1 files changed, 128 insertions, 67 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index 08f837b66..4518ecbbc 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -66,7 +66,7 @@ void spi_free_slave(struct spi_slave *slave)
 int spi_claim_bus(struct spi_slave *slave)
 {
 	struct davinci_spi_slave *ds = to_davinci_spi(slave);
-	unsigned int scalar, data1_reg_val = 0;
+	unsigned int scalar;
 
 	/* Enable the SPI hardware */
 	writel(SPIGCR0_SPIRST_MASK, &ds->regs->gcr0);
@@ -93,11 +93,6 @@ int spi_claim_bus(struct spi_slave *slave)
 	writel(8 | (scalar << SPIFMT_PRESCALE_SHIFT) |
 		(1 << SPIFMT_PHASE_SHIFT), &ds->regs->fmt0);
 
-	/* hold cs active at end of transfer until explicitly de-asserted */
-	data1_reg_val = (1 << SPIDAT1_CSHOLD_SHIFT) |
-			(slave->cs << SPIDAT1_CSNR_SHIFT);
-	writel(data1_reg_val, &ds->regs->dat1);
-
 	/*
 	 * Including a minor delay. No science here. Should be good even with
 	 * no delay
@@ -113,8 +108,7 @@ int spi_claim_bus(struct spi_slave *slave)
 	writel(0, &ds->regs->lvl);
 
 	/* enable SPI */
-	writel((readl(&ds->regs->gcr1) |
-		SPIGCR1_SPIENA_MASK), &ds->regs->gcr1);
+	writel((readl(&ds->regs->gcr1) | SPIGCR1_SPIENA_MASK), &ds->regs->gcr1);
 
 	return 0;
 }
@@ -127,14 +121,125 @@ void spi_release_bus(struct spi_slave *slave)
 	writel(SPIGCR0_SPIRST_MASK, &ds->regs->gcr0);
 }
 
+/*
+ * This functions needs to act like a macro to avoid pipeline reloads in the
+ * loops below. Use always_inline. This gains us about 160KiB/s and the bloat
+ * appears to be zero bytes (da830).
+ */
+__attribute__((always_inline))
+static inline u32 davinci_spi_xfer_data(struct davinci_spi_slave *ds, u32 data)
+{
+	u32	buf_reg_val;
+
+	/* send out data */
+	writel(data, &ds->regs->dat1);
+
+	/* wait for the data to clock in/out */
+	while ((buf_reg_val = readl(&ds->regs->buf)) & SPIBUF_RXEMPTY_MASK)
+		;
+
+	return buf_reg_val;
+}
+
+static int davinci_spi_read(struct spi_slave *slave, unsigned int len,
+			    u8 *rxp, unsigned long flags)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+	unsigned int data1_reg_val;
+
+	/* enable CS hold, CS[n] and clear the data bits */
+	data1_reg_val = ((1 << SPIDAT1_CSHOLD_SHIFT) |
+			 (slave->cs << SPIDAT1_CSNR_SHIFT));
+
+	/* wait till TXFULL is deasserted */
+	while (readl(&ds->regs->buf) & SPIBUF_TXFULL_MASK)
+		;
+
+	/* preload the TX buffer to avoid clock starvation */
+	writel(data1_reg_val, &ds->regs->dat1);
+
+	/* keep reading 1 byte until only 1 byte left */
+	while ((len--) > 1)
+		*rxp++ = davinci_spi_xfer_data(ds, data1_reg_val);
+
+	/* clear CS hold when we reach the end */
+	if (flags & SPI_XFER_END)
+		data1_reg_val &= ~(1 << SPIDAT1_CSHOLD_SHIFT);
+
+	/* read the last byte */
+	*rxp = davinci_spi_xfer_data(ds, data1_reg_val);
+
+	return 0;
+}
+
+static int davinci_spi_write(struct spi_slave *slave, unsigned int len,
+		const u8 *txp, unsigned long flags)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+	unsigned int data1_reg_val;
+
+	/* enable CS hold and clear the data bits */
+	data1_reg_val = ((1 << SPIDAT1_CSHOLD_SHIFT) |
+			 (slave->cs << SPIDAT1_CSNR_SHIFT));
+
+	/* wait till TXFULL is deasserted */
+	while (readl(&ds->regs->buf) & SPIBUF_TXFULL_MASK)
+		;
+
+	/* preload the TX buffer to avoid clock starvation */
+	if (len > 2) {
+		writel(data1_reg_val | *txp++, &ds->regs->dat1);
+		len--;
+	}
+
+	/* keep writing 1 byte until only 1 byte left */
+	while ((len--) > 1)
+		davinci_spi_xfer_data(ds, data1_reg_val | *txp++);
+
+	/* clear CS hold when we reach the end */
+	if (flags & SPI_XFER_END)
+		data1_reg_val &= ~(1 << SPIDAT1_CSHOLD_SHIFT);
+
+	/* write the last byte */
+	davinci_spi_xfer_data(ds, data1_reg_val | *txp);
+
+	return 0;
+}
+
+#ifndef CONFIG_SPI_HALF_DUPLEX
+static int davinci_spi_read_write(struct spi_slave *slave, unsigned int len,
+				  u8 *rxp, const u8 *txp, unsigned long flags)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+	unsigned int data1_reg_val;
+
+	/* enable CS hold and clear the data bits */
+	data1_reg_val = ((1 << SPIDAT1_CSHOLD_SHIFT) |
+			 (slave->cs << SPIDAT1_CSNR_SHIFT));
+
+	/* wait till TXFULL is deasserted */
+	while (readl(&ds->regs->buf) & SPIBUF_TXFULL_MASK)
+		;
+
+	/* keep reading and writing 1 byte until only 1 byte left */
+	while ((len--) > 1)
+		*rxp++ = davinci_spi_xfer_data(ds, data1_reg_val | *txp++);
+
+	/* clear CS hold when we reach the end */
+	if (flags & SPI_XFER_END)
+		data1_reg_val &= ~(1 << SPIDAT1_CSHOLD_SHIFT);
+
+	/* read and write the last byte */
+	*rxp = davinci_spi_xfer_data(ds, data1_reg_val | *txp);
+
+	return 0;
+}
+#endif
+
 int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 		const void *dout, void *din, unsigned long flags)
 {
-	struct davinci_spi_slave *ds = to_davinci_spi(slave);
-	unsigned int	len, data1_reg_val = readl(&ds->regs->dat1);
-	unsigned int	i_cnt = 0, o_cnt = 0, buf_reg_val;
-	const u8	*txp = dout; /* dout can be NULL for read operation */
-	u8		*rxp = din;  /* din can be NULL for write operation */
+	unsigned int len;
 
