diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
new file mode 100644
index 0000000..02d57fb
--- /dev/null
+++ b/drivers/spi/spi-bitbang.c
@@ -0,0 +1,505 @@
+/*
+ * polling/bitbanging SPI master controller driver utilities
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * FIRST PART (OPTIONAL):  word-at-a-time spi_transfer support.
+ * Use this for GPIO or shift-register level hardware APIs.
+ *
+ * spi_bitbang_cs is in spi_device->controller_state, which is unavailable
+ * to glue code.  These bitbang setup() and cleanup() routines are always
+ * used, though maybe they're called from controller-aware code.
+ *
+ * chipselect() and friends may use use spi_device->controller_data and
+ * controller registers as appropriate.
+ *
+ *
+ * NOTE:  SPI controller pins can often be used as GPIO pins instead,
+ * which means you could use a bitbang driver either to get hardware
+ * working quickly, or testing for differences that aren't speed related.
+ */
+
+struct spi_bitbang_cs {
+	unsigned	nsecs;	/* (clock cycle time)/2 */
+	u32		(*txrx_word)(struct spi_device *spi, unsigned nsecs,
+					u32 word, u8 bits);
+	unsigned	(*txrx_bufs)(struct spi_device *,
+					u32 (*txrx_word)(
+						struct spi_device *spi,
+						unsigned nsecs,
+						u32 word, u8 bits),
+					unsigned, struct spi_transfer *);
+};
+
+static unsigned bitbang_txrx_8(
+	struct spi_device	*spi,
+	u32			(*txrx_word)(struct spi_device *spi,
+					unsigned nsecs,
+					u32 word, u8 bits),
+	unsigned		ns,
+	struct spi_transfer	*t
+) {
+	unsigned		bits = t->bits_per_word ? : spi->bits_per_word;
+	unsigned		count = t->len;
+	const u8		*tx = t->tx_buf;
+	u8			*rx = t->rx_buf;
+
+	while (likely(count > 0)) {
+		u8		word = 0;
+
+		if (tx)
+			word = *tx++;
+		word = txrx_word(spi, ns, word, bits);
+		if (rx)
+			*rx++ = word;
+		count -= 1;
+	}
+	return t->len - count;
+}
+
+static unsigned bitbang_txrx_16(
+	struct spi_device	*spi,
+	u32			(*txrx_word)(struct spi_device *spi,
+					unsigned nsecs,
+					u32 word, u8 bits),
+	unsigned		ns,
+	struct spi_transfer	*t
+) {
+	unsigned		bits = t->bits_per_word ? : spi->bits_per_word;
+	unsigned		count = t->len;
+	const u16		*tx = t->tx_buf;
+	u16			*rx = t->rx_buf;
+
+	while (likely(count > 1)) {
+		u16		word = 0;
+
+		if (tx)
+			word = *tx++;
+		word = txrx_word(spi, ns, word, bits);
+		if (rx)
+			*rx++ = word;
+		count -= 2;
+	}
+	return t->len - count;
+}
+
+static unsigned bitbang_txrx_32(
+	struct spi_device	*spi,
+	u32			(*txrx_word)(struct spi_device *spi,
+					unsigned nsecs,
+					u32 word, u8 bits),
+	unsigned		ns,
+	struct spi_transfer	*t
+) {
+	unsigned		bits = t->bits_per_word ? : spi->bits_per_word;
+	unsigned		count = t->len;
+	const u32		*tx = t->tx_buf;
+	u32			*rx = t->rx_buf;
+
+	while (likely(count > 3)) {
+		u32		word = 0;
+
+		if (tx)
+			word = *tx++;
+		word = txrx_word(spi, ns, word, bits);
+		if (rx)
+			*rx++ = word;
+		count -= 4;
+	}
+	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
+ */
+int spi_bitbang_setup(struct spi_device *spi)
+{
+	struct spi_bitbang_cs	*cs = spi->controller_state;
+	struct spi_bitbang	*bitbang;
+	int			retval;
+	unsigned long		flags;
+
+	bitbang = spi_master_get_devdata(spi->master);
+
+	if (!cs) {
+		cs = kzalloc(sizeof *cs, GFP_KERNEL);
+		if (!cs)
+			return -ENOMEM;
+		spi->controller_state = cs;
+	}
+
+	/* 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;
+
+	retval = bitbang->setup_transfer(spi, NULL);
+	if (retval < 0)
+		return retval;
+
+	dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
+
+	/* NOTE we _need_ to call chipselect() early, ideally with adapter
+	 * setup, unless the hardware defaults cooperate to avoid confusion
+	 * between normal (active low) and inverted chipselects.
+	 */
+
+	/* deselect chip (low or high) */
+	spin_lock_irqsave(&bitbang->lock, flags);
+	if (!bitbang->busy) {
+		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
+		ndelay(cs->nsecs);
+	}
+	spin_unlock_irqrestore(&bitbang->lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_setup);
+
+/**
+ * spi_bitbang_cleanup - default cleanup for per-word I/O loops
+ */
+void spi_bitbang_cleanup(struct spi_device *spi)
+{
+	kfree(spi->controller_state);
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_cleanup);
+
+static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct spi_bitbang_cs	*cs = spi->controller_state;
+	unsigned		nsecs = cs->nsecs;
+
+	return cs->txrx_bufs(spi, cs->txrx_word, nsecs, t);
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * SECOND PART ... simple transfer queue runner.
