[PATCH 5/5] tty: serial: uartlite: Prevent changing fixed parameters
From: Sean Anderson <hidden>
Date: 2021-07-23 22:32:20
Subsystem:
the rest, tty layer and serial drivers, xilinx uartlite serial driver · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby, Peter Korsgaard
This device does not support changing baud, parity, data bits, stop bits, or detecting breaks. Disable "changing" these settings to prevent their termios from diverging from the actual state of the uart. To inform users of these limitations, warn if the new termios change these parameters. We only do this once to avoid spamming the log. These warnings are inspired by those in the sifive driver. Signed-off-by: Sean Anderson <redacted> --- drivers/tty/serial/uartlite.c | 52 +++++++++++++++++++++++++++++++++-- 1 file changed, 49 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
index 39c17ab206ca..0aed70039f46 100644
--- a/drivers/tty/serial/uartlite.c
+++ b/drivers/tty/serial/uartlite.c@@ -314,7 +314,54 @@ static void ulite_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) { unsigned long flags; - unsigned int baud; + struct uartlite_data *pdata = port->private_data; + tcflag_t old_cflag; + + if (termios->c_iflag & BRKINT) + dev_err_once(port->dev, "BREAK detection not supported\n"); + termios->c_iflag &= ~BRKINT; + + if (termios->c_cflag & CSTOPB) + dev_err_once(port->dev, "only one stop bit supported\n"); + termios->c_cflag &= ~CSTOPB; + + old_cflag = termios->c_cflag; + termios->c_cflag &= ~(PARENB | PARODD); + if (pdata->parity == 'e') + termios->c_cflag |= PARENB; + else if (pdata->parity == 'o') + termios->c_cflag |= PARENB | PARODD; + + if (termios->c_cflag != old_cflag) + dev_err_once(port->dev, "only '%c' parity supported\n", + pdata->parity); + + old_cflag = termios->c_cflag; + termios->c_cflag &= ~CSIZE; + switch (termios->c_cflag & CSIZE) { + case 5: + termios->c_cflag |= CS5; + break; + case 6: + termios->c_cflag |= CS6; + break; + case 7: + termios->c_cflag |= CS7; + break; + default: + case 8: + termios->c_cflag |= CS8; + break; + } + if (termios->c_cflag != old_cflag) + dev_err_once(port->dev, "only %d data bits supported\n", + pdata->bits); + + old_cflag = termios->c_cflag; + tty_termios_encode_baud_rate(termios, pdata->baud, pdata->baud); + if (termios->c_cflag != old_cflag) + dev_err_once(port->dev, "only %d baud supported\n", + pdata->baud); spin_lock_irqsave(&port->lock, flags);
@@ -337,8 +384,7 @@ static void ulite_set_termios(struct uart_port *port, struct ktermios *termios, | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN; /* update timeout */ - baud = uart_get_baud_rate(port, termios, old, 0, 460800); - uart_update_timeout(port, termios->c_cflag, baud); + uart_update_timeout(port, termios->c_cflag, pdata->baud); spin_unlock_irqrestore(&port->lock, flags); }
--
2.25.1