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serial: bcm63xx-uart: add polling support

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The tty framework can support polling console to allow operation
in situations where interrupts are turned off. Adding polling mode
support allows using KGDB over serial console,

Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://lore.kernel.org/r/20230322223956.84647-1-arend.vanspriel@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Arend van Spriel 2023-03-22 23:39:56 +01:00 committed by Greg Kroah-Hartman
parent f1d81e3cf0
commit 945de8be2f
1 changed files with 38 additions and 0 deletions
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38
drivers/tty/serial/bcm63xx_uart.c
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@ -596,6 +596,40 @@ static int bcm_uart_verify_port(struct uart_port *port,
return 0;
}
#ifdef CONFIG_CONSOLE_POLL
/*
* return true when outstanding tx equals fifo size
*/
static bool bcm_uart_tx_full(struct uart_port *port)
{
unsigned int val;
val = bcm_uart_readl(port, UART_MCTL_REG);
val = (val & UART_MCTL_TXFIFOFILL_MASK) >> UART_MCTL_TXFIFOFILL_SHIFT;
return !(port->fifosize - val);
}
static int bcm_uart_poll_get_char(struct uart_port *port)
{
unsigned int iestat;
iestat = bcm_uart_readl(port, UART_IR_REG);
if (!(iestat & UART_IR_STAT(UART_IR_RXNOTEMPTY)))
return NO_POLL_CHAR;
return bcm_uart_readl(port, UART_FIFO_REG);
}
static void bcm_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
while (bcm_uart_tx_full(port)) {
cpu_relax();
}
bcm_uart_writel(port, c, UART_FIFO_REG);
}
#endif
/* serial core callbacks */
static const struct uart_ops bcm_uart_ops = {
.tx_empty = bcm_uart_tx_empty,
@ -614,6 +648,10 @@ static const struct uart_ops bcm_uart_ops = {
.request_port = bcm_uart_request_port,
.config_port = bcm_uart_config_port,
.verify_port = bcm_uart_verify_port,
#ifdef CONFIG_CONSOLE_POLL
.poll_get_char = bcm_uart_poll_get_char,
.poll_put_char = bcm_uart_poll_put_char,
#endif
};