On 18. 10. 23, 11:17, Crescent CY Hsieh wrote:
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
Oh, I noticed only now. Can we implement this properly? I mean by
defining e.g. SER_RS422_ENABLED? And add checks to
uart_check_rs485_flags() that only one of 485/422 is set and whatever
else makes sense.
+ * RS485_2W (half-duplex) = SER_RS485_ENABLED
+ * RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX
+ */
thanks,
--
js
suse labs
