Breaking the single big ISR that has both Rx and Tx
in a single function into smaller ones
Signed-off-by: Nava kishore Manne <navam@xxxxxxxxxx>
---
Changes for v2:
--Splits up the ISR without any functional changes as suggested
by Peter Hurley
drivers/tty/serial/xilinx_uartps.c | 247 ++++++++++++++++++++-----------------
1 file changed, 135 insertions(+), 112 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 009e0db..2e1b0a8 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -172,6 +172,9 @@ struct cdns_uart {
#define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
clk_rate_change_nb);
+static void cdns_uart_handle_tx(void *dev_id);
+static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus);
+
/**
* cdns_uart_isr - Interrupt handler
* @irq: Irq number
@@ -183,9 +186,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
{
struct uart_port *port = (struct uart_port *)dev_id;
unsigned long flags;
- unsigned int isrstatus, numbytes;
- unsigned int data;
- char status = TTY_NORMAL;
+ unsigned int isrstatus;
spin_lock_irqsave(&port->lock, flags);
@@ -194,116 +195,12 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
*/
isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
- /*
- * There is no hardware break detection, so we interpret framing
- * error with all-zeros data as a break sequence. Most of the time,
- * there's another non-zero byte at the end of the sequence.
- */
- if (isrstatus & CDNS_UART_IXR_FRAMING) {
- while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
- CDNS_UART_SR_RXEMPTY)) {
- if (!readl(port->membase + CDNS_UART_FIFO_OFFSET)) {
- port->read_status_mask |= CDNS_UART_IXR_BRK;
- isrstatus &= ~CDNS_UART_IXR_FRAMING;
- }
- }
- writel(CDNS_UART_IXR_FRAMING,
- port->membase + CDNS_UART_ISR_OFFSET);
- }
-
- /* drop byte with parity error if IGNPAR specified */
- if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
- isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);
-
- isrstatus &= port->read_status_mask;
- isrstatus &= ~port->ignore_status_mask;
-
- if ((isrstatus & CDNS_UART_IXR_TOUT) ||
- (isrstatus & CDNS_UART_IXR_RXTRIG)) {
- /* Receive Timeout Interrupt */
- while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
- CDNS_UART_SR_RXEMPTY)) {
- data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
-
- /* Non-NULL byte after BREAK is garbage (99%) */
- if (data && (port->read_status_mask &
- CDNS_UART_IXR_BRK)) {
- port->read_status_mask &= ~CDNS_UART_IXR_BRK;
- port->icount.brk++;
- if (uart_handle_break(port))
- continue;
- }
-
-#ifdef SUPPORT_SYSRQ
- /*
- * uart_handle_sysrq_char() doesn't work if
- * spinlocked, for some reason
- */
- if (port->sysrq) {
- spin_unlock(&port->lock);
- if (uart_handle_sysrq_char(port,
- (unsigned char)data)) {
- spin_lock(&port->lock);
- continue;
- }
- spin_lock(&port->lock);
- }
-#endif
-
- port->icount.rx++;
-
- if (isrstatus & CDNS_UART_IXR_PARITY) {
- port->icount.parity++;
- status = TTY_PARITY;
- } else if (isrstatus & CDNS_UART_IXR_FRAMING) {
- port->icount.frame++;
- status = TTY_FRAME;
- } else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
- port->icount.overrun++;
- }
-
- uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
- data, status);
- }
- spin_unlock(&port->lock);
- tty_flip_buffer_push(&port->state->port);
- spin_lock(&port->lock);
- }
-
- /* Dispatch an appropriate handler */
- if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
- if (uart_circ_empty(&port->state->xmit)) {
- writel(CDNS_UART_IXR_TXEMPTY,
- port->membase + CDNS_UART_IDR_OFFSET);
- } else {
- numbytes = port->fifosize;
- /* Break if no more data available in the UART buffer */
- while (numbytes--) {
- if (uart_circ_empty(&port->state->xmit))
- break;
- /* Get the data from the UART circular buffer
- * and write it to the cdns_uart's TX_FIFO
- * register.
- */
- writel(port->state->xmit.buf[
- port->state->xmit.tail],
- port->membase + CDNS_UART_FIFO_OFFSET);
-
- port->icount.tx++;
-
- /* Adjust the tail of the UART buffer and wrap
- * the buffer if it reaches limit.
- */
- port->state->xmit.tail =
- (port->state->xmit.tail + 1) &
- (UART_XMIT_SIZE - 1);
- }
-
- if (uart_circ_chars_pending(
- &port->state->xmit) < WAKEUP_CHARS)
- uart_write_wakeup(port);
- }
+ if (isrstatus & CDNS_UART_IXR_TXEMPTY) {
+ cdns_uart_handle_tx(dev_id);
+ isrstatus &= ~CDNS_UART_IXR_TXEMPTY;
}
+ if (isrstatus & CDNS_UART_IXR_MASK)
+ cdns_uart_handle_rx(dev_id, isrstatus);
writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
@@ -408,6 +305,132 @@ static unsigned int cdns_uart_set_baud_rate(struct uart_port *port,
return calc_baud;
}
+/**
+ * cdns_uart_handle_tx - Handle the bytes to be Txed.
