[PATCH V2 6/8] spi: lpspi: add dma mode support

From: Clark Wang
Date: Wed Mar 06 2019 - 01:30:58 EST

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Add dma mode support for LPSPI. Any frame longer than half txfifosize will
be sent by dma mode.

For now, there are some limits:
1. The maximum transfer speed in master mode depends on the slave device,
at least 40MHz(tested by spi-nor on 8qm-lpddr4-arm2 base board);
2. The maximum transfer speed in slave mode is 15MHz(imx7ulp),
22MHz(8qm/qxp). In order to reach the maximum speed which is mentioned
in datasheet, the load of connect wires between master and slave
should be less than 15pF.

Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
Acked-by: Fugang Duan <Fugang.duan@xxxxxxx>
---
V2:
- replace a if judgement by switch statement
- seperate a Debug print fix into next patch
---
drivers/spi/spi-fsl-lpspi.c | 312 ++++++++++++++++++++++++++++++++++--
1 file changed, 301 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index a25e0e03f058..9ff32fb67a29 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -8,6 +8,8 @@
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
@@ -20,6 +22,7 @@
#include <linux/of_gpio.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
+#include <linux/platform_data/dma-imx.h>
#include <linux/platform_data/spi-imx.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
@@ -31,6 +34,9 @@

#define FSL_LPSPI_RPM_TIMEOUT 50 /* 50ms */

+/* The maximum bytes that edma can transfer once.*/
+#define FSL_LPSPI_MAX_EDMA_BYTES ((1 << 15) - 1)
+
/* i.MX7ULP LPSPI registers */
#define IMX7ULP_VERID 0x0
#define IMX7ULP_PARAM 0x4
@@ -64,6 +70,8 @@
#define IER_FCIE BIT(9)
#define IER_RDIE BIT(1)
#define IER_TDIE BIT(0)
+#define DER_RDDE BIT(1)
+#define DER_TDDE BIT(0)
#define CFGR1_PCSCFG BIT(27)
#define CFGR1_PINCFG (BIT(24)|BIT(25))
#define CFGR1_PCSPOL BIT(8)
@@ -91,6 +99,7 @@ struct lpspi_config {
struct fsl_lpspi_data {
struct device *dev;
void __iomem *base;
+ unsigned long base_phys;
struct clk *clk_ipg;
struct clk *clk_per;
bool is_slave;
@@ -111,6 +120,11 @@ struct fsl_lpspi_data {

bool slave_aborted;

+ /* DMA */
+ bool usedma;
+ struct completion dma_rx_completion;
+ struct completion dma_tx_completion;
+
int chipselect[0];
};

@@ -158,6 +172,35 @@ static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
writel(enable, fsl_lpspi->base + IMX7ULP_IER);
}

+static int fsl_lpspi_bytes_per_word(const int bpw)
+{
+ return DIV_ROUND_UP(bpw, BITS_PER_BYTE);
+}
+
+static bool fsl_lpspi_can_dma(struct spi_controller *controller,
+ struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ unsigned int bytes_per_word;
+
+ if (!controller->dma_rx)
+ return false;
+
+ bytes_per_word = fsl_lpspi_bytes_per_word(transfer->bits_per_word);
+
+ switch (bytes_per_word)
+ {
+ case 1:
+ case 2:
+ case 4:
+ break;
+ default:
+ return false;
+ }
+
+ return true;
+}
+
static int lpspi_prepare_xfer_hardware(struct spi_controller *controller)
{
struct fsl_lpspi_data *fsl_lpspi =
@@ -245,11 +288,13 @@ static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi)
* For the first transfer, clear TCR_CONTC to assert SS.
* For subsequent transfer, set TCR_CONTC to keep SS asserted.
*/
- temp |= TCR_CONT;
- if (fsl_lpspi->is_first_byte)
- temp &= ~TCR_CONTC;
- else
- temp |= TCR_CONTC;
+ if (!fsl_lpspi->usedma) {
+ temp |= TCR_CONT;
+ if (fsl_lpspi->is_first_byte)
+ temp &= ~TCR_CONTC;
+ else
+ temp |= TCR_CONTC;
+ }
}
writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

@@ -260,7 +305,11 @@ static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
{
u32 temp;

