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@codeaurora.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Ivan T. Ivanov <iivanov@mm-sol.com
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 312 insertions, 32 deletions

diff --git a/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt b/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
index e2c88df2cc15..5c090771c016 100644
--- a/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
+++ b/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
@@ -33,6 +33,11 @@ Optional properties:
                 nodes.  If unspecified, a single SPI device without a chip
                 select can be used.
 
+- 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
@@ -51,6 +56,9 @@ Example:
                 clocks = <&gcc GCC_BLSP2_QUP2_SPI_APPS_CLK>, <&gcc GCC_BLSP2_AHB_CLK>;
                 clock-names = "core", "iface";
 
+                dmas = <&blsp1_bam 13>, <&blsp1_bam 12>;
+                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 ff9cdbdb6672..4b5fc4d67b6e 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_DMA_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
@@ -140,9 +144,14 @@ struct spi_qup {
         struct completion       done;
         int                     error;
         int                     w_size; /* bytes per SPI word */
+        int                     n_words;
         int                     tx_bytes;
         int                     rx_bytes;
         int                     qup_v1;
+
+        int                     use_dma;
+        struct dma_slave_config rx_conf;
+        struct dma_slave_config tx_conf;
 };
 
 
@@ -198,7 +207,6 @@ static int spi_qup_set_state(struct spi_qup *controller, u32 state)
         return 0;
 }
 
-
 static void spi_qup_fifo_read(struct spi_qup *controller,
                             struct spi_transfer *xfer)
 {
@@ -266,6 +274,107 @@ static void spi_qup_fifo_write(struct spi_qup *controller,
         }
 }
 
+static void spi_qup_dma_done(void *data)
+{
+        struct spi_qup *qup = data;
+
+        complete(&qup->done);
+}
+
+static int spi_qup_prep_sg(struct spi_master *master, struct spi_transfer *xfer,
+                           enum dma_transfer_direction dir,
+                           dma_async_tx_callback callback)
+{
+        struct spi_qup *qup = spi_master_get_devdata(master);
+        unsigned long flags = DMA_PREP_INTERRUPT | DMA_PREP_FENCE;
+        struct dma_async_tx_descriptor *desc;
+        struct scatterlist *sgl;
+        struct dma_chan *chan;
+        dma_cookie_t cookie;
+        unsigned int nents;
+
+        if (dir == DMA_MEM_TO_DEV) {
+                chan = master->dma_tx;
+                nents = xfer->tx_sg.nents;
+                sgl = xfer->tx_sg.sgl;
+        } else {
+                chan = master->dma_rx;
+                nents = xfer->rx_sg.nents;
+                sgl = xfer->rx_sg.sgl;
+        }
+
+        desc = dmaengine_prep_slave_sg(chan, sgl, nents, dir, flags);
+        if (!desc)
+                return -EINVAL;
+
+        desc->callback = callback;
+        desc->callback_param = qup;
+
+        cookie = dmaengine_submit(desc);
+
+        return dma_submit_error(cookie);
+}
+
+static void spi_qup_dma_terminate(struct spi_master *master,
+                                  struct spi_transfer *xfer)
+{
+        if (xfer->tx_buf)
+                dmaengine_terminate_all(master->dma_tx);
+        if (xfer->rx_buf)
+                dmaengine_terminate_all(master->dma_rx);
+}
+
+static int spi_qup_do_dma(struct spi_master *master, struct spi_transfer *xfer)
+{
+        dma_async_tx_callback rx_done = NULL, tx_done = NULL;
+        int ret;
+
+        if (xfer->rx_buf)
+                rx_done = spi_qup_dma_done;
+        else if (xfer->tx_buf)
+                tx_done = spi_qup_dma_done;
+
+        if (xfer->rx_buf) {
+                ret = spi_qup_prep_sg(master, xfer, DMA_DEV_TO_MEM, rx_done);
+                if (ret)
+                        return ret;
+
+                dma_async_issue_pending(master->dma_rx);
+        }
+
+        if (xfer->tx_buf) {
+                ret = spi_qup_prep_sg(master, xfer, DMA_MEM_TO_DEV, tx_done);
+                if (ret)
+                        return ret;
+
+                dma_async_issue_pending(master->dma_tx);
+        }
+
+        return 0;
+}
+
+static int spi_qup_do_pio(struct spi_master *master, struct spi_transfer *xfer)
+{
+        struct spi_qup *qup = spi_master_get_devdata(master);
+        int 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;
+        }
+
+        spi_qup_fifo_write(qup, xfer);
+
+        return 0;
+}
+
 static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 {
         struct spi_qup *controller = dev_id;
@@ -315,11 +424,13 @@ 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;
@@ -332,13 +443,35 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
         return IRQ_HANDLED;
 }
 
