[V4,2/5] spi: s3c64xx: added support for polling mode

Commit Message

[e-mail] April 15, 2013, 8:40 a.m. UTC

From: Girish K S <[e-mail]>

The 64xx spi driver supports partial polling mode.
Only the last chunk of the transfer length is transferred
or recieved in polling mode.

Some SoC's that adopt this controller might not have have dma
interface. This patch adds support for complete polling mode
and gives flexibity for the user to select poll/dma mode.

Signed-off-by: Girish K S <[e-mail]>
---
changes in v4:
		Handled the dma allocation failure and switching to poll
if dma resource allocation failed

changes in v3:
		Separated the polling mode and gpio handling separately

changes in v2:
		changed the logic to handle the buffer from the user space.
moved out the timeout code as a separate function.

 drivers/spi/spi-s3c64xx.c |  133 ++++++++++++++++++++++++++++++---------------
 1 files changed, 89 insertions(+), 44 deletions(-)

Comments

[e-mail] April 16, 2013, 11:28 a.m. UTC | #1

On Tue, Apr 16, 2013 at 4:50 PM, Mark Brown <[e-mail]> wrote:
> On Mon, Apr 15, 2013 at 02:10:27PM +0530, Girish K S wrote:
>> From: Girish K S <[e-mail]>
>>
>> The 64xx spi driver supports partial polling mode.
>> Only the last chunk of the transfer length is transferred
>> or recieved in polling mode.
>
> I'm missing patch 1 of this series.

its already  merged to stable tree after your review

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Mark Brown April 16, 2013, 12:12 p.m. UTC | #2

On Tue, Apr 16, 2013 at 04:58:47PM +0530, Girish KS wrote:
> On Tue, Apr 16, 2013 at 4:50 PM, Mark Brown <[e-mail]> wrote:

> > I'm missing patch 1 of this series.

> its already  merged to stable tree after your review

The patch numbering should reflect what you're posting.  If you're only
sending four patches they should be numbered 1-4, otherwise it looks
like there's something missing.  The goal with the numbers is to help
people get the patches in the right order, the name should be enough to
associate with other versions of the same patch.

------------------------------------------------------------------------------
Precog is a next-generation analytics platform capable of advanced
analytics on semi-structured data. The platform includes APIs for building
apps and a phenomenal toolset for data science. Developers can use
our toolset for easy data analysis & visualization. Get a free account!
http://www2.precog.com/precogplatform/slashdotnewsletter

[e-mail] April 17, 2013, 10:22 a.m. UTC | #3

On Tue, Apr 16, 2013 at 5:42 PM, Mark Brown <[e-mail]> wrote:
> On Tue, Apr 16, 2013 at 04:58:47PM +0530, Girish KS wrote:
>> On Tue, Apr 16, 2013 at 4:50 PM, Mark Brown <[e-mail]> wrote:
>
>> > I'm missing patch 1 of this series.
>
>> its already  merged to stable tree after your review
>
> The patch numbering should reflect what you're posting.  If you're only
> sending four patches they should be numbered 1-4, otherwise it looks
> like there's something missing.  The goal with the numbers is to help
> people get the patches in the right order, the name should be enough to
> associate with other versions of the same patch.

OK. I will submit a new series ignoring the already merged patch.

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analytics on semi-structured data. The platform includes APIs for building
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Patch

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 4188b2f..a6fdc71 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -35,6 +35,7 @@ 
 #include <linux/platform_data/spi-s3c64xx.h>
 
 #define MAX_SPI_PORTS		3
+#define S3C64XX_SPI_QUIRK_POLL		(1 << 0)
 
 /* Registers and bit-fields */
 
@@ -126,6 +127,7 @@ 
 #define S3C64XX_SPI_TRAILCNT		S3C64XX_SPI_MAX_TRAILCNT
 
 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+#define is_polling(x)	(x->port_conf->quirks & S3C64XX_SPI_QUIRK_POLL)
 
