linux-kernel - [PATCH] serial: 8250_of: Add basic PM runtime support

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Date:   Wed, 2 Aug 2017 11:32:18 -0500
From:   Franklin S Cooper Jr <fcooper@...com>
To:     <gregkh@...uxfoundation.org>, <linux-serial@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     Franklin S Cooper Jr <fcooper@...com>
Subject: [PATCH] serial: 8250_of: Add basic PM runtime support

Add basic PM Runtime support.

Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
---
 drivers/tty/serial/8250/8250_of.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 6c5a8ca..94e7c93 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -18,6 +18,7 @@
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
 #include <linux/clk.h>
 #include <linux/reset.h>
 
@@ -65,6 +66,10 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 	int ret;
 
 	memset(port, 0, sizeof *port);
+
+	pm_runtime_enable(&ofdev->dev);
+	pm_runtime_get_sync(&ofdev->dev);
+
 	if (of_property_read_u32(np, "clock-frequency", &clk)) {
 
 		/* Get clk rate through clk driver if present */
@@ -72,12 +77,13 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 		if (IS_ERR(info->clk)) {
 			dev_warn(&ofdev->dev,
 				"clk or clock-frequency not defined\n");
-			return PTR_ERR(info->clk);
+			ret = PTR_ERR(info->clk);
+			goto err_pmruntime;
 		}
 
 		ret = clk_prepare_enable(info->clk);
 		if (ret < 0)
-			return ret;
+			goto err_pmruntime;
 
 		clk = clk_get_rate(info->clk);
 	}
@@ -170,8 +176,10 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 err_dispose:
 	irq_dispose_mapping(port->irq);
 err_unprepare:
-	if (info->clk)
-		clk_disable_unprepare(info->clk);
+	clk_disable_unprepare(info->clk);
+err_pmruntime:
+	pm_runtime_put_sync(&ofdev->dev);
+	pm_runtime_disable(&ofdev->dev);
 	return ret;
 }
 
@@ -227,8 +235,9 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 	return 0;
 err_dispose:
 	irq_dispose_mapping(port8250.port.irq);
-	if (info->clk)
-		clk_disable_unprepare(info->clk);
+	pm_runtime_put_sync(&ofdev->dev);
+	pm_runtime_disable(&ofdev->dev);
+	clk_disable_unprepare(info->clk);
 err_free:
 	kfree(info);
 	return ret;
@@ -244,8 +253,9 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
 	serial8250_unregister_port(info->line);
 
 	reset_control_assert(info->rst);
-	if (info->clk)
-		clk_disable_unprepare(info->clk);
+	pm_runtime_put_sync(&ofdev->dev);
+	pm_runtime_disable(&ofdev->dev);
+	clk_disable_unprepare(info->clk);
 	kfree(info);
 	return 0;
 }
@@ -259,9 +269,10 @@ static int of_serial_suspend(struct device *dev)
 
 	serial8250_suspend_port(info->line);
 
-	if (info->clk && (!uart_console(port) || console_suspend_enabled))
+	if ((!uart_console(port) || console_suspend_enabled)) {
+		pm_runtime_put_sync(&ofdev->dev);
 		clk_disable_unprepare(info->clk);
-
+	}
 	return 0;
 }
 
@@ -271,8 +282,10 @@ static int of_serial_resume(struct device *dev)
 	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
 	struct uart_port *port = &port8250->port;
 
-	if (info->clk && (!uart_console(port) || console_suspend_enabled))
+	if ((!uart_console(port) || console_suspend_enabled)) {
+		pm_runtime_get_sync(&ofdev->dev);
 		clk_prepare_enable(info->clk);
+	}
 
 	serial8250_resume_port(info->line);
 
-- 
2.9.4.dirty