linux-kernel - [PATCH 1/2] serial: sifive: Add suspend and resume operations

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Date:   Tue,  8 Aug 2023 15:26:25 +0800
From:   Nick Hu <nick.hu@...ive.com>
To:     nick.hu@...ive.com, zong.li@...ive.com, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, palmer@...belt.com, paul.walmsley@...ive.com,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Cc:     Ben Dooks <ben.dooks@...ethink.co.uk>
Subject: [PATCH 1/2] serial: sifive: Add suspend and resume operations

If the Sifive Uart is not used as the wake up source, suspend the uart
before the system enter the suspend state to prevent it woken up by
unexpected uart interrupt. Resume the uart once the system woken up.

Signed-off-by: Nick Hu <nick.hu@...ive.com>
Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
---
 drivers/tty/serial/sifive.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index a19db49327e2..87994cb69007 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -1022,6 +1022,31 @@ static int sifive_serial_remove(struct platform_device *dev)
 	return 0;
 }
 
+static int sifive_serial_suspend(struct device *dev)
+{
+	int ret = 0;
+	struct sifive_serial_port *ssp = dev_get_drvdata(dev);
+
+	if (ssp && ssp->port.type != PORT_UNKNOWN)
+		ret = uart_suspend_port(&sifive_serial_uart_driver, &ssp->port);
+
+	return ret;
+}
+
+static int sifive_serial_resume(struct device *dev)
+{
+	int ret = 0;
+	struct sifive_serial_port *ssp = dev_get_drvdata(dev);
+
+	if (ssp && ssp->port.type != PORT_UNKNOWN)
+		ret = uart_resume_port(&sifive_serial_uart_driver, &ssp->port);
+
+	return ret;
+}
+
+DEFINE_SIMPLE_DEV_PM_OPS(sifive_uart_pm_ops, sifive_serial_suspend,
+			 sifive_serial_resume);
+
 static const struct of_device_id sifive_serial_of_match[] = {
 	{ .compatible = "sifive,fu540-c000-uart0" },
 	{ .compatible = "sifive,uart0" },
@@ -1034,6 +1059,7 @@ static struct platform_driver sifive_serial_platform_driver = {
 	.remove		= sifive_serial_remove,
 	.driver		= {
 		.name	= SIFIVE_SERIAL_NAME,
+		.pm = pm_sleep_ptr(&sifive_uart_pm_ops),
 		.of_match_table = of_match_ptr(sifive_serial_of_match),
 	},
 };
-- 
2.34.1