Linux-libre 4.2-gnu

1 files changed, 250 insertions, 52 deletions

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 9bd10a9b4..1c758cd1e 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -41,29 +41,38 @@
 
 /* AT91 TWI register definitions */
 #define	AT91_TWI_CR		0x0000	/* Control Register */
-#define	AT91_TWI_START		0x0001	/* Send a Start Condition */
-#define	AT91_TWI_STOP		0x0002	/* Send a Stop Condition */
-#define	AT91_TWI_MSEN		0x0004	/* Master Transfer Enable */
-#define	AT91_TWI_SVDIS		0x0020	/* Slave Transfer Disable */
-#define	AT91_TWI_QUICK		0x0040	/* SMBus quick command */
-#define	AT91_TWI_SWRST		0x0080	/* Software Reset */
+#define	AT91_TWI_START		BIT(0)	/* Send a Start Condition */
+#define	AT91_TWI_STOP		BIT(1)	/* Send a Stop Condition */
+#define	AT91_TWI_MSEN		BIT(2)	/* Master Transfer Enable */
+#define	AT91_TWI_MSDIS		BIT(3)	/* Master Transfer Disable */
+#define	AT91_TWI_SVEN		BIT(4)	/* Slave Transfer Enable */
+#define	AT91_TWI_SVDIS		BIT(5)	/* Slave Transfer Disable */
+#define	AT91_TWI_QUICK		BIT(6)	/* SMBus quick command */
+#define	AT91_TWI_SWRST		BIT(7)	/* Software Reset */
+#define	AT91_TWI_ACMEN		BIT(16) /* Alternative Command Mode Enable */
+#define	AT91_TWI_ACMDIS		BIT(17) /* Alternative Command Mode Disable */
+#define	AT91_TWI_THRCLR		BIT(24) /* Transmit Holding Register Clear */
+#define	AT91_TWI_RHRCLR		BIT(25) /* Receive Holding Register Clear */
+#define	AT91_TWI_LOCKCLR	BIT(26) /* Lock Clear */
+#define	AT91_TWI_FIFOEN		BIT(28) /* FIFO Enable */
+#define	AT91_TWI_FIFODIS	BIT(29) /* FIFO Disable */
 
 #define	AT91_TWI_MMR		0x0004	/* Master Mode Register */
 #define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */
-#define	AT91_TWI_MREAD		0x1000	/* Master Read Direction */
+#define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */
 
 #define	AT91_TWI_IADR		0x000c	/* Internal Address Register */
 
 #define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
 
 #define	AT91_TWI_SR		0x0020	/* Status Register */
-#define	AT91_TWI_TXCOMP		0x0001	/* Transmission Complete */
-#define	AT91_TWI_RXRDY		0x0002	/* Receive Holding Register Ready */
-#define	AT91_TWI_TXRDY		0x0004	/* Transmit Holding Register Ready */
-
-#define	AT91_TWI_OVRE		0x0040	/* Overrun Error */
-#define	AT91_TWI_UNRE		0x0080	/* Underrun Error */
-#define	AT91_TWI_NACK		0x0100	/* Not Acknowledged */
+#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */
+#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */
+#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */
+#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */
+#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */
+#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */
+#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */
 
 #define	AT91_TWI_INT_MASK \
 	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)
@@ -74,17 +83,40 @@
 #define	AT91_TWI_RHR		0x0030	/* Receive Holding Register */
 #define	AT91_TWI_THR		0x0034	/* Transmit Holding Register */
 
