[PATCH v4] spi: qup: Add DMA capabilities

From: Stanimir Varbanov
Date: Wed Mar 04 2015 - 05:02:29 EST

From: Andy Gross <agross@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx>
---

v3 -> v4
- correct error path when setting to reset state fails

Third version can be found at https://lkml.org/lkml/2015/2/27/369
v2 -> v3
- now using one dma done callback on rx channel if bidirectional transfer
and on tx channel if only transmit transfer
- rearranged the spi_qup_transfer_one() in order to reuse wait for
completion and completion init code
- move dma init function early in .probe to avoid controller reset if
probe deffer
- add function to get controller mode

Second version can be found at https://lkml.org/lkml/2015/2/24/316

--------------------------------------------------------------------------------
v1 -> v2
This is reworked version with comments addressed
- use SPI core DMA mapping code
- implemented .can_dma callback
- use dmaengine api's to account deferred_probe

First version can be found at https://lkml.org/lkml/2014/6/26/481

regards,
Stan

.../devicetree/bindings/spi/qcom,spi-qup.txt | 8 +
drivers/spi/spi-qup.c | 336 ++++++++++++++++++--
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 e2c88df..5c09077 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 ff9cdbd..4b5fc4d 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);

--
1.7.0.4

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