Merge commit '8700c95adb03' into timers/nohz

The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.

Merge a common upstream merge point that has these
updates.

Conflicts:
	include/linux/perf_event.h
	kernel/rcutree.h
	kernel/rcutree_plugin.h

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 660 insertions, 68 deletions

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 656d137db25..787bd2c22bc 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -15,16 +15,17 @@
 #include <linux/platform_device.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/spi/spi.h>
 #include <linux/slab.h>
 #include <linux/platform_data/atmel.h>
+#include <linux/platform_data/dma-atmel.h>
 #include <linux/of.h>
 
-#include <asm/io.h>
-#include <asm/gpio.h>
-#include <mach/cpu.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
 
 /* SPI register offsets */
 #define SPI_CR					0x0000
@@ -39,6 +40,7 @@
 #define SPI_CSR1				0x0034
 #define SPI_CSR2				0x0038
 #define SPI_CSR3				0x003c
+#define SPI_VERSION				0x00fc
 #define SPI_RPR					0x0100
 #define SPI_RCR					0x0104
 #define SPI_TPR					0x0108
@@ -71,6 +73,8 @@
 #define SPI_FDIV_SIZE				1
 #define SPI_MODFDIS_OFFSET			4
 #define SPI_MODFDIS_SIZE			1
+#define SPI_WDRBT_OFFSET			5
+#define SPI_WDRBT_SIZE				1
 #define SPI_LLB_OFFSET				7
 #define SPI_LLB_SIZE				1
 #define SPI_PCS_OFFSET				16
@@ -180,6 +184,27 @@
 #define spi_writel(port,reg,value) \
 	__raw_writel((value), (port)->regs + SPI_##reg)
 
+/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
+ * cache operations; better heuristics consider wordsize and bitrate.
+ */
+#define DMA_MIN_BYTES	16
+
+struct atmel_spi_dma {
+	struct dma_chan			*chan_rx;
+	struct dma_chan			*chan_tx;
+	struct scatterlist		sgrx;
+	struct scatterlist		sgtx;
+	struct dma_async_tx_descriptor	*data_desc_rx;
+	struct dma_async_tx_descriptor	*data_desc_tx;
+
+	struct at_dma_slave	dma_slave;
+};
+
+struct atmel_spi_caps {
+	bool	is_spi2;
+	bool	has_wdrbt;
+	bool	has_dma_support;
+};
 
 /*
  * The core SPI transfer engine just talks to a register bank to set up
@@ -188,7 +213,9 @@
  */
 struct atmel_spi {
 	spinlock_t		lock;
+	unsigned long		flags;
 
+	phys_addr_t		phybase;
 	void __iomem		*regs;
 	int			irq;
 	struct clk		*clk;
@@ -197,13 +224,23 @@ struct atmel_spi {
 
 	u8			stopping;
 	struct list_head	queue;
+	struct tasklet_struct	tasklet;
 	struct spi_transfer	*current_transfer;
 	unsigned long		current_remaining_bytes;
 	struct spi_transfer	*next_transfer;
 	unsigned long		next_remaining_bytes;
+	int			done_status;
 
+	/* scratch buffer */
 	void			*buffer;
 	dma_addr_t		buffer_dma;
+
+	struct atmel_spi_caps	caps;
+
+	bool			use_dma;
+	bool			use_pdc;
+	/* dmaengine data */
+	struct atmel_spi_dma	dma;
 };
 
 /* Controller-specific per-slave state */
@@ -222,14 +259,10 @@ struct atmel_spi_device {
  *  - SPI_SR.TXEMPTY, SPI_SR.NSSR (and corresponding irqs)
  *  - SPI_CSRx.CSAAT
  *  - SPI_CSRx.SBCR allows faster clocking
- *
- * We can determine the controller version by reading the VERSION
- * register, but I haven't checked that it exists on all chips, and
- * this is cheaper anyway.
  */
-static bool atmel_spi_is_v2(void)
+static bool atmel_spi_is_v2(struct atmel_spi *as)
 {
-	return !cpu_is_at91rm9200();
+	return as->caps.is_spi2;
 }
 
 /*
@@ -250,11 +283,6 @@ static bool atmel_spi_is_v2(void)
  * Master on Chip Select 0.")  No workaround exists for that ... so for
  * nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
  * and (c) will trigger that first erratum in some cases.
- *
- * TODO: Test if the atmel_spi_is_v2() branch below works on
- * AT91RM9200 if we use some other register than CSR0. However, don't
- * do this unconditionally since AP7000 has an errata where the BITS
- * field in CSR0 overrides all other CSRs.
  */
 
 static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
@@ -263,15 +291,25 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 	unsigned active = spi->mode & SPI_CS_HIGH;
 	u32 mr;
 