+static u32
+spi_qup_get_mode(struct spi_master *master, struct spi_transfer *xfer)
+{
+        struct spi_qup *qup = spi_master_get_devdata(master);
+        u32 mode;
+
+        qup->w_size = 4;
+
+        if (xfer->bits_per_word <= 8)
+                qup->w_size = 1;
+        else if (xfer->bits_per_word <= 16)
+                qup->w_size = 2;
+
+        qup->n_words = xfer->len / qup->w_size;
+
+        if (qup->n_words <= (qup->in_fifo_sz / sizeof(u32)))
+                mode = QUP_IO_M_MODE_FIFO;
+        else
+                mode = QUP_IO_M_MODE_BLOCK;
+
+        return mode;
+}
 
 /* set clock freq ... bits per word */
 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, control;
-        int ret, n_words, w_size;
+        int ret, n_words;
 
         if (spi->mode & SPI_LOOP && xfer->len > controller->in_fifo_sz) {
                 dev_err(controller->dev, "too big size for loopback %d > %d\n",
@@ -358,35 +491,54 @@ static int spi_qup_io_config(struct spi_device *spi, struct spi_transfer *xfer)
                 return -EIO;
         }
 
-        w_size = 4;
-        if (xfer->bits_per_word <= 8)
-                w_size = 1;
-        else if (xfer->bits_per_word <= 16)
-                w_size = 2;
-
-        n_words = xfer->len / w_size;
-        controller->w_size = w_size;
+        mode = spi_qup_get_mode(spi->master, xfer);
+        n_words = controller->n_words;
 
-        if (n_words <= (controller->in_fifo_sz / sizeof(u32))) {
-                mode = QUP_IO_M_MODE_FIFO;
+        if (mode == QUP_IO_M_MODE_FIFO) {
                 writel_relaxed(n_words, controller->base + QUP_MX_READ_CNT);
                 writel_relaxed(n_words, controller->base + QUP_MX_WRITE_CNT);
                 /* must be zero for FIFO */
                 writel_relaxed(0, controller->base + QUP_MX_INPUT_CNT);
                 writel_relaxed(0, controller->base + QUP_MX_OUTPUT_CNT);
-        } else {
-                mode = QUP_IO_M_MODE_BLOCK;
+        } else if (!controller->use_dma) {
                 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);
+        } else {
+                mode = QUP_IO_M_MODE_BAM;
+                writel_relaxed(0, controller->base + QUP_MX_READ_CNT);
+                writel_relaxed(0, controller->base + QUP_MX_WRITE_CNT);
+
+                if (!controller->qup_v1) {
+                        void __iomem *input_cnt;
+
+                        input_cnt = controller->base + QUP_MX_INPUT_CNT;
+                        /*
+                         * for DMA transfers, both QUP_MX_INPUT_CNT and
+                         * QUP_MX_OUTPUT_CNT must be zero to all cases but one.
+                         * That case is a non-balanced transfer when there is
+                         * only a rx_buf.
+                         */
+                        if (xfer->tx_buf)
+                                writel_relaxed(0, input_cnt);
+                        else
+                                writel_relaxed(n_words, input_cnt);
+
+                        writel_relaxed(0, controller->base + QUP_MX_OUTPUT_CNT);
+                }
         }
 
         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);
 
@@ -428,11 +580,31 @@ 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);
 
         /* only write to OPERATIONAL_MASK when register is present */
-        if (!controller->qup_v1)
-                writel_relaxed(0, controller->base + QUP_OPERATIONAL_MASK);
+        if (!controller->qup_v1) {
+                u32 mask = 0;
+
+                /*
+                 * mask INPUT and OUTPUT service flags to prevent IRQs on FIFO
+                 * status change in BAM mode
+                 */
+
+                if (mode == QUP_IO_M_MODE_BAM)
+                        mask = QUP_OP_IN_SERVICE_FLAG | QUP_OP_OUT_SERVICE_FLAG;
+
+                writel_relaxed(mask, controller->base + QUP_OPERATIONAL_MASK);
+        }
+
         return 0;
 }
 
@@ -461,17 +633,13 @@ 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(master, xfer);
+        else
+                ret = spi_qup_do_pio(master, xfer);
 
-        if (spi_qup_set_state(controller, QUP_STATE_PAUSE)) {
-                dev_warn(controller->dev, "cannot set PAUSE state\n");
+        if (ret)
                 goto exit;
-        }
-
-        spi_qup_fifo_write(controller, xfer);
 
         if (spi_qup_set_state(controller, QUP_STATE_RUN)) {
                 dev_warn(controller->dev, "cannot set EXECUTE state\n");
@@ -480,6 +648,7 @@ static int spi_qup_transfer_one(struct spi_master *master,
 
