[PATCH v2 4/9] tty: serial: fsl_lpuart: fix DMA mapping

[Michael Walle <michael@walle.cc>]

Use the correct device to request the DMA mapping. Otherwise the IOMMU
doesn't get the mapping and it will generate a page fault.

The error messages look like:
[   19.012140] arm-smmu 5000000.iommu: Unhandled context fault: fsr=0x402, iova=0xbbfff800, fsynr=0x3e0021, cbfrsynra=0x828, cb=9
[   19.023593] arm-smmu 5000000.iommu: Unhandled context fault: fsr=0x402, iova=0xbbfff800, fsynr=0x3e0021, cbfrsynra=0x828, cb=9

This was tested on a custom board with a LS1028A SoC.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/tty/serial/fsl_lpuart.c | 47 +++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index fd9f60d0817a..b65db29a1cd0 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -409,6 +409,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
 	struct circ_buf *xmit = &sport->port.state->xmit;
 	struct scatterlist *sgl = sport->tx_sgl;
 	struct device *dev = sport->port.dev;
+	struct dma_chan *chan = sport->dma_tx_chan;
 	int ret;
 
 	if (sport->dma_tx_in_progress)
@@ -427,17 +428,18 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
 		sg_set_buf(sgl + 1, xmit->buf, xmit->head);
 	}
 
-	ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+	ret = dma_map_sg(chan->device->dev, sgl, sport->dma_tx_nents,
+			 DMA_TO_DEVICE);
 	if (!ret) {
 		dev_err(dev, "DMA mapping error for TX.\n");
 		return;
 	}
 
-	sport->dma_tx_desc = dmaengine_prep_slave_sg(sport->dma_tx_chan, sgl,
+	sport->dma_tx_desc = dmaengine_prep_slave_sg(chan, sgl,
 					ret, DMA_MEM_TO_DEV,
 					DMA_PREP_INTERRUPT);
 	if (!sport->dma_tx_desc) {
-		dma_unmap_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+		dma_unmap_sg(chan->device->dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 		dev_err(dev, "Cannot prepare TX slave DMA!\n");
 		return;
 	}
@@ -446,7 +448,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
 	sport->dma_tx_desc->callback_param = sport;
 	sport->dma_tx_in_progress = true;
 	sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc);
-	dma_async_issue_pending(sport->dma_tx_chan);
+	dma_async_issue_pending(chan);
 }
 
 static bool lpuart_stopped_or_empty(struct uart_port *port)
@@ -459,11 +461,13 @@ static void lpuart_dma_tx_complete(void *arg)
 	struct lpuart_port *sport = arg;
 	struct scatterlist *sgl = &sport->tx_sgl[0];
 	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct dma_chan *chan = sport->dma_tx_chan;
 	unsigned long flags;
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 
-	dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+	dma_unmap_sg(chan->device->dev, sgl, sport->dma_tx_nents,
+		     DMA_TO_DEVICE);
 
 	xmit->tail = (xmit->tail + sport->dma_tx_bytes) & (UART_XMIT_SIZE - 1);
 
@@ -529,15 +533,16 @@ static bool lpuart_is_32(struct lpuart_port *sport)
 static void lpuart_flush_buffer(struct uart_port *port)
 {
 	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+	struct dma_chan *chan = sport->dma_tx_chan;
 	u32 val;
 
 	if (sport->lpuart_dma_tx_use) {
 		if (sport->dma_tx_in_progress) {
-			dma_unmap_sg(sport->port.dev, &sport->tx_sgl[0],
+			dma_unmap_sg(chan->device->dev, &sport->tx_sgl[0],
 				sport->dma_tx_nents, DMA_TO_DEVICE);
 			sport->dma_tx_in_progress = false;
 		}
-		dmaengine_terminate_all(sport->dma_tx_chan);
+		dmaengine_terminate_all(chan);
 	}
 
 	if (lpuart_is_32(sport)) {
@@ -993,6 +998,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 	struct tty_port *port = &sport->port.state->port;
 	struct dma_tx_state state;
 	enum dma_status dmastat;
+	struct dma_chan *chan = sport->dma_rx_chan;
 	struct circ_buf *ring = &sport->rx_ring;
 	unsigned long flags;
 	int count = 0;
@@ -1053,10 +1059,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 
-	dmastat = dmaengine_tx_status(sport->dma_rx_chan,
-				sport->dma_rx_cookie,
-				&state);
-
+	dmastat = dmaengine_tx_status(chan, sport->dma_rx_cookie, &state);
 	if (dmastat == DMA_ERROR) {
 		dev_err(sport->port.dev, "Rx DMA transfer failed!\n");
 		spin_unlock_irqrestore(&sport->port.lock, flags);
@@ -1064,7 +1067,8 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 	}
 
