Message-Id: <1403816781-31008-1-git-send-email-agross@codeaurora.org>
Date:	Thu, 26 Jun 2014 16:06:21 -0500
From:	Andy Gross <agross@...eaurora.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	linux-spi@...r.kernel.org, Sagar Dharia <sdharia@...eaurora.org>,
	Daniel Sneddon <dsneddon@...eaurora.org>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org, Andy Gross <agross@...eaurora.org>
Subject: [PATCH] spi: qup: Add DMA capabilities

This patch adds DMA capabilities to the spi-qup driver.  If DMA channels are
present, the QUP will use DMA instead of block mode for transfers to/from SPI
peripherals for transactions larger than the length of a block.

Signed-off-by: Andy Gross <agross@...eaurora.org>
---
 .../devicetree/bindings/spi/qcom,spi-qup.txt       |   10 +
 drivers/spi/spi-qup.c                              |  361 ++++++++++++++++++--
 2 files changed, 350 insertions(+), 21 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt b/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
index b82a268..4d8977a 100644
--- a/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
+++ b/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
@@ -23,6 +23,12 @@ Optional properties:
 - spi-max-frequency: Specifies maximum SPI clock frequency,
                      Units - Hz. Definition as per
                      Documentation/devicetree/bindings/spi/spi-bus.txt
+- dmas :             Two DMA channel specifiers following the convention outlined
+                     in bindings/dma/dma.txt
+- dma-names:         Names for the dma channels, if present. There must be at
+                     least one channel named "tx" for transmit and named "rx" for
+                     receive.
+
 
 SPI slave nodes must be children of the SPI master node and can contain
 properties described in Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -41,6 +47,10 @@ Example:
 		clocks = <&gcc GCC_BLSP2_QUP2_SPI_APPS_CLK>, <&gcc GCC_BLSP2_AHB_CLK>;
 		clock-names = "core", "iface";
 
+		dmas = <&blsp2_bam 2>,
+			<&blsp2_bam 3>;
+		dma-names = "rx", "tx";
+
 		pinctrl-names = "default";
 		pinctrl-0 = <&spi8_default>;
 
diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index fc1de86..9b01db5 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -22,6 +22,8 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/spi/spi.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
 
 #define QUP_CONFIG			0x0000
 #define QUP_STATE			0x0004
@@ -116,6 +118,8 @@
 
 #define SPI_NUM_CHIPSELECTS		4
 
+#define SPI_MAX_XFER			(SZ_64K - 64)
+
 /* high speed mode is when bus rate is greater then 26MHz */
 #define SPI_HS_MIN_RATE			26000000
 #define SPI_MAX_RATE			50000000
@@ -142,6 +146,17 @@ struct spi_qup {
 	int			w_size;	/* bytes per SPI word */
 	int			tx_bytes;
 	int			rx_bytes;
+
+	int			use_dma;
+
+	struct dma_chan		*rx_chan;
+	struct dma_slave_config	rx_conf;
+	struct dma_chan		*tx_chan;
+	struct dma_slave_config tx_conf;
+	dma_addr_t		rx_dma;
+	dma_addr_t		tx_dma;
+	void			*dummy;
+	atomic_t		dma_outstanding;
 };
 
 
@@ -265,6 +280,221 @@ static void spi_qup_fifo_write(struct spi_qup *controller,
 	}
 }
 
