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Subject[PATCH v4 2/4] tty: serial: fsl_lpuart: fix DMA mapping
Date
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 | 48 +++++++++++++++++++--------------
1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 33798df4d727..f45f97cb769c 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 +428,19 @@ 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 +449,7 @@ 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 +462,13 @@ 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 +534,16 @@ 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 +999,7 @@ 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 +1060,7 @@ 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 +1068,8 @@ 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 +1111,7 @@ 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 +1143,7 @@ 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 +1165,8 @@ 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 +1177,7 @@ 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 +1185,7 @@ 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 +1199,7 @@ 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 +1217,12 @@ 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
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