Patchwork [U-Boot] OMAP3 SPI : Fixed bugs related to SPI transfer

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Submitter Ajoy Kumar Das
Date Nov. 18, 2012, 7:10 a.m.
Message ID <1353222615-11255-1-git-send-email-akdas75@yahoo.in>
Download mbox | patch
Permalink /patch/199895/
State Awaiting Upstream
Delegated to: Tom Rini
Headers show

Comments

Ajoy Kumar Das - Nov. 18, 2012, 7:10 a.m.
From: ajoy <akdas75@yahoo.in>

Added posted writes (read after writes) to effect the
change immediately for channel confiuration and channel
enable register

Disable the channel to purge receieve data in TX_ONLY
mode transfer otherwise rx data will get affected by
the next immediate RX_ONLY mode transfer

Wait for the EOT bit to be set after last byte has been
loaded to TX shift register in the the TX_ONLY mode.This
ensures TX data has been completely shifted out

Disable the channel in RX_ONLY mode before reading the
last data from  RXX register to prevent the SPI slave
to transmit next word

Signed-off-by: Ajoy Kumar Das <akdas75@yahoo.in>
Cc: Tom Rini <trini@ti.com>
Cc: jacopo mondi <j.mondi@voltaelectronics.com>
---
 drivers/spi/omap3_spi.c |   84 +++++++++++++++++++++++++++--------------------
 drivers/spi/omap3_spi.h |    1 +
 2 files changed, 49 insertions(+), 36 deletions(-)
Peter Korsgaard - Nov. 18, 2012, 1:23 p.m.
>>>>> "Ajoy" == Ajoy Kumar Das <akdas75@yahoo.in> writes:

 Ajoy> From: ajoy <akdas75@yahoo.in>
 Ajoy> Added posted writes (read after writes) to effect the
 Ajoy> change immediately for channel confiuration and channel
 Ajoy> enable register

 Ajoy> Disable the channel to purge receieve data in TX_ONLY
 Ajoy> mode transfer otherwise rx data will get affected by
 Ajoy> the next immediate RX_ONLY mode transfer

 Ajoy> Wait for the EOT bit to be set after last byte has been
 Ajoy> loaded to TX shift register in the the TX_ONLY mode.This
 Ajoy> ensures TX data has been completely shifted out

 Ajoy> Disable the channel in RX_ONLY mode before reading the
 Ajoy> last data from  RXX register to prevent the SPI slave
 Ajoy> to transmit next word

So it is 4 seperate fixes? Could you please split it up in 4 seperate
patches?
Ajoy Kumar Das - Nov. 18, 2012, 4:40 p.m.
Hi Peter
  I described the entire patch in small paragraphs
  so it is better to understand
   
  The first paragraph is for posted writes
  (courtesy linux OMAP3 SPI driver code)

  The last three paragraphs actually fixes the
  bug related to the operation of the OMAP3 
  SPI controller in TX_ONLY and RX_ONLY mode.
   
  Only after implementing the those three things
  'together' the TX_ONLY and RX_ONLY transfers works perfectly.
  The problem occurs when the RX transfer is immediately
  followed by the TX transfer.  

  So shall I divide them in four patches  according to the paragraphs
  Or shall I make two patches according to the functionality getting fixed 

  Please suggest

Ajoy
Tom Rini - Dec. 10, 2012, 8:16 p.m.
On Sat, Nov 17, 2012 at 09:10:15PM -0000, Ajoy Kumar Das wrote:

> From: ajoy <akdas75@yahoo.in>
> 
> Added posted writes (read after writes) to effect the
> change immediately for channel confiuration and channel
> enable register
> 
> Disable the channel to purge receieve data in TX_ONLY
> mode transfer otherwise rx data will get affected by
> the next immediate RX_ONLY mode transfer
> 
> Wait for the EOT bit to be set after last byte has been
> loaded to TX shift register in the the TX_ONLY mode.This
> ensures TX data has been completely shifted out
> 
> Disable the channel in RX_ONLY mode before reading the
> last data from  RXX register to prevent the SPI slave
> to transmit next word
> 
> Signed-off-by: Ajoy Kumar Das <akdas75@yahoo.in>
> Cc: Tom Rini <trini@ti.com>
> Cc: jacopo mondi <j.mondi@voltaelectronics.com>

Applied to u-boot-ti/master, thanks!