+static void qup_dma_callback(void *data)
+{
+	struct spi_qup *controller = data;
+
+	if (atomic_dec_and_test(&controller->dma_outstanding))
+		complete(&controller->done);
+}
+
+static int spi_qup_do_dma(struct spi_qup *controller, struct spi_transfer *xfer)
+{
+	struct dma_async_tx_descriptor *rxd, *txd;
+	dma_cookie_t rx_cookie, tx_cookie;
+	u32 xfer_len, rx_align = 0, tx_align = 0, n_words;
+	struct scatterlist tx_sg[2], rx_sg[2];
+	int ret = 0;
+	u32 bytes_to_xfer = xfer->len;
+	u32 offset = 0;
+	u32 rx_nents = 0, tx_nents = 0;
+	dma_addr_t rx_dma = 0, tx_dma = 0, rx_dummy_dma = 0, tx_dummy_dma = 0;
+
+
+	if (xfer->rx_buf) {
+		rx_dma = dma_map_single(controller->dev, xfer->rx_buf,
+			xfer->len, DMA_FROM_DEVICE);
+
+		if (dma_mapping_error(controller->dev, rx_dma)) {
+			ret = -ENOMEM;
+			return ret;
+		}
+
+		/* check to see if we need dummy buffer for leftover bytes */
+		rx_align = xfer->len % controller->in_blk_sz;
+		if (rx_align) {
+			rx_dummy_dma = dma_map_single(controller->dev,
+				controller->dummy, controller->in_fifo_sz,
+				DMA_FROM_DEVICE);
+
+			if (dma_mapping_error(controller->dev, rx_dummy_dma)) {
+				ret = -ENOMEM;
+				goto err_map_rx_dummy;
+			}
+		}
+	}
+
+	if (xfer->tx_buf) {
+		tx_dma = dma_map_single(controller->dev,
+			(void *)xfer->tx_buf, xfer->len, DMA_TO_DEVICE);
+
+		if (dma_mapping_error(controller->dev, tx_dma)) {
+			ret = -ENOMEM;
+			goto err_map_tx;
+		}
+
+		/* check to see if we need dummy buffer for leftover bytes */
+		tx_align = xfer->len % controller->out_blk_sz;
+		if (tx_align) {
+			memcpy(controller->dummy + SZ_1K,
+				xfer->tx_buf + xfer->len - tx_align,
+				tx_align);
+			memset(controller->dummy + SZ_1K + tx_align, 0,
+				controller->out_blk_sz - tx_align);
+
+			tx_dummy_dma = dma_map_single(controller->dev,
+				controller->dummy + SZ_1K,
+				controller->out_blk_sz, DMA_TO_DEVICE);
+
+			if (dma_mapping_error(controller->dev, tx_dummy_dma)) {
+				ret = -ENOMEM;
+				goto err_map_tx_dummy;
+			}
+		}
+	}
+
+	atomic_set(&controller->dma_outstanding, 0);
+
+	while (bytes_to_xfer > 0) {
+		xfer_len = min_t(u32, bytes_to_xfer, SPI_MAX_XFER);
+		n_words = DIV_ROUND_UP(xfer_len, controller->w_size);
+
+		/* write out current word count to controller */
+		writel_relaxed(n_words, controller->base + QUP_MX_INPUT_CNT);
+		writel_relaxed(n_words, controller->base + QUP_MX_OUTPUT_CNT);
+
+		reinit_completion(&controller->done);
+
+		if (xfer->tx_buf) {
+			/* recalc align for each transaction */
+			tx_align = xfer_len % controller->out_blk_sz;
+
+			if (tx_align)
+				tx_nents = 2;
+			else
+				tx_nents = 1;
+
+			/* initialize scatterlists */
+			sg_init_table(tx_sg, tx_nents);
+			sg_dma_len(&tx_sg[0]) = xfer_len - tx_align;
+			sg_dma_address(&tx_sg[0]) = tx_dma + offset;
+
+			/* account for non block size transfer */
+			if (tx_align) {
+				sg_dma_len(&tx_sg[1]) = controller->out_blk_sz;
+				sg_dma_address(&tx_sg[1]) = tx_dummy_dma;
+			}
+
+			txd = dmaengine_prep_slave_sg(controller->tx_chan,
+					tx_sg, tx_nents, DMA_MEM_TO_DEV, 0);
+			if (!txd) {
+				ret = -ENOMEM;
+				goto err_unmap;
+			}
+
+			atomic_inc(&controller->dma_outstanding);
+
+			txd->callback = qup_dma_callback;
+			txd->callback_param = controller;
+
+			tx_cookie = dmaengine_submit(txd);
+
+			dma_async_issue_pending(controller->tx_chan);
+		}
+
+		if (xfer->rx_buf) {
+			/* recalc align for each transaction */
+			rx_align = xfer_len % controller->in_blk_sz;
+
+			if (rx_align)
+				rx_nents = 2;
+			else
+				rx_nents = 1;
+
+			/* initialize scatterlists */
+			sg_init_table(rx_sg, rx_nents);
+			sg_dma_address(&rx_sg[0]) = rx_dma + offset;
+			sg_dma_len(&rx_sg[0]) = xfer_len - rx_align;
+
+			/* account for non block size transfer */
+			if (rx_align) {
+				sg_dma_len(&rx_sg[1]) = controller->in_blk_sz;
+				sg_dma_address(&rx_sg[1]) = rx_dummy_dma;
+			}
+
+			rxd = dmaengine_prep_slave_sg(controller->rx_chan,
+					rx_sg, rx_nents, DMA_DEV_TO_MEM, 0);
+			if (!rxd) {
+				ret = -ENOMEM;
+				goto err_unmap;
+			}
+
+			atomic_inc(&controller->dma_outstanding);
+
+			rxd->callback = qup_dma_callback;
+			rxd->callback_param = controller;
+
+			rx_cookie = dmaengine_submit(rxd);
+
+			dma_async_issue_pending(controller->rx_chan);
+		}
+
+		if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+			dev_warn(controller->dev, "cannot set EXECUTE state\n");
+			goto err_unmap;
+		}
+
+		if (!wait_for_completion_timeout(&controller->done,
+			msecs_to_jiffies(1000))) {
+			ret = -ETIMEDOUT;
+
+			/* clear out all the DMA transactions */
+			if (xfer->tx_buf)
+				dmaengine_terminate_all(controller->tx_chan);
+			if (xfer->rx_buf)
+				dmaengine_terminate_all(controller->rx_chan);
+
+			goto err_unmap;
+		}
+
+		if (rx_align)
+			memcpy(xfer->rx_buf + offset + xfer->len - rx_align,
+				controller->dummy, rx_align);
+
+		/* adjust remaining bytes to transfer */
+		bytes_to_xfer -= xfer_len;
+		offset += xfer_len;
+
+
+		/* reset mini-core state so we can program next transaction */
+		if (spi_qup_set_state(controller, QUP_STATE_RESET)) {
+			dev_err(controller->dev, "cannot set RESET state\n");
+			goto err_unmap;
+		}
+	}
+
+	ret = 0;
+
+err_unmap:
+	if (tx_align)
+		dma_unmap_single(controller->dev, tx_dummy_dma,
+			controller->out_fifo_sz, DMA_TO_DEVICE);
+err_map_tx_dummy:
+	if (xfer->tx_buf)
+		dma_unmap_single(controller->dev, tx_dma, xfer->len,
+			DMA_TO_DEVICE);
+err_map_tx:
+	if (rx_align)
+		dma_unmap_single(controller->dev, rx_dummy_dma,
+			controller->in_fifo_sz, DMA_FROM_DEVICE);
+err_map_rx_dummy:
+	if (xfer->rx_buf)
+		dma_unmap_single(controller->dev, rx_dma, xfer->len,
+			DMA_FROM_DEVICE);
+
+	return ret;
+}
+
 static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 {
 	struct spi_qup *controller = dev_id;
@@ -314,11 +544,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 		error = -EIO;
 	}
 
