From 974e2f6a0554685493cc44406bc7d8ba0a3b0e33 Mon Sep 17 00:00:00 2001 From: Jarkko Sonninen Date: Sat, 8 Jul 2023 17:56:50 +0300 Subject: USB: serial: xr: add TIOCGRS485 and TIOCSRS485 ioctls Exar devices like XR21B1411 can control an RS485 transceiver by automatically asserting the RTS#/RS485 pin before sending data and deasserting it when the last stop bit has been transmitted. The polarity of the RST#/RS485 signal is configurable and the hardware also supports half-duplex turn-around delay and address matching mode. Add support for enabling and disabling RS-485 mode and configuring the RST#/RS485 signal polarity using the TIOCGRS485 and TIOCSRS485 ioctls. Support for half-duplex turn-around delay and address matching mode are left unimplemented for now. User enables RS-485 mode by setting SER_RS485_ENABLED flag in struct serial_rs485 flags. User should also set either SER_RS485_RTS_ON_SEND or SER_RS485_RTS_AFTER_SEND to select the behaviour of the RTS#/RS485 pin. Setting SER_RS485_RTS_ON_SEND will drive RTS#/RS485 low during transmission. Signed-off-by: Jarkko Sonninen [ johan: let SER_RS485_RTS_ON_SEND determine SER_RS485_RTS_AFTER_SEND ] Signed-off-by: Johan Hovold --- drivers/usb/serial/xr_serial.c | 89 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 88 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c index 4ec7c5892b84..1d9a12628f81 100644 --- a/drivers/usb/serial/xr_serial.c +++ b/drivers/usb/serial/xr_serial.c @@ -93,6 +93,7 @@ struct xr_txrx_clk_mask { #define XR_GPIO_MODE_SEL_DTR_DSR 0x2 #define XR_GPIO_MODE_SEL_RS485 0x3 #define XR_GPIO_MODE_SEL_RS485_ADDR 0x4 +#define XR_GPIO_MODE_RS485_TX_H 0x8 #define XR_GPIO_MODE_TX_TOGGLE 0x100 #define XR_GPIO_MODE_RX_TOGGLE 0x200 @@ -237,6 +238,7 @@ static const struct xr_type xr_types[] = { struct xr_data { const struct xr_type *type; u8 channel; /* zero-based index or interface number */ + struct serial_rs485 rs485; }; static int xr_set_reg(struct usb_serial_port *port, u8 channel, u16 reg, u16 val) @@ -629,6 +631,7 @@ static void xr_set_flow_mode(struct tty_struct *tty, struct xr_data *data = usb_get_serial_port_data(port); const struct xr_type *type = data->type; u16 flow, gpio_mode; + bool rs485_enabled; int ret; ret = xr_get_reg_uart(port, type->gpio_mode, &gpio_mode); @@ -645,7 +648,17 @@ static void xr_set_flow_mode(struct tty_struct *tty, /* Set GPIO mode for controlling the pins manually by default. */ gpio_mode &= ~XR_GPIO_MODE_SEL_MASK; - if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) { + rs485_enabled = !!(data->rs485.flags & SER_RS485_ENABLED); + if (rs485_enabled) { + dev_dbg(&port->dev, "Enabling RS-485\n"); + gpio_mode |= XR_GPIO_MODE_SEL_RS485; + if (data->rs485.flags & SER_RS485_RTS_ON_SEND) + gpio_mode &= ~XR_GPIO_MODE_RS485_TX_H; + else + gpio_mode |= XR_GPIO_MODE_RS485_TX_H; + } + + if (C_CRTSCTS(tty) && C_BAUD(tty) != B0 && !rs485_enabled) { dev_dbg(&port->dev, "Enabling hardware flow ctrl\n"); gpio_mode |= XR_GPIO_MODE_SEL_RTS_CTS; flow = XR_UART_FLOW_MODE_HW; @@ -809,6 +822,79 @@ static void xr_cdc_set_line_coding(struct tty_struct *tty, kfree(lc); } +static void xr_sanitize_serial_rs485(struct serial_rs485 *rs485) +{ + if (!(rs485->flags & SER_RS485_ENABLED)) { + memset(rs485, 0, sizeof(*rs485)); + return; + } + + /* RTS always toggles after TX */ + if (rs485->flags & SER_RS485_RTS_ON_SEND) + rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; + else + rs485->flags |= SER_RS485_RTS_AFTER_SEND; + + /* Only the flags are implemented at the moment */ + rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | + SER_RS485_RTS_AFTER_SEND; + rs485->delay_rts_before_send = 0; + rs485->delay_rts_after_send = 0; + memset(rs485->padding, 0, sizeof(rs485->padding)); +} + +static int xr_get_rs485_config(struct tty_struct *tty, + struct serial_rs485 __user *argp) +{ + struct usb_serial_port *port = tty->driver_data; + struct xr_data *data = usb_get_serial_port_data(port); + + down_read(&tty->termios_rwsem); + if (copy_to_user(argp, &data->rs485, sizeof(data->rs485))) { + up_read(&tty->termios_rwsem); + return -EFAULT; + } + up_read(&tty->termios_rwsem); + + return 0; +} + +static int xr_set_rs485_config(struct tty_struct *tty, + struct serial_rs485 __user *argp) +{ + struct usb_serial_port *port = tty->driver_data; + struct xr_data *data = usb_get_serial_port_data(port); + struct serial_rs485 rs485; + + if (copy_from_user(&rs485, argp, sizeof(rs485))) + return -EFAULT; + xr_sanitize_serial_rs485(&rs485); + + down_write(&tty->termios_rwsem); + data->rs485 = rs485; + xr_set_flow_mode(tty, port, NULL); + up_write(&tty->termios_rwsem); + + if (copy_to_user(argp, &rs485, sizeof(rs485))) + return -EFAULT; + + return 0; +} + +static int xr_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) +{ + void __user *argp = (void __user *)arg; + + switch (cmd) { + case TIOCGRS485: + return xr_get_rs485_config(tty, argp); + case TIOCSRS485: + return xr_set_rs485_config(tty, argp); + } + + return -ENOIOCTLCMD; +} + static void xr_set_termios(struct tty_struct *tty, struct usb_serial_port *port, const struct ktermios *old_termios) @@ -1010,6 +1096,7 @@ static struct usb_serial_driver xr_device = { .set_termios = xr_set_termios, .tiocmget = xr_tiocmget, .tiocmset = xr_tiocmset, + .ioctl = xr_ioctl, .dtr_rts = xr_dtr_rts }; -- cgit