+#define	AT91_TWI_ACR		0x0040	/* Alternative Command Register */
+#define	AT91_TWI_ACR_DATAL(len)	((len) & 0xff)
+#define	AT91_TWI_ACR_DIR	BIT(8)
+
+#define	AT91_TWI_FMR		0x0050	/* FIFO Mode Register */
+#define	AT91_TWI_FMR_TXRDYM(mode)	(((mode) & 0x3) << 0)
+#define	AT91_TWI_FMR_TXRDYM_MASK	(0x3 << 0)
+#define	AT91_TWI_FMR_RXRDYM(mode)	(((mode) & 0x3) << 4)
+#define	AT91_TWI_FMR_RXRDYM_MASK	(0x3 << 4)
+#define	AT91_TWI_ONE_DATA	0x0
+#define	AT91_TWI_TWO_DATA	0x1
+#define	AT91_TWI_FOUR_DATA	0x2
+
+#define	AT91_TWI_FLR		0x0054	/* FIFO Level Register */
+
+#define	AT91_TWI_FSR		0x0060	/* FIFO Status Register */
+#define	AT91_TWI_FIER		0x0064	/* FIFO Interrupt Enable Register */
+#define	AT91_TWI_FIDR		0x0068	/* FIFO Interrupt Disable Register */
+#define	AT91_TWI_FIMR		0x006c	/* FIFO Interrupt Mask Register */
+
+#define	AT91_TWI_VER		0x00fc	/* Version Register */
+
 struct at91_twi_pdata {
 	unsigned clk_max_div;
 	unsigned clk_offset;
 	bool has_unre_flag;
+	bool has_alt_cmd;
 	struct at_dma_slave dma_slave;
 };
 
 struct at91_twi_dma {
 	struct dma_chan *chan_rx;
 	struct dma_chan *chan_tx;
-	struct scatterlist sg;
+	struct scatterlist sg[2];
 	struct dma_async_tx_descriptor *data_desc;
 	enum dma_data_direction direction;
 	bool buf_mapped;
@@ -107,6 +139,7 @@ struct at91_twi_dev {
 	struct at91_twi_pdata *pdata;
 	bool use_dma;
 	bool recv_len_abort;
+	u32 fifo_size;
 	struct at91_twi_dma dma;
 };
 
@@ -140,6 +173,9 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev)
 {
 	at91_disable_twi_interrupts(dev);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+	/* FIFO should be enabled immediately after the software reset */
+	if (dev->fifo_size)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
 	at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
@@ -186,7 +222,7 @@ static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
 		dma->xfer_in_progress = false;
 	}
 	if (dma->buf_mapped) {
-		dma_unmap_single(dev->dev, sg_dma_address(&dma->sg),
+		dma_unmap_single(dev->dev, sg_dma_address(&dma->sg[0]),
 				 dev->buf_len, dma->direction);
 		dma->buf_mapped = false;
 	}
@@ -196,14 +232,16 @@ static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
 
 static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
 {
-	if (dev->buf_len <= 0)
+	if (!dev->buf_len)
 		return;
 
-	at91_twi_write(dev, AT91_TWI_THR, *dev->buf);
+	/* 8bit write works with and without FIFO */
+	writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
 
 	/* send stop when last byte has been written */
 	if (--dev->buf_len == 0)
-		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+		if (!dev->pdata->has_alt_cmd)
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 
 	dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len);
 
@@ -214,7 +252,7 @@ static void at91_twi_write_data_dma_callback(void *data)
 {
 	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
 
-	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg),
+	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
 			 dev->buf_len, DMA_TO_DEVICE);
 
 	/*
@@ -225,7 +263,8 @@ static void at91_twi_write_data_dma_callback(void *data)
 	 * we just have to enable TXCOMP one.
 	 */
 	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
-	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+	if (!dev->pdata->has_alt_cmd)
+		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 }
 
 static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
@@ -234,8 +273,9 @@ static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
 	struct dma_async_tx_descriptor *txdesc;
 	struct at91_twi_dma *dma = &dev->dma;
 	struct dma_chan *chan_tx = dma->chan_tx;
+	unsigned int sg_len = 1;
 
-	if (dev->buf_len <= 0)
+	if (!dev->buf_len)
 		return;
 
 	dma->direction = DMA_TO_DEVICE;
@@ -249,10 +289,43 @@ static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
 	}
 	dma->buf_mapped = true;
 	at91_twi_irq_restore(dev);
-	sg_dma_len(&dma->sg) = dev->buf_len;
-	sg_dma_address(&dma->sg) = dma_addr;
 
