[PATCH] tty: serial: 8250: Add SystemBase Multi I/O cards

From: Michael Walle

Date: Wed Feb 25 2026 - 03:19:24 EST


Add support for the SystemBase Multi I/O serial cards, which are
"compatible" with a standard 16550A controllers, except that they need
to have their interrupts enabled in a proprietary way.

Tested with a Delock "Serial PCI Express x1 Card 8x Serial RS-232".

Signed-off-by: Michael Walle <mwalle@xxxxxxxxxx>
---
drivers/tty/serial/8250/8250_pci.c | 51 ++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 6589bb531cc6..7957a552b6ab 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -100,6 +100,8 @@
#define PCI_DEVICE_ID_ADDIDATA_CPCI7420_NG 0x7025
#define PCI_DEVICE_ID_ADDIDATA_CPCI7300_NG 0x7026

+#define PCI_VENDOR_ID_SYSTEMBASE 0x14a1
+
/* Unknown vendors/cards - this should not be in linux/pci_ids.h */
#define PCI_SUBDEVICE_ID_UNKNOWN_0x1584 0x1584
#define PCI_SUBDEVICE_ID_UNKNOWN_0x1588 0x1588
@@ -2128,6 +2130,35 @@ pci_moxa_setup(struct serial_private *priv,
return setup_port(priv, port, bar, offset, 0);
}

+#define SB_OPTR_IMR0 0x0c /* Interrupt mask register, p0 to p7 */
+static int pci_systembase_init(struct pci_dev *dev)
+{
+ resource_size_t iobase;
+
+ if (!IS_ENABLED(CONFIG_HAS_IOPORT))
+ return serial_8250_warn_need_ioport(dev);
+
+ iobase = pci_resource_start(dev, 1);
+
+ /* This will support up to 8 ports */
+ outb(0xff, iobase + SB_OPTR_IMR0);
+
+ return 0;
+}
+
+static void pci_systembase_exit(struct pci_dev *dev)
+{
+ resource_size_t iobase;
+
+ if (!IS_ENABLED(CONFIG_HAS_IOPORT)) {
+ serial_8250_warn_need_ioport(dev);
+ return;
+ }
+
+ iobase = pci_resource_start(dev, 0);
+ outb(0x00, iobase + SB_OPTR_IMR0);
+}
+
/*
* Master list of serial port init/setup/exit quirks.
* This does not describe the general nature of the port.
@@ -2476,6 +2507,16 @@ static struct pci_serial_quirk pci_serial_quirks[] = {
.init = pci_siig_init,
.setup = pci_siig_setup,
},
+ /* Systembase */
+ {
+ .vendor = PCI_VENDOR_ID_SYSTEMBASE,
+ .device = 0x0008,
+ .subvendor = PCI_ANY_ID,
+ .subdevice = PCI_ANY_ID,
+ .init = pci_systembase_init,
+ .setup = pci_default_setup,
+ .exit = pci_systembase_exit,
+ },
/*
* Titan cards
*/
@@ -3041,6 +3082,7 @@ enum pci_board_num_t {
pbn_b0_1_921600,
pbn_b0_2_921600,
pbn_b0_4_921600,
+ pbn_b0_8_921600,

pbn_b0_2_1130000,

@@ -3241,6 +3283,12 @@ static struct pciserial_board pci_boards[] = {
.base_baud = 921600,
.uart_offset = 8,
},
+ [pbn_b0_8_921600] = {
+ .flags = FL_BASE0,
+ .num_ports = 8,
+ .base_baud = 921600,
+ .uart_offset = 8,
+ },

[pbn_b0_2_1130000] = {
.flags = FL_BASE0,
@@ -6152,6 +6200,9 @@ static const struct pci_device_id serial_pci_tbl[] = {
PCI_ANY_ID, PCI_ANY_ID,
0, 0, pbn_b0_1_115200 },

+ /* Systembase Multi I/O cards */
+ { PCI_VDEVICE(SYSTEMBASE, 0x0008), pbn_b0_8_921600 },
+
/* Fintek PCI serial cards */
{ PCI_DEVICE(0x1c29, 0x1104), .driver_data = pbn_fintek_4 },
{ PCI_DEVICE(0x1c29, 0x1108), .driver_data = pbn_fintek_8 },
--
2.47.3