Commit 32330c83 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

mxser: switch from xmit_buf to kfifo 



Use kfifo for xmit buffer handling. The change is mostly
straightforward. It saves complexity both on the stuffing side
(mxser_write() and mxser_put_char()) and pulling side
(mxser_transmit_chars()). In fact, the loop in mxser_write() can be
completely deleted as the wrap of the buffer is taken care of in the
kfifo code now.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220124071430.14907-8-jslaby@suse.cz


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 92cc9d1d

drivers/tty/mxser.c

+27 −47
Original line number Diff line number Diff line
@@ -275,9 +275,6 @@ struct mxser_port { 
	u8 read_status_mask;

	u8 ignore_status_mask;

	u8 xmit_fifo_size;

	unsigned int xmit_head;

	unsigned int xmit_tail;

	unsigned int xmit_cnt;



	spinlock_t slock;

};
@@ -813,7 +810,7 @@ static int mxser_activate(struct tty_port *port, struct tty_struct *tty) 
	(void) inb(info->ioaddr + UART_MSR);



	clear_bit(TTY_IO_ERROR, &tty->flags);

	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

	kfifo_reset(&port->xmit_fifo);



	/*

	 * and set the speed of the serial port
@@ -901,9 +898,8 @@ static void mxser_flush_buffer(struct tty_struct *tty) 
	struct mxser_port *info = tty->driver_data;

	unsigned long flags;





	spin_lock_irqsave(&info->slock, flags);

	info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

	kfifo_reset(&info->port.xmit_fifo);



	outb(info->FCR | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,

		info->ioaddr + UART_FCR);
@@ -920,50 +916,34 @@ static void mxser_close(struct tty_struct *tty, struct file *filp) 


static int mxser_write(struct tty_struct *tty, const unsigned char *buf, int count)

{

	int c, total = 0;

	struct mxser_port *info = tty->driver_data;

	unsigned long flags;

	int written;

	bool is_empty;



	while (1) {

		c = min_t(int, count, min(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,

					  SERIAL_XMIT_SIZE - info->xmit_head));

		if (c <= 0)

			break;



		memcpy(info->port.xmit_buf + info->xmit_head, buf, c);

	spin_lock_irqsave(&info->slock, flags);

		info->xmit_head = (info->xmit_head + c) &

				  (SERIAL_XMIT_SIZE - 1);

		info->xmit_cnt += c;

	written = kfifo_in(&info->port.xmit_fifo, buf, count);

	is_empty = kfifo_is_empty(&info->port.xmit_fifo);

	spin_unlock_irqrestore(&info->slock, flags);



		buf += c;

		count -= c;

		total += c;

	}



	if (info->xmit_cnt && !tty->flow.stopped)

	if (!is_empty && !tty->flow.stopped)

		if (!tty->hw_stopped || mxser_16550A_or_MUST(info))

			mxser_start_tx(info);



	return total;

	return written;

}



static int mxser_put_char(struct tty_struct *tty, unsigned char ch)

{

	struct mxser_port *info = tty->driver_data;

	unsigned long flags;



	if (info->xmit_cnt >= SERIAL_XMIT_SIZE - 1)

		return 0;

	int ret;



	spin_lock_irqsave(&info->slock, flags);

	info->port.xmit_buf[info->xmit_head++] = ch;

	info->xmit_head &= SERIAL_XMIT_SIZE - 1;

	info->xmit_cnt++;

	ret = kfifo_put(&info->port.xmit_fifo, ch);

	spin_unlock_irqrestore(&info->slock, flags);



	return 1;

	return ret;

}
@@ -971,7 +951,7 @@ static void mxser_flush_chars(struct tty_struct *tty) 
{

	struct mxser_port *info = tty->driver_data;



	if (!info->xmit_cnt || tty->flow.stopped ||

	if (kfifo_is_empty(&info->port.xmit_fifo) || tty->flow.stopped ||

			(tty->hw_stopped && !mxser_16550A_or_MUST(info)))

		return;
@@ -981,16 +961,15 @@ static void mxser_flush_chars(struct tty_struct *tty) 
static unsigned int mxser_write_room(struct tty_struct *tty)

{

	struct mxser_port *info = tty->driver_data;

	int ret;



	ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;

	return ret < 0 ? 0 : ret;

	return kfifo_avail(&info->port.xmit_fifo);

}



static unsigned int mxser_chars_in_buffer(struct tty_struct *tty)

{

	struct mxser_port *info = tty->driver_data;

	return info->xmit_cnt;



	return kfifo_len(&info->port.xmit_fifo);

}



/*
@@ -1379,7 +1358,7 @@ static void mxser_start(struct tty_struct *tty) 
	unsigned long flags;



	spin_lock_irqsave(&info->slock, flags);

	if (info->xmit_cnt)

	if (!kfifo_is_empty(&info->port.xmit_fifo))

		__mxser_start_tx(info);

	spin_unlock_irqrestore(&info->slock, flags);

}
@@ -1610,7 +1589,7 @@ static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port 
		return;

	}



	if (!port->xmit_cnt || tty->flow.stopped ||

	if (kfifo_is_empty(&port->port.xmit_fifo) || tty->flow.stopped ||

			(tty->hw_stopped && !mxser_16550A_or_MUST(port))) {

		__mxser_stop_tx(port);

		return;
@@ -1618,18 +1597,19 @@ static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port 


	count = port->xmit_fifo_size;

	do {

		outb(port->port.xmit_buf[port->xmit_tail++],

			port->ioaddr + UART_TX);

		port->xmit_tail &= SERIAL_XMIT_SIZE - 1;

		port->icount.tx++;

		if (!--port->xmit_cnt)

		unsigned char c;



		if (!kfifo_get(&port->port.xmit_fifo, &c))

			break;



		outb(c, port->ioaddr + UART_TX);

		port->icount.tx++;

	} while (--count > 0);



	if (port->xmit_cnt < WAKEUP_CHARS)

	if (kfifo_len(&port->port.xmit_fifo) < WAKEUP_CHARS)

		tty_wakeup(tty);



	if (!port->xmit_cnt)

	if (kfifo_is_empty(&port->port.xmit_fifo))

		__mxser_stop_tx(port);

}