PIO.
@@ -441,26 +414,26 @@ static int mxs_spi_transfer_one(struct spi_master *master,
 				STMP_OFFSET_REG_CLR);
 
 			if (t->tx_buf)
-				status = mxs_spi_txrx_pio(spi, cs,
+				status = mxs_spi_txrx_pio(spi,
 						(void *)t->tx_buf,
-						t->len, &first, &last, 1);
+						t->len, flag | TXRX_WRITE);
 			if (t->rx_buf)
-				status = mxs_spi_txrx_pio(spi, cs,
+				status = mxs_spi_txrx_pio(spi,
 						t->rx_buf, t->len,
-						&first, &last, 0);
+						flag);
 		} else {
 			writel(BM_SSP_CTRL1_DMA_ENABLE,
 				ssp->base + HW_SSP_CTRL1(ssp) +
 				STMP_OFFSET_REG_SET);
 
 			if (t->tx_buf)
-				status = mxs_spi_txrx_dma(spi, cs,
+				status = mxs_spi_txrx_dma(spi,
 						(void *)t->tx_buf, t->len,
-						&first, &last, 1);
+						flag | TXRX_WRITE);
 			if (t->rx_buf)
-				status = mxs_spi_txrx_dma(spi, cs,
+				status = mxs_spi_txrx_dma(spi,
 						t->rx_buf, t->len,
-						&first, &last, 0);
+						flag);
 		}
 
 		if (status) {
@@ -469,7 +442,6 @@ static int mxs_spi_transfer_one(struct spi_master *master,
 		}
 
 		m->actual_length += t->len;
-		first = last = 0;
 	}
 
 	m->status = status;
@@ -563,7 +535,6 @@ static int mxs_spi_probe(struct platform_device *pdev)
 		goto out_dma_release;
 
 	clk_set_rate(ssp->clk, clk_freq);
-	ssp->clk_rate = clk_get_rate(ssp->clk) / 1000;
 
 	ret = stmp_reset_block(ssp->base);
 	if (ret)