-	if (atmel_spi_is_v2()) {
-		/*
-		 * Always use CSR0. This ensures that the clock
-		 * switches to the correct idle polarity before we
-		 * toggle the CS.
+	if (atmel_spi_is_v2(as)) {
+		spi_writel(as, CSR0 + 4 * spi->chip_select, asd->csr);
+		/* For the low SPI version, there is a issue that PDC transfer
+		 * on CS1,2,3 needs SPI_CSR0.BITS config as SPI_CSR1,2,3.BITS
 		 */
 		spi_writel(as, CSR0, asd->csr);
-		spi_writel(as, MR, SPI_BF(PCS, 0x0e) | SPI_BIT(MODFDIS)
-				| SPI_BIT(MSTR));
+		if (as->caps.has_wdrbt) {
+			spi_writel(as, MR,
+					SPI_BF(PCS, ~(0x01 << spi->chip_select))
+					| SPI_BIT(WDRBT)
+					| SPI_BIT(MODFDIS)
+					| SPI_BIT(MSTR));
+		} else {
+			spi_writel(as, MR,
+					SPI_BF(PCS, ~(0x01 << spi->chip_select))
+					| SPI_BIT(MODFDIS)
+					| SPI_BIT(MSTR));
+		}
+
 		mr = spi_readl(as, MR);
 		gpio_set_value(asd->npcs_pin, active);
 	} else {
@@ -318,10 +356,26 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
 			asd->npcs_pin, active ? " (low)" : "",
 			mr);
 
-	if (atmel_spi_is_v2() || spi->chip_select != 0)
+	if (atmel_spi_is_v2(as) || spi->chip_select != 0)
 		gpio_set_value(asd->npcs_pin, !active);
 }
 
+static void atmel_spi_lock(struct atmel_spi *as)
+{
+	spin_lock_irqsave(&as->lock, as->flags);
+}
+
+static void atmel_spi_unlock(struct atmel_spi *as)
+{
+	spin_unlock_irqrestore(&as->lock, as->flags);
+}
+
+static inline bool atmel_spi_use_dma(struct atmel_spi *as,
+				struct spi_transfer *xfer)
+{
+	return as->use_dma && xfer->len >= DMA_MIN_BYTES;
+}
+
 static inline int atmel_spi_xfer_is_last(struct spi_message *msg,
 					struct spi_transfer *xfer)
 {
@@ -333,6 +387,265 @@ static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer)
 	return xfer->delay_usecs == 0 && !xfer->cs_change;
 }
 
