linux-kernel - [PATCH v4 3/3] serial: 8250_of: manage bus clock in suspend/resume

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Message-ID: <20250411203828.1491595-4-elder@riscstar.com>
Date: Fri, 11 Apr 2025 15:38:27 -0500
From: Alex Elder <elder@...cstar.com>
To: gregkh@...uxfoundation.org,
	jirislaby@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org
Cc: andy.shevchenko@...il.com,
	dlan@...too.org,
	benjamin.larsson@...exis.eu,
	bastien.curutchet@...tlin.com,
	andriy.shevchenko@...ux.intel.com,
	u.kleine-koenig@...libre.com,
	lkundrak@...sk,
	devicetree@...r.kernel.org,
	linux-serial@...r.kernel.org,
	spacemit@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 3/3] serial: 8250_of: manage bus clock in suspend/resume

Save the bus clock pointer in the of_serial_info structure, and use
that to disable the bus clock on suspend and re-enable it on resume.

Signed-off-by: Alex Elder <elder@...cstar.com>
---
 drivers/tty/serial/8250/8250_of.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index a90a5462aa72a..d178b6c54ea18 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -24,6 +24,7 @@
 
 struct of_serial_info {
 	struct clk *clk;
+	struct clk *bus_clk;
 	struct reset_control *rst;
 	int type;
 	int line;
@@ -138,6 +139,7 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 			goto err_pmruntime;
 		}
 
+		info->bus_clk = bus_clk;
 		port->uartclk = clk_get_rate(info->clk);
 	}
 	/* If current-speed was set, then try not to change it. */
@@ -299,6 +301,7 @@ static int of_serial_suspend(struct device *dev)
 	if (!uart_console(port) || console_suspend_enabled) {
 		pm_runtime_put_sync(dev);
 		clk_disable_unprepare(info->clk);
+		clk_disable_unprepare(info->bus_clk);
 	}
 	return 0;
 }
@@ -311,6 +314,7 @@ static int of_serial_resume(struct device *dev)
 
 	if (!uart_console(port) || console_suspend_enabled) {
 		pm_runtime_get_sync(dev);
+		clk_prepare_enable(info->bus_clk);
 		clk_prepare_enable(info->clk);
 	}
 
-- 
2.45.2