diff mbox series

[08/15] tty: serial: qcom-geni-serial: split out the FIFO tx code

Message ID 20221118122539.384993-9-brgl@bgdev.pl (mailing list archive)
State Superseded
Headers show
Series serial: qcom-geni-serial: implement support for SE DMA | expand

Commit Message

Bartosz Golaszewski Nov. 18, 2022, 12:25 p.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

qcom_geni_serial_handle_tx() is pretty big, let's move the code that
handles the actual writing of data to a separate function which makes
sense in preparation for introducing a dma variant of handle_tx().

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/tty/serial/qcom_geni_serial.c | 60 +++++++++++++++------------
 1 file changed, 33 insertions(+), 27 deletions(-)

Comments

Konrad Dybcio Nov. 18, 2022, 1:27 p.m. UTC | #1 
On 18/11/2022 13:25, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> qcom_geni_serial_handle_tx() is pretty big, let's move the code that
> handles the actual writing of data to a separate function which makes
> sense in preparation for introducing a dma variant of handle_tx().
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Konrad
>   drivers/tty/serial/qcom_geni_serial.c | 60 +++++++++++++++------------
>   1 file changed, 33 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 39041538e5d2..4b155ca0ac74 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -701,19 +701,48 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
>   	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
>   }
>   
> +static int qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
> +					    unsigned int chunk)
> +{
> +	struct qcom_geni_serial_port *port = to_dev_port(uport);
> +	struct circ_buf *xmit = &uport->state->xmit;
> +	size_t remaining = chunk;
> +	int i, tail = xmit->tail;
> +
> +	for (i = 0; i < chunk; ) {
> +		unsigned int tx_bytes;
> +		u8 buf[sizeof(u32)];
> +		int c;
> +
> +		memset(buf, 0, sizeof(buf));
> +		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
> +
> +		for (c = 0; c < tx_bytes ; c++) {
> +			buf[c] = xmit->buf[tail++];
> +			tail &= UART_XMIT_SIZE - 1;
> +		}
> +
> +		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
> +
> +		i += tx_bytes;
> +		uport->icount.tx += tx_bytes;
> +		remaining -= tx_bytes;
> +		port->tx_remaining -= tx_bytes;
> +	}
> +
> +	return tail;
> +}
> +
>   static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>   		bool active)
>   {
>   	struct qcom_geni_serial_port *port = to_dev_port(uport);
>   	struct circ_buf *xmit = &uport->state->xmit;
>   	size_t avail;
> -	size_t remaining;
>   	size_t pending;
> -	int i;
>   	u32 status;
>   	u32 irq_en;
>   	unsigned int chunk;
> -	int tail;
>   
>   	status = readl(uport->membase + SE_GENI_TX_FIFO_STATUS);
>   
> @@ -732,7 +761,6 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>   	avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
>   	avail *= BYTES_PER_FIFO_WORD;
>   
> -	tail = xmit->tail;
>   	chunk = min(avail, pending);
>   	if (!chunk)
>   		goto out_write_wakeup;
> @@ -747,29 +775,7 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>   					uport->membase + SE_GENI_M_IRQ_EN);
>   	}
>   
> -	remaining = chunk;
> -	for (i = 0; i < chunk; ) {
> -		unsigned int tx_bytes;
> -		u8 buf[sizeof(u32)];
> -		int c;
> -
> -		memset(buf, 0, sizeof(buf));
> -		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
> -
> -		for (c = 0; c < tx_bytes ; c++) {
> -			buf[c] = xmit->buf[tail++];
> -			tail &= UART_XMIT_SIZE - 1;
> -		}
> -
> -		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
> -
> -		i += tx_bytes;
> -		uport->icount.tx += tx_bytes;
> -		remaining -= tx_bytes;
> -		port->tx_remaining -= tx_bytes;
> -	}
> -
> -	xmit->tail = tail;
> +	xmit->tail = qcom_geni_serial_send_chunk_fifo(uport, chunk);
>   
>   	/*
>   	 * The tx fifo watermark is level triggered and latched. Though we had
Ilpo Järvinen Nov. 18, 2022, 3:30 p.m. UTC | #2 
On Fri, 18 Nov 2022, Bartosz Golaszewski wrote:

> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> qcom_geni_serial_handle_tx() is pretty big, let's move the code that
> handles the actual writing of data to a separate function which makes
> sense in preparation for introducing a dma variant of handle_tx().
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
>  drivers/tty/serial/qcom_geni_serial.c | 60 +++++++++++++++------------
>  1 file changed, 33 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 39041538e5d2..4b155ca0ac74 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -701,19 +701,48 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
>  	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
>  }
>  
> +static int qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
> +					    unsigned int chunk)
> +{

Some of the comments I have for this function you might want to implement 
in a different patch than this simple move to own function.

> +	struct qcom_geni_serial_port *port = to_dev_port(uport);
> +	struct circ_buf *xmit = &uport->state->xmit;
> +	size_t remaining = chunk;
> +	int i, tail = xmit->tail;

Why there's remaining and i variables, both seem to provide a chunk sized 
limit? Couldn't one be dropped?

You could drop local tail handling, it doesn't seem to add much value.

