[PATCH v6 10/14] spi: qup: allow block mode to generate multiple transactions

[Varadarajan Narayanan]

This let's you write more to the SPI bus than 64K-1 which is important
if the block size of a SPI device is >= 64K or some other device wants
to do something larger.

This has the benefit of completely removing spi_message from the spi-qup
transactions

Signed-off-by: Matthew McClintock <mmcclint@xxxxxxxxxxxxxx>
Signed-off-by: Varadarajan Narayanan <varada@xxxxxxxxxxxxxx>
---
 drivers/spi/spi-qup.c | 128 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 80 insertions(+), 48 deletions(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index 1aa6078..707b1ec 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -120,7 +120,7 @@
 
 #define SPI_NUM_CHIPSELECTS		4
 
-#define SPI_MAX_DMA_XFER		(SZ_64K - 64)
+#define SPI_MAX_XFER			(SZ_64K - 64)
 
 /* high speed mode is when bus rate is greater then 26MHz */
 #define SPI_HS_MIN_RATE			26000000
@@ -149,6 +149,8 @@ struct spi_qup {
 	int			n_words;
 	int			tx_bytes;
 	int			rx_bytes;
+	const u8		*tx_buf;
+	u8			*rx_buf;
 	int			qup_v1;
 
 	int			mode;
@@ -173,6 +175,12 @@ static inline bool spi_qup_is_dma_xfer(int mode)
 	return false;
 }
 
+/* get's the transaction size length */
+static inline unsigned int spi_qup_len(struct spi_qup *controller)
+{
+	return controller->n_words * controller->w_size;
+}
+
 static inline bool spi_qup_is_valid_state(struct spi_qup *controller)
 {
 	u32 opstate = readl_relaxed(controller->base + QUP_STATE);
@@ -225,10 +233,9 @@ static int spi_qup_set_state(struct spi_qup *controller, u32 state)
 	return 0;
 }
 
-static void spi_qup_read_from_fifo(struct spi_qup *controller,
-	struct spi_transfer *xfer, u32 num_words)
+static void spi_qup_read_from_fifo(struct spi_qup *controller, u32 num_words)
 {
-	u8 *rx_buf = xfer->rx_buf;
+	u8 *rx_buf = controller->rx_buf;
 	int i, shift, num_bytes;
 	u32 word;
 
@@ -236,8 +243,9 @@ static void spi_qup_read_from_fifo(struct spi_qup *controller,
 
 		word = readl_relaxed(controller->base + QUP_INPUT_FIFO);
 
-		num_bytes = min_t(int, xfer->len - controller->rx_bytes,
-					controller->w_size);
+		num_bytes = min_t(int, spi_qup_len(controller) -
+				       controller->rx_bytes,
+				       controller->w_size);
 
 		if (!rx_buf) {
 			controller->rx_bytes += num_bytes;
@@ -258,13 +266,12 @@ static void spi_qup_read_from_fifo(struct spi_qup *controller,
 	}
 }
 
-static void spi_qup_read(struct spi_qup *controller,
-			    struct spi_transfer *xfer)
+static void spi_qup_read(struct spi_qup *controller)
 {
 	u32 remainder, words_per_block, num_words;
 	bool is_block_mode = controller->mode == QUP_IO_M_MODE_BLOCK;
 
-	remainder = DIV_ROUND_UP(xfer->len - controller->rx_bytes,
+	remainder = DIV_ROUND_UP(spi_qup_len(controller) - controller->rx_bytes,
 				 controller->w_size);
 	words_per_block = controller->in_blk_sz >> 2;
 
@@ -285,7 +292,7 @@ static void spi_qup_read(struct spi_qup *controller,
 		}
 
 		/* read up to the maximum transfer size available */
-		spi_qup_read_from_fifo(controller, xfer, num_words);
+		spi_qup_read_from_fifo(controller, num_words);
 
 		remainder -= num_words;
 
@@ -307,18 +314,18 @@ static void spi_qup_read(struct spi_qup *controller,
 
 }
 
-static void spi_qup_write_to_fifo(struct spi_qup *controller,
-	struct spi_transfer *xfer, u32 num_words)
+static void spi_qup_write_to_fifo(struct spi_qup *controller, u32 num_words)
 {
-	const u8 *tx_buf = xfer->tx_buf;
+	const u8 *tx_buf = controller->tx_buf;
 	int i, num_bytes;
 	u32 word, data;
 
 	for (; num_words; num_words--) {
 		word = 0;
 
-		num_bytes = min_t(int, xfer->len - controller->tx_bytes,
-				    controller->w_size);
+		num_bytes = min_t(int, spi_qup_len(controller) -
+				       controller->tx_bytes,
+				       controller->w_size);
 		if (tx_buf)
 			for (i = 0; i < num_bytes; i++) {
 				data = tx_buf[controller->tx_bytes + i];
@@ -338,13 +345,12 @@ static void spi_qup_dma_done(void *data)
 	complete(&qup->done);
 }
 
-static void spi_qup_write(struct spi_qup *controller,
-			    struct spi_transfer *xfer)
+static void spi_qup_write(struct spi_qup *controller)
 {
 	bool is_block_mode = controller->mode == QUP_IO_M_MODE_BLOCK;
 	u32 remainder, words_per_block, num_words;
 
-	remainder = DIV_ROUND_UP(xfer->len - controller->tx_bytes,
+	remainder = DIV_ROUND_UP(spi_qup_len(controller) - controller->tx_bytes,
 				 controller->w_size);
 	words_per_block = controller->out_blk_sz >> 2;
 
