MOXA PCIe boards have 4 serial interfaces and don't require additional
stuff to switch between interfaces:
- RS232
- RS422
- RS485_2W (half-duplex)
- RS485_4W (full-duplex)
By using ioctl command "TIOCRS485", it can switch between default
interface and RS485 if supported.
That means, for RS422/RS485 board, it can switch between RS422 and
RS485 by setting the flags within struct serial_rs485.
However, for the RS232/RS422/RS485 board, it can only switch between
RS232 and RS485, there's no flag for switching interface into RS422.
This patch uses "SER_RS485_TERMINATE_BUS" to represent RS422 as a
workaround solution:
- RS232 = (no flags are set)
- RS422 = SER_RS485_ENABLED | SER_RS485_TERMINATE_BUS
- RS485_2W (half-duplex) = SER_RS485_ENABLED
- RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX
Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@xxxxxxxx>
---
drivers/tty/serial/8250/8250_pci.c | 58 ++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 29a28e72b..098ac466b 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1974,6 +1974,10 @@ pci_sunix_setup(struct serial_private *priv,
#define MOXA_RS485_2W 0x0F
#define MOXA_UIR_OFFSET 0x04
+static const struct serial_rs485 pci_moxa_rs485_supported = {
+ .flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX | SER_RS485_TERMINATE_BUS,
+};
+
static bool pci_moxa_is_mini_pcie(unsigned short device)
{
if (device == PCI_DEVICE_ID_MOXA_CP102N ||
@@ -2024,6 +2028,46 @@ static int pci_moxa_set_interface(const struct pci_dev *dev,
return 0;
}
+/*
+ * MOXA PCIe boards support switching the serial interface using the ioctl
+ * command "TIOCSRS485", but there is currently no dedicated flag for switching
+ * to RS422. As a workaround, we utilize the "SER_RS485_TERMINATE_BUS" flag to
+ * represent RS422.
+ *
+ * RS232 = (no flags are set)
+ * RS422 = SER_RS485_ENABLED | SER_RS485_TERMINATE_BUS
+ * RS485_2W (half-duplex) = SER_RS485_ENABLED
+ * RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX
+ */
+static int pci_moxa_rs485_config(struct uart_port *port,
+ struct ktermios *termios,
+ struct serial_rs485 *rs485)
+{
+ struct pci_dev *dev = to_pci_dev(port->dev);
+ unsigned short device = dev->device;
+ u8 mode = MOXA_RS232;
+
+ if (rs485->flags & SER_RS485_ENABLED) {
+ if (rs485->flags & SER_RS485_TERMINATE_BUS) {
+ mode = MOXA_RS422;
+ } else {
+ if (rs485->flags & SER_RS485_RX_DURING_TX)
+ mode = MOXA_RS485_4W;
+ else
+ mode = MOXA_RS485_2W;
+ }
+ } else {
+ /*
+ * RS232 is not supported for MOXA PCIe boards with device IDs
+ * matching the pattern 0x*3**.
+ */
+ if (pci_moxa_match_second_digit(device, 0x0300))
+ return -EOPNOTSUPP;
+ }
+
+ return pci_moxa_set_interface(dev, port->port_id, mode);
+}
+
static int pci_moxa_init(struct pci_dev *dev)
{
unsigned short device = dev->device;
@@ -2063,9 +2107,23 @@ pci_moxa_setup(struct serial_private *priv,
const struct pciserial_board *board,
struct uart_8250_port *port, int idx)
{
+ struct pci_dev *dev = priv->dev;
+ unsigned short device = dev->device;
unsigned int bar = FL_GET_BASE(board->flags);
int offset;
+ /*
+ * For the device IDs of MOXA PCIe boards match the pattern 0x*1** and 0x*3**,
+ * these boards support switching interface between RS422/RS485 using TIOCSRS485.
+ */
+ if (pci_moxa_match_second_digit(device, 0x0100) ||
+ pci_moxa_match_second_digit(device, 0x0300)) {
+ port->port.rs485_config = pci_moxa_rs485_config;
+ port->port.rs485_supported = pci_moxa_rs485_supported;
+
+ if (pci_moxa_match_second_digit(device, 0x0300))
+ port->port.rs485.flags |= SER_RS485_ENABLED | SER_RS485_TERMINATE_BUS;
+ }
if (board->num_ports == 4 && idx == 3)
offset = 7 * board->uart_offset;
else
--
2.34.1