- temp = fsl_lpspi->watermark >> 1 | (fsl_lpspi->watermark >> 1) << 16;
+ if (!fsl_lpspi->usedma)
+ temp = fsl_lpspi->watermark >> 1 |
+ (fsl_lpspi->watermark >> 1) << 16;
+ else
+ temp = fsl_lpspi->watermark >> 1;

writel(temp, fsl_lpspi->base + IMX7ULP_FCR);

@@ -302,6 +351,53 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
return 0;
}

+static int fsl_lpspi_dma_configure(struct spi_controller *controller)
+{
+ int ret;
+ enum dma_slave_buswidth buswidth;
+ struct dma_slave_config rx = {}, tx = {};
+ struct fsl_lpspi_data *fsl_lpspi =
+ spi_controller_get_devdata(controller);
+
+ switch (fsl_lpspi_bytes_per_word(fsl_lpspi->config.bpw)) {
+ case 4:
+ buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ case 2:
+ buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ case 1:
+ buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ tx.direction = DMA_MEM_TO_DEV;
+ tx.dst_addr = fsl_lpspi->base_phys + IMX7ULP_TDR;
+ tx.dst_addr_width = buswidth;
+ tx.dst_maxburst = 1;
+ ret = dmaengine_slave_config(controller->dma_tx, &tx);
+ if (ret) {
+ dev_err(fsl_lpspi->dev, "TX dma configuration failed with %d\n",
+ ret);
+ return ret;
+ }
+
+ rx.direction = DMA_DEV_TO_MEM;
+ rx.src_addr = fsl_lpspi->base_phys + IMX7ULP_RDR;
+ rx.src_addr_width = buswidth;
+ rx.src_maxburst = 1;
+ ret = dmaengine_slave_config(controller->dma_rx, &rx);
+ if (ret) {
+ dev_err(fsl_lpspi->dev, "RX dma configuration failed with %d\n",
+ ret);
+ return ret;
+ }
+
+ return 0;
+}
+
static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
{
u32 temp;
@@ -327,10 +423,16 @@ static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
temp |= CR_RRF | CR_RTF | CR_MEN;
writel(temp, fsl_lpspi->base + IMX7ULP_CR);

+ temp = 0;
+ if (fsl_lpspi->usedma)
+ temp = DER_TDDE | DER_RDDE;
+ writel(temp, fsl_lpspi->base + IMX7ULP_DER);
+
return 0;
}

-static int fsl_lpspi_setup_transfer(struct spi_device *spi,
+static int fsl_lpspi_setup_transfer(struct spi_controller *controller,
+ struct spi_device *spi,
struct spi_transfer *t)
{
struct fsl_lpspi_data *fsl_lpspi =
@@ -363,6 +465,11 @@ static int fsl_lpspi_setup_transfer(struct spi_device *spi,
else
fsl_lpspi->watermark = fsl_lpspi->txfifosize;

+ if (fsl_lpspi_can_dma(controller, spi, t))
+ fsl_lpspi->usedma = 1;
+ else
+ fsl_lpspi->usedma = 0;
+
return fsl_lpspi_config(fsl_lpspi);
}

@@ -401,8 +508,10 @@ static int fsl_lpspi_reset(struct fsl_lpspi_data *fsl_lpspi)
{
u32 temp;

- /* Disable all interrupt */
- fsl_lpspi_intctrl(fsl_lpspi, 0);
+ if (!fsl_lpspi->usedma) {
+ /* Disable all interrupt */
+ fsl_lpspi_intctrl(fsl_lpspi, 0);
+ }

/* W1C for all flags in SR */
temp = 0x3F << 8;
@@ -415,6 +524,176 @@ static int fsl_lpspi_reset(struct fsl_lpspi_data *fsl_lpspi)
return 0;
}