@@ -364,7 +370,7 @@ static void spi_qup_write(struct spi_qup *controller,
 			num_words = 1;
 		}
 
-		spi_qup_write_to_fifo(controller, xfer, num_words);
+		spi_qup_write_to_fifo(controller, num_words);
 
 		remainder -= num_words;
 
@@ -471,36 +477,62 @@ static int spi_qup_do_pio(struct spi_device *spi, struct spi_transfer *xfer,
 {
 	struct spi_master *master = spi->master;
 	struct spi_qup *qup = spi_master_get_devdata(master);
-	int ret;
+	int ret, n_words, iterations, offset = 0;
 
-	ret = spi_qup_io_config(spi, xfer);
-	if (ret)
-		return ret;
+	n_words = qup->n_words;
+	iterations = n_words / SPI_MAX_XFER; /* round down */
+	qup->rx_buf = xfer->rx_buf;
+	qup->tx_buf = xfer->tx_buf;
 
-	ret = spi_qup_set_state(qup, QUP_STATE_RUN);
-	if (ret) {
-		dev_warn(qup->dev, "cannot set RUN state\n");
-		return ret;
-	}
+	do {
+		if (iterations)
+			qup->n_words = SPI_MAX_XFER;
+		else
+			qup->n_words = n_words % SPI_MAX_XFER;
 
-	ret = spi_qup_set_state(qup, QUP_STATE_PAUSE);
-	if (ret) {
-		dev_warn(qup->dev, "cannot set PAUSE state\n");
-		return ret;
-	}
+		if (qup->tx_buf && offset)
+			qup->tx_buf = xfer->tx_buf + offset * SPI_MAX_XFER;
 
-	if (qup->mode == QUP_IO_M_MODE_FIFO)
-		spi_qup_write(qup, xfer);
+		if (qup->rx_buf && offset)
+			qup->rx_buf = xfer->rx_buf + offset * SPI_MAX_XFER;
 
-	ret = spi_qup_set_state(qup, QUP_STATE_RUN);
-	if (ret) {
-		dev_warn(qup->dev, "%s(%d): cannot set RUN state\n",
-				__func__, __LINE__);
-		return ret;
-	}
+		/*
+		 * if the transaction is small enough, we need
+		 * to fallback to FIFO mode
+		 */
+		if (qup->n_words <= (qup->in_fifo_sz / sizeof(u32)))
+			qup->mode = QUP_IO_M_MODE_FIFO;
 
-	if (!wait_for_completion_timeout(&qup->done, timeout))
-		return -ETIMEDOUT;
+		ret = spi_qup_io_config(spi, xfer);
+		if (ret)
+			return ret;
+
+		ret = spi_qup_set_state(qup, QUP_STATE_RUN);
+		if (ret) {
+			dev_warn(qup->dev, "cannot set RUN state\n");
+			return ret;
+		}
+
+		ret = spi_qup_set_state(qup, QUP_STATE_PAUSE);
+		if (ret) {
+			dev_warn(qup->dev, "cannot set PAUSE state\n");
+			return ret;
+		}
+
+		if (qup->mode == QUP_IO_M_MODE_FIFO)
+			spi_qup_write(qup);
+
+		ret = spi_qup_set_state(qup, QUP_STATE_RUN);
+		if (ret) {
+			dev_warn(qup->dev, "cannot set RUN state\n");
+			return ret;
+		}
+
+		if (!wait_for_completion_timeout(&qup->done, timeout))
+			return -ETIMEDOUT;
+
+		offset++;
+	} while (iterations--);
 
 	return 0;
 }
@@ -508,7 +540,6 @@ static int spi_qup_do_pio(struct spi_device *spi, struct spi_transfer *xfer,
 static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 {
 	struct spi_qup *controller = dev_id;
-	struct spi_transfer *xfer = controller->xfer;
 	u32 opflags, qup_err, spi_err;
 	int error = 0;
 
@@ -545,10 +576,10 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 		writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
 	} else {
 		if (opflags & QUP_OP_IN_SERVICE_FLAG)
-			spi_qup_read(controller, xfer);
+			spi_qup_read(controller);
 
 		if (opflags & QUP_OP_OUT_SERVICE_FLAG)
-			spi_qup_write(controller, xfer);
+			spi_qup_write(controller);
 	}
 
 	if ((opflags & QUP_OP_MAX_INPUT_DONE_FLAG) || error)
@@ -755,7 +786,8 @@ static int spi_qup_transfer_one(struct spi_master *master,
 		return ret;
 
 	timeout = DIV_ROUND_UP(xfer->speed_hz, MSEC_PER_SEC);
-	timeout = DIV_ROUND_UP(xfer->len * 8, timeout);
+	timeout = DIV_ROUND_UP(min_t(unsigned long, SPI_MAX_XFER,
+				     xfer->len) * 8, timeout);
 	timeout = 100 * msecs_to_jiffies(timeout);
 
 	reinit_completion(&controller->done);
@@ -969,7 +1001,7 @@ static int spi_qup_probe(struct platform_device *pdev)
 	master->dev.of_node = pdev->dev.of_node;
 	master->auto_runtime_pm = true;
 	master->dma_alignment = dma_get_cache_alignment();
-	master->max_dma_len = SPI_MAX_DMA_XFER;
+	master->max_dma_len = SPI_MAX_XFER;
 
 	platform_set_drvdata(pdev, master);
 
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation