[PATCH v2 15/15] serial: 8250_mxpcie: implement rx_trig_bytes callbacks via MUEx50 RTL

[Crescent Hsieh <crescentcy.hsieh@moxa.com>]

The MUEx50 UART exposes a programmable RX trigger level via the RTL
register.

Implement uart_port RX trigger set/get callbacks for the mxpcie driver
and wire them up to the generic rx_trig_bytes sysfs interface. Store the
configured trigger level in the per-port private data.

Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
---
 drivers/tty/serial/8250/8250_mxpcie.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c
index da81ea7970f0..78a7d1994f63 100644
--- a/drivers/tty/serial/8250/8250_mxpcie.c
+++ b/drivers/tty/serial/8250/8250_mxpcie.c
@@ -50,6 +50,7 @@
 #define MOXA_PUART_BASE_BAUD	921600
 #define MOXA_PUART_OFFSET	0x200
 #define MOXA_PUART_FIFO_SIZE	128
+#define MOXA_PUART_RX_TRIGGER_DEFAULT	96
 
 /* Special Function Register (SFR) */
 #define MOXA_PUART_SFR		0x07
@@ -113,6 +114,7 @@ struct mxpcie8250_port {
 	struct work_struct work;
 	unsigned long event_flags;
 	int line;
+	u8 rx_trig_level;
 };
 
 struct mxpcie8250 {
@@ -259,8 +261,27 @@ static void mxpcie8250_set_termios(struct uart_port *port,
 	serial_out(up, MOXA_PUART_EFR, efr);
 }
 
+static int mxpcie8250_get_rxtrig(struct uart_port *port)
+{
+	return serial_port_in(port, MOXA_PUART_RTL);
+}
+
+static int mxpcie8250_set_rxtrig(struct uart_port *port, unsigned char bytes)
+{
+	struct mxpcie8250 *priv = dev_get_drvdata(port->dev);
+
+	if (bytes > MOXA_PUART_FIFO_SIZE)
+		return -EINVAL;
+
+	serial_port_out(port, MOXA_PUART_RTL, bytes);
+	priv->port[port->port_id].rx_trig_level = bytes;
+
+	return 0;
+}
+
 static int mxpcie8250_startup(struct uart_port *port)
 {
+	struct mxpcie8250 *priv = dev_get_drvdata(port->dev);
 	struct uart_8250_port *up = up_to_u8250p(port);
 	int ret;
 
@@ -285,7 +306,7 @@ static int mxpcie8250_startup(struct uart_port *port)
 	serial_out(up, MOXA_PUART_SFR, MOXA_PUART_SFR_950);
 
 	serial_out(up, MOXA_PUART_TTL, 0);
-	serial_out(up, MOXA_PUART_RTL, 96);
+	serial_out(up, MOXA_PUART_RTL, priv->port[port->port_id].rx_trig_level);
 	serial_out(up, MOXA_PUART_FCL, 16);
 	serial_out(up, MOXA_PUART_FCH, 110);
 
@@ -583,6 +604,8 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
 	up.port.regshift = 0;
 
 	up.port.set_termios = mxpcie8250_set_termios;
+	up.port.get_rxtrig = mxpcie8250_get_rxtrig;
+	up.port.set_rxtrig = mxpcie8250_set_rxtrig;
 	up.port.startup = mxpcie8250_startup;
 	up.port.shutdown = mxpcie8250_shutdown;
 	up.port.throttle = mxpcie8250_throttle;
@@ -606,6 +629,7 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
 		}
 		new_port = serial8250_get_port(priv->port[i].line);
 
+		priv->port[i].rx_trig_level = MOXA_PUART_RX_TRIGGER_DEFAULT;
 		priv->port[i].port = &new_port->port;
 
 		INIT_WORK(&priv->port[i].work, mxpcie8250_work_handler);
-- 
2.45.2