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serial: fsl_lpuart: handle break and make sysrq work

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Although there is already sysrq characters handling, a break condition
was never detected. Add support for it.

The LPUART can't distinguish between a framing error and a break
condition. We assume it is a break if the received data is all zero.

Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210512141255.18277-6-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Walle 2021-05-12 16:12:51 +02:00 committed by Greg Kroah-Hartman
parent 5697df7322
commit 5541a9bacf
1 changed files with 24 additions and 8 deletions
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32
drivers/tty/serial/fsl_lpuart.c
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@ -910,6 +910,7 @@ static void lpuart32_rxint(struct lpuart_port *sport)
unsigned int flg, ignored = 0;
struct tty_port *port = &sport->port.state->port;
unsigned long rx, sr;
bool is_break;
spin_lock(&sport->port.lock);
@ -924,14 +925,27 @@ static void lpuart32_rxint(struct lpuart_port *sport)
rx = lpuart32_read(&sport->port, UARTDATA);
rx &= UARTDATA_MASK;
/*
* The LPUART can't distinguish between a break and a framing error,
* thus we assume it is a break if the received data is zero.
*/
is_break = (sr & UARTSTAT_FE) && !rx;
if (is_break && uart_handle_break(&sport->port))
continue;
if (uart_prepare_sysrq_char(&sport->port, rx))
continue;
if (sr & (UARTSTAT_PE | UARTSTAT_OR | UARTSTAT_FE)) {
if (sr & UARTSTAT_PE)
sport->port.icount.parity++;
else if (sr & UARTSTAT_FE)
if (sr & UARTSTAT_PE) {
if (is_break)
sport->port.icount.brk++;
else
sport->port.icount.parity++;
} else if (sr & UARTSTAT_FE) {
sport->port.icount.frame++;
}
if (sr & UARTSTAT_OR)
sport->port.icount.overrun++;
@ -944,15 +958,17 @@ static void lpuart32_rxint(struct lpuart_port *sport)
sr &= sport->port.read_status_mask;
if (sr & UARTSTAT_PE)
flg = TTY_PARITY;
else if (sr & UARTSTAT_FE)
if (sr & UARTSTAT_PE) {
if (is_break)
flg = TTY_BREAK;
else
flg = TTY_PARITY;
} else if (sr & UARTSTAT_FE) {
flg = TTY_FRAME;
}
if (sr & UARTSTAT_OR)
flg = TTY_OVERRUN;
sport->port.sysrq = 0;
}
tty_insert_flip_char(port, rx, flg);