From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali@kernel.org>

Date: Tue, 28 Jun 2022 12:09:22 +0200

Subject: serial: mvebu-uart: correctly report configured baudrate value

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Git-commit: 4f532c1e25319e42996ec18a1f473fd50c8e575d

Patch-mainline: v5.19-rc7

References: git-fixes

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: 68a0db1d7da2 ("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>

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>

---

 drivers/tty/serial/mvebu-uart.c |   25 +++++++++++++------------

 1 file changed, 13 insertions(+), 12 deletions(-)

--- a/drivers/tty/serial/mvebu-uart.c

+++ b/drivers/tty/serial/mvebu-uart.c

@@ -453,13 +453,13 @@ static void mvebu_uart_shutdown(struct u

 	}

 }

-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;

 	if (!port->uartclk)

-		return -EOPNOTSUPP;

+		return 0;

 	/*

 	 * The baudrate is derived from the UART clock thanks to two divisors:

@@ -479,7 +479,7 @@ static int mvebu_uart_baud_rate_set(stru

 	brdv |= d_divisor;

 	writel(brdv, port->membase + UART_BRDV);

-	return 0;

+	return DIV_ROUND_CLOSEST(port->uartclk, d_divisor * m_divisor);

 }

 static void mvebu_uart_set_termios(struct uart_port *port,

@@ -516,15 +516,11 @@ static void mvebu_uart_set_termios(struc

 	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) {

@@ -535,6 +531,11 @@ static void mvebu_uart_set_termios(struc

 		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);

 }