Commit 293f8995 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

tty: serial: 21285: stop using the unused[] variable from struct uart_port 



Much like the samsung_tty driver (now I know where they copied the idea
from), the 21285 uart driver uses 2 bytes from the "unused" array of
struct uart_port to keep tx/rx enabled/disabled state.  Those fields are
going away (they were never really needed in the first place), so fix up
the 21285 driver by another horrible hack.

Instead of creating a whole structure for just 2 bytes, just use two
bits from the private_data pointer instead, as that pointer is never
used.  The two bits reflect if tx/rx is now enabled/disabled.

Astute readers will note that once rx is disabled, nothing ever seems to
turn it back on, making one wonder if anyone has ever done this.

Reported-by: default avatarkbuild test robot <lkp@intel.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20191219145109.GA1962496@kroah.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 82cfd2e6

drivers/tty/serial/21285.c

+45 −10
Original line number Diff line number Diff line
@@ -41,8 +41,43 @@ 


static const char serial21285_name[] = "Footbridge UART";



#define tx_enabled(port)	((port)->unused[0])

#define rx_enabled(port)	((port)->unused[1])

/*

 * We only need 2 bits of data, so instead of creating a whole structure for

 * this, use bits of the private_data pointer of the uart port structure.

 */

#define tx_enabled_bit	0

#define rx_enabled_bit	1



static bool is_enabled(struct uart_port *port, int bit)

{

	unsigned long private_data = (unsigned long)port->private_data;



	if (test_bit(bit, &private_data))

		return true;

	return false;

}



static void enable(struct uart_port *port, int bit)

{

	unsigned long private_data = (unsigned long)port->private_data;



	set_bit(bit, &private_data);

}



static void disable(struct uart_port *port, int bit)

{

	unsigned long private_data = (unsigned long)port->private_data;



	clear_bit(bit, &private_data);

}



#define is_tx_enabled(port)	is_enabled(port, tx_enabled_bit)

#define tx_enable(port)		enable(port, tx_enabled_bit)

#define tx_disable(port)	disable(port, tx_enabled_bit)



#define is_rx_enabled(port)	is_enabled(port, rx_enabled_bit)

#define rx_enable(port)		enable(port, rx_enabled_bit)

#define rx_disable(port)	disable(port, rx_enabled_bit)



/*

 * The documented expression for selecting the divisor is:
@@ -57,25 +92,25 @@ static const char serial21285_name[] = "Footbridge UART"; 


static void serial21285_stop_tx(struct uart_port *port)

{

	if (tx_enabled(port)) {

	if (is_tx_enabled(port)) {

		disable_irq_nosync(IRQ_CONTX);

		tx_enabled(port) = 0;

		tx_disable(port);

	}

}



static void serial21285_start_tx(struct uart_port *port)

{

	if (!tx_enabled(port)) {

	if (!is_tx_enabled(port)) {

		enable_irq(IRQ_CONTX);

		tx_enabled(port) = 1;

		tx_enable(port);

	}

}



static void serial21285_stop_rx(struct uart_port *port)

{

	if (rx_enabled(port)) {

	if (is_rx_enabled(port)) {

		disable_irq_nosync(IRQ_CONRX);

		rx_enabled(port) = 0;

		rx_disable(port);

	}

}
@@ -185,8 +220,8 @@ static int serial21285_startup(struct uart_port *port) 
{

	int ret;



	tx_enabled(port) = 1;

	rx_enabled(port) = 1;

	tx_enable(port);

	rx_enable(port);



	ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,

			  serial21285_name, port);

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