 #define RXBUSY    (1<<2)
 #define TXBUSY    (1<<3)
@@ -154,6 +156,7 @@  struct s3c64xx_spi_port_config {
 	int	fifo_lvl_mask[MAX_SPI_PORTS];
 	int	rx_lvl_offset;
 	int	tx_st_done;
+	int	quirks;
 	bool	high_speed;
 	bool	clk_from_cmu;
 };
@@ -419,6 +422,27 @@  static inline void enable_cs(struct s3c64xx_spi_driver_data *sdd,
 
 	cs = spi->controller_data;
 	gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 1 : 0);
+
+	/* Start the signals */
+	writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+}
+
+static u32 wait_for_timeout(struct s3c64xx_spi_driver_data *sdd,
+					int timeout_ms)
+{
+	void __iomem *regs = sdd->regs;
+	unsigned long val;
+	u32 status;
+	/* max fifo depth available */
+	u32 max_fifo = (FIFO_LVL_MASK(sdd) >> 1) + 1;
+
+	val = msecs_to_loops(timeout_ms);
+	do {
+		status = readl(regs + S3C64XX_SPI_STATUS);
+	} while (RX_FIFO_LVL(status, sdd) < max_fifo && --val);
+
+	/* return the actual received data length */
+	return RX_FIFO_LVL(status, sdd);
 }
 
 static int wait_for_xfer(struct s3c64xx_spi_driver_data *sdd,
@@ -443,20 +467,19 @@  static int wait_for_xfer(struct s3c64xx_spi_driver_data *sdd,
 		} while (RX_FIFO_LVL(status, sdd) < xfer->len && --val);
 	}
 
-	if (!val)
-		return -EIO;
-
 	if (dma_mode) {
 		u32 status;
 
 		/*
+		 * If the previous xfer was completed within timeout, then
+		 * proceed further else return -EIO.
 		 * DmaTx returns after simply writing data in the FIFO,
 		 * w/o waiting for real transmission on the bus to finish.
 		 * DmaRx returns only after Dma read data from FIFO which
 		 * needs bus transmission to finish, so we don't worry if
 		 * Xfer involved Rx(with or without Tx).
 		 */
-		if (xfer->rx_buf == NULL) {
+		if (val && !xfer->rx_buf) {
 			val = msecs_to_loops(10);
 			status = readl(regs + S3C64XX_SPI_STATUS);
 			while ((TX_FIFO_LVL(status, sdd)
@@ -466,30 +489,53 @@  static int wait_for_xfer(struct s3c64xx_spi_driver_data *sdd,
 				status = readl(regs + S3C64XX_SPI_STATUS);
 			}
 
-			if (!val)
-				return -EIO;
 		}
+
+		/* If timed out while checking rx/tx status return error */
+		if (!val)
+			return -EIO;
 	} else {
+		int loops;
+		u32 cpy_len;
+		u8 *buf;
+
 		/* If it was only Tx */
-		if (xfer->rx_buf == NULL) {
+		if (!xfer->rx_buf) {
 			sdd->state &= ~TXBUSY;
 			return 0;
 		}
 
-		switch (sdd->cur_bpw) {
-		case 32:
-			ioread32_rep(regs + S3C64XX_SPI_RX_DATA,
-				xfer->rx_buf, xfer->len / 4);
-			break;
-		case 16:
-			ioread16_rep(regs + S3C64XX_SPI_RX_DATA,
-				xfer->rx_buf, xfer->len / 2);
-			break;
-		default:
-			ioread8_rep(regs + S3C64XX_SPI_RX_DATA,
-				xfer->rx_buf, xfer->len);
-			break;
-		}
+		/*
+		 * If the receive length is bigger than the controller fifo
+		 * size, calculate the loops and read the fifo as many times.
+		 * loops = length / max fifo size (calculated by using the
+		 * fifo mask).
+		 * For any size less than the fifo size the below code is
+		 * executed atleast once.
+		 */
+		loops = xfer->len / ((FIFO_LVL_MASK(sdd) >> 1) + 1);
+		buf = xfer->rx_buf;
+		do{
+			/* wait for data to be received in the fifo */
+			cpy_len = wait_for_timeout(sdd, ms);
+
+			switch (sdd->cur_bpw) {
+			case 32:
+				ioread32_rep(regs + S3C64XX_SPI_RX_DATA,
+					buf, cpy_len / 4);
+				break;
+			case 16:
+				ioread16_rep(regs + S3C64XX_SPI_RX_DATA,
+					buf, cpy_len / 2);
+				break;
+			default:
+				ioread8_rep(regs + S3C64XX_SPI_RX_DATA,
+					buf, cpy_len);
+				break;
+			}
+
+			buf = buf + cpy_len;
+		}while(loops--);
 		sdd->state &= ~RXBUSY;
 	}
 
