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authorArend van Spriel2023-03-22 23:39:56 +0100
committerGreg Kroah-Hartman2023-03-29 10:54:23 +0200
commit945de8be2f7ff7d4dd578d97307ae650b95de294 (patch)
tree5ae0cdb92692eab680ae75941132c62d8f8ec83c /drivers/tty
parentf1d81e3cf0e91bf3455a643b87184c2288cfba8e (diff)
serial: bcm63xx-uart: add polling support
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>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/bcm63xx_uart.c38
1 files changed, 38 insertions, 0 deletions
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
};