[PATCH 5/6] tty: serial: 8250: Add support for Moxa PCIe boards to switch interface

Crescent Hsieh
2024-06-07T11:43:58Z

This patch adds support for Moxa PCIe serial boards to switch the serial
interface by using ioctl() command "TIOCSRS485" with the flags of struct
"serial_rs485":

- RS232 = (no flags are set)
- RS422 = SER_RS485_ENABLED | SER_RS485_MODE_RS422
- RS485_2W (half-duplex) = SER_RS485_ENABLED
- RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX

Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
---
drivers/tty/serial/8250/8250_pci.c | 46 ++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index e4e6493a5497..e2fcddec9ab5 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -2010,6 +2010,10 @@ enum {
MOXA_SUPP_RS485 = BIT(2),
};

+static const struct serial_rs485 pci_moxa_rs485_supported = {
+ .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX | SER_RS485_MODE_RS422,
+};
+
static bool pci_moxa_is_pcie(unsigned short device)
{
if (device == PCI_DEVICE_ID_MOXA_CP102E ||
@@ -2078,6 +2082,37 @@ 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".
+ *
+ * RS232 = (no flags are set)
+ * RS422 = SER_RS485_ENABLED | SER_RS485_MODE_RS422
+ * 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);
+ u8 mode = MOXA_RS232;
+
+ if (rs485->flags & SER_RS485_ENABLED) {
+ if (rs485->flags & SER_RS485_MODE_RS422)
+ mode = MOXA_RS422;
+ else if (rs485->flags & SER_RS485_RX_DURING_TX)
+ mode = MOXA_RS485_4W;
+ else
+ mode = MOXA_RS485_2W;
+ } else {
+ if (!(pci_moxa_supported_rs(dev) & MOXA_SUPP_RS232))
+ return -ENODEV;
+ }
+
+ return pci_moxa_set_interface(dev, port->port_id, mode);
+}
+
static int pci_moxa_init(struct pci_dev *dev)
{
unsigned short device = dev->device;
@@ -2120,9 +2155,20 @@ 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 int bar = FL_GET_BASE(board->flags);
int offset;

+ if (pci_moxa_is_pcie(dev->device) || pci_moxa_is_mini_pcie(dev->device)) {
+ if (pci_moxa_supported_rs(dev) & MOXA_SUPP_RS485) {
+ port->port.rs485_config = pci_moxa_rs485_config;
+ port->port.rs485_supported = pci_moxa_rs485_supported;
+
+ if (!(pci_moxa_supported_rs(dev) & MOXA_SUPP_RS232))
+ port->port.rs485.flags = SER_RS485_ENABLED | SER_RS485_MODE_RS422;
+ }
+ }
+
if (board->num_ports == 4 && idx == 3)
offset = 7 * board->uart_offset;
else
--
2.34.1