[PATCH 2/2] tty: serial: 8250: Add support for MOXA PCIe boards to switch interface
From: Crescent CY Hsieh
Date: Fri Oct 27 2023 - 02:26:18 EST
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 adds a flag call "SER_RS422_ENALBED" in serial.h and modifies
serial_core.c to make it possible to switch interface between RS232,
RS422 and RS485.
Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@xxxxxxxx>
---
drivers/tty/serial/8250/8250_pci.c | 44 ++++++++++++++++++++++++++++++
drivers/tty/serial/serial_core.c | 21 ++++++++++++--
include/uapi/linux/serial.h | 4 +++
3 files changed, 66 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 66a2450da..6eabf6bf5 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1983,6 +1983,10 @@ 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_RS422_ENABLED,
+};
+
static bool pci_moxa_is_mini_pcie(unsigned short device)
{
if (device == PCI_DEVICE_ID_MOXA_CP102N ||
@@ -2032,6 +2036,37 @@ 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_RS422_ENABLED
+ * 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_RX_DURING_TX)
+ mode = MOXA_RS485_4W;
+ else
+ mode = MOXA_RS485_2W;
+ } else if (rs485->flags & SER_RS422_ENABLED) {
+ mode = MOXA_RS422;
+ } 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;
@@ -2067,9 +2102,18 @@ 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_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_RS422_ENABLED;
+ }
+
if (board->num_ports == 4 && idx == 3)
offset = 7 * board->uart_offset;
else
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 831d03361..e4ea0e428 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1305,7 +1305,7 @@ static int uart_get_icount(struct tty_struct *tty,
#define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
- SER_RS485_TERMINATE_BUS)
+ SER_RS485_TERMINATE_BUS | SER_RS422_ENABLED)
static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
{
@@ -1371,11 +1371,26 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
{
u32 supported_flags = port->rs485_supported.flags;
- if (!(rs485->flags & SER_RS485_ENABLED)) {
+ if (!(rs485->flags & SER_RS485_ENABLED) && !(rs485->flags & SER_RS422_ENABLED)) {
memset(rs485, 0, sizeof(*rs485));
return;
}
+ /* Pick sane setting if the user enables both interfaces */
+ if (rs485->flags & SER_RS485_ENABLED && rs485->flags & SER_RS422_ENABLED) {
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): Invalid serial interface setting, using RS485 instead\n",
+ port->name, port->line);
+ rs485->flags &= ~(SER_RS422_ENABLED);
+ }
+
+ /* Clear other bits and return if enable RS422 */
+ if (rs485->flags & SER_RS422_ENABLED) {
+ memset(rs485, 0, sizeof(*rs485));
+ rs485->flags |= SER_RS422_ENABLED;
+ return;
+ }
+
/* Pick sane settings if the user hasn't */
if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
@@ -1400,7 +1415,7 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
static void uart_set_rs485_termination(struct uart_port *port,
const struct serial_rs485 *rs485)
{
- if (!(rs485->flags & SER_RS485_ENABLED))
+ if (!(rs485->flags & SER_RS485_ENABLED) && !(rs485->flags & SER_RS422_ENABLED))
return;
gpiod_set_value_cansleep(port->rs485_term_gpio,
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 53bc1af67..427609fd5 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -137,6 +137,8 @@ struct serial_icounter_struct {
* * %SER_RS485_ADDRB - Enable RS485 addressing mode.
* * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv). Requires %SER_RS485_ADDRB.
* * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest). Requires %SER_RS485_ADDRB.
+ *
+ * * %SER_RS422_ENABLED - RS422 enabled.
*/
struct serial_rs485 {
__u32 flags;
@@ -149,6 +151,8 @@ struct serial_rs485 {
#define SER_RS485_ADDR_RECV (1 << 7)
#define SER_RS485_ADDR_DEST (1 << 8)
+#define SER_RS422_ENABLED (1 << 9)
+
__u32 delay_rts_before_send;
__u32 delay_rts_after_send;
--
2.34.1