+static void fsl_lpspi_dma_rx_callback(void *cookie)
+{
+ struct fsl_lpspi_data *fsl_lpspi = (struct fsl_lpspi_data *)cookie;
+
+ complete(&fsl_lpspi->dma_rx_completion);
+}
+
+static void fsl_lpspi_dma_tx_callback(void *cookie)
+{
+ struct fsl_lpspi_data *fsl_lpspi = (struct fsl_lpspi_data *)cookie;
+
+ complete(&fsl_lpspi->dma_tx_completion);
+}
+
+static int fsl_lpspi_calculate_timeout(struct fsl_lpspi_data *fsl_lpspi,
+ int size)
+{
+ unsigned long timeout = 0;
+
+ /* Time with actual data transfer and CS change delay related to HW */
+ timeout = (8 + 4) * size / fsl_lpspi->config.speed_hz;
+
+ /* Add extra second for scheduler related activities */
+ timeout += 1;
+
+ /* Double calculated timeout */
+ return msecs_to_jiffies(2 * timeout * MSEC_PER_SEC);
+}
+
+static int fsl_lpspi_dma_transfer(struct spi_controller *controller,
+ struct fsl_lpspi_data *fsl_lpspi,
+ struct spi_transfer *transfer)
+{
+ struct dma_async_tx_descriptor *desc_tx, *desc_rx;
+ unsigned long transfer_timeout;
+ unsigned long timeout;
+ struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;
+ int ret;
+
+ ret = fsl_lpspi_dma_configure(controller);
+ if (ret)
+ return ret;
+
+ desc_rx = dmaengine_prep_slave_sg(controller->dma_rx,
+ rx->sgl, rx->nents, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_rx)
+ return -EINVAL;
+
+ desc_rx->callback = fsl_lpspi_dma_rx_callback;
+ desc_rx->callback_param = (void *)fsl_lpspi;
+ dmaengine_submit(desc_rx);
+ reinit_completion(&fsl_lpspi->dma_rx_completion);
+ dma_async_issue_pending(controller->dma_rx);
+
+ desc_tx = dmaengine_prep_slave_sg(controller->dma_tx,
+ tx->sgl, tx->nents, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_tx) {
+ dmaengine_terminate_all(controller->dma_tx);
+ return -EINVAL;
+ }
+
+ desc_tx->callback = fsl_lpspi_dma_tx_callback;
+ desc_tx->callback_param = (void *)fsl_lpspi;
+ dmaengine_submit(desc_tx);
+ reinit_completion(&fsl_lpspi->dma_tx_completion);
+ dma_async_issue_pending(controller->dma_tx);
+
+ fsl_lpspi->slave_aborted = false;
+
+ if (!fsl_lpspi->is_slave) {
+ transfer_timeout = fsl_lpspi_calculate_timeout(fsl_lpspi,
+ transfer->len);
+
+ /* Wait eDMA to finish the data transfer.*/
+ timeout = wait_for_completion_timeout(&fsl_lpspi->dma_tx_completion,
+ transfer_timeout);
+ if (!timeout) {
+ dev_err(fsl_lpspi->dev, "I/O Error in DMA TX\n");
+ dmaengine_terminate_all(controller->dma_tx);
+ dmaengine_terminate_all(controller->dma_rx);
+ fsl_lpspi_reset(fsl_lpspi);
+ return -ETIMEDOUT;
+ }
+
+ timeout = wait_for_completion_timeout(&fsl_lpspi->dma_rx_completion,
+ transfer_timeout);
+ if (!timeout) {
+ dev_err(fsl_lpspi->dev, "I/O Error in DMA RX\n");
+ dmaengine_terminate_all(controller->dma_tx);
+ dmaengine_terminate_all(controller->dma_rx);
+ fsl_lpspi_reset(fsl_lpspi);
+ return -ETIMEDOUT;
+ }
+ } else {
+ if (wait_for_completion_interruptible(&fsl_lpspi->dma_tx_completion) ||
+ fsl_lpspi->slave_aborted) {
+ dev_dbg(fsl_lpspi->dev,
+ "I/O Error in DMA TX interrupted\n");
+ dmaengine_terminate_all(controller->dma_tx);
+ dmaengine_terminate_all(controller->dma_rx);
+ fsl_lpspi_reset(fsl_lpspi);
+ return -EINTR;
+ }
+
+ if (wait_for_completion_interruptible(&fsl_lpspi->dma_rx_completion) ||
+ fsl_lpspi->slave_aborted) {
+ dev_dbg(fsl_lpspi->dev,
+ "I/O Error in DMA RX interrupted\n");
+ dmaengine_terminate_all(controller->dma_tx);
+ dmaengine_terminate_all(controller->dma_rx);
+ fsl_lpspi_reset(fsl_lpspi);
+ return -EINTR;
+ }
+ }
+
+ fsl_lpspi_reset(fsl_lpspi);
+
+ return 0;
+}
+
+static void fsl_lpspi_dma_exit(struct spi_controller *controller)
+{
+ if (controller->dma_rx) {
+ dma_release_channel(controller->dma_rx);
+ controller->dma_rx = NULL;
+ }
+
+ if (controller->dma_tx) {
+ dma_release_channel(controller->dma_tx);
+ controller->dma_tx = NULL;
+ }
+}
+
+static int fsl_lpspi_dma_init(struct device *dev,
+ struct fsl_lpspi_data *fsl_lpspi,
+ struct spi_controller *controller)
+{
+ int ret;
+
+ /* Prepare for TX DMA: */
+ controller->dma_tx = dma_request_slave_channel_reason(dev, "tx");
+ if (IS_ERR(controller->dma_tx)) {
+ ret = PTR_ERR(controller->dma_tx);
+ dev_dbg(dev, "can't get the TX DMA channel, error %d!\n", ret);
+ controller->dma_tx = NULL;
+ goto err;
+ }
+
+ /* Prepare for RX DMA: */
+ controller->dma_rx = dma_request_slave_channel_reason(dev, "rx");
+ if (IS_ERR(controller->dma_rx)) {
+ ret = PTR_ERR(controller->dma_rx);
+ dev_dbg(dev, "can't get the RX DMA channel, error %d\n", ret);
+ controller->dma_rx = NULL;
+ goto err;
+ }
+
+ init_completion(&fsl_lpspi->dma_rx_completion);
+ init_completion(&fsl_lpspi->dma_tx_completion);
+ controller->can_dma = fsl_lpspi_can_dma;
+ controller->max_dma_len = FSL_LPSPI_MAX_EDMA_BYTES;
+
+ return 0;
+err:
+ fsl_lpspi_dma_exit(controller);
+ return ret;
+}
+
static int fsl_lpspi_pio_transfer(struct spi_controller *controller,
struct spi_transfer *t)
{
@@ -449,14 +728,17 @@ static int fsl_lpspi_transfer_one(struct spi_controller *controller,
int ret;

