serial: 8250: extract serial8250_set_TRG_levels()

serial8250_do_startup() contains peculiar trigger levels setup for
special ports (16850, ALTR_16550_*). Move this away to a separate
function: serial8250_set_TRG_levels().

And use switch-case instead of 'if's.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250611100319.186924-15-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 21ff56a31b56c7f74e680cd823b7347e15449bb8..c09a90b38d8fcb5908e1d6b09acd0080754d388e 100644 (file)
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2159,6 +2159,46 @@ static void serial8250_startup_special(struct uart_port *port)
        }
 }
 
+static void serial8250_set_TRG_levels(struct uart_port *port)
+{
+       struct uart_8250_port *up = up_to_u8250p(port);
+
+       switch (port->type) {
+       /* For a XR16C850, we need to set the trigger levels */
+       case PORT_16850: {
+               u8 fctr;
+
+               serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+               fctr = serial_in(up, UART_FCTR) & ~(UART_FCTR_RX|UART_FCTR_TX);
+               fctr |= UART_FCTR_TRGD;
+               serial_port_out(port, UART_FCTR, fctr | UART_FCTR_RX);
+               serial_port_out(port, UART_TRG, UART_TRG_96);
+               serial_port_out(port, UART_FCTR, fctr | UART_FCTR_TX);
+               serial_port_out(port, UART_TRG, UART_TRG_96);
+
+               serial_port_out(port, UART_LCR, 0);
+               break;
+       }
+       /* For the Altera 16550 variants, set TX threshold trigger level. */
+       case PORT_ALTR_16550_F32:
+       case PORT_ALTR_16550_F64:
+       case PORT_ALTR_16550_F128:
+               if (port->fifosize <= 1)
+                       return;
+
+               /* Bounds checking of TX threshold (valid 0 to fifosize-2) */
+               if (up->tx_loadsz < 2 || up->tx_loadsz > port->fifosize) {
+                       dev_err(port->dev, "TX FIFO Threshold errors, skipping\n");
+                       return;
+               }
+               serial_port_out(port, UART_ALTR_AFR, UART_ALTR_EN_TXFIFO_LW);
+               serial_port_out(port, UART_ALTR_TX_LOW, port->fifosize - up->tx_loadsz);
+               port->handle_irq = serial8250_tx_threshold_handle_irq;
+               break;
+       }
+}
+
 int serial8250_do_startup(struct uart_port *port)
 {
        struct uart_8250_port *up = up_to_u8250p(port);
@@ -2208,42 +2248,7 @@ int serial8250_do_startup(struct uart_port *port)
                goto out;
        }
 
-       /*
-        * For a XR16C850, we need to set the trigger levels
-        */
-       if (port->type == PORT_16850) {
-               unsigned char fctr;
-
-               serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-
-               fctr = serial_in(up, UART_FCTR) & ~(UART_FCTR_RX|UART_FCTR_TX);
-               serial_port_out(port, UART_FCTR,
-                               fctr | UART_FCTR_TRGD | UART_FCTR_RX);
-               serial_port_out(port, UART_TRG, UART_TRG_96);
-               serial_port_out(port, UART_FCTR,
-                               fctr | UART_FCTR_TRGD | UART_FCTR_TX);
-               serial_port_out(port, UART_TRG, UART_TRG_96);
-
-               serial_port_out(port, UART_LCR, 0);
-       }
-
-       /*
-        * For the Altera 16550 variants, set TX threshold trigger level.
-        */
-       if (((port->type == PORT_ALTR_16550_F32) ||
-            (port->type == PORT_ALTR_16550_F64) ||
-            (port->type == PORT_ALTR_16550_F128)) && (port->fifosize > 1)) {
-               /* Bounds checking of TX threshold (valid 0 to fifosize-2) */
-               if ((up->tx_loadsz < 2) || (up->tx_loadsz > port->fifosize)) {
-                       dev_err(port->dev, "TX FIFO Threshold errors, skipping\n");
-               } else {
-                       serial_port_out(port, UART_ALTR_AFR,
-                                       UART_ALTR_EN_TXFIFO_LW);
-                       serial_port_out(port, UART_ALTR_TX_LOW,
-                                       port->fifosize - up->tx_loadsz);
-                       port->handle_irq = serial8250_tx_threshold_handle_irq;
-               }
-       }
+       serial8250_set_TRG_levels(port);
 
        /* Check if we need to have shared IRQs */
        if (port->irq && (up->port.flags & UPF_SHARE_IRQ))