 	/* CPU claims ownership of RX DMA buffer */
-	dma_sync_sg_for_cpu(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+	dma_sync_sg_for_cpu(chan->device->dev, &sport->rx_sgl, 1,
+			    DMA_FROM_DEVICE);
 
 	/*
 	 * ring->head points to the end of data already written by the DMA.
@@ -1106,7 +1110,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 		sport->port.icount.rx += count;
 	}
 
-	dma_sync_sg_for_device(sport->port.dev, &sport->rx_sgl, 1,
+	dma_sync_sg_for_device(chan->device->dev, &sport->rx_sgl, 1,
 			       DMA_FROM_DEVICE);
 
 	spin_unlock_irqrestore(&sport->port.lock, flags);
@@ -1138,6 +1142,7 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	struct tty_port *port = &sport->port.state->port;
 	struct tty_struct *tty = port->tty;
 	struct ktermios *termios = &tty->termios;
+	struct dma_chan *chan = sport->dma_rx_chan;
 
 	baud = tty_get_baud_rate(tty);
 
@@ -1159,7 +1164,8 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 		return -ENOMEM;
 
 	sg_init_one(&sport->rx_sgl, ring->buf, sport->rx_dma_rng_buf_len);
-	nent = dma_map_sg(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+	nent = dma_map_sg(chan->device->dev, &sport->rx_sgl, 1,
+			  DMA_FROM_DEVICE);
 
 	if (!nent) {
 		dev_err(sport->port.dev, "DMA Rx mapping error\n");
@@ -1170,7 +1176,7 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	dma_rx_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 	dma_rx_sconfig.src_maxburst = 1;
 	dma_rx_sconfig.direction = DMA_DEV_TO_MEM;
-	ret = dmaengine_slave_config(sport->dma_rx_chan, &dma_rx_sconfig);
+	ret = dmaengine_slave_config(chan, &dma_rx_sconfig);
 
 	if (ret < 0) {
 		dev_err(sport->port.dev,
@@ -1178,7 +1184,7 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 		return ret;
 	}
 
-	sport->dma_rx_desc = dmaengine_prep_dma_cyclic(sport->dma_rx_chan,
+	sport->dma_rx_desc = dmaengine_prep_dma_cyclic(chan,
 				 sg_dma_address(&sport->rx_sgl),
 				 sport->rx_sgl.length,
 				 sport->rx_sgl.length / 2,
@@ -1192,7 +1198,7 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	sport->dma_rx_desc->callback = lpuart_dma_rx_complete;
 	sport->dma_rx_desc->callback_param = sport;
 	sport->dma_rx_cookie = dmaengine_submit(sport->dma_rx_desc);
-	dma_async_issue_pending(sport->dma_rx_chan);
+	dma_async_issue_pending(chan);
 
 	if (lpuart_is_32(sport)) {
 		unsigned long temp = lpuart32_read(&sport->port, UARTBAUD);
@@ -1210,11 +1216,12 @@ static void lpuart_dma_rx_free(struct uart_port *port)
 {
 	struct lpuart_port *sport = container_of(port,
 					struct lpuart_port, port);
+	struct dma_chan *chan = sport->dma_rx_chan;
 
-	if (sport->dma_rx_chan)
-		dmaengine_terminate_all(sport->dma_rx_chan);
+	if (chan)
+		dmaengine_terminate_all(chan);
 
-	dma_unmap_sg(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+	dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
 	kfree(sport->rx_ring.buf);
 	sport->rx_ring.tail = 0;
 	sport->rx_ring.head = 0;
-- 
2.20.1