1 files changed, 84 insertions, 20 deletions

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index f037e5593269..dd2f950b21a7 100644
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -138,6 +138,45 @@ static unsigned bitbang_txrx_32(
 	return t->len - count;
 }
 
+int spi_bitbang_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct spi_bitbang_cs	*cs = spi->controller_state;
+	u8			bits_per_word;
+	u32			hz;
+
+	if (t) {
+		bits_per_word = t->bits_per_word;
+		hz = t->speed_hz;
+	} else {
+		bits_per_word = 0;
+		hz = 0;
+	}
+
+	/* spi_transfer level calls that work per-word */
+	if (!bits_per_word)
+		bits_per_word = spi->bits_per_word;
+	if (bits_per_word <= 8)
+		cs->txrx_bufs = bitbang_txrx_8;
+	else if (bits_per_word <= 16)
+		cs->txrx_bufs = bitbang_txrx_16;
+	else if (bits_per_word <= 32)
+		cs->txrx_bufs = bitbang_txrx_32;
+	else
+		return -EINVAL;
+
+	/* nsecs = (clock period)/2 */
+	if (!hz)
+		hz = spi->max_speed_hz;
+	if (hz) {
+		cs->nsecs = (1000000000/2) / hz;
+		if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
+
 /**
  * spi_bitbang_setup - default setup for per-word I/O loops
  */
@@ -145,8 +184,16 @@ int spi_bitbang_setup(struct spi_device *spi)
 {
 	struct spi_bitbang_cs	*cs = spi->controller_state;
 	struct spi_bitbang	*bitbang;
+	int			retval;
 
-	if (!spi->max_speed_hz)
+	bitbang = spi_master_get_devdata(spi->master);
+
+	/* REVISIT: some systems will want to support devices using lsb-first
+	 * bit encodings on the wire.  In pure software that would be trivial,
+	 * just bitbang_txrx_le_cphaX() routines shifting the other way, and
+	 * some hardware controllers also have this support.
+	 */
+	if ((spi->mode & SPI_LSB_FIRST) != 0)
 		return -EINVAL;
 
 	if (!cs) {
@@ -155,32 +202,20 @@ int spi_bitbang_setup(struct spi_device *spi)
 			return -ENOMEM;
 		spi->controller_state = cs;
 	}
-	bitbang = spi_master_get_devdata(spi->master);
 
 	if (!spi->bits_per_word)
 		spi->bits_per_word = 8;
 
-	/* spi_transfer level calls that work per-word */
-	if (spi->bits_per_word <= 8)
-		cs->txrx_bufs = bitbang_txrx_8;
-	else if (spi->bits_per_word <= 16)
-		cs->txrx_bufs = bitbang_txrx_16;
-	else if (spi->bits_per_word <= 32)
-		cs->txrx_bufs = bitbang_txrx_32;
-	else
-		return -EINVAL;
-
 	/* per-word shift register access, in hardware or bitbanging */
 	cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
 	if (!cs->txrx_word)
 		return -EINVAL;
 
-	/* nsecs = (clock period)/2 */
-	cs->nsecs = (1000000000/2) / (spi->max_speed_hz);
-	if (cs->nsecs > MAX_UDELAY_MS * 1000)
-		return -EINVAL;
+	retval = spi_bitbang_setup_transfer(spi, NULL);
+	if (retval < 0)
+		return retval;
 
-	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
+	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
 			__FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
 			spi->bits_per_word, 2 * cs->nsecs);
 
@@ -246,6 +281,8 @@ static void bitbang_work(void *_bitbang)
 		unsigned		tmp;
 		unsigned		cs_change;
 		int			status;
+		int			(*setup_transfer)(struct spi_device *,
+						struct spi_transfer *);
 
 		m = container_of(bitbang->queue.next, struct spi_message,
 				queue);
@@ -262,6 +299,7 @@ static void bitbang_work(void *_bitbang)
 		tmp = 0;
 		cs_change = 1;
 		status = 0;
+		setup_transfer = NULL;
 
 		list_for_each_entry (t, &m->transfers, transfer_list) {
 			if (bitbang->shutdown) {
@@ -269,6 +307,20 @@ static void bitbang_work(void *_bitbang)
 				break;
 			}
 
+			/* override or restore speed and wordsize */
+			if (t->speed_hz || t->bits_per_word) {
+				setup_transfer = bitbang->setup_transfer;
+				if (!setup_transfer) {
+					status = -ENOPROTOOPT;
+					break;
+				}
+			}
+			if (setup_transfer) {
+				status = setup_transfer(spi, t);
+				if (status < 0)
+					break;
+			}
+
 			/* set up default clock polarity, and activate chip;
 			 * this implicitly updates clock and spi modes as
 			 * previously recorded for this device via setup().
@@ -325,6 +377,10 @@ static void bitbang_work(void *_bitbang)
 		m->status = status;
 		m->complete(m->context);
 
+		/* restore speed and wordsize */
+		if (setup_transfer)
+			setup_transfer(spi, NULL);
+
 		/* normally deactivate chipselect ... unless no error and
 		 * cs_change has hinted that the next message will probably
 		 * be for this chip too.
@@ -348,6 +404,7 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
 {
 	struct spi_bitbang	*bitbang;
 	unsigned long		flags;
+	int			status = 0;
 
 	m->actual_length = 0;
 	m->status = -EINPROGRESS;
@@ -357,11 +414,15 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
 		return -ESHUTDOWN;
 
 	spin_lock_irqsave(&bitbang->lock, flags);
-	list_add_tail(&m->queue, &bitbang->queue);
-	queue_work(bitbang->workqueue, &bitbang->work);
+	if (!spi->max_speed_hz)
+		status = -ENETDOWN;
+	else {
+		list_add_tail(&m->queue, &bitbang->queue);
+		queue_work(bitbang->workqueue, &bitbang->work);
+	}
 	spin_unlock_irqrestore(&bitbang->lock, flags);
 
-	return 0;
+	return status;
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
 
@@ -406,6 +467,9 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
 		bitbang->use_dma = 0;
 		bitbang->txrx_bufs = spi_bitbang_bufs;
 		if (!bitbang->master->setup) {
+			if (!bitbang->setup_transfer)
+				bitbang->setup_transfer =
+					 spi_bitbang_setup_transfer;
 			bitbang->master->setup = spi_bitbang_setup;
 			bitbang->master->cleanup = spi_bitbang_cleanup;
 		}