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Message-ID: <20251130104222.63077-22-crescentcy.hsieh@moxa.com>
Date: Sun, 30 Nov 2025 18:42:12 +0800
From: Crescent Hsieh <crescentcy.hsieh@...a.com>
To: gregkh@...uxfoundation.org,
jirislaby@...nel.org,
ilpo.jarvinen@...ux.intel.com,
andy.shevchenko@...il.com
Cc: linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org,
crescentcy.hsieh@...a.com
Subject: [PATCH v1 21/31] serial: 8250_mxpcie: implement rx_trig_bytes callbacks and persist per-port level
This patch implements device-specific RX trigger handling for the
rx_trig_bytes sysfs attribute by programming MOXA_PUART_RTL directly.
Changes:
- Add a per-port structure to persist both the registered line and the
RX trigger level, allowing the level to be restored on startup.
- Implement uart_port callbacks:
- set_rxtrig(port, bytes): program MOXA_PUART_RTL and cache the value
- get_rxtrig(port): read back MOXA_PUART_RTL
- Use the cached RX trigger level during startup instead of a fixed
default, while keeping the initial default at 96 for backward
compatibility.
With these callbacks in place, writes to rx_trig_bytes update the
hardware-specific register immediately, and the selected threshold is
preserved across open/close cycles.
No functional change for other 8250 drivers.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@...a.com>
---
drivers/tty/serial/8250/8250_mxpcie.c | 49 +++++++++++++++++++++++----
1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c
index 9ba171274221..04b9c9ff5cbf 100644
--- a/drivers/tty/serial/8250/8250_mxpcie.c
+++ b/drivers/tty/serial/8250/8250_mxpcie.c
@@ -93,11 +93,16 @@
#define MOXA_EVEN_RS_MASK GENMASK(3, 0)
#define MOXA_ODD_RS_MASK GENMASK(7, 4)
+struct mxpcie8250_port {
+ int line;
+ u8 rx_trig_level;
+};
+
struct mxpcie8250 {
struct pci_dev *pdev;
unsigned int supp_rs;
unsigned int num_ports;
- int line[];
+ struct mxpcie8250_port port[];
};
enum {
@@ -243,6 +248,8 @@ static void mxpcie8250_set_termios(struct uart_port *port,
static int mxpcie8250_startup(struct uart_port *port)
{
+ struct pci_dev *pdev = to_pci_dev(port->dev);
+ struct mxpcie8250 *priv = pci_get_drvdata(pdev);
struct uart_8250_port *up = up_to_u8250p(port);
int i, ret;
@@ -255,7 +262,7 @@ 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);
@@ -441,6 +448,31 @@ static void mxpcie8250_break_ctl(struct uart_port *port, int break_state)
serial8250_do_break_ctl(port, break_state);
}
+static int mxpcie8250_set_rxtrig(struct uart_port *port, unsigned char bytes)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+ struct pci_dev *pdev = to_pci_dev(port->dev);
+ struct mxpcie8250 *priv = pci_get_drvdata(pdev);
+
+ if (bytes > 128)
+ return -EINVAL;
+
+ serial_out(up, MOXA_PUART_RTL, bytes);
+ priv->port[port->port_id].rx_trig_level = bytes;
+
+ return 0;
+}
+
+static int mxpcie8250_get_rxtrig(struct uart_port *port)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+ int rx_trig_byte;
+
+ rx_trig_byte = serial_in(up, MOXA_PUART_RTL);
+
+ return rx_trig_byte;
+}
+
static int mxpcie8250_init(struct pci_dev *pdev)
{
resource_size_t iobar_addr = pci_resource_start(pdev, 2);
@@ -513,7 +545,7 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
num_ports = mxpcie8250_get_nports(pdev->device);
- priv = devm_kzalloc(&pdev->dev, struct_size(priv, line, num_ports), GFP_KERNEL);
+ priv = devm_kzalloc(&pdev->dev, struct_size(priv, port, num_ports), GFP_KERNEL);
if (!priv)
return -ENOMEM;
@@ -539,6 +571,8 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
up.port.unthrottle = mxpcie8250_unthrottle;
up.port.handle_irq = mxpcie8250_handle_irq;
up.port.break_ctl = mxpcie8250_break_ctl;
+ up.port.set_rxtrig = mxpcie8250_set_rxtrig;
+ up.port.get_rxtrig = mxpcie8250_get_rxtrig;
for (i = 0; i < num_ports; i++) {
if (mxpcie8250_setup(pdev, priv, &up, i))
@@ -547,15 +581,16 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
dev_dbg(&pdev->dev, "Setup PCI port: port %lx, irq %d, type %d\n",
up.port.iobase, up.port.irq, up.port.iotype);
- priv->line[i] = serial8250_register_8250_port(&up);
+ priv->port[i].line = serial8250_register_8250_port(&up);
- if (priv->line[i] < 0) {
+ if (priv->port[i].line < 0) {
dev_err(&pdev->dev,
"Couldn't register serial port %lx, irq %d, type %d, error %d\n",
up.port.iobase, up.port.irq,
- up.port.iotype, priv->line[i]);
+ up.port.iotype, priv->port[i].line);
break;
}
+ priv->port[i].rx_trig_level = 96;
}
pci_set_drvdata(pdev, priv);
@@ -568,7 +603,7 @@ static void mxpcie8250_remove(struct pci_dev *pdev)
unsigned int i;
for (i = 0; i < priv->num_ports; i++)
- serial8250_unregister_port(priv->line[i]);
+ serial8250_unregister_port(priv->port[i].line);
}
static const struct pci_device_id mxpcie8250_pci_ids[] = {
--
2.45.2
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