+static int atmel_spi_dma_slave_config(struct atmel_spi *as,
+				struct dma_slave_config *slave_config,
+				u8 bits_per_word)
+{
+	int err = 0;
+
+	if (bits_per_word > 8) {
+		slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+		slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+	} else {
+		slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+		slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	}
+
+	slave_config->dst_addr = (dma_addr_t)as->phybase + SPI_TDR;
+	slave_config->src_addr = (dma_addr_t)as->phybase + SPI_RDR;
+	slave_config->src_maxburst = 1;
+	slave_config->dst_maxburst = 1;
+	slave_config->device_fc = false;
+
+	slave_config->direction = DMA_MEM_TO_DEV;
+	if (dmaengine_slave_config(as->dma.chan_tx, slave_config)) {
+		dev_err(&as->pdev->dev,
+			"failed to configure tx dma channel\n");
+		err = -EINVAL;
+	}
+
+	slave_config->direction = DMA_DEV_TO_MEM;
+	if (dmaengine_slave_config(as->dma.chan_rx, slave_config)) {
+		dev_err(&as->pdev->dev,
+			"failed to configure rx dma channel\n");
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+static bool filter(struct dma_chan *chan, void *slave)
+{
+	struct	at_dma_slave *sl = slave;
+
+	if (sl->dma_dev == chan->device->dev) {
+		chan->private = sl;
+		return true;
+	} else {
+		return false;
+	}
+}
+
+static int atmel_spi_configure_dma(struct atmel_spi *as)
+{
+	struct at_dma_slave *sdata = &as->dma.dma_slave;
+	struct dma_slave_config	slave_config;
+	int err;
+
+	if (sdata && sdata->dma_dev) {
+		dma_cap_mask_t mask;
+
+		/* Try to grab two DMA channels */
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+		as->dma.chan_tx = dma_request_channel(mask, filter, sdata);
+		if (as->dma.chan_tx)
+			as->dma.chan_rx =
+				dma_request_channel(mask, filter, sdata);
+	}
+	if (!as->dma.chan_rx || !as->dma.chan_tx) {
+		dev_err(&as->pdev->dev,
+			"DMA channel not available, SPI unable to use DMA\n");
+		err = -EBUSY;
+		goto error;
+	}
+
+	err = atmel_spi_dma_slave_config(as, &slave_config, 8);
+	if (err)
+		goto error;
+
+	dev_info(&as->pdev->dev,
+			"Using %s (tx) and %s (rx) for DMA transfers\n",
+			dma_chan_name(as->dma.chan_tx),
+			dma_chan_name(as->dma.chan_rx));
+	return 0;
+error:
+	if (as->dma.chan_rx)
+		dma_release_channel(as->dma.chan_rx);
+	if (as->dma.chan_tx)
+		dma_release_channel(as->dma.chan_tx);
+	return err;
+}
+
+static void atmel_spi_stop_dma(struct atmel_spi *as)
+{
+	if (as->dma.chan_rx)
+		as->dma.chan_rx->device->device_control(as->dma.chan_rx,
+							DMA_TERMINATE_ALL, 0);
+	if (as->dma.chan_tx)
+		as->dma.chan_tx->device->device_control(as->dma.chan_tx,
+							DMA_TERMINATE_ALL, 0);
+}
+
+static void atmel_spi_release_dma(struct atmel_spi *as)
+{
+	if (as->dma.chan_rx)
+		dma_release_channel(as->dma.chan_rx);
+	if (as->dma.chan_tx)
+		dma_release_channel(as->dma.chan_tx);
+}
+
+/* This function is called by the DMA driver from tasklet context */
+static void dma_callback(void *data)
+{
+	struct spi_master	*master = data;
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+
+	/* trigger SPI tasklet */
+	tasklet_schedule(&as->tasklet);
+}
+
+/*
+ * Next transfer using PIO.
+ * lock is held, spi tasklet is blocked
+ */
+static void atmel_spi_next_xfer_pio(struct spi_master *master,
+				struct spi_transfer *xfer)
+{
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+
+	dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_pio\n");
+
+	as->current_remaining_bytes = xfer->len;
+
+	/* Make sure data is not remaining in RDR */
+	spi_readl(as, RDR);
+	while (spi_readl(as, SR) & SPI_BIT(RDRF)) {
+		spi_readl(as, RDR);
+		cpu_relax();
+	}
+
+	if (xfer->tx_buf)
+		spi_writel(as, TDR, *(u8 *)(xfer->tx_buf));
+	else
+		spi_writel(as, TDR, 0);
+
+	dev_dbg(master->dev.parent,
+		"  start pio xfer %p: len %u tx %p rx %p\n",
+		xfer, xfer->len, xfer->tx_buf, xfer->rx_buf);
+
+	/* Enable relevant interrupts */
+	spi_writel(as, IER, SPI_BIT(RDRF) | SPI_BIT(OVRES));
+}
+
+/*
+ * Submit next transfer for DMA.
+ * lock is held, spi tasklet is blocked
+ */
+static int atmel_spi_next_xfer_dma_submit(struct spi_master *master,
+				struct spi_transfer *xfer,
+				u32 *plen)
+{
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+	struct dma_chan		*rxchan = as->dma.chan_rx;
+	struct dma_chan		*txchan = as->dma.chan_tx;
+	struct dma_async_tx_descriptor *rxdesc;
+	struct dma_async_tx_descriptor *txdesc;
+	struct dma_slave_config	slave_config;
+	dma_cookie_t		cookie;
+	u32	len = *plen;
+
+	dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_dma_submit\n");
+
+	/* Check that the channels are available */
+	if (!rxchan || !txchan)
+		return -ENODEV;
+
+	/* release lock for DMA operations */
+	atmel_spi_unlock(as);
+
+	/* prepare the RX dma transfer */
+	sg_init_table(&as->dma.sgrx, 1);
+	if (xfer->rx_buf) {
+		as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen;
+	} else {
+		as->dma.sgrx.dma_address = as->buffer_dma;
+		if (len > BUFFER_SIZE)
+			len = BUFFER_SIZE;
+	}
+
+	/* prepare the TX dma transfer */
+	sg_init_table(&as->dma.sgtx, 1);
+	if (xfer->tx_buf) {
+		as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen;
+	} else {
+		as->dma.sgtx.dma_address = as->buffer_dma;
+		if (len > BUFFER_SIZE)
+			len = BUFFER_SIZE;
+		memset(as->buffer, 0, len);
+	}
+
+	sg_dma_len(&as->dma.sgtx) = len;
+	sg_dma_len(&as->dma.sgrx) = len;
+
+	*plen = len;
+
+	if (atmel_spi_dma_slave_config(as, &slave_config, 8))
+		goto err_exit;
+
+	/* Send both scatterlists */
+	rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
+					&as->dma.sgrx,
+					1,
+					DMA_FROM_DEVICE,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
+					NULL);
+	if (!rxdesc)
+		goto err_dma;
+
+	txdesc = txchan->device->device_prep_slave_sg(txchan,
+					&as->dma.sgtx,
+					1,
+					DMA_TO_DEVICE,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
+					NULL);
+	if (!txdesc)
+		goto err_dma;
+
+	dev_dbg(master->dev.parent,
+		"  start dma xfer %p: len %u tx %p/%08x rx %p/%08x\n",
+		xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
+		xfer->rx_buf, xfer->rx_dma);
+
+	/* Enable relevant interrupts */
+	spi_writel(as, IER, SPI_BIT(OVRES));
+
+	/* Put the callback on the RX transfer only, that should finish last */
+	rxdesc->callback = dma_callback;
+	rxdesc->callback_param = master;
+
+	/* Submit and fire RX and TX with TX last so we're ready to read! */
+	cookie = rxdesc->tx_submit(rxdesc);
+	if (dma_submit_error(cookie))
+		goto err_dma;
+	cookie = txdesc->tx_submit(txdesc);
+	if (dma_submit_error(cookie))
+		goto err_dma;
+	rxchan->device->device_issue_pending(rxchan);
+	txchan->device->device_issue_pending(txchan);
+
+	/* take back lock */
+	atmel_spi_lock(as);
+	return 0;
+
+err_dma:
+	spi_writel(as, IDR, SPI_BIT(OVRES));
+	atmel_spi_stop_dma(as);
+err_exit:
+	atmel_spi_lock(as);
+	return -ENOMEM;
+}
+
 static void atmel_spi_next_xfer_data(struct spi_master *master,
 				struct spi_transfer *xfer,
 				dma_addr_t *tx_dma,
@@ -350,6 +663,7 @@ static void atmel_spi_next_xfer_data(struct spi_master *master,
 		if (len > BUFFER_SIZE)
 			len = BUFFER_SIZE;
 	}
+
 	if (xfer->tx_buf)
 		*tx_dma = xfer->tx_dma + xfer->len - *plen;
 	else {
@@ -365,10 +679,10 @@ static void atmel_spi_next_xfer_data(struct spi_master *master,
 }
 