@@ -505,6 +551,9 @@  static inline void disable_cs(struct s3c64xx_spi_driver_data *sdd,
 		sdd->tgl_spi = NULL;
 
 	gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 0 : 1);
+
+	/* Quiese the signals */
+	writel(S3C64XX_SPI_SLAVE_SIG_INACT, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
 }
 
 static void s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
@@ -586,7 +635,7 @@  static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
 	struct device *dev = &sdd->pdev->dev;
 	struct spi_transfer *xfer;
 
-	if (msg->is_dma_mapped)
+	if (is_polling(sdd) || msg->is_dma_mapped)
 		return 0;
 
 	/* First mark all xfer unmapped */
@@ -635,7 +684,7 @@  static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
 	struct device *dev = &sdd->pdev->dev;
 	struct spi_transfer *xfer;
 
-	if (msg->is_dma_mapped)
+	if (is_polling(sdd) || msg->is_dma_mapped)
 		return;
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
@@ -713,7 +762,8 @@  static int s3c64xx_spi_transfer_one_message(struct spi_master *master,
 		}
 
 		/* Polling method for xfers not bigger than FIFO capacity */
-		if (xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
+		if (is_polling(sdd) ||
+			xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
 			use_dma = 0;
 		else
 			use_dma = 1;
@@ -729,17 +779,10 @@  static int s3c64xx_spi_transfer_one_message(struct spi_master *master,
 		/* Slave Select */
 		enable_cs(sdd, spi);
 
-		/* Start the signals */
-		writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
-
 		spin_unlock_irqrestore(&sdd->lock, flags);
 
 		status = wait_for_xfer(sdd, xfer, use_dma);
 
-		/* Quiese the signals */
-		writel(S3C64XX_SPI_SLAVE_SIG_INACT,
-		       sdd->regs + S3C64XX_SPI_SLAVE_SEL);
-
 		if (status) {
 			dev_err(&spi->dev, "I/O Error: rx-%d tx-%d res:rx-%c tx-%c len-%d\n",
 				xfer->rx_buf ? 1 : 0, xfer->tx_buf ? 1 : 0,
@@ -795,7 +838,7 @@  static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi);
 
 	/* Acquire DMA channels */
-	while (!acquire_dma(sdd))
+	while (!is_polling(sdd) && !acquire_dma(sdd))
 		usleep_range(10000, 11000);
 
 	pm_runtime_get_sync(&sdd->pdev->dev);
@@ -808,8 +851,10 @@  static int s3c64xx_spi_unprepare_transfer(struct spi_master *spi)
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi);
 
 	/* Free DMA channels */
-	sdd->ops->release(sdd->rx_dma.ch, &s3c64xx_spi_dma_client);
-	sdd->ops->release(sdd->tx_dma.ch, &s3c64xx_spi_dma_client);
+	if (!is_polling(sdd)) {
+		sdd->ops->release(sdd->rx_dma.ch, &s3c64xx_spi_dma_client);
+		sdd->ops->release(sdd->tx_dma.ch, &s3c64xx_spi_dma_client);
+	}
 
 	pm_runtime_put(&sdd->pdev->dev);
 
@@ -1220,19 +1265,19 @@  static int s3c64xx_spi_probe(struct platform_device *pdev)
 	if (!sdd->pdev->dev.of_node) {
 		res = platform_get_resource(pdev, IORESOURCE_DMA,  0);
 		if (!res) {
-			dev_err(&pdev->dev, "Unable to get SPI tx dma "
-					"resource\n");
-			return -ENXIO;
-		}
-		sdd->tx_dma.dmach = res->start;
+			dev_warn(&pdev->dev, "Unable to get SPI tx dma "
+					"resource. Switching to poll mode\n");
+			sdd->port_conf->quirks = S3C64XX_SPI_QUIRK_POLL;
+		} else
+			sdd->tx_dma.dmach = res->start;
 
 		res = platform_get_resource(pdev, IORESOURCE_DMA,  1);
 		if (!res) {
-			dev_err(&pdev->dev, "Unable to get SPI rx dma "
-					"resource\n");
-			return -ENXIO;
-		}
-		sdd->rx_dma.dmach = res->start;
+			dev_warn(&pdev->dev, "Unable to get SPI rx dma "
+					"resource. Switching to poll mode\n");
+			sdd->port_conf->quirks = S3C64XX_SPI_QUIRK_POLL;
+		} else
+			sdd->rx_dma.dmach = res->start;
 	}
 
 	sdd->tx_dma.direction = DMA_MEM_TO_DEV;