diff options
| author | Pali Rohár <pali@kernel.org> | 2021-09-27 11:37:04 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-10-05 15:02:58 +0200 |
| commit | 32262e2e429cdb31f9e957e997d53458762931b7 (patch) | |
| tree | 70a666e9895aba562b6910e876383e2feb29391d /drivers/tty | |
| parent | 027b57170bf8bb6999a28e4a5f3d78bf1db0f90c (diff) | |
serial: 8250: Fix reporting real baudrate value in c_ospeed field
In most cases it is not possible to set exact baudrate value to hardware.
So fix reporting real baudrate value which was set to hardware via c_ospeed
termios field. It can be retrieved by ioctl(TCGETS2) from userspace.
Real baudrate value is calculated from chosen hardware divisor and base
clock. It is implemented in a new function serial8250_compute_baud_rate()
which is inverse of serial8250_get_divisor() function.
With this change is fixed also UART timeout value (it is updated via
uart_update_timeout() function), which is calculated from the now fixed
baudrate value too.
Cc: stable@vger.kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20210927093704.19768-1-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 66374704747e..dc6900b2daa8 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2584,6 +2584,19 @@ static unsigned int serial8250_get_divisor(struct uart_port *port, return serial8250_do_get_divisor(port, baud, frac); } +static unsigned int serial8250_compute_baud_rate(struct uart_port *port, + unsigned int quot) +{ + if ((port->flags & UPF_MAGIC_MULTIPLIER) && quot == 0x8001) + return port->uartclk / 4; + else if ((port->flags & UPF_MAGIC_MULTIPLIER) && quot == 0x8002) + return port->uartclk / 8; + else if (port->type == PORT_NPCM) + return DIV_ROUND_CLOSEST(port->uartclk - 2 * (quot + 2), 16 * (quot + 2)); + else + return DIV_ROUND_CLOSEST(port->uartclk, 16 * quot); +} + static unsigned char serial8250_compute_lcr(struct uart_8250_port *up, tcflag_t c_cflag) { @@ -2714,11 +2727,14 @@ void serial8250_update_uartclk(struct uart_port *port, unsigned int uartclk) baud = serial8250_get_baud_rate(port, termios, NULL); quot = serial8250_get_divisor(port, baud, &frac); + baud = serial8250_compute_baud_rate(port, quot); serial8250_rpm_get(up); spin_lock_irqsave(&port->lock, flags); uart_update_timeout(port, termios->c_cflag, baud); + if (tty_termios_baud_rate(termios)) + tty_termios_encode_baud_rate(termios, baud, baud); serial8250_set_divisor(port, baud, quot, frac); serial_port_out(port, UART_LCR, up->lcr); @@ -2750,6 +2766,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, baud = serial8250_get_baud_rate(port, termios, old); quot = serial8250_get_divisor(port, baud, &frac); + baud = serial8250_compute_baud_rate(port, quot); /* * Ok, we're now changing the port state. Do it with |