 /*
- * Submit next transfer for DMA.
+ * Submit next transfer for PDC.
  * lock is held, spi irq is blocked
  */
-static void atmel_spi_next_xfer(struct spi_master *master,
+static void atmel_spi_pdc_next_xfer(struct spi_master *master,
 				struct spi_message *msg)
 {
 	struct atmel_spi	*as = spi_master_get_devdata(master);
@@ -465,6 +779,48 @@ static void atmel_spi_next_xfer(struct spi_master *master,
 	spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
 }
 
+/*
+ * Choose way to submit next transfer and start it.
+ * lock is held, spi tasklet is blocked
+ */
+static void atmel_spi_dma_next_xfer(struct spi_master *master,
+				struct spi_message *msg)
+{
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+	struct spi_transfer	*xfer;
+	u32	remaining, len;
+
+	remaining = as->current_remaining_bytes;
+	if (remaining) {
+		xfer = as->current_transfer;
+		len = remaining;
+	} else {
+		if (!as->current_transfer)
+			xfer = list_entry(msg->transfers.next,
+				struct spi_transfer, transfer_list);
+		else
+			xfer = list_entry(
+				as->current_transfer->transfer_list.next,
+					struct spi_transfer, transfer_list);
+
+		as->current_transfer = xfer;
+		len = xfer->len;
+	}
+
+	if (atmel_spi_use_dma(as, xfer)) {
+		u32 total = len;
+		if (!atmel_spi_next_xfer_dma_submit(master, xfer, &len)) {
+			as->current_remaining_bytes = total - len;
+			return;
+		} else {
+			dev_err(&msg->spi->dev, "unable to use DMA, fallback to PIO\n");
+		}
+	}
+
+	/* use PIO if error appened using DMA */
+	atmel_spi_next_xfer_pio(master, xfer);
+}
+
 static void atmel_spi_next_message(struct spi_master *master)
 {
 	struct atmel_spi	*as = spi_master_get_devdata(master);
@@ -489,7 +845,10 @@ static void atmel_spi_next_message(struct spi_master *master)
 	} else
 		cs_activate(as, spi);
 
