korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 12:28:41 +08:00
Code Issues Packages Projects Releases Wiki Activity

serial: 8250: Create serial_lsr_in()

Browse Source 
LSR register readers need to be careful in order to not lose bits that
are not preserved across reads. Create a helper that takes care of
storing the non-preserved bits into lsr_save_flags.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220608095431.18376-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ilpo Järvinen 2022-06-08 12:54:27 +03:00 committed by Greg Kroah-Hartman
parent ce338e4477
commit bdb70c424d
3 changed files with 25 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/tty/serial/8250/8250.h
View File

@ -123,6 +123,26 @@ static inline void serial_out(struct uart_8250_port *up, int offset, int value)
up->port.serial_out(&up->port, offset, value);
}
/**
* serial_lsr_in - Read LSR register and preserve flags across reads
* @up: uart 8250 port
*
* Read LSR register and handle saving non-preserved flags across reads.
* The flags that are not preserved across reads are stored into
* up->lsr_saved_flags.
*
* Returns LSR value or'ed with the preserved flags (if any).
*/
static inline unsigned int serial_lsr_in(struct uart_8250_port *up)
{
unsigned int lsr = up->lsr_saved_flags;
lsr |= serial_in(up, UART_LSR);
up->lsr_saved_flags = lsr & LSR_SAVE_FLAGS;
return lsr;
}
/*
* For the 16C950
*/

3
drivers/tty/serial/8250/8250_core.c
View File

@ -276,8 +276,7 @@ static void serial8250_backup_timeout(struct timer_list *t)
* the "Diva" UART used on the management processor on many HP
* ia64 and parisc boxes.
*/
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
lsr = serial_lsr_in(up);
if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) &&
(!uart_circ_empty(&up->port.state->xmit) || up->port.x_char) &&
(lsr & UART_LSR_THRE)) {

15
drivers/tty/serial/8250/8250_port.c
View File

@ -1508,11 +1508,9 @@ static inline void __stop_tx(struct uart_8250_port *p)
struct uart_8250_em485 *em485 = p->em485;
if (em485) {
unsigned char lsr = serial_in(p, UART_LSR);
unsigned char lsr = serial_lsr_in(p);
u64 stop_delay = 0;
p->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
if (!(lsr & UART_LSR_THRE))
return;
/*
@ -1569,10 +1567,8 @@ static inline void __start_tx(struct uart_port *port)
if (serial8250_set_THRI(up)) {
if (up->bugs & UART_BUG_TXEN) {
unsigned char lsr;
unsigned char lsr = serial_lsr_in(up);
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
if (lsr & UART_LSR_THRE)
serial8250_tx_chars(up);
}
@ -2002,8 +1998,7 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
serial8250_rpm_get(up);
spin_lock_irqsave(&port->lock, flags);
lsr = serial_port_in(port, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
lsr = serial_lsr_in(up);
spin_unlock_irqrestore(&port->lock, flags);
serial8250_rpm_put(up);
@ -2079,9 +2074,7 @@ static void wait_for_lsr(struct uart_8250_port *up, int bits)
/* Wait up to 10ms for the character(s) to be sent. */
for (;;) {
status = serial_in(up, UART_LSR);
up->lsr_saved_flags |= status & LSR_SAVE_FLAGS;
status = serial_lsr_in(up);
if ((status & bits) == bits)
break;