-	txdesc = dmaengine_prep_slave_sg(chan_tx, &dma->sg, 1, DMA_MEM_TO_DEV,
+	if (dev->fifo_size) {
+		size_t part1_len, part2_len;
+		struct scatterlist *sg;
+		unsigned fifo_mr;
+
+		sg_len = 0;
+
+		part1_len = dev->buf_len & ~0x3;
+		if (part1_len) {
+			sg = &dma->sg[sg_len++];
+			sg_dma_len(sg) = part1_len;
+			sg_dma_address(sg) = dma_addr;
+		}
+
+		part2_len = dev->buf_len & 0x3;
+		if (part2_len) {
+			sg = &dma->sg[sg_len++];
+			sg_dma_len(sg) = part2_len;
+			sg_dma_address(sg) = dma_addr + part1_len;
+		}
+
+		/*
+		 * DMA controller is triggered when at least 4 data can be
+		 * written into the TX FIFO
+		 */
+		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+		fifo_mr &= ~AT91_TWI_FMR_TXRDYM_MASK;
+		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_FOUR_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+	} else {
+		sg_dma_len(&dma->sg[0]) = dev->buf_len;
+		sg_dma_address(&dma->sg[0]) = dma_addr;
+	}
+
+	txdesc = dmaengine_prep_slave_sg(chan_tx, dma->sg, sg_len,
+					 DMA_MEM_TO_DEV,
 					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!txdesc) {
 		dev_err(dev->dev, "dma prep slave sg failed\n");
@@ -274,10 +347,11 @@ error:
 
 static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
 {
-	if (dev->buf_len <= 0)
+	if (!dev->buf_len)
 		return;
 
-	*dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
+	/* 8bit read works with and without FIFO */
+	*dev->buf = readb_relaxed(dev->base + AT91_TWI_RHR);
 	--dev->buf_len;
 
 	/* return if aborting, we only needed to read RHR to clear RXRDY*/
@@ -301,7 +375,7 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
 	}
 
 	/* send stop if second but last byte has been read */
-	if (dev->buf_len == 1)
+	if (!dev->pdata->has_alt_cmd && dev->buf_len == 1)
 		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 
 	dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len);
@@ -312,14 +386,18 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
 static void at91_twi_read_data_dma_callback(void *data)
 {
 	struct at91_twi_dev *dev = (struct at91_twi_dev *)data;
+	unsigned ier = AT91_TWI_TXCOMP;
 
-	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg),
+	dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
 			 dev->buf_len, DMA_FROM_DEVICE);
 
-	/* The last two bytes have to be read without using dma */
-	dev->buf += dev->buf_len - 2;
-	dev->buf_len = 2;
-	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_RXRDY | AT91_TWI_TXCOMP);
+	if (!dev->pdata->has_alt_cmd) {
+		/* The last two bytes have to be read without using dma */
+		dev->buf += dev->buf_len - 2;
+		dev->buf_len = 2;
+		ier |= AT91_TWI_RXRDY;
+	}
+	at91_twi_write(dev, AT91_TWI_IER, ier);
 }
 
 static void at91_twi_read_data_dma(struct at91_twi_dev *dev)
@@ -328,23 +406,38 @@ static void at91_twi_read_data_dma(struct at91_twi_dev *dev)
 	struct dma_async_tx_descriptor *rxdesc;
 	struct at91_twi_dma *dma = &dev->dma;
 	struct dma_chan *chan_rx = dma->chan_rx;
+	size_t buf_len;
 
+	buf_len = (dev->pdata->has_alt_cmd) ? dev->buf_len : dev->buf_len - 2;
 	dma->direction = DMA_FROM_DEVICE;
 
 	/* Keep in mind that we won't use dma to read the last two bytes */
 	at91_twi_irq_save(dev);
-	dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len - 2,
-				  DMA_FROM_DEVICE);
+	dma_addr = dma_map_single(dev->dev, dev->buf, buf_len, DMA_FROM_DEVICE);
 	if (dma_mapping_error(dev->dev, dma_addr)) {
 		dev_err(dev->dev, "dma map failed\n");
 		return;
 	}
 	dma->buf_mapped = true;
 	at91_twi_irq_restore(dev);
-	dma->sg.dma_address = dma_addr;
-	sg_dma_len(&dma->sg) = dev->buf_len - 2;
 
