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serial: mvebu-uart: correctly report configured baudrate value

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commit 4f532c1e25319e42996ec18a1f473fd50c8e575d upstream.

Functions tty_termios_encode_baud_rate() and uart_update_timeout() should
be called with the baudrate value which was set to hardware. Linux then
report exact values via ioctl(TCGETS2) to userspace.

Change mvebu_uart_baud_rate_set() function to return baudrate value which
was set to hardware and propagate this value to above mentioned functions.

With this change userspace would see precise value in termios c_ospeed
field.

Fixes: 68a0db1d7d ("serial: mvebu-uart: add function to change baudrate")
Cc: stable <stable@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20220628100922.10717-1-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pali Rohár 2022-06-28 12:09:22 +02:00 committed by Greg Kroah-Hartman
parent 2230428fb8
commit c68f6e2e4f
1 changed files with 13 additions and 12 deletions
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25
drivers/tty/serial/mvebu-uart.c
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@ -443,13 +443,13 @@ static void mvebu_uart_shutdown(struct uart_port *port)
}
}
static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
static unsigned int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
{
unsigned int d_divisor, m_divisor;
u32 brdv, osamp;
if (!port->uartclk)
return -EOPNOTSUPP;
return 0;
/*
* The baudrate is derived from the UART clock thanks to two divisors:
@ -473,7 +473,7 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
osamp &= ~OSAMP_DIVISORS_MASK;
writel(osamp, port->membase + UART_OSAMP);
return 0;
return DIV_ROUND_CLOSEST(port->uartclk, d_divisor * m_divisor);
}
static void mvebu_uart_set_termios(struct uart_port *port,
@ -510,15 +510,11 @@ static void mvebu_uart_set_termios(struct uart_port *port,
max_baud = 230400;
baud = uart_get_baud_rate(port, termios, old, min_baud, max_baud);
if (mvebu_uart_baud_rate_set(port, baud)) {
/* No clock available, baudrate cannot be changed */
if (old)
baud = uart_get_baud_rate(port, old, NULL,
min_baud, max_baud);
} else {
tty_termios_encode_baud_rate(termios, baud, baud);
uart_update_timeout(port, termios->c_cflag, baud);
}
baud = mvebu_uart_baud_rate_set(port, baud);
/* In case baudrate cannot be changed, report previous old value */
if (baud == 0 && old)
baud = tty_termios_baud_rate(old);
/* Only the following flag changes are supported */
if (old) {
@ -529,6 +525,11 @@ static void mvebu_uart_set_termios(struct uart_port *port,
termios->c_cflag |= CS8;
}
if (baud != 0) {
tty_termios_encode_baud_rate(termios, baud, baud);
uart_update_timeout(port, termios->c_cflag, baud);
}
spin_unlock_irqrestore(&port->lock, flags);
}