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tty: msm_serial: use dmaengine_prep_slave_sg()
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This is a preparatory for the serial-to-kfifo switch. kfifo understands
only scatter-gatter approach, so switch to that.

No functional change intended, it's just dmaengine_prep_slave_single()
inline expanded.

And in this case, switch from dma_map_single() to dma_map_sg() too. This
needs struct msm_dma changes. I split the rx and tx parts into an union.
TX is now struct scatterlist, RX remains the old good phys-virt-count
triple.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Link: https://lore.kernel.org/r/20240405060826.2521-12-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jiri Slaby (SUSE) authored and Greg Kroah-Hartman committed Apr 9, 2024
1 parent 9054605 commit f8fef2f
Showing 1 changed file with 49 additions and 37 deletions.
86 changes: 49 additions & 37 deletions drivers/tty/serial/msm_serial.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -161,11 +161,16 @@ enum {
struct msm_dma {
struct dma_chan *chan;
enum dma_data_direction dir;
dma_addr_t phys;
unsigned char *virt;
union {
struct {
dma_addr_t phys;
unsigned char *virt;
unsigned int count;
} rx;
struct scatterlist tx_sg;
};
dma_cookie_t cookie;
u32 enable_bit;
unsigned int count;
struct dma_async_tx_descriptor *desc;
};

Expand Down Expand Up @@ -249,8 +254,12 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
unsigned int mapped;
u32 val;

mapped = dma->count;
dma->count = 0;
if (dma->dir == DMA_TO_DEVICE) {
mapped = sg_dma_len(&dma->tx_sg);
} else {
mapped = dma->rx.count;
dma->rx.count = 0;
}

dmaengine_terminate_all(dma->chan);

Expand All @@ -265,8 +274,13 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
val &= ~dma->enable_bit;
msm_write(port, val, UARTDM_DMEN);

if (mapped)
dma_unmap_single(dev, dma->phys, mapped, dma->dir);
if (mapped) {
if (dma->dir == DMA_TO_DEVICE) {
dma_unmap_sg(dev, &dma->tx_sg, 1, dma->dir);
sg_init_table(&dma->tx_sg, 1);
} else
dma_unmap_single(dev, dma->rx.phys, mapped, dma->dir);
}
}

static void msm_release_dma(struct msm_port *msm_port)
Expand All @@ -285,7 +299,7 @@ static void msm_release_dma(struct msm_port *msm_port)
if (dma->chan) {
msm_stop_dma(&msm_port->uart, dma);
dma_release_channel(dma->chan);
kfree(dma->virt);
kfree(dma->rx.virt);
}

memset(dma, 0, sizeof(*dma));
Expand Down Expand Up @@ -357,8 +371,8 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)

of_property_read_u32(dev->of_node, "qcom,rx-crci", &crci);

dma->virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
if (!dma->virt)
dma->rx.virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
if (!dma->rx.virt)
goto rel_rx;

memset(&conf, 0, sizeof(conf));
Expand All @@ -385,7 +399,7 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)

return;
err:
kfree(dma->virt);
kfree(dma->rx.virt);
rel_rx:
dma_release_channel(dma->chan);
no_rx:
Expand Down Expand Up @@ -420,7 +434,7 @@ static void msm_start_tx(struct uart_port *port)
struct msm_dma *dma = &msm_port->tx_dma;

/* Already started in DMA mode */
if (dma->count)
if (sg_dma_len(&dma->tx_sg))
return;

msm_port->imr |= MSM_UART_IMR_TXLEV;
Expand Down Expand Up @@ -448,12 +462,12 @@ static void msm_complete_tx_dma(void *args)
uart_port_lock_irqsave(port, &flags);

/* Already stopped */
if (!dma->count)
if (!sg_dma_len(&dma->tx_sg))
goto done;

dmaengine_tx_status(dma->chan, dma->cookie, &state);

dma_unmap_single(port->dev, dma->phys, dma->count, dma->dir);
dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);

val = msm_read(port, UARTDM_DMEN);
val &= ~dma->enable_bit;
Expand All @@ -464,9 +478,9 @@ static void msm_complete_tx_dma(void *args)
msm_write(port, MSM_UART_CR_TX_ENABLE, MSM_UART_CR);
}

count = dma->count - state.residue;
count = sg_dma_len(&dma->tx_sg) - state.residue;
uart_xmit_advance(port, count);
dma->count = 0;
sg_init_table(&dma->tx_sg, 1);

