spi/bitbang: Factor out message transfer from message pump loop

In order to make it easier to convert to transfer_one_message() lift the
code that does the actual message transfer out of the work function that
implements the message pump. This should have no functional impact, it's
just a simple code motion patch.
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-bitbang.c

@@ -255,117 +255,126 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
  * Drivers can provide word-at-a-time i/o primitives, or provide
  * transfer-at-a-time ones to leverage dma or fifo hardware.
  */
-static void bitbang_work(struct work_struct *work)
+static int spi_bitbang_transfer_one(struct spi_device *spi,
+				    struct spi_message *m)
 {
-	struct spi_bitbang	*bitbang =
-		container_of(work, struct spi_bitbang, work);
-	unsigned long		flags;
-	struct spi_message	*m, *_m;
+	struct spi_bitbang 	*bitbang;
+	unsigned		nsecs;
+	struct spi_transfer	*t = NULL;
+	unsigned		tmp;
+	unsigned		cs_change;
+	int			status;
+	int			do_setup = -1;
 
-	spin_lock_irqsave(&bitbang->lock, flags);
-	bitbang->busy = 1;
-	list_for_each_entry_safe(m, _m, &bitbang->queue, queue) {
-		struct spi_device	*spi;
-		unsigned		nsecs;
-		struct spi_transfer	*t = NULL;
-		unsigned		tmp;
-		unsigned		cs_change;
-		int			status;
-		int			do_setup = -1;
+	bitbang = spi_master_get_devdata(spi->master);
 
-		list_del(&m->queue);
-		spin_unlock_irqrestore(&bitbang->lock, flags);
+	/* FIXME this is made-up ... the correct value is known to
+	 * word-at-a-time bitbang code, and presumably chipselect()
+	 * should enforce these requirements too?
+	 */
+	nsecs = 100;
 
-		/* FIXME this is made-up ... the correct value is known to
-		 * word-at-a-time bitbang code, and presumably chipselect()
-		 * should enforce these requirements too?
-		 */
-		nsecs = 100;
+	tmp = 0;
+	cs_change = 1;
+	status = 0;
 
-		spi = m->spi;
-		tmp = 0;
-		cs_change = 1;
-		status = 0;
+	list_for_each_entry (t, &m->transfers, transfer_list) {
 
-		list_for_each_entry (t, &m->transfers, transfer_list) {
-
-			/* override speed or wordsize? */
-			if (t->speed_hz || t->bits_per_word)
-				do_setup = 1;
-
-			/* init (-1) or override (1) transfer params */
-			if (do_setup != 0) {
-				status = bitbang->setup_transfer(spi, t);
-				if (status < 0)
-					break;
-				if (do_setup == -1)
-					do_setup = 0;
-			}
-
-			/* set up default clock polarity, and activate chip;
-			 * this implicitly updates clock and spi modes as
-			 * previously recorded for this device via setup().
-			 * (and also deselects any other chip that might be
-			 * selected ...)
-			 */
-			if (cs_change) {
-				bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
-				ndelay(nsecs);
-			}
-			cs_change = t->cs_change;
-			if (!t->tx_buf && !t->rx_buf && t->len) {
-				status = -EINVAL;
-				break;
-			}
+		/* override speed or wordsize? */
+		if (t->speed_hz || t->bits_per_word)
+			do_setup = 1;
 
-			/* transfer data.  the lower level code handles any
-			 * new dma mappings it needs. our caller always gave
-			 * us dma-safe buffers.
-			 */
-			if (t->len) {
-				/* REVISIT dma API still needs a designated
-				 * DMA_ADDR_INVALID; ~0 might be better.
-				 */
-				if (!m->is_dma_mapped)
-					t->rx_dma = t->tx_dma = 0;
-				status = bitbang->txrx_bufs(spi, t);
-			}
-			if (status > 0)
-				m->actual_length += status;
-			if (status != t->len) {
-				/* always report some kind of error */
-				if (status >= 0)
-					status = -EREMOTEIO;
+		/* init (-1) or override (1) transfer params */
+		if (do_setup != 0) {
+			status = bitbang->setup_transfer(spi, t);
+			if (status < 0)
 				break;
-			}
-			status = 0;
-
-			/* protocol tweaks before next transfer */
-			if (t->delay_usecs)
-				udelay(t->delay_usecs);
-
-			if (cs_change && !list_is_last(&t->transfer_list, &m->transfers)) {
-				/* sometimes a short mid-message deselect of the chip
-				 * may be needed to terminate a mode or command
-				 */
-				ndelay(nsecs);
-				bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
-				ndelay(nsecs);
-			}
+			if (do_setup == -1)
+				do_setup = 0;
 		}
 
-		m->status = status;
-		m->complete(m->context);
+		/* set up default clock polarity, and activate chip;
+		 * this implicitly updates clock and spi modes as
+		 * previously recorded for this device via setup().
+		 * (and also deselects any other chip that might be
+		 * selected ...)
+		 */
+		if (cs_change) {
+			bitbang->chipselect(spi, BITBANG_CS_ACTIVE);
+			ndelay(nsecs);
+		}
+		cs_change = t->cs_change;
+		if (!t->tx_buf && !t->rx_buf && t->len) {
+			status = -EINVAL;
+			break;
+		}
 
-		/* normally deactivate chipselect ... unless no error and
-		 * cs_change has hinted that the next message will probably
-		 * be for this chip too.
+		/* transfer data.  the lower level code handles any
+		 * new dma mappings it needs. our caller always gave
+		 * us dma-safe buffers.
 		 */
-		if (!(status == 0 && cs_change)) {
+		if (t->len) {
+			/* REVISIT dma API still needs a designated
+			 * DMA_ADDR_INVALID; ~0 might be better.
+			 */
+			if (!m->is_dma_mapped)
+				t->rx_dma = t->tx_dma = 0;
+			status = bitbang->txrx_bufs(spi, t);
+		}
+		if (status > 0)
+			m->actual_length += status;
+		if (status != t->len) {
+			/* always report some kind of error */
+			if (status >= 0)
+				status = -EREMOTEIO;
+			break;
+		}
+		status = 0;
+
+		/* protocol tweaks before next transfer */
+		if (t->delay_usecs)
+			udelay(t->delay_usecs);
+
+		if (cs_change && !list_is_last(&t->transfer_list, &m->transfers)) {
+			/* sometimes a short mid-message deselect of the chip
+			 * may be needed to terminate a mode or command
+			 */
 			ndelay(nsecs);
 			bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
 			ndelay(nsecs);
 		}
+	}
+
+	m->status = status;
+	m->complete(m->context);
+
+	/* normally deactivate chipselect ... unless no error and
+	 * cs_change has hinted that the next message will probably
+	 * be for this chip too.
+	 */
+	if (!(status == 0 && cs_change)) {
+		ndelay(nsecs);
+		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
+		ndelay(nsecs);
+	}
+
+	return status;
+}
+
+static void bitbang_work(struct work_struct *work)
+{
+	struct spi_bitbang	*bitbang =
+		container_of(work, struct spi_bitbang, work);
+	unsigned long		flags;
+	struct spi_message	*m, *_m;
+
+	spin_lock_irqsave(&bitbang->lock, flags);
+	bitbang->busy = 1;
+	list_for_each_entry_safe(m, _m, &bitbang->queue, queue) {
+		list_del(&m->queue);
+		spin_unlock_irqrestore(&bitbang->lock, flags);
+
+		spi_bitbang_transfer_one(m->spi, m);
 
 		spin_lock_irqsave(&bitbang->lock, flags);
 	}