-	atmel_spi_next_xfer(master, msg);
+	if (as->use_pdc)
+		atmel_spi_pdc_next_xfer(master, msg);
+	else
+		atmel_spi_dma_next_xfer(master, msg);
 }
 
 /*
@@ -542,38 +901,213 @@ static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
 				 xfer->len, DMA_FROM_DEVICE);
 }
 
+static void atmel_spi_disable_pdc_transfer(struct atmel_spi *as)
+{
+	spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
+}
+
 static void
 atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
-		struct spi_message *msg, int status, int stay)
+		struct spi_message *msg, int stay)
 {
-	if (!stay || status < 0)
+	if (!stay || as->done_status < 0)
 		cs_deactivate(as, msg->spi);
 	else
 		as->stay = msg->spi;
 
 	list_del(&msg->queue);
-	msg->status = status;
+	msg->status = as->done_status;
 
 	dev_dbg(master->dev.parent,
 		"xfer complete: %u bytes transferred\n",
 		msg->actual_length);
 
-	spin_unlock(&as->lock);
+	atmel_spi_unlock(as);
 	msg->complete(msg->context);
-	spin_lock(&as->lock);
+	atmel_spi_lock(as);
 
 	as->current_transfer = NULL;
 	as->next_transfer = NULL;
+	as->done_status = 0;
 
 	/* continue if needed */
-	if (list_empty(&as->queue) || as->stopping)
-		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
-	else
+	if (list_empty(&as->queue) || as->stopping) {
+		if (as->use_pdc)
+			atmel_spi_disable_pdc_transfer(as);
+	} else {
 		atmel_spi_next_message(master);
+	}
+}
+
+/* Called from IRQ
+ * lock is held
+ *
+ * Must update "current_remaining_bytes" to keep track of data
+ * to transfer.
+ */
+static void
+atmel_spi_pump_pio_data(struct atmel_spi *as, struct spi_transfer *xfer)
+{
+	u8		*txp;
+	u8		*rxp;
+	unsigned long	xfer_pos = xfer->len - as->current_remaining_bytes;
+
+	if (xfer->rx_buf) {
+		rxp = ((u8 *)xfer->rx_buf) + xfer_pos;
+		*rxp = spi_readl(as, RDR);
+	} else {
+		spi_readl(as, RDR);
+	}
+
+	as->current_remaining_bytes--;
+
+	if (as->current_remaining_bytes) {
+		if (xfer->tx_buf) {
+			txp = ((u8 *)xfer->tx_buf) + xfer_pos + 1;
+			spi_writel(as, TDR, *txp);
+		} else {
+			spi_writel(as, TDR, 0);
+		}
+	}
+}
+
+/* Tasklet
+ * Called from DMA callback + pio transfer and overrun IRQ.
+ */
+static void atmel_spi_tasklet_func(unsigned long data)
+{
+	struct spi_master	*master = (struct spi_master *)data;
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+	struct spi_message	*msg;
+	struct spi_transfer	*xfer;
+
+	dev_vdbg(master->dev.parent, "atmel_spi_tasklet_func\n");
+
+	atmel_spi_lock(as);
+
+	xfer = as->current_transfer;
+
+	if (xfer == NULL)
+		/* already been there */
+		goto tasklet_out;
+
+	msg = list_entry(as->queue.next, struct spi_message, queue);
+
+	if (as->current_remaining_bytes == 0) {
+		if (as->done_status < 0) {
+			/* error happened (overrun) */
+			if (atmel_spi_use_dma(as, xfer))
+				atmel_spi_stop_dma(as);
+		} else {
+			/* only update length if no error */
+			msg->actual_length += xfer->len;
+		}
+
+		if (atmel_spi_use_dma(as, xfer))
+			if (!msg->is_dma_mapped)
+				atmel_spi_dma_unmap_xfer(master, xfer);
+
+		if (xfer->delay_usecs)
+			udelay(xfer->delay_usecs);
+
+		if (atmel_spi_xfer_is_last(msg, xfer) || as->done_status < 0) {
+			/* report completed (or erroneous) message */
+			atmel_spi_msg_done(master, as, msg, xfer->cs_change);
+		} else {
+			if (xfer->cs_change) {
+				cs_deactivate(as, msg->spi);
+				udelay(1);
+				cs_activate(as, msg->spi);
+			}
+
+			/*
+			 * Not done yet. Submit the next transfer.
+			 *
+			 * FIXME handle protocol options for xfer
+			 */
+			atmel_spi_dma_next_xfer(master, msg);
+		}
+	} else {
+		/*
+		 * Keep going, we still have data to send in
+		 * the current transfer.
+		 */
+		atmel_spi_dma_next_xfer(master, msg);
+	}
+
+tasklet_out:
+	atmel_spi_unlock(as);
 }
 