-	rxdesc = dmaengine_prep_slave_sg(chan_rx, &dma->sg, 1, DMA_DEV_TO_MEM,
+	if (dev->fifo_size && IS_ALIGNED(buf_len, 4)) {
+		unsigned fifo_mr;
+
+		/*
+		 * DMA controller is triggered when at least 4 data can be
+		 * read from the RX FIFO
+		 */
+		fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+		fifo_mr &= ~AT91_TWI_FMR_RXRDYM_MASK;
+		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_FOUR_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+	}
+
+	sg_dma_len(&dma->sg[0]) = buf_len;
+	sg_dma_address(&dma->sg[0]) = dma_addr;
+
+	rxdesc = dmaengine_prep_slave_sg(chan_rx, dma->sg, 1, DMA_DEV_TO_MEM,
 					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!rxdesc) {
 		dev_err(dev->dev, "dma prep slave sg failed\n");
@@ -393,6 +486,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	int ret;
 	unsigned long time_left;
 	bool has_unre_flag = dev->pdata->has_unre_flag;
+	bool has_alt_cmd = dev->pdata->has_alt_cmd;
 
 	/*
 	 * WARNING: the TXCOMP bit in the Status Register is NOT a clear on
@@ -402,6 +496,21 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	 * empty and STOP condition has been sent.
 	 * Consequently, we should enable NACK interrupt rather than TXCOMP to
 	 * detect transmission failure.
+	 * Indeed let's take the case of an i2c write command using DMA.
+	 * Whenever the slave doesn't acknowledge a byte, the LOCK, NACK and
+	 * TXCOMP bits are set together into the Status Register.
+	 * LOCK is a clear on write bit, which is set to prevent the DMA
+	 * controller from sending new data on the i2c bus after a NACK
+	 * condition has happened. Once locked, this i2c peripheral stops
+	 * triggering the DMA controller for new data but it is more than
+	 * likely that a new DMA transaction is already in progress, writing
+	 * into the Transmit Holding Register. Since the peripheral is locked,
+	 * these new data won't be sent to the i2c bus but they will remain
+	 * into the Transmit Holding Register, so TXCOMP bit is cleared.
+	 * Then when the interrupt handler is called, the Status Register is
+	 * read: the TXCOMP bit is clear but NACK bit is still set. The driver
+	 * manage the error properly, without waiting for timeout.
+	 * This case can be reproduced easyly when writing into an at24 eeprom.
 	 *
 	 * Besides, the TXCOMP bit is already set before the i2c transaction
 	 * has been started. For read transactions, this bit is cleared when
@@ -417,9 +526,9 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	 * condition since we don't know whether the TXCOMP interrupt is enabled
 	 * before or after the DMA has started to write into THR. So the TXCOMP
 	 * interrupt is enabled later by at91_twi_write_data_dma_callback().
-	 * Immediately after in that DMA callback, we still need to send the
-	 * STOP condition manually writing the corresponding bit into the
-	 * Control Register.
+	 * Immediately after in that DMA callback, if the alternative command
+	 * mode is not used, we still need to send the STOP condition manually
+	 * writing the corresponding bit into the Control Register.
 	 */
 
 	dev_dbg(dev->dev, "transfer: %s %d bytes.\n",
@@ -428,6 +537,21 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	reinit_completion(&dev->cmd_complete);
 	dev->transfer_status = 0;
 
