omap3_spi: receive transmit mode

Implementation of receive-transmit mode for
omap3 MCSPI.

Introduces full duplex communication, needed by
some spi devices (such as enc28j60).

Signed-off-by: jacopo mondi <mondi@cs.unibo.it> <j.mondi@voltaelectronics.com>

diff --git a/drivers/spi/omap3_spi.c b/drivers/spi/omap3_spi.c
index af12c0e590b954830fa91cd41c51a01e5e39e110..9346c0b5b4af679d3015af0bbb35b78eecbc005d 100644 (file)
--- a/drivers/spi/omap3_spi.c
+++ b/drivers/spi/omap3_spi.c
@@ -297,6 +297,65 @@ int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
        return 0;
 }
 
+/*McSPI Transmit Receive Mode*/
+int omap3_spi_txrx(struct spi_slave *slave,
+               unsigned int len, const u8 *txp, u8 *rxp, unsigned long flags)
+{
+       struct omap3_spi_slave *ds = to_omap3_spi(slave);
+       int timeout = SPI_WAIT_TIMEOUT;
+       int chconf = readl(&ds->regs->channel[ds->slave.cs].chconf);
+       int irqstatus = readl(&ds->regs->irqstatus);
+       int i=0;
+
+       /*Enable SPI channel*/
+       if (flags & SPI_XFER_BEGIN)
+               writel(OMAP3_MCSPI_CHCTRL_EN,
+                      &ds->regs->channel[ds->slave.cs].chctrl);
+
+       /*set TRANSMIT-RECEIVE Mode*/
+       chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
+       chconf |= OMAP3_MCSPI_CHCONF_FORCE;
+       writel(chconf, &ds->regs->channel[ds->slave.cs].chconf);
+
+       /*Shift in and out 1 byte at time*/
+       for (i=0; i < len; i++){
+               /* Write: wait for TX empty (TXS == 1)*/
+               irqstatus |= (1<< (4*(ds->slave.bus)));
+               while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
+                        OMAP3_MCSPI_CHSTAT_TXS)) {
+                       if (--timeout <= 0) {
+                               printf("SPI TXS timed out, status=0x%08x\n",
+                                      readl(&ds->regs->channel[ds->slave.cs].chstat));
+                               return -1;
+                       }
+               }
+               /* Write the data */
+               writel(txp[i], &ds->regs->channel[ds->slave.cs].tx);
+
+               /*Read: wait for RX containing data (RXS == 1)*/
+               while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
+                        OMAP3_MCSPI_CHSTAT_RXS)) {
+                       if (--timeout <= 0) {
+                               printf("SPI RXS timed out, status=0x%08x\n",
+                                      readl(&ds->regs->channel[ds->slave.cs].chstat));
+                               return -1;
+                       }
+               }
+               /* Read the data */
+               rxp[i] = readl(&ds->regs->channel[ds->slave.cs].rx);
+       }
+
+       /*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);
+       }
+
+       return 0;
+}
+
 int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
             const void *dout, void *din, unsigned long flags)
 {
@@ -329,10 +388,11 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                }
                ret = 0;
        } else {
-               if (dout != NULL)
+               if (dout != NULL && din != NULL)
+                       ret = omap3_spi_txrx(slave, len, txp, rxp, flags);
+               else if (dout != NULL)
                        ret = omap3_spi_write(slave, len, txp, flags);
-
-               if (din != NULL)
+               else if (din != NULL)
                        ret = omap3_spi_read(slave, len, rxp, flags);
        }
        return ret;

diff --git a/drivers/spi/omap3_spi.h b/drivers/spi/omap3_spi.h
index b8e3a4c44c4f0531c956865a010cc70a6077a5bd..0ac801cb251f68e9a382d1b088b099a38c2d466d 100644 (file)
--- a/drivers/spi/omap3_spi.h
+++ b/drivers/spi/omap3_spi.h
@@ -109,6 +109,8 @@ static inline struct omap3_spi_slave *to_omap3_spi(struct spi_slave *slave)
        return container_of(slave, struct omap3_spi_slave, slave);
 }
 
+int omap3_spi_txrx(struct spi_slave *slave, unsigned int len, const u8 *txp,
+                       u8 *rxp, unsigned long flags);
 int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
                    unsigned long flags);
 int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,