> +	for (i = 0; i < chunk; ) {
> +		unsigned int tx_bytes;
> +		u8 buf[sizeof(u32)];
> +		int c;
> +
> +		memset(buf, 0, sizeof(buf));
> +		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);

It's a bit confusing to mix sizeof(u32) and BYTES_PER_FIFO_WORD for the 
same purpose, no?

> +		for (c = 0; c < tx_bytes ; c++) {
> +			buf[c] = xmit->buf[tail++];
> +			tail &= UART_XMIT_SIZE - 1;

If you drop the local tail, this becomes:

			buf[c] = xmit->buf[xmit->tail];
			uart_xmit_advance(uport, 1);

> +		}
> +
> +		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
> +
> +		i += tx_bytes;
> +		uport->icount.tx += tx_bytes;

With uart_xmit_advance, this is to be dropped.

> +		remaining -= tx_bytes;
> +		port->tx_remaining -= tx_bytes;
> +	}
> +
> +	return tail;
> +}
> +
>  static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>  		bool active)
>  {
>  	struct qcom_geni_serial_port *port = to_dev_port(uport);
>  	struct circ_buf *xmit = &uport->state->xmit;
>  	size_t avail;
> -	size_t remaining;
>  	size_t pending;
> -	int i;
>  	u32 status;
>  	u32 irq_en;
>  	unsigned int chunk;
> -	int tail;
>  
>  	status = readl(uport->membase + SE_GENI_TX_FIFO_STATUS);
>  
> @@ -732,7 +761,6 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>  	avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
>  	avail *= BYTES_PER_FIFO_WORD;
>  
> -	tail = xmit->tail;
>  	chunk = min(avail, pending);
>  	if (!chunk)
>  		goto out_write_wakeup;
> @@ -747,29 +775,7 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
>  					uport->membase + SE_GENI_M_IRQ_EN);
>  	}
>  
> -	remaining = chunk;
> -	for (i = 0; i < chunk; ) {
> -		unsigned int tx_bytes;
> -		u8 buf[sizeof(u32)];
> -		int c;
> -
> -		memset(buf, 0, sizeof(buf));
> -		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
> -
> -		for (c = 0; c < tx_bytes ; c++) {
> -			buf[c] = xmit->buf[tail++];
> -			tail &= UART_XMIT_SIZE - 1;
> -		}
> -
> -		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
> -
> -		i += tx_bytes;
> -		uport->icount.tx += tx_bytes;
> -		remaining -= tx_bytes;
> -		port->tx_remaining -= tx_bytes;
> -	}
> -
> -	xmit->tail = tail;
> +	xmit->tail = qcom_geni_serial_send_chunk_fifo(uport, chunk);

Why you want to assign to xmit->tail here?

>  
>  	/*
>  	 * The tx fifo watermark is level triggered and latched. Though we had
>
diff mbox series

Patch

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 39041538e5d2..4b155ca0ac74 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -701,19 +701,48 @@  static void qcom_geni_serial_start_rx(struct uart_port *uport)
 	writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
 }
 
+static int qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
+					    unsigned int chunk)
+{
+	struct qcom_geni_serial_port *port = to_dev_port(uport);
+	struct circ_buf *xmit = &uport->state->xmit;
+	size_t remaining = chunk;
+	int i, tail = xmit->tail;
+
+	for (i = 0; i < chunk; ) {
+		unsigned int tx_bytes;
+		u8 buf[sizeof(u32)];
+		int c;
+
+		memset(buf, 0, sizeof(buf));
+		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
+
+		for (c = 0; c < tx_bytes ; c++) {
+			buf[c] = xmit->buf[tail++];
+			tail &= UART_XMIT_SIZE - 1;
+		}
+
+		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
+
+		i += tx_bytes;
+		uport->icount.tx += tx_bytes;
+		remaining -= tx_bytes;
+		port->tx_remaining -= tx_bytes;
+	}
+
+	return tail;
+}
+
 static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 		bool active)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
 	struct circ_buf *xmit = &uport->state->xmit;
 	size_t avail;
-	size_t remaining;
 	size_t pending;
-	int i;
 	u32 status;
 	u32 irq_en;
 	unsigned int chunk;
-	int tail;
 
 	status = readl(uport->membase + SE_GENI_TX_FIFO_STATUS);
 
@@ -732,7 +761,6 @@  static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 	avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
 	avail *= BYTES_PER_FIFO_WORD;
 
-	tail = xmit->tail;
 	chunk = min(avail, pending);
 	if (!chunk)
 		goto out_write_wakeup;
@@ -747,29 +775,7 @@  static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
 					uport->membase + SE_GENI_M_IRQ_EN);
 	}
 
-	remaining = chunk;
-	for (i = 0; i < chunk; ) {
-		unsigned int tx_bytes;
-		u8 buf[sizeof(u32)];
-		int c;
-
-		memset(buf, 0, sizeof(buf));
-		tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);
-
-		for (c = 0; c < tx_bytes ; c++) {
-			buf[c] = xmit->buf[tail++];
-			tail &= UART_XMIT_SIZE - 1;
-		}
-
-		iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
-
-		i += tx_bytes;
-		uport->icount.tx += tx_bytes;
-		remaining -= tx_bytes;
-		port->tx_remaining -= tx_bytes;
-	}
-
-	xmit->tail = tail;
+	xmit->tail = qcom_geni_serial_send_chunk_fifo(uport, chunk);
 
 	/*
 	 * The tx fifo watermark is level triggered and latched. Though we had