+	if (dev->fifo_size) {
+		unsigned fifo_mr = at91_twi_read(dev, AT91_TWI_FMR);
+
+		/* Reset FIFO mode register */
+		fifo_mr &= ~(AT91_TWI_FMR_TXRDYM_MASK |
+			     AT91_TWI_FMR_RXRDYM_MASK);
+		fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_ONE_DATA);
+		fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_ONE_DATA);
+		at91_twi_write(dev, AT91_TWI_FMR, fifo_mr);
+
+		/* Flush FIFOs */
+		at91_twi_write(dev, AT91_TWI_CR,
+			       AT91_TWI_THRCLR | AT91_TWI_RHRCLR);
+	}
+
 	if (!dev->buf_len) {
 		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK);
 		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
@@ -440,14 +564,16 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 		}
 
 		/* if only one byte is to be read, immediately stop transfer */
-		if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN))
+		if (!has_alt_cmd && dev->buf_len <= 1 &&
+		    !(dev->msg->flags & I2C_M_RECV_LEN))
 			start_flags |= AT91_TWI_STOP;
 		at91_twi_write(dev, AT91_TWI_CR, start_flags);
 		/*
-		 * When using dma, the last byte has to be read manually in
-		 * order to not send the stop command too late and then
-		 * to receive extra data. In practice, there are some issues
-		 * if you use the dma to read n-1 bytes because of latency.
+		 * When using dma without alternative command mode, the last
+		 * byte has to be read manually in order to not send the stop
+		 * command too late and then to receive extra data.
+		 * In practice, there are some issues if you use the dma to
+		 * read n-1 bytes because of latency.
 		 * Reading n-2 bytes with dma and the two last ones manually
 		 * seems to be the best solution.
 		 */
@@ -476,6 +602,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	time_left = wait_for_completion_timeout(&dev->cmd_complete,
 					      dev->adapter.timeout);
 	if (time_left == 0) {
+		dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR);
 		dev_err(dev->dev, "controller timed out\n");
 		at91_init_twi_bus(dev);
 		ret = -ETIMEDOUT;
@@ -496,6 +623,12 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 		ret = -EIO;
 		goto error;
 	}
+	if ((has_alt_cmd || dev->fifo_size) &&
+	    (dev->transfer_status & AT91_TWI_LOCK)) {
+		dev_err(dev->dev, "tx locked\n");
+		ret = -EIO;
+		goto error;
+	}
 	if (dev->recv_len_abort) {
 		dev_err(dev->dev, "invalid smbus block length recvd\n");
 		ret = -EPROTO;
@@ -507,7 +640,15 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	return 0;
 
 error:
+	/* first stop DMA transfer if still in progress */
 	at91_twi_dma_cleanup(dev);
+	/* then flush THR/FIFO and unlock TX if locked */
+	if ((has_alt_cmd || dev->fifo_size) &&
+	    (dev->transfer_status & AT91_TWI_LOCK)) {
+		dev_dbg(dev->dev, "unlock tx\n");
+		at91_twi_write(dev, AT91_TWI_CR,
+			       AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
+	}
 	return ret;
 }
 
@@ -517,6 +658,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 	int ret;
 	unsigned int_addr_flag = 0;
 	struct i2c_msg *m_start = msg;
+	bool is_read, use_alt_cmd = false;
 
 	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
 
@@ -539,8 +681,23 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 		at91_twi_write(dev, AT91_TWI_IADR, internal_address);
 	}
 
-	at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag
-		       | ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
+	is_read = (m_start->flags & I2C_M_RD);
+	if (dev->pdata->has_alt_cmd) {
+		if (m_start->len > 0) {
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMEN);
+			at91_twi_write(dev, AT91_TWI_ACR,
+				       AT91_TWI_ACR_DATAL(m_start->len) |
+				       ((is_read) ? AT91_TWI_ACR_DIR : 0));
+			use_alt_cmd = true;
+		} else {
+			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMDIS);
+		}
+	}
+
+	at91_twi_write(dev, AT91_TWI_MMR,
+		       (m_start->addr << 16) |
+		       int_addr_flag |
+		       ((!use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0));
 
 	dev->buf_len = m_start->len;
 	dev->buf = m_start->buf;
@@ -581,30 +738,35 @@ static struct at91_twi_pdata at91rm9200_config = {
 	.clk_max_div = 5,
 	.clk_offset = 3,
 	.has_unre_flag = true,
+	.has_alt_cmd = false,
 };
 