 	if (bitlen == 0)
 		/* Finish any previously submitted transfers */
@@ -154,63 +259,19 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 
 	len = bitlen / 8;
 
-	/* do an empty read to clear the current contents */
-	readl(&ds->regs->buf);
-
-	/* keep writing and reading 1 byte until done */
-	while ((i_cnt < len) || (o_cnt < len)) {
-		/* read RX buffer and flags */
-		buf_reg_val = readl(&ds->regs->buf);
-
-		/* if data is available */
-		if ((i_cnt < len) &&
-			(buf_reg_val & SPIBUF_RXEMPTY_MASK) == 0) {
-			/*
-			 * If there is no read buffer simply
-			 * ignore the read character
-			 */
-			if (rxp)
-				*rxp++ = buf_reg_val & 0xFF;
-			/* increment read words count */
-			i_cnt++;
-		}
-
-		/*
-		 * if the tx buffer is empty and there
-		 * is still data to transmit
-		 */
-		if ((o_cnt < len) &&
-			((buf_reg_val & SPIBUF_TXFULL_MASK) == 0)) {
-			/* write the data */
-			data1_reg_val &= ~0xFFFF;
-			if (txp)
-				data1_reg_val |= *txp++;
-			/*
-			 * Write to DAT1 is required to keep
-			 * the serial transfer going.
-			 * We just terminate when we reach the end.
-			 */
-			if ((o_cnt == (len - 1)) && (flags & SPI_XFER_END)) {
-				/* clear CS hold */
-				writel(data1_reg_val &
-						~(1 << SPIDAT1_CSHOLD_SHIFT),
-						&ds->regs->dat1);
-			} else {
-				/* enable CS hold and write TX register */
-				data1_reg_val |= ((1 << SPIDAT1_CSHOLD_SHIFT) |
-					(slave->cs << SPIDAT1_CSNR_SHIFT));
-				writel(data1_reg_val, &ds->regs->dat1);
-			}
-			/* increment written words count */
-			o_cnt++;
-		}
-	}
-	return 0;
+	if (!dout)
+		return davinci_spi_read(slave, len, din, flags);
+	else if (!din)
+		return davinci_spi_write(slave, len, dout, flags);
+#ifndef CONFIG_SPI_HALF_DUPLEX
+	else
+		return davinci_spi_read_write(slave, len, din, dout, flags);
+#endif
 
 out:
 	if (flags & SPI_XFER_END) {
-		writel(data1_reg_val &
-			~(1 << SPIDAT1_CSHOLD_SHIFT), &ds->regs->dat1);
+		u8 dummy = 0;
+		davinci_spi_write(slave, 1, &dummy, flags);
 	}
 	return 0;
 }