fsl_lpspi->is_first_byte = true;
- ret = fsl_lpspi_setup_transfer(spi, t);
+ ret = fsl_lpspi_setup_transfer(controller, spi, t);
if (ret < 0)
return ret;

fsl_lpspi_set_cmd(fsl_lpspi);
fsl_lpspi->is_first_byte = false;

- ret = fsl_lpspi_pio_transfer(controller, t);
+ if (fsl_lpspi->usedma)
+ ret = fsl_lpspi_dma_transfer(controller, fsl_lpspi, t);
+ else
+ ret = fsl_lpspi_pio_transfer(controller, t);
if (ret < 0)
return ret;

@@ -606,6 +888,7 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
ret = PTR_ERR(fsl_lpspi->base);
goto out_controller_put;
}
+ fsl_lpspi->base_phys = res->start;

irq = platform_get_irq(pdev, 0);
if (irq < 0) {
@@ -647,6 +930,13 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);

+ ret = fsl_lpspi_dma_init(&pdev->dev, fsl_lpspi, controller);
+ if (ret == -EPROBE_DEFER)
+ goto out_controller_put;
+
+ if (ret < 0)
+ dev_err(&pdev->dev, "dma setup error %d, use pio\n", ret);
+
ret = devm_spi_register_controller(&pdev->dev, controller);
if (ret < 0) {
dev_err(&pdev->dev, "spi_register_controller error.\n");
--
2.17.1

Next message: Clark Wang: "[PATCH V2 7/8] spi: lpspi: Add the missing NULL check"
Previous message: Clark Wang: "[PATCH V2 5/8] spi: lpspi: use the core way to implement cs-gpio function"
In reply to: Clark Wang: "[PATCH V2 5/8] spi: lpspi: use the core way to implement cs-gpio function"
Next in thread: Clark Wang: "[PATCH V2 7/8] spi: lpspi: Add the missing NULL check"
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