+/* Interrupt
+ *
+ * No need for locking in this Interrupt handler: done_status is the
+ * only information modified. What we need is the update of this field
+ * before tasklet runs. This is ensured by using barrier.
+ */
 static irqreturn_t
-atmel_spi_interrupt(int irq, void *dev_id)
+atmel_spi_pio_interrupt(int irq, void *dev_id)
+{
+	struct spi_master	*master = dev_id;
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+	u32			status, pending, imr;
+	struct spi_transfer	*xfer;
+	int			ret = IRQ_NONE;
+
+	imr = spi_readl(as, IMR);
+	status = spi_readl(as, SR);
+	pending = status & imr;
+
+	if (pending & SPI_BIT(OVRES)) {
+		ret = IRQ_HANDLED;
+		spi_writel(as, IDR, SPI_BIT(OVRES));
+		dev_warn(master->dev.parent, "overrun\n");
+
+		/*
+		 * When we get an overrun, we disregard the current
+		 * transfer. Data will not be copied back from any
+		 * bounce buffer and msg->actual_len will not be
+		 * updated with the last xfer.
+		 *
+		 * We will also not process any remaning transfers in
+		 * the message.
+		 *
+		 * All actions are done in tasklet with done_status indication
+		 */
+		as->done_status = -EIO;
+		smp_wmb();
+
+		/* Clear any overrun happening while cleaning up */
+		spi_readl(as, SR);
+
+		tasklet_schedule(&as->tasklet);
+
+	} else if (pending & SPI_BIT(RDRF)) {
+		atmel_spi_lock(as);
+
+		if (as->current_remaining_bytes) {
+			ret = IRQ_HANDLED;
+			xfer = as->current_transfer;
+			atmel_spi_pump_pio_data(as, xfer);
+			if (!as->current_remaining_bytes) {
+				/* no more data to xfer, kick tasklet */
+				spi_writel(as, IDR, pending);
+				tasklet_schedule(&as->tasklet);
+			}
+		}
+
+		atmel_spi_unlock(as);
+	} else {
+		WARN_ONCE(pending, "IRQ not handled, pending = %x\n", pending);
+		ret = IRQ_HANDLED;
+		spi_writel(as, IDR, pending);
+	}
+
+	return ret;
+}
+
+static irqreturn_t
+atmel_spi_pdc_interrupt(int irq, void *dev_id)
 {
 	struct spi_master	*master = dev_id;
 	struct atmel_spi	*as = spi_master_get_devdata(master);
@@ -582,7 +1116,7 @@ atmel_spi_interrupt(int irq, void *dev_id)
 	u32			status, pending, imr;
 	int			ret = IRQ_NONE;
 
-	spin_lock(&as->lock);
+	atmel_spi_lock(as);
 
 	xfer = as->current_transfer;
 	msg = list_entry(as->queue.next, struct spi_message, queue);
@@ -641,7 +1175,8 @@ atmel_spi_interrupt(int irq, void *dev_id)
 		/* Clear any overrun happening while cleaning up */
 		spi_readl(as, SR);
 
-		atmel_spi_msg_done(master, as, msg, -EIO, 0);
+		as->done_status = -EIO;
+		atmel_spi_msg_done(master, as, msg, 0);
 	} else if (pending & (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX))) {
 		ret = IRQ_HANDLED;
 
@@ -659,7 +1194,7 @@ atmel_spi_interrupt(int irq, void *dev_id)
 
 			if (atmel_spi_xfer_is_last(msg, xfer)) {
 				/* report completed message */
-				atmel_spi_msg_done(master, as, msg, 0,
+				atmel_spi_msg_done(master, as, msg,
 						xfer->cs_change);
 			} else {
 				if (xfer->cs_change) {
@@ -673,18 +1208,18 @@ atmel_spi_interrupt(int irq, void *dev_id)
 				 *
 				 * FIXME handle protocol options for xfer
 				 */
-				atmel_spi_next_xfer(master, msg);
+				atmel_spi_pdc_next_xfer(master, msg);
 			}
 		} else {
 			/*
 			 * Keep going, we still have data to send in
 			 * the current transfer.
 			 */
-			atmel_spi_next_xfer(master, msg);
+			atmel_spi_pdc_next_xfer(master, msg);
 		}
 	}
 
