X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=drivers%2Fspi%2Fatmel_spi.c;h=e81d59d789108041fee33e62b22b82d14e34fef3;hb=8a392625b665c676a77c62f8608d10ff430bcb83;hp=85687aaf9cabf5876381d647764613a13a9aab9e;hpb=83f7a2c118833d3738b4d162ea3c17d0bd8ffa94;p=linux-2.6-omap-h63xx.git

diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
index 85687aaf9ca..e81d59d7891 100644
--- a/drivers/spi/atmel_spi.c
+++ b/drivers/spi/atmel_spi.c
@@ -497,7 +497,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 	struct atmel_spi	*as;
 	u32			scbr, csr;
 	unsigned int		bits = spi->bits_per_word;
-	unsigned long		bus_hz, sck_hz;
+	unsigned long		bus_hz;
 	unsigned int		npcs_pin;
 	int			ret;
 
@@ -536,14 +536,25 @@ static int atmel_spi_setup(struct spi_device *spi)
 		return -EINVAL;
 	}
 
-	/* speed zero convention is used by some upper layers */
+	/*
+	 * Pre-new_1 chips start out at half the peripheral
+	 * bus speed.
+	 */
 	bus_hz = clk_get_rate(as->clk);
+	if (!as->new_1)
+		bus_hz /= 2;
+
 	if (spi->max_speed_hz) {
-		/* assume div32/fdiv/mbz == 0 */
-		if (!as->new_1)
-			bus_hz /= 2;
-		scbr = ((bus_hz + spi->max_speed_hz - 1)
-			/ spi->max_speed_hz);
+		/*
+		 * Calculate the lowest divider that satisfies the
+		 * constraint, assuming div32/fdiv/mbz == 0.
+		 */
+		scbr = DIV_ROUND_UP(bus_hz, spi->max_speed_hz);
+
+		/*
+		 * If the resulting divider doesn't fit into the
+		 * register bitfield, we can't satisfy the constraint.
+		 */
 		if (scbr >= (1 << SPI_SCBR_SIZE)) {
 			dev_dbg(&spi->dev,
 				"setup: %d Hz too slow, scbr %u; min %ld Hz\n",
@@ -551,8 +562,8 @@ static int atmel_spi_setup(struct spi_device *spi)
 			return -EINVAL;
 		}
 	} else
+		/* speed zero means "as slow as possible" */
 		scbr = 0xff;
-	sck_hz = bus_hz / scbr;
 
 	csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8);
 	if (spi->mode & SPI_CPOL)
@@ -589,7 +600,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 
 	dev_dbg(&spi->dev,
 		"setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
-		sck_hz, bits, spi->mode, spi->chip_select, csr);
+		bus_hz / scbr, bits, spi->mode, spi->chip_select, csr);
 
 	spi_writel(as, CSR0 + 4 * spi->chip_select, csr);
 
@@ -616,7 +627,7 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 		return -ESHUTDOWN;
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-		if (!(xfer->tx_buf || xfer->rx_buf)) {
+		if (!(xfer->tx_buf || xfer->rx_buf) && xfer->len) {
 			dev_dbg(&spi->dev, "missing rx or tx buf\n");
 			return -EINVAL;
 		}
@@ -863,3 +874,4 @@ module_exit(atmel_spi_exit);
 MODULE_DESCRIPTION("Atmel AT32/AT91 SPI Controller driver");
 MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
 MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:atmel_spi");