Patch

diff --git a/drivers/spi/omap3_spi.c b/drivers/spi/omap3_spi.c
index 6791a7e..dd4ae7c 100644
--- a/drivers/spi/omap3_spi.c
+++ b/drivers/spi/omap3_spi.c
@@ -57,6 +57,20 @@  static void spi_reset(struct omap3_spi_slave *ds)
 	writel(OMAP3_MCSPI_WAKEUPENABLE_WKEN, &ds->regs->wakeupenable);
 }
 
+static void omap3_spi_write_chconf(struct omap3_spi_slave *ds, int val)
+{
+	writel(val, &ds->regs->channel[ds->slave.cs].chconf);
+	/* Flash post writes to make immediate effect */
+	readl(&ds->regs->channel[ds->slave.cs].chconf);
+}
+
+static void omap3_spi_set_enable(struct omap3_spi_slave *ds, int enable)
+{
+	writel(enable, &ds->regs->channel[ds->slave.cs].chctrl);
+        /* Flash post writes to make immediate effect */
+	readl(&ds->regs->channel[ds->slave.cs].chctrl); 
+}
+
 void spi_init()
 {
 	/* do nothing */
@@ -211,8 +225,8 @@  int spi_claim_bus(struct spi_slave *slave)
 
 	/* Transmit & receive mode */
 	conf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
-
-	writel(conf, &ds->regs->channel[ds->slave.cs].chconf);
+	
+	omap3_spi_write_chconf(ds,conf);
 
 	return 0;
 }
@@ -233,14 +247,13 @@  int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
 	int timeout = SPI_WAIT_TIMEOUT;
 	int chconf = readl(&ds->regs->channel[ds->slave.cs].chconf);
 
-	if (flags & SPI_XFER_BEGIN)
-		writel(OMAP3_MCSPI_CHCTRL_EN,
-		       &ds->regs->channel[ds->slave.cs].chctrl);
+	/* Enable the channel */
+	omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);
 
 	chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
 	chconf |= OMAP3_MCSPI_CHCONF_TRM_TX_ONLY;
 	chconf |= OMAP3_MCSPI_CHCONF_FORCE;
-	writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
+	omap3_spi_write_chconf(ds,chconf);
 
 	for (i = 0; i < len; i++) {
 		/* wait till TX register is empty (TXS == 1) */
@@ -256,15 +269,17 @@  int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
 		writel(txp[i], &ds->regs->channel[ds->slave.cs].tx);
 	}
 
+        /* wait to finish of transfer */
+        while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
+                         OMAP3_MCSPI_CHSTAT_EOT));
+
+	/* Disable the channel otherwise the next immediate RX will get affected */
+	omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);
+
 	if (flags & SPI_XFER_END) {
-		/* wait to finish of transfer */
-		while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
-			 OMAP3_MCSPI_CHSTAT_EOT));
 
 		chconf &= ~OMAP3_MCSPI_CHCONF_FORCE;
-		writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
-
-		writel(0, &ds->regs->channel[ds->slave.cs].chctrl);
+		omap3_spi_write_chconf(ds,chconf);
 	}
 	return 0;
 }
@@ -277,15 +292,14 @@  int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
 	int timeout = SPI_WAIT_TIMEOUT;
 	int chconf = readl(&ds->regs->channel[ds->slave.cs].chconf);
 
