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Message-Id: <20251001-ar933x-kgdb-support-v1-1-5fffd9e36a01@simonwunderlich.de>
Date: Wed, 01 Oct 2025 13:47:26 +0200
From: Sven Eckelmann <se@...onwunderlich.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
Sven Eckelmann <se@...onwunderlich.de>
Subject: [PATCH] serial: ar933x: Add polling support
KGDB requires at least the polling hooks .poll_get_char and .poll_put_char
to transmit/receive character via the serial driver.
Signed-off-by: Sven Eckelmann <se@...onwunderlich.de>
---
drivers/tty/serial/ar933x_uart.c | 62 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)
diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index 8bb33556b31208a1707ca7a48db0aa2ca81452bd..5b491db9d2fc01e051f629f224024ac4dc4d35ff 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -560,6 +560,64 @@ static int ar933x_uart_verify_port(struct uart_port *port,
return 0;
}
+#ifdef CONFIG_CONSOLE_POLL
+static int ar933x_poll_get_char(struct uart_port *port)
+{
+ struct ar933x_uart_port *up =
+ container_of(port, struct ar933x_uart_port, port);
+ unsigned int rdata;
+ unsigned char ch;
+ u32 imr;
+
+ /* Disable all interrupts */
+ imr = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
+ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
+
+ rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
+ if ((rdata & AR933X_UART_DATA_RX_CSR) == 0) {
+ /* Enable interrupts */
+ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);
+ return NO_POLL_CHAR;
+ }
+
+ /* remove the character from the FIFO */
+ ar933x_uart_write(up, AR933X_UART_DATA_REG,
+ AR933X_UART_DATA_RX_CSR);
+
+ ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
+
+ /* Enable interrupts */
+ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);
+
+ return ch;
+}
+
+static void ar933x_poll_put_char(struct uart_port *port, unsigned char c)
+{
+ struct ar933x_uart_port *up =
+ container_of(port, struct ar933x_uart_port, port);
+ u32 imr;
+
+ /* Disable all interrupts */
+ imr = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
+ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
+
+ /* Wait until FIFO is empty */
+ while (!(ar933x_uart_read(up, AR933X_UART_DATA_REG) & AR933X_UART_DATA_TX_CSR))
+ cpu_relax();
+
+ /* Write a character */
+ ar933x_uart_putc(up, c);
+
+ /* Wait until FIFO is empty */
+ while (!(ar933x_uart_read(up, AR933X_UART_DATA_REG) & AR933X_UART_DATA_TX_CSR))
+ cpu_relax();
+
+ /* Enable interrupts */
+ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);
+}
+#endif
+
static const struct uart_ops ar933x_uart_ops = {
.tx_empty = ar933x_uart_tx_empty,
.set_mctrl = ar933x_uart_set_mctrl,
@@ -576,6 +634,10 @@ static const struct uart_ops ar933x_uart_ops = {
.request_port = ar933x_uart_request_port,
.config_port = ar933x_uart_config_port,
.verify_port = ar933x_uart_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_get_char = ar933x_poll_get_char,
+ .poll_put_char = ar933x_poll_put_char,
+#endif
};
static int ar933x_config_rs485(struct uart_port *port, struct ktermios *termios,
---
base-commit: f83ec76bf285bea5727f478a68b894f5543ca76e
change-id: 20251001-ar933x-kgdb-support-25f5451b2a59
Best regards,
--
Sven Eckelmann <se@...onwunderlich.de>
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