diff mbox series

[5.10.y-cip,2/7] tty: serial: sh-sci: Add support for tx end interrupt handling

Message ID 20230605110512.111017-3-biju.das.jz@bp.renesas.com (mailing list archive)
State Accepted
Headers show
Series Add SCI support for RZ/G2L alike SoCs | expand

Commit Message

Biju Das June 5, 2023, 11:05 a.m. UTC 
commit d61ae331d6f35183b38e0c992bc01bf15d8591c3 upstream.

As per the RZ/G2L users hardware manual (Rev.1.20 Sep, 2022), section
23.3.7 Serial Data Transmission (Asynchronous Mode), it is mentioned
that, set the SCR.TIE bit to 0 and SCR.TEIE bit to 1, after the last
data to be transmitted are written to the TDR.

This will generate tx end interrupt and in the handler set SCR.TE and
SCR.TEIE to 0.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230412145053.114847-5-biju.das.jz@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 drivers/tty/serial/sh-sci.c | 31 ++++++++++++++++++++++++++++---
 drivers/tty/serial/sh-sci.h |  3 +++
 2 files changed, 31 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index fe29b05f42c4..39db677a84e7 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -855,9 +855,16 @@  static void sci_transmit_chars(struct uart_port *port)
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
-	if (uart_circ_empty(xmit))
-		sci_stop_tx(port);
+	if (uart_circ_empty(xmit)) {
+		if (port->type == PORT_SCI) {
+			ctrl = serial_port_in(port, SCSCR);
+			ctrl &= ~SCSCR_TIE;
+			ctrl |= SCSCR_TEIE;
+			serial_port_out(port, SCSCR, ctrl);
+		}
 
+		sci_stop_tx(port);
+	}
 }
 
 /* On SH3, SCIF may read end-of-break as a space->mark char */
@@ -1766,6 +1773,24 @@  static irqreturn_t sci_tx_interrupt(int irq, void *ptr)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t sci_tx_end_interrupt(int irq, void *ptr)
+{
+	struct uart_port *port = ptr;
+	unsigned long flags;
+	unsigned short ctrl;
+
+	if (port->type != PORT_SCI)
+		return sci_tx_interrupt(irq, ptr);
+
+	spin_lock_irqsave(&port->lock, flags);
+	ctrl = serial_port_in(port, SCSCR);
+	ctrl &= ~(SCSCR_TE | SCSCR_TEIE);
+	serial_port_out(port, SCSCR, ctrl);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
 static irqreturn_t sci_br_interrupt(int irq, void *ptr)
 {
 	struct uart_port *port = ptr;
@@ -1902,7 +1927,7 @@  static const struct sci_irq_desc {
 
 	[SCIx_TEI_IRQ] = {
 		.desc = "tx end",
-		.handler = sci_tx_interrupt,
+		.handler = sci_tx_end_interrupt,
 	},
 
 	/*
diff --git a/drivers/tty/serial/sh-sci.h b/drivers/tty/serial/sh-sci.h
index c0ae78632dda..0b65563c4e9e 100644
--- a/drivers/tty/serial/sh-sci.h
+++ b/drivers/tty/serial/sh-sci.h
@@ -59,6 +59,9 @@  enum {
 #define SCSMR_SRC_19	0x0600	/* Sampling rate 1/19 */
 #define SCSMR_SRC_27	0x0700	/* Sampling rate 1/27 */
 
+/* Serial Control Register, SCI only bits */
+#define SCSCR_TEIE	BIT(2)  /* Transmit End Interrupt Enable */
+
 /* Serial Control Register, SCIFA/SCIFB only bits */
 #define SCSCR_TDRQE	BIT(15)	/* Tx Data Transfer Request Enable */
 #define SCSCR_RDRQE	BIT(14)	/* Rx Data Transfer Request Enable */