-	if (opflags & QUP_OP_IN_SERVICE_FLAG)
-		spi_qup_fifo_read(controller, xfer);
+	if (!controller->use_dma) {
+		if (opflags & QUP_OP_IN_SERVICE_FLAG)
+			spi_qup_fifo_read(controller, xfer);
 
-	if (opflags & QUP_OP_OUT_SERVICE_FLAG)
-		spi_qup_fifo_write(controller, xfer);
+		if (opflags & QUP_OP_OUT_SERVICE_FLAG)
+			spi_qup_fifo_write(controller, xfer);
+	}
 
 	spin_lock_irqsave(&controller->lock, flags);
 	controller->error = error;
@@ -338,6 +570,8 @@ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer *xfer)
 	struct spi_qup *controller = spi_master_get_devdata(spi->master);
 	u32 config, iomode, mode;
 	int ret, n_words, w_size;
+	size_t dma_align = dma_get_cache_alignment();
+	u32 dma_available = 0;
 
 	if (spi->mode & SPI_LOOP && xfer->len > controller->in_fifo_sz) {
 		dev_err(controller->dev, "too big size for loopback %d > %d\n",
@@ -366,6 +600,11 @@ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer *xfer)
 	n_words = xfer->len / w_size;
 	controller->w_size = w_size;
 
