OMAP3 SPI : Fixed bugs related to SPI transfer
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>
diff --git a/drivers/spi/omap3_spi.c b/drivers/spi/omap3_spi.c
index 6791a7e..344d5b8 100644
--- a/drivers/spi/omap3_spi.c
+++ b/drivers/spi/omap3_spi.c
@@ -57,6 +57,20 @@
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 */
@@ -212,7 +226,7 @@
/* 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 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 @@
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;
}
@@ -277,14 +292,13 @@
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);
@@ -298,15 +312,18 @@
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;
@@ -323,14 +340,12 @@
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++){
@@ -359,13 +374,13 @@
/* 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 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 @@
#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)