-	if (flags & SPI_XFER_BEGIN)
-		writel(OMAP3_MCSPI_CHCTRL_EN,
-		       &ds->regs->channel[ds->slave.cs].chctrl);
+	/* Enable the channel */
+	omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);
 
 	chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
 	chconf |= OMAP3_MCSPI_CHCONF_TRM_RX_ONLY;
 	chconf |= OMAP3_MCSPI_CHCONF_FORCE;
-	writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
-
+	omap3_spi_write_chconf(ds,chconf);
+	
 	writel(0, &ds->regs->channel[ds->slave.cs].tx);
 
 	for (i = 0; i < len; i++) {
@@ -298,15 +312,18 @@  int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
 				return -1;
 			}
 		}
+
+		/* Disable the channel to prevent furher receiving */
+		if(i == (len - 1))
+			omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);	
+		
 		/* Read the data */
 		rxp[i] = readl(&ds->regs->channel[ds->slave.cs].rx);
 	}
 
 	if (flags & SPI_XFER_END) {
 		chconf &= ~OMAP3_MCSPI_CHCONF_FORCE;
-		writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
-
-		writel(0, &ds->regs->channel[ds->slave.cs].chctrl);
+		omap3_spi_write_chconf(ds,chconf);
 	}
 
 	return 0;
@@ -323,15 +340,13 @@  int omap3_spi_txrx(struct spi_slave *slave,
 	int i=0;
 
 	/*Enable SPI channel*/
-	if (flags & SPI_XFER_BEGIN)
-		writel(OMAP3_MCSPI_CHCTRL_EN,
-		       &ds->regs->channel[ds->slave.cs].chctrl);
-
+	omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);
+	
 	/*set TRANSMIT-RECEIVE Mode*/
 	chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
 	chconf |= OMAP3_MCSPI_CHCONF_FORCE;
-	writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
-
+	omap3_spi_write_chconf(ds,chconf);
+	
 	/*Shift in and out 1 byte at time*/
 	for (i=0; i < len; i++){
 		/* Write: wait for TX empty (TXS == 1)*/
@@ -359,13 +374,13 @@  int omap3_spi_txrx(struct spi_slave *slave,
 		/* Read the data */
 		rxp[i] = readl(&ds->regs->channel[ds->slave.cs].rx);
 	}
+	/* Disable the channel */
+        omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);
 
 	/*if transfer must be terminated disable the channel*/
 	if (flags & SPI_XFER_END) {
 		chconf &= ~OMAP3_MCSPI_CHCONF_FORCE;
-		writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
-
-		writel(0, &ds->regs->channel[ds->slave.cs].chctrl);
+		omap3_spi_write_chconf(ds,chconf);
 	}
 
 	return 0;
@@ -389,17 +404,14 @@  int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 		int chconf = readl(&ds->regs->channel[ds->slave.cs].chconf);
 
 		if (flags & SPI_XFER_BEGIN) {
-			writel(OMAP3_MCSPI_CHCTRL_EN,
-			       &ds->regs->channel[ds->slave.cs].chctrl);
+			omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);
 			chconf |= OMAP3_MCSPI_CHCONF_FORCE;
-			writel(chconf,
-			       &ds->regs->channel[ds->slave.cs].chconf);
+			omap3_spi_write_chconf(ds,chconf);	
 		}
 		if (flags & SPI_XFER_END) {
 			chconf &= ~OMAP3_MCSPI_CHCONF_FORCE;
-			writel(chconf,
-			       &ds->regs->channel[ds->slave.cs].chconf);
-			writel(0, &ds->regs->channel[ds->slave.cs].chctrl);
+			omap3_spi_write_chconf(ds,chconf);
+			omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);
 		}
 		ret = 0;
 	} else {
diff --git a/drivers/spi/omap3_spi.h b/drivers/spi/omap3_spi.h
index bffa43c..5e00208 100644
--- a/drivers/spi/omap3_spi.h
+++ b/drivers/spi/omap3_spi.h
@@ -99,6 +99,7 @@  struct mcspi {
 #define OMAP3_MCSPI_CHSTAT_EOT		(1 << 2)
 
 #define OMAP3_MCSPI_CHCTRL_EN		(1 << 0)
+#define OMAP3_MCSPI_CHCTRL_DIS		(0 << 0)
 
 #define OMAP3_MCSPI_WAKEUPENABLE_WKEN	(1 << 0)