+	if (controller->rx_chan &&
+		IS_ALIGNED((size_t)xfer->tx_buf, dma_align) &&
+		IS_ALIGNED((size_t)xfer->rx_buf, dma_align))
+		dma_available = 1;
+
 	if (n_words <= (controller->in_fifo_sz / sizeof(u32))) {
 		mode = QUP_IO_M_MODE_FIFO;
 		writel_relaxed(n_words, controller->base + QUP_MX_READ_CNT);
@@ -373,19 +612,31 @@ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer *xfer)
 		/* must be zero for FIFO */
 		writel_relaxed(0, controller->base + QUP_MX_INPUT_CNT);
 		writel_relaxed(0, controller->base + QUP_MX_OUTPUT_CNT);
-	} else {
+		controller->use_dma = 0;
+	} else if (!dma_available) {
 		mode = QUP_IO_M_MODE_BLOCK;
 		writel_relaxed(n_words, controller->base + QUP_MX_INPUT_CNT);
 		writel_relaxed(n_words, controller->base + QUP_MX_OUTPUT_CNT);
 		/* must be zero for BLOCK and BAM */
 		writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
 		writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
+		controller->use_dma = 0;
+	} else {
+		mode = QUP_IO_M_MODE_DMOV;
+		writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
+		writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
+		controller->use_dma = 1;
 	}
 
 	iomode = readl_relaxed(controller->base + QUP_IO_M_MODES);
 	/* Set input and output transfer mode */
 	iomode &= ~(QUP_IO_M_INPUT_MODE_MASK | QUP_IO_M_OUTPUT_MODE_MASK);
-	iomode &= ~(QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN);
+
+	if (!controller->use_dma)
+		iomode &= ~(QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN);
+	else
+		iomode |= QUP_IO_M_PACK_EN | QUP_IO_M_UNPACK_EN;
+
 	iomode |= (mode << QUP_IO_M_OUTPUT_MODE_MASK_SHIFT);
 	iomode |= (mode << QUP_IO_M_INPUT_MODE_MASK_SHIFT);
 
@@ -418,6 +669,14 @@ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer *xfer)
 	config &= ~(QUP_CONFIG_NO_INPUT | QUP_CONFIG_NO_OUTPUT | QUP_CONFIG_N);
 	config |= xfer->bits_per_word - 1;
 	config |= QUP_CONFIG_SPI_MODE;
+
+	if (controller->use_dma) {
+		if (!xfer->tx_buf)
+			config |= QUP_CONFIG_NO_OUTPUT;
+		if (!xfer->rx_buf)
+			config |= QUP_CONFIG_NO_INPUT;
+	}
+
 	writel_relaxed(config, controller->base + QUP_CONFIG);
 
 	writel_relaxed(0, controller->base + QUP_OPERATIONAL_MASK);
@@ -474,25 +733,29 @@ static int spi_qup_transfer_one(struct spi_master *master,
 	controller->tx_bytes = 0;
 	spin_unlock_irqrestore(&controller->lock, flags);
 
-	if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
-		dev_warn(controller->dev, "cannot set RUN state\n");
-		goto exit;
-	}
+	if (controller->use_dma) {
+		ret = spi_qup_do_dma(controller, xfer);
+	} else {
+		if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+			dev_warn(controller->dev, "cannot set RUN state\n");
+			goto exit;
+		}
 
-	if (spi_qup_set_state(controller, QUP_STATE_PAUSE)) {
-		dev_warn(controller->dev, "cannot set PAUSE state\n");
-		goto exit;
-	}
+		if (spi_qup_set_state(controller, QUP_STATE_PAUSE)) {
+			dev_warn(controller->dev, "cannot set PAUSE state\n");
+			goto exit;
+		}
 