+ * @dev_id: Id of the UART port
+ * Return: None
+ */
+static void cdns_uart_handle_tx(void *dev_id)
+{
+ struct uart_port *port = (struct uart_port *)dev_id;
+ unsigned int numbytes;
+
+ if (uart_circ_empty(&port->state->xmit)) {
+ writel(CDNS_UART_IXR_TXEMPTY,
+ port->membase + CDNS_UART_IDR_OFFSET);
+ } else {
+ numbytes = port->fifosize;
+ /* Break if no more data available in the UART buffer */
+ while (numbytes--) {
+ if (uart_circ_empty(&port->state->xmit))
+ break;
+ /* Get the data from the UART circular buffer
+ * and write it to the cdns_uart's TX_FIFO
+ * register.
+ */
+ writel(port->state->xmit.buf[port->state->xmit.tail],
+ port->membase + CDNS_UART_FIFO_OFFSET);
+ port->icount.tx++;
+
+ /* Adjust the tail of the UART buffer and wrap
+ * the buffer if it reaches limit.
+ */
+ port->state->xmit.tail = (port->state->xmit.tail + 1) &
+ (UART_XMIT_SIZE - 1);
+ }
+
+ if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(port);
+ }
+}
+
+/**
+ * cdns_uart_handle_rx - Handle the received bytes along with Rx errors.
+ * @dev_id: Id of the UART port
+ * @isrstatus: The interrupt status register value as read
+ * Return: None
+ */
+static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
+{
+ struct uart_port *port = (struct uart_port *)dev_id;
+ unsigned int data;
+ char status = TTY_NORMAL;
+
+ /*
+ * There is no hardware break detection, so we interpret framing
+ * error with all-zeros data as a break sequence. Most of the time,
+ * there's another non-zero byte at the end of the sequence.
+ */
+ if (isrstatus & CDNS_UART_IXR_FRAMING) {
+ while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
+ CDNS_UART_SR_RXEMPTY)) {
+ if (!readl(port->membase + CDNS_UART_FIFO_OFFSET)) {
+ port->read_status_mask |= CDNS_UART_IXR_BRK;
+ isrstatus &= ~CDNS_UART_IXR_FRAMING;
+ }
+ }
+ writel(CDNS_UART_IXR_FRAMING,
+ port->membase + CDNS_UART_ISR_OFFSET);
+ }
+
+ /* drop byte with parity error if IGNPAR specified */
+ if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
+ isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);
+
+ isrstatus &= port->read_status_mask;
+ isrstatus &= ~port->ignore_status_mask;
+ if ((isrstatus & CDNS_UART_IXR_TOUT) ||
+ (isrstatus & CDNS_UART_IXR_RXTRIG)) {
+ /* Receive Timeout Interrupt */
+ while ((readl(port->membase + CDNS_UART_SR_OFFSET) &
+ CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
+ data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+
+ /* Non-NULL byte after BREAK is garbage (99%) */
+ if (data && (port->read_status_mask
+ &CDNS_UART_IXR_BRK)) {
+ port->read_status_mask &= ~CDNS_UART_IXR_BRK;
+ port->icount.brk++;
+ if (uart_handle_break(port))
+ continue;
+ }
+
+#ifdef SUPPORT_SYSRQ
+ /*
+ * uart_handle_sysrq_char() doesn't work if
+ * spinlocked, for some reason
+ */
+ if (port->sysrq) {
+ spin_unlock(&port->lock);
+ if (uart_handle_sysrq_char(port,
+ (unsigned char)data)) {
+ spin_lock(&port->lock);
+ continue;
+ }
+ spin_lock(&port->lock);
+ }
+#endif
+
+ port->icount.rx++;
+
+ if (isrstatus & CDNS_UART_IXR_PARITY) {
+ port->icount.parity++;
+ status = TTY_PARITY;
+ } else if (isrstatus & CDNS_UART_IXR_FRAMING) {
+ port->icount.frame++;
+ status = TTY_FRAME;
+ } else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
+ port->icount.overrun++;
+ }
+
+ uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
+ data, status);
+ }
+ spin_unlock(&port->lock);
+ tty_flip_buffer_push(&port->state->port);
+ spin_lock(&port->lock);
+}
+}
#ifdef CONFIG_COMMON_CLK
/**
* cdns_uart_clk_notitifer_cb - Clock notifier callback
--
2.1.2
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