/* Restore "Tx FIFO below watermark" interrupt */
msm_port->imr |= MSM_UART_IMR_TXLEV;
Expand All @@ -485,19 +499,18 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
struct circ_buf *xmit = &msm_port->uart.state->xmit;
struct uart_port *port = &msm_port->uart;
struct msm_dma *dma = &msm_port->tx_dma;
void *cpu_addr;
int ret;
u32 val;

cpu_addr = &xmit->buf[xmit->tail];
sg_init_table(&dma->tx_sg, 1);
sg_set_buf(&dma->tx_sg, &xmit->buf[xmit->tail], count);

dma->phys = dma_map_single(port->dev, cpu_addr, count, dma->dir);
ret = dma_mapping_error(port->dev, dma->phys);
ret = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
if (ret)
return ret;

dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
count, DMA_MEM_TO_DEV,
dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT |
DMA_PREP_FENCE);
if (!dma->desc) {
Expand All @@ -520,8 +533,6 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
msm_port->imr &= ~MSM_UART_IMR_TXLEV;
msm_write(port, msm_port->imr, MSM_UART_IMR);

dma->count = count;

val = msm_read(port, UARTDM_DMEN);
val |= dma->enable_bit;

Expand All @@ -536,7 +547,8 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
dma_async_issue_pending(dma->chan);
return 0;
unmap:
dma_unmap_single(port->dev, dma->phys, count, dma->dir);
dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
sg_init_table(&dma->tx_sg, 1);
return ret;
}

Expand All @@ -553,7 +565,7 @@ static void msm_complete_rx_dma(void *args)
uart_port_lock_irqsave(port, &flags);

/* Already stopped */
if (!dma->count)
if (!dma->rx.count)
goto done;

val = msm_read(port, UARTDM_DMEN);
Expand All @@ -570,14 +582,14 @@ static void msm_complete_rx_dma(void *args)

port->icount.rx += count;

dma->count = 0;
dma->rx.count = 0;

dma_unmap_single(port->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
dma_unmap_single(port->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);

for (i = 0; i < count; i++) {
char flag = TTY_NORMAL;

if (msm_port->break_detected && dma->virt[i] == 0) {
if (msm_port->break_detected && dma->rx.virt[i] == 0) {
port->icount.brk++;
flag = TTY_BREAK;
msm_port->break_detected = false;
Expand All @@ -588,9 +600,9 @@ static void msm_complete_rx_dma(void *args)
if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK))
flag = TTY_NORMAL;

sysrq = uart_prepare_sysrq_char(port, dma->virt[i]);
sysrq = uart_prepare_sysrq_char(port, dma->rx.virt[i]);
if (!sysrq)
tty_insert_flip_char(tport, dma->virt[i], flag);
tty_insert_flip_char(tport, dma->rx.virt[i], flag);
}

msm_start_rx_dma(msm_port);
Expand All @@ -614,13 +626,13 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
if (!dma->chan)
return;

dma->phys = dma_map_single(uart->dev, dma->virt,
dma->rx.phys = dma_map_single(uart->dev, dma->rx.virt,
UARTDM_RX_SIZE, dma->dir);
ret = dma_mapping_error(uart->dev, dma->phys);
ret = dma_mapping_error(uart->dev, dma->rx.phys);
if (ret)
goto sw_mode;

dma->desc = dmaengine_prep_slave_single(dma->chan, dma->phys,
dma->desc = dmaengine_prep_slave_single(dma->chan, dma->rx.phys,
UARTDM_RX_SIZE, DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT);
if (!dma->desc)
Expand Down Expand Up @@ -648,7 +660,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)

msm_write(uart, msm_port->imr, MSM_UART_IMR);

dma->count = UARTDM_RX_SIZE;
dma->rx.count = UARTDM_RX_SIZE;

dma_async_issue_pending(dma->chan);

Expand All @@ -668,7 +680,7 @@ static void msm_start_rx_dma(struct msm_port *msm_port)

return;
unmap:
dma_unmap_single(uart->dev, dma->phys, UARTDM_RX_SIZE, dma->dir);
dma_unmap_single(uart->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);

sw_mode:
/*
Expand Down Expand Up @@ -955,7 +967,7 @@ static irqreturn_t msm_uart_irq(int irq, void *dev_id)
}

if (misr & (MSM_UART_IMR_RXLEV | MSM_UART_IMR_RXSTALE)) {
if (dma->count) {
if (dma->rx.count) {
val = MSM_UART_CR_CMD_STALE_EVENT_DISABLE;
msm_write(port, val, MSM_UART_CR);
val = MSM_UART_CR_CMD_RESET_STALE_INT;
Expand Down

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