-	spi_qup_fifo_write(controller, xfer);
+		spi_qup_fifo_write(controller, xfer);
 
-	if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
-		dev_warn(controller->dev, "cannot set EXECUTE state\n");
-		goto exit;
-	}
+		if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
+			dev_warn(controller->dev, "cannot set EXECUTE state\n");
+			goto exit;
+		}
 
-	if (!wait_for_completion_timeout(&controller->done, timeout))
-		ret = -ETIMEDOUT;
+		if (!wait_for_completion_timeout(&controller->done, timeout))
+			ret = -ETIMEDOUT;
+	}
 exit:
 	spi_qup_set_state(controller, QUP_STATE_RESET);
 	spin_lock_irqsave(&controller->lock, flags);
@@ -580,6 +843,7 @@ static int spi_qup_probe(struct platform_device *pdev)
 	master->transfer_one = spi_qup_transfer_one;
 	master->dev.of_node = pdev->dev.of_node;
 	master->auto_runtime_pm = true;
+	master->dma_alignment = dma_get_cache_alignment();
 
 	platform_set_drvdata(pdev, master);
 
@@ -632,6 +896,56 @@ static int spi_qup_probe(struct platform_device *pdev)
 	writel_relaxed(SPI_ERROR_CLK_UNDER_RUN | SPI_ERROR_CLK_OVER_RUN,
 		       base + SPI_ERROR_FLAGS_EN);
 
+	/* allocate dma resources, if available */
+	controller->rx_chan = dma_request_slave_channel(&pdev->dev, "rx");
+	if (controller->rx_chan) {
+		controller->tx_chan =
+			dma_request_slave_channel(&pdev->dev, "tx");
+
+		if (!controller->tx_chan) {
+			dev_err(&pdev->dev, "Failed to allocate dma tx chan");
+			dma_release_channel(controller->rx_chan);
+		}
+
+		/* set DMA parameters */
+		controller->rx_conf.device_fc = 1;
+		controller->rx_conf.src_addr = res->start + QUP_INPUT_FIFO;
+		controller->rx_conf.src_maxburst = controller->in_blk_sz;
+
+		controller->tx_conf.device_fc = 1;
+		controller->tx_conf.dst_addr = res->start + QUP_OUTPUT_FIFO;
+		controller->tx_conf.dst_maxburst = controller->out_blk_sz;
+
+		if (dmaengine_slave_config(controller->rx_chan,
+				&controller->rx_conf)) {
+			dev_err(&pdev->dev, "failed to configure RX channel\n");
+
+			dma_release_channel(controller->rx_chan);
+			dma_release_channel(controller->tx_chan);
+			controller->tx_chan = NULL;
+			controller->rx_chan = NULL;
+		} else if (dmaengine_slave_config(controller->tx_chan,
+				&controller->tx_conf)) {
+			dev_err(&pdev->dev, "failed to configure TX channel\n");
+
+			dma_release_channel(controller->rx_chan);
+			dma_release_channel(controller->tx_chan);
+			controller->tx_chan = NULL;
+			controller->rx_chan = NULL;
+		}
+
+		controller->dummy = devm_kmalloc(controller->dev, PAGE_SIZE,
+			GFP_KERNEL);
+
+		if (!controller->dummy) {
+			dma_release_channel(controller->rx_chan);
+			dma_release_channel(controller->tx_chan);
+			controller->tx_chan = NULL;
+			controller->rx_chan = NULL;
+		}
+	}
+
+
 	writel_relaxed(0, base + SPI_CONFIG);
 	writel_relaxed(SPI_IO_C_NO_TRI_STATE, base + SPI_IO_CONTROL);
 
@@ -741,6 +1055,11 @@ static int spi_qup_remove(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	if (controller->rx_chan)
+		dma_release_channel(controller->rx_chan);
+	if (controller->tx_chan)
+		dma_release_channel(controller->tx_chan);
+
 	clk_disable_unprepare(controller->cclk);
 	clk_disable_unprepare(controller->iclk);
 
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