[PATCH v4 08/13] tty: serial: qcom-geni-serial: refactor qcom_geni_serial_handle_tx()

From: Bartosz Golaszewski
Date: Tue Nov 29 2022 - 06:01:06 EST


From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

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().

Let's also shuffle the code a bit, drop unneeded variables and use
uart_xmit_advance() instead of handling tail->xmit manually.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
drivers/tty/serial/qcom_geni_serial.c | 55 +++++++++++++--------------
1 file changed, 27 insertions(+), 28 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 68a1402fbe58..ece5b4d543fc 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -93,7 +93,7 @@
#define IO_MACRO_IO2_IO3_SWAP 0x4640

/* We always configure 4 bytes per FIFO word */
-#define BYTES_PER_FIFO_WORD 4
+#define BYTES_PER_FIFO_WORD 4U

struct qcom_geni_private_data {
/* NOTE: earlycon port will have NULL here */
@@ -704,19 +704,41 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
}

+static void 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;
+ unsigned int tx_bytes, remaining = chunk;
+ u8 buf[BYTES_PER_FIFO_WORD];
+ int c;
+
+ while (remaining) {
+ memset(buf, 0, sizeof(buf));
+ tx_bytes = min(remaining, BYTES_PER_FIFO_WORD);
+
+ for (c = 0; c < tx_bytes ; c++) {
+ buf[c] = xmit->buf[xmit->tail];
+ uart_xmit_advance(uport, 1);
+ }
+
+ iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
+
+ remaining -= tx_bytes;
+ port->tx_remaining -= tx_bytes;
+ }
+}
+
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);

@@ -735,7 +757,6 @@ 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;
@@ -750,29 +771,7 @@ 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;
+ qcom_geni_serial_send_chunk_fifo(uport, chunk);

/*
* The tx fifo watermark is level triggered and latched. Though we had
--
2.37.2