-	spin_unlock(&as->lock);
+	atmel_spi_unlock(as);
 
 	return ret;
 }
@@ -719,7 +1254,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 	}
 
 	/* see notes above re chipselect */
-	if (!atmel_spi_is_v2()
+	if (!atmel_spi_is_v2(as)
 			&& spi->chip_select == 0
 			&& (spi->mode & SPI_CS_HIGH)) {
 		dev_dbg(&spi->dev, "setup: can't be active-high\n");
@@ -728,7 +1263,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 
 	/* v1 chips start out at half the peripheral bus speed. */
 	bus_hz = clk_get_rate(as->clk);
-	if (!atmel_spi_is_v2())
+	if (!atmel_spi_is_v2(as))
 		bus_hz /= 2;
 
 	if (spi->max_speed_hz) {
@@ -789,13 +1324,11 @@ static int atmel_spi_setup(struct spi_device *spi)
 		spi->controller_state = asd;
 		gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
 	} else {
-		unsigned long		flags;
-
-		spin_lock_irqsave(&as->lock, flags);
+		atmel_spi_lock(as);
 		if (as->stay == spi)
 			as->stay = NULL;
 		cs_deactivate(as, spi);
-		spin_unlock_irqrestore(&as->lock, flags);
+		atmel_spi_unlock(as);
 	}
 
 	asd->csr = csr;
@@ -804,7 +1337,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 		"setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
 		bus_hz / scbr, bits, spi->mode, spi->chip_select, csr);
 
-	if (!atmel_spi_is_v2())
+	if (!atmel_spi_is_v2(as))
 		spi_writel(as, CSR0 + 4 * spi->chip_select, csr);
 
 	return 0;
@@ -814,7 +1347,6 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 {
 	struct atmel_spi	*as;
 	struct spi_transfer	*xfer;
-	unsigned long		flags;
 	struct device		*controller = spi->master->dev.parent;
 	u8			bits;
 	struct atmel_spi_device	*asd;
@@ -854,13 +1386,10 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 
 		/*
 		 * DMA map early, for performance (empties dcache ASAP) and
-		 * better fault reporting.  This is a DMA-only driver.
-		 *
-		 * NOTE that if dma_unmap_single() ever starts to do work on
-		 * platforms supported by this driver, we would need to clean
-		 * up mappings for previously-mapped transfers.
+		 * better fault reporting.
 		 */
-		if (!msg->is_dma_mapped) {
+		if ((!msg->is_dma_mapped) && (atmel_spi_use_dma(as, xfer)
+			|| as->use_pdc)) {
 			if (atmel_spi_dma_map_xfer(as, xfer) < 0)
 				return -ENOMEM;
 		}
@@ -879,11 +1408,11 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 	msg->status = -EINPROGRESS;
 	msg->actual_length = 0;
 
-	spin_lock_irqsave(&as->lock, flags);
+	atmel_spi_lock(as);
 	list_add_tail(&msg->queue, &as->queue);
 	if (!as->current_transfer)
 		atmel_spi_next_message(spi->master);
-	spin_unlock_irqrestore(&as->lock, flags);
+	atmel_spi_unlock(as);
 
 	return 0;
 }
@@ -893,23 +1422,39 @@ static void atmel_spi_cleanup(struct spi_device *spi)
 	struct atmel_spi	*as = spi_master_get_devdata(spi->master);
 	struct atmel_spi_device	*asd = spi->controller_state;
 	unsigned		gpio = (unsigned) spi->controller_data;
-	unsigned long		flags;
 
 	if (!asd)
 		return;
 
