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serial: 8250: Use high-level writing function for FIFO

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Currently serial8250_console_fifo_write() directly writes into
the UART_TX register rather than using the high-level function
serial8250_console_putchar(). This is because
serial8250_console_putchar() waits for the holding register to
become empty, which would defeat the purpose of the FIFO code.

Move the LSR_THRE waiting to a new function
serial8250_console_wait_putchar() so that the FIFO code can use
serial8250_console_putchar(). This will be particularly important
for a follow-up commit, where output bytes are inspected to track
newlines.

This is only refactoring and has no functional change.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250107212702.169493-4-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
John Ogness 2025-01-07 22:32:59 +01:06 committed by Greg Kroah-Hartman
parent 8d5cfb1fe5
commit 95a1b409ba
1 changed files with 10 additions and 4 deletions
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14
drivers/tty/serial/8250/8250_port.c
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@ -3298,11 +3298,16 @@ EXPORT_SYMBOL_GPL(serial8250_set_defaults);
#ifdef CONFIG_SERIAL_8250_CONSOLE
static void serial8250_console_putchar(struct uart_port *port, unsigned char ch)
{
serial_port_out(port, UART_TX, ch);
}
static void serial8250_console_wait_putchar(struct uart_port *port, unsigned char ch)
{
struct uart_8250_port *up = up_to_u8250p(port);
wait_for_xmitr(up, UART_LSR_THRE);
serial_port_out(port, UART_TX, ch);
serial8250_console_putchar(port, ch);
}
/*
@ -3352,6 +3357,7 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
{
const char *end = s + count;
unsigned int fifosize = up->tx_loadsz;
struct uart_port *port = &up->port;
unsigned int tx_count = 0;
bool cr_sent = false;
unsigned int i;
@ -3362,10 +3368,10 @@ static void serial8250_console_fifo_write(struct uart_8250_port *up,
for (i = 0; i < fifosize && s != end; ++i) {
if (*s == '\n' && !cr_sent) {
serial_out(up, UART_TX, '\r');
serial8250_console_putchar(port, '\r');
cr_sent = true;
} else {
serial_out(up, UART_TX, *s++);
serial8250_console_putchar(port, *s++);
cr_sent = false;
}
}
@ -3445,7 +3451,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
if (likely(use_fifo))
serial8250_console_fifo_write(up, s, count);
else
uart_console_write(port, s, count, serial8250_console_putchar);
uart_console_write(port, s, count, serial8250_console_wait_putchar);
/*
* Finally, wait for transmitter to become empty