+ *
+ * This costs a task context per controller, running the queue by
+ * performing each transfer in sequence.  Smarter hardware can queue
+ * several DMA transfers at once, and process several controller queues
+ * in parallel; this driver doesn't match such hardware very well.
+ *
+ * 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)
+{
+	struct spi_bitbang	*bitbang =
+		container_of(work, struct spi_bitbang, work);
+	unsigned long		flags;
+
+	spin_lock_irqsave(&bitbang->lock, flags);
+	bitbang->busy = 1;
+	while (!list_empty(&bitbang->queue)) {
+		struct spi_message	*m;
+		struct spi_device	*spi;
+		unsigned		nsecs;
+		struct spi_transfer	*t = NULL;
+		unsigned		tmp;
+		unsigned		cs_change;
+		int			status;
+		int			do_setup = -1;
+
+		m = container_of(bitbang->queue.next, struct spi_message,
+				queue);
+		list_del_init(&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;
+
+		spi = m->spi;
+		tmp = 0;
+		cs_change = 1;
+		status = 0;
+
+		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;
+			}
+
+			/* 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;
+				break;
+			}
+			status = 0;
+
+			/* protocol tweaks before next transfer */
+			if (t->delay_usecs)
+				udelay(t->delay_usecs);
+
+			if (!cs_change)
+				continue;
+			if (t->transfer_list.next == &m->transfers)
+				break;
+
+			/* 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);
+		}
+
+		spin_lock_irqsave(&bitbang->lock, flags);
+	}
+	bitbang->busy = 0;
+	spin_unlock_irqrestore(&bitbang->lock, flags);
+}
+
+/**
+ * spi_bitbang_transfer - default submit to transfer queue
+ */
+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;
+
+	bitbang = spi_master_get_devdata(spi->master);
+
+	spin_lock_irqsave(&bitbang->lock, flags);
+	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 status;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
+
+/*----------------------------------------------------------------------*/
+
+/**
+ * spi_bitbang_start - start up a polled/bitbanging SPI master driver
+ * @bitbang: driver handle
+ *
+ * Caller should have zero-initialized all parts of the structure, and then
+ * provided callbacks for chip selection and I/O loops.  If the master has
+ * a transfer method, its final step should call spi_bitbang_transfer; or,
+ * that's the default if the transfer routine is not initialized.  It should
+ * also set up the bus number and number of chipselects.
+ *
+ * For i/o loops, provide callbacks either per-word (for bitbanging, or for
+ * hardware that basically exposes a shift register) or per-spi_transfer
+ * (which takes better advantage of hardware like fifos or DMA engines).
+ *
+ * Drivers using per-word I/O loops should use (or call) spi_bitbang_setup,
+ * spi_bitbang_cleanup and spi_bitbang_setup_transfer to handle those spi
+ * master methods.  Those methods are the defaults if the bitbang->txrx_bufs
+ * routine isn't initialized.
+ *
+ * This routine registers the spi_master, which will process requests in a
+ * dedicated task, keeping IRQs unblocked most of the time.  To stop
+ * processing those requests, call spi_bitbang_stop().
+ */
+int spi_bitbang_start(struct spi_bitbang *bitbang)
+{
+	int	status;
+
+	if (!bitbang->master || !bitbang->chipselect)
+		return -EINVAL;
+
+	INIT_WORK(&bitbang->work, bitbang_work);
+	spin_lock_init(&bitbang->lock);
+	INIT_LIST_HEAD(&bitbang->queue);
+
+	if (!bitbang->master->mode_bits)
+		bitbang->master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags;
+
+	if (!bitbang->master->transfer)
+		bitbang->master->transfer = spi_bitbang_transfer;
+	if (!bitbang->txrx_bufs) {
+		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;
+		}
+	} else if (!bitbang->master->setup)
+		return -EINVAL;
+	if (bitbang->master->transfer == spi_bitbang_transfer &&
+			!bitbang->setup_transfer)
+		return -EINVAL;
+
+	/* this task is the only thing to touch the SPI bits */
+	bitbang->busy = 0;
+	bitbang->workqueue = create_singlethread_workqueue(
+			dev_name(bitbang->master->dev.parent));
+	if (bitbang->workqueue == NULL) {
+		status = -EBUSY;
+		goto err1;
+	}
+
+	/* driver may get busy before register() returns, especially
+	 * if someone registered boardinfo for devices
+	 */
+	status = spi_register_master(bitbang->master);
+	if (status < 0)
+		goto err2;
+
+	return status;
+
+err2:
+	destroy_workqueue(bitbang->workqueue);
+err1:
+	return status;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_start);
+
+/**
+ * spi_bitbang_stop - stops the task providing spi communication
+ */
+int spi_bitbang_stop(struct spi_bitbang *bitbang)
+{
+	spi_unregister_master(bitbang->master);
+
+	WARN_ON(!list_empty(&bitbang->queue));
+
+	destroy_workqueue(bitbang->workqueue);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bitbang_stop);
+
+MODULE_LICENSE("GPL");
+