         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);
@@ -487,6 +656,97 @@ exit:
         if (!ret)
                 ret = controller->error;
         spin_unlock_irqrestore(&controller->lock, flags);
+
+        if (ret && controller->use_dma)
+                spi_qup_dma_terminate(master, xfer);
+
+        return ret;
+}
+
+static bool spi_qup_can_dma(struct spi_master *master, struct spi_device *spi,
+                            struct spi_transfer *xfer)
+{
+        struct spi_qup *qup = spi_master_get_devdata(master);
+        size_t dma_align = dma_get_cache_alignment();
+        u32 mode;
+
+        qup->use_dma = 0;
+
+        if (xfer->rx_buf && (xfer->len % qup->in_blk_sz ||
+            IS_ERR_OR_NULL(master->dma_rx) ||
+            !IS_ALIGNED((size_t)xfer->rx_buf, dma_align)))
+                return false;
+
+        if (xfer->tx_buf && (xfer->len % qup->out_blk_sz ||
+            IS_ERR_OR_NULL(master->dma_tx) ||
+            !IS_ALIGNED((size_t)xfer->tx_buf, dma_align)))
+                return false;
+
+        mode = spi_qup_get_mode(master, xfer);
+        if (mode == QUP_IO_M_MODE_FIFO)
+                return false;
+
+        qup->use_dma = 1;
+
+        return true;
+}
+
+static void spi_qup_release_dma(struct spi_master *master)
+{
+        if (!IS_ERR_OR_NULL(master->dma_rx))
+                dma_release_channel(master->dma_rx);
+        if (!IS_ERR_OR_NULL(master->dma_tx))
+                dma_release_channel(master->dma_tx);
+}
+
+static int spi_qup_init_dma(struct spi_master *master, resource_size_t base)
+{
+        struct spi_qup *spi = spi_master_get_devdata(master);
+        struct dma_slave_config *rx_conf = &spi->rx_conf,
+                                *tx_conf = &spi->tx_conf;
+        struct device *dev = spi->dev;
+        int ret;
+
+        /* allocate dma resources, if available */
+        master->dma_rx = dma_request_slave_channel_reason(dev, "rx");
+        if (IS_ERR(master->dma_rx))
+                return PTR_ERR(master->dma_rx);
+
+        master->dma_tx = dma_request_slave_channel_reason(dev, "tx");
+        if (IS_ERR(master->dma_tx)) {
+                ret = PTR_ERR(master->dma_tx);
+                goto err_tx;
+        }
+
+        /* set DMA parameters */
+        rx_conf->direction = DMA_DEV_TO_MEM;
+        rx_conf->device_fc = 1;
+        rx_conf->src_addr = base + QUP_INPUT_FIFO;
+        rx_conf->src_maxburst = spi->in_blk_sz;
+
+        tx_conf->direction = DMA_MEM_TO_DEV;
+        tx_conf->device_fc = 1;
+        tx_conf->dst_addr = base + QUP_OUTPUT_FIFO;
+        tx_conf->dst_maxburst = spi->out_blk_sz;
+
+        ret = dmaengine_slave_config(master->dma_rx, rx_conf);
+        if (ret) {
+                dev_err(dev, "failed to configure RX channel\n");
+                goto err;
+        }
+
+        ret = dmaengine_slave_config(master->dma_tx, tx_conf);
+        if (ret) {
+                dev_err(dev, "failed to configure TX channel\n");
+                goto err;
+        }
+
+        return 0;
+
+err:
+        dma_release_channel(master->dma_tx);
+err_tx:
+        dma_release_channel(master->dma_rx);
         return ret;
 }
 
@@ -562,6 +822,8 @@ 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();
+        master->max_dma_len = SPI_MAX_DMA_XFER;
 
         platform_set_drvdata(pdev, master);
 
@@ -573,6 +835,12 @@ static int spi_qup_probe(struct platform_device *pdev)
         controller->cclk = cclk;
         controller->irq = irq;
 
+        ret = spi_qup_init_dma(master, res->start);
+        if (ret == -EPROBE_DEFER)
+                goto error;
+        else if (!ret)
+                master->can_dma = spi_qup_can_dma;
+
         /* set v1 flag if device is version 1 */
         if (of_device_is_compatible(dev->of_node, "qcom,spi-qup-v1.1.1"))
                 controller->qup_v1 = 1;
@@ -609,7 +877,7 @@ static int spi_qup_probe(struct platform_device *pdev)
         ret = spi_qup_set_state(controller, QUP_STATE_RESET);
         if (ret) {
                 dev_err(dev, "cannot set RESET state\n");
-                goto error;
+                goto error_dma;
         }
 
         writel_relaxed(0, base + QUP_OPERATIONAL);
@@ -633,7 +901,7 @@ static int spi_qup_probe(struct platform_device *pdev)
         ret = devm_request_irq(dev, irq, spi_qup_qup_irq,
                                IRQF_TRIGGER_HIGH, pdev->name, controller);
         if (ret)
-                goto error;
+                goto error_dma;
 
         pm_runtime_set_autosuspend_delay(dev, MSEC_PER_SEC);
         pm_runtime_use_autosuspend(dev);
@@ -648,6 +916,8 @@ static int spi_qup_probe(struct platform_device *pdev)
 
 disable_pm:
         pm_runtime_disable(&pdev->dev);
+error_dma:
+        spi_qup_release_dma(master);
 error:
         clk_disable_unprepare(cclk);
         clk_disable_unprepare(iclk);
@@ -739,6 +1009,8 @@ static int spi_qup_remove(struct platform_device *pdev)
         if (ret)
                 return ret;
 
+        spi_qup_release_dma(master);
+
         clk_disable_unprepare(controller->cclk);
         clk_disable_unprepare(controller->iclk);