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@xxxxxxxxxxxx>
---
drivers/tty/serial/bcm63xx_uart.c | 38 +++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/drivers/tty/serial/bcm63xx_uart.c b/drivers/tty/serial/bcm63xx_uart.c
index 62bc7244dc67..55e82d0bf92d 100644
--- a/drivers/tty/serial/bcm63xx_uart.c
+++ b/drivers/tty/serial/bcm63xx_uart.c
@@ -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
};
--
2.32.0
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