[PATCH 1/2] spi: sun4i: add DMA support

Priit Laes
2016-02-26T05:56:56Z

From: Emilio L?pez <emilio@elopez.com.ar>

This patch adds support for 64 byte or bigger transfers on the
sun4i SPI controller. Said transfers will be performed via DMA.

Signed-off-by: Emilio L?pez <emilio@elopez.com.ar>
Tested-by: Michal Suchanek <hramrach@gmail.com>
Tested-by: Priit Laes <plaes@plaes.org>
---
drivers/spi/spi-sun4i.c | 140 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 128 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c
index 1ddd9e2..78141a6 100644
--- a/drivers/spi/spi-sun4i.c
+++ b/drivers/spi/spi-sun4i.c
@@ -14,6 +14,8 @@
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
@@ -34,6 +36,7 @@
#define SUN4I_CTL_CPHA BIT(2)
#define SUN4I_CTL_CPOL BIT(3)
#define SUN4I_CTL_CS_ACTIVE_LOW BIT(4)
+#define SUN4I_CTL_DMAMC_DEDICATED BIT(5)
#define SUN4I_CTL_LMTF BIT(6)
#define SUN4I_CTL_TF_RST BIT(8)
#define SUN4I_CTL_RF_RST BIT(9)
@@ -51,6 +54,8 @@
#define SUN4I_INT_STA_REG 0x10

#define SUN4I_DMA_CTL_REG 0x14
+#define SUN4I_DMA_CTL_RF_READY BIT(0)
+#define SUN4I_DMA_CTL_TF_NOT_FULL BIT(10)

#define SUN4I_WAIT_REG 0x18

@@ -130,6 +135,13 @@ static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len)
}
}

+static bool sun4i_spi_can_dma(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *tfr)
+{
+ return tfr->len >= SUN4I_FIFO_DEPTH;
+}
+
static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
{
struct sun4i_spi *sspi = spi_master_get_devdata(spi->master);
@@ -172,14 +184,11 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
struct spi_transfer *tfr)
{
struct sun4i_spi *sspi = spi_master_get_devdata(master);
+ struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
unsigned int mclk_rate, div, timeout;
unsigned int tx_len = 0;
+ u32 reg, trigger = 0;
int ret = 0;
- u32 reg;
-
- /* We don't support transfer larger than the FIFO */
- if (tfr->len > SUN4I_FIFO_DEPTH)
- return -EINVAL;

reinit_completion(&sspi->done);
sspi->tx_buf = tfr->tx_buf;
@@ -189,7 +198,6 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
/* Clear pending interrupts */
sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);

-
reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);

/* Reset FIFOs */
@@ -269,12 +277,65 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));

- /* Fill the TX FIFO */
- sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
-
/* Enable the interrupts */
sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);

+ if (sun4i_spi_can_dma(master, spi, tfr)) {
+ dev_dbg(&sspi->master->dev, "Using DMA mode for transfer\n");
+
+ if (sspi->tx_buf) {
+ desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
+ tfr->tx_sg.sgl, tfr->tx_sg.nents,
+ DMA_TO_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_tx) {
+ dev_err(&sspi->master->dev,
+ "Couldn't prepare dma slave\n");
+ return -EIO;
+ }
+
+ trigger |= SUN4I_DMA_CTL_TF_NOT_FULL;
+
+ dmaengine_submit(desc_tx);
+ dma_async_issue_pending(master->dma_tx);
+
+ }
+
+ if (sspi->rx_buf) {
+ desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
+ tfr->rx_sg.sgl, tfr->rx_sg.nents,
+ DMA_FROM_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_rx) {
+ dev_err(&sspi->master->dev,
+ "Couldn't prepare dma slave\n");
+ return -EIO;
+ }
+
+ trigger |= SUN4I_DMA_CTL_RF_READY;
+
+ dmaengine_submit(desc_rx);
+ dma_async_issue_pending(master->dma_rx);
+ }
+
+ /* Enable Dedicated DMA requests */
+ reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
+ reg |= SUN4I_CTL_DMAMC_DEDICATED;
+ sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);
+ sun4i_spi_write(sspi, SUN4I_DMA_CTL_REG, trigger);
+ } else {
+ dev_dbg(&sspi->master->dev, "Using PIO mode for transfer\n");
+
+ /* Disable DMA requests */
+ reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
+ sun4i_spi_write(sspi, SUN4I_CTL_REG,
+ reg & ~SUN4I_CTL_DMAMC_DEDICATED);
+ sun4i_spi_write(sspi, SUN4I_DMA_CTL_REG, 0);
+
+ /* Fill the TX FIFO */
+ sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);
+ }
+
/* Start the transfer */
reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);
@@ -286,7 +347,12 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
goto out;
}

- sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
+ if (sun4i_spi_can_dma(master, spi, tfr) && desc_rx) {
+ /* The receive transfer should be the last one to finish */
+ dma_wait_for_async_tx(desc_rx);
+ } else {
+ sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
+ }

out:
sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);
@@ -351,6 +417,7 @@ static int sun4i_spi_runtime_suspend(struct device *dev)

static int sun4i_spi_probe(struct platform_device *pdev)
{
+ struct dma_slave_config dma_sconfig;
struct spi_master *master;
struct sun4i_spi *sspi;
struct resource *res;
@@ -386,7 +453,9 @@ static int sun4i_spi_probe(struct platform_device *pdev)
goto err_free_master;
}

+ init_completion(&sspi->done);
sspi->master = master;
+ master->can_dma = sun4i_spi_can_dma;
master->set_cs = sun4i_spi_set_cs;
master->transfer_one = sun4i_spi_transfer_one;
master->num_chipselect = 4;
@@ -409,7 +478,45 @@ static int sun4i_spi_probe(struct platform_device *pdev)
goto err_free_master;
}

- init_completion(&sspi->done);
+ master->dma_tx = dma_request_slave_channel_reason(&pdev->dev, "tx");
+ if (IS_ERR(master->dma_tx)) {
+ dev_err(&pdev->dev, "Unable to acquire DMA channel TX\n");
+ ret = PTR_ERR(master->dma_tx);
+ goto err_free_master;
+ }
+
+ dma_sconfig.direction = DMA_MEM_TO_DEV;
+ dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ dma_sconfig.dst_addr = res->start + SUN4I_TXDATA_REG;
+ dma_sconfig.src_maxburst = 1;
+ dma_sconfig.dst_maxburst = 1;
+
+ ret = dmaengine_slave_config(master->dma_tx, &dma_sconfig);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to configure TX DMA slave\n");
+ goto err_tx_dma_release;
+ }
+
+ master->dma_rx = dma_request_slave_channel_reason(&pdev->dev, "rx");
+ if (IS_ERR(master->dma_rx)) {
+ dev_err(&pdev->dev, "Unable to acquire DMA channel RX\n");
+ ret = PTR_ERR(master->dma_rx);
+ goto err_tx_dma_release;
+ }
+
+ dma_sconfig.direction = DMA_DEV_TO_MEM;
+ dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ dma_sconfig.src_addr = res->start + SUN4I_RXDATA_REG;
+ dma_sconfig.src_maxburst = 1;
+ dma_sconfig.dst_maxburst = 1;
+
+ ret = dmaengine_slave_config(master->dma_rx, &dma_sconfig);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to configure RX DMA slave\n");
+ goto err_rx_dma_release;
+ }

/*
* This wake-up/shutdown pattern is to be able to have the
@@ -418,7 +525,7 @@ static int sun4i_spi_probe(struct platform_device *pdev)
ret = sun4i_spi_runtime_resume(&pdev->dev);
if (ret) {
dev_err(&pdev->dev, "Couldn't resume the device\n");
- goto err_free_master;
+ goto err_rx_dma_release;
}

pm_runtime_set_active(&pdev->dev);
@@ -436,6 +543,10 @@ static int sun4i_spi_probe(struct platform_device *pdev)
err_pm_disable:
pm_runtime_disable(&pdev->dev);
sun4i_spi_runtime_suspend(&pdev->dev);
+err_rx_dma_release:
+ dma_release_channel(master->dma_rx);
+err_tx_dma_release:
+ dma_release_channel(master->dma_tx);
err_free_master:
spi_master_put(master);
return ret;
@@ -443,8 +554,13 @@ err_free_master:

static int sun4i_spi_remove(struct platform_device *pdev)
{
+ struct spi_master *master = platform_get_drvdata(pdev);
+
pm_runtime_disable(&pdev->dev);

+ dma_release_channel(master->dma_rx);
+ dma_release_channel(master->dma_tx);
+
return 0;
}

--
2.7.2