 static struct at91_twi_pdata at91sam9261_config = {
 	.clk_max_div = 5,
 	.clk_offset = 4,
 	.has_unre_flag = false,
+	.has_alt_cmd = false,
 };
 
 static struct at91_twi_pdata at91sam9260_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
 	.has_unre_flag = false,
+	.has_alt_cmd = false,
 };
 
 static struct at91_twi_pdata at91sam9g20_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
 	.has_unre_flag = false,
+	.has_alt_cmd = false,
 };
 
 static struct at91_twi_pdata at91sam9g10_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
 	.has_unre_flag = false,
+	.has_alt_cmd = false,
 };
 
 static const struct platform_device_id at91_twi_devtypes[] = {
@@ -633,6 +795,14 @@ static struct at91_twi_pdata at91sam9x5_config = {
 	.clk_max_div = 7,
 	.clk_offset = 4,
 	.has_unre_flag = false,
+	.has_alt_cmd = false,
+};
+
+static struct at91_twi_pdata sama5d2_config = {
+	.clk_max_div = 7,
+	.clk_offset = 4,
+	.has_unre_flag = true,
+	.has_alt_cmd = true,
 };
 
 static const struct of_device_id atmel_twi_dt_ids[] = {
@@ -655,6 +825,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
 		.compatible = "atmel,at91sam9x5-i2c",
 		.data = &at91sam9x5_config,
 	}, {
+		.compatible = "atmel,sama5d2-i2c",
+		.data = &sama5d2_config,
+	}, {
 		/* sentinel */
 	}
 };
@@ -666,13 +839,32 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
 	int ret = 0;
 	struct dma_slave_config slave_config;
 	struct at91_twi_dma *dma = &dev->dma;
+	enum dma_slave_buswidth addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	/*
+	 * The actual width of the access will be chosen in
+	 * dmaengine_prep_slave_sg():
+	 * for each buffer in the scatter-gather list, if its size is aligned
+	 * to addr_width then addr_width accesses will be performed to transfer
+	 * the buffer. On the other hand, if the buffer size is not aligned to
+	 * addr_width then the buffer is transferred using single byte accesses.
+	 * Please refer to the Atmel eXtended DMA controller driver.
+	 * When FIFOs are used, the TXRDYM threshold can always be set to
+	 * trigger the XDMAC when at least 4 data can be written into the TX
+	 * FIFO, even if single byte accesses are performed.
+	 * However the RXRDYM threshold must be set to fit the access width,
+	 * deduced from buffer length, so the XDMAC is triggered properly to
+	 * read data from the RX FIFO.
+	 */
+	if (dev->fifo_size)
+		addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 
 	memset(&slave_config, 0, sizeof(slave_config));
 	slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
-	slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	slave_config.src_addr_width = addr_width;
 	slave_config.src_maxburst = 1;
 	slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR;
-	slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	slave_config.dst_addr_width = addr_width;
 	slave_config.dst_maxburst = 1;
 	slave_config.device_fc = false;
 
@@ -704,7 +896,7 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
 		goto error;
 	}
 
-	sg_init_table(&dma->sg, 1);
+	sg_init_table(dma->sg, 2);
 	dma->buf_mapped = false;
 	dma->xfer_in_progress = false;
 	dev->use_dma = true;
@@ -790,6 +982,11 @@ static int at91_twi_probe(struct platform_device *pdev)
 			return rc;
 	}
 
+	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
+				  &dev->fifo_size)) {
+		dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size);
+	}
+
 	rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
 			&bus_clk_rate);
 	if (rc)
@@ -826,7 +1023,8 @@ static int at91_twi_probe(struct platform_device *pdev)
 		return rc;
 	}
 
-	dev_info(dev->dev, "AT91 i2c bus driver.\n");
+	dev_info(dev->dev, "AT91 i2c bus driver (hw version: %#x).\n",
+		 at91_twi_read(dev, AT91_TWI_VER));
 	return 0;
 }