-	spin_lock_irqsave(&as->lock, flags);
+	atmel_spi_lock(as);
 	if (as->stay == spi) {
 		as->stay = NULL;
 		cs_deactivate(as, spi);
 	}
-	spin_unlock_irqrestore(&as->lock, flags);
+	atmel_spi_unlock(as);
 
 	spi->controller_state = NULL;
 	gpio_free(gpio);
 	kfree(asd);
 }
 
+static inline unsigned int atmel_get_version(struct atmel_spi *as)
+{
+	return spi_readl(as, VERSION) & 0x00000fff;
+}
+
+static void atmel_get_caps(struct atmel_spi *as)
+{
+	unsigned int version;
+
+	version = atmel_get_version(as);
+	dev_info(&as->pdev->dev, "version: 0x%x\n", version);
+
+	as->caps.is_spi2 = version > 0x121;
+	as->caps.has_wdrbt = version >= 0x210;
+	as->caps.has_dma_support = version >= 0x212;
+}
+
 /*-------------------------------------------------------------------------*/
 
 static int atmel_spi_probe(struct platform_device *pdev)
@@ -963,15 +1508,39 @@ static int atmel_spi_probe(struct platform_device *pdev)
 
 	spin_lock_init(&as->lock);
 	INIT_LIST_HEAD(&as->queue);
+
 	as->pdev = pdev;
 	as->regs = ioremap(regs->start, resource_size(regs));
 	if (!as->regs)
 		goto out_free_buffer;
+	as->phybase = regs->start;
 	as->irq = irq;
 	as->clk = clk;
 
-	ret = request_irq(irq, atmel_spi_interrupt, 0,
-			dev_name(&pdev->dev), master);
+	atmel_get_caps(as);
+
+	as->use_dma = false;
+	as->use_pdc = false;
+	if (as->caps.has_dma_support) {
+		if (atmel_spi_configure_dma(as) == 0)
+			as->use_dma = true;
+	} else {
+		as->use_pdc = true;
+	}
+
+	if (as->caps.has_dma_support && !as->use_dma)
+		dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n");
+
+	if (as->use_pdc) {
+		ret = request_irq(irq, atmel_spi_pdc_interrupt, 0,
+					dev_name(&pdev->dev), master);
+	} else {
+		tasklet_init(&as->tasklet, atmel_spi_tasklet_func,
+					(unsigned long)master);
+
+		ret = request_irq(irq, atmel_spi_pio_interrupt, 0,
+					dev_name(&pdev->dev), master);
+	}
 	if (ret)
 		goto out_unmap_regs;
 
@@ -979,8 +1548,15 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	clk_enable(clk);
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
-	spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
-	spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
+	if (as->caps.has_wdrbt) {
+		spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
+				| SPI_BIT(MSTR));
+	} else {
+		spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
+	}
+
+	if (as->use_pdc)
+		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
 	spi_writel(as, CR, SPI_BIT(SPIEN));
 
 	/* go! */
@@ -989,11 +1565,14 @@ static int atmel_spi_probe(struct platform_device *pdev)
 
 	ret = spi_register_master(master);
 	if (ret)
-		goto out_reset_hw;
+		goto out_free_dma;
 
 	return 0;
 
-out_reset_hw:
+out_free_dma:
+	if (as->use_dma)
+		atmel_spi_release_dma(as);
+
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 	clk_disable(clk);
@@ -1001,6 +1580,8 @@ out_reset_hw:
 out_unmap_regs:
 	iounmap(as->regs);
 out_free_buffer:
+	if (!as->use_pdc)
+		tasklet_kill(&as->tasklet);
 	dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
 			as->buffer_dma);
 out_free:
@@ -1014,10 +1595,16 @@ static int atmel_spi_remove(struct platform_device *pdev)
 	struct spi_master	*master = platform_get_drvdata(pdev);
 	struct atmel_spi	*as = spi_master_get_devdata(master);
 	struct spi_message	*msg;
+	struct spi_transfer	*xfer;
 
 	/* reset the hardware and block queue progress */
 	spin_lock_irq(&as->lock);
 	as->stopping = 1;
+	if (as->use_dma) {
+		atmel_spi_stop_dma(as);
+		atmel_spi_release_dma(as);
+	}
+
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 	spi_readl(as, SR);
@@ -1025,13 +1612,18 @@ static int atmel_spi_remove(struct platform_device *pdev)
 
 	/* Terminate remaining queued transfers */
 	list_for_each_entry(msg, &as->queue, queue) {
-		/* REVISIT unmapping the dma is a NOP on ARM and AVR32
-		 * but we shouldn't depend on that...
-		 */
+		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+			if (!msg->is_dma_mapped
+				&& (atmel_spi_use_dma(as, xfer)
+					|| as->use_pdc))
+				atmel_spi_dma_unmap_xfer(master, xfer);
+		}
 		msg->status = -ESHUTDOWN;
 		msg->complete(msg->context);
 	}
 
+	if (!as->use_pdc)
+		tasklet_kill(&as->tasklet);
 	dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
 			as->buffer_dma);