serial: 8250_omap: Set the console genpd always on if no console suspend

If the console suspend is disabled, the genpd of the console shall not
be powered-off during suspend.
Set the flag GENPD_FLAG_ALWAYS_ON to the corresponding genpd during
suspend, and restore the original value during the resume.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20231017130540.1149721-1-thomas.richard@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: thom24

drivers/tty/serial/8250/8250_omap.c

@@ -28,6 +28,7 @@
 #include <linux/pm_wakeirq.h>
 #include <linux/dma-mapping.h>
 #include <linux/sys_soc.h>
+#include <linux/pm_domain.h>
 
 #include "8250.h"
 
@@ -115,6 +116,12 @@
 /* RX FIFO occupancy indicator */
 #define UART_OMAP_RX_LVL		0x19
 
+/*
+ * Copy of the genpd flags for the console.
+ * Only used if console suspend is disabled
+ */
+static unsigned int genpd_flags_console;
+
 struct omap8250_priv {
 	void __iomem *membase;
 	int line;
@@ -1623,6 +1630,7 @@ static int omap8250_suspend(struct device *dev)
 {
 	struct omap8250_priv *priv = dev_get_drvdata(dev);
 	struct uart_8250_port *up = serial8250_get_port(priv->line);
+	struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
 	int err = 0;
 
 	serial8250_suspend_port(priv->line);
@@ -1633,8 +1641,19 @@ static int omap8250_suspend(struct device *dev)
 	if (!device_may_wakeup(dev))
 		priv->wer = 0;
 	serial_out(up, UART_OMAP_WER, priv->wer);
-	if (uart_console(&up->port) && console_suspend_enabled)
-		err = pm_runtime_force_suspend(dev);
+	if (uart_console(&up->port)) {
+		if (console_suspend_enabled)
+			err = pm_runtime_force_suspend(dev);
+		else {
+			/*
+			 * The pd shall not be powered-off (no console suspend).
+			 * Make copy of genpd flags before to set it always on.
+			 * The original value is restored during the resume.
+			 */
+			genpd_flags_console = genpd->flags;
+			genpd->flags |= GENPD_FLAG_ALWAYS_ON;
+		}
+	}
 	flush_work(&priv->qos_work);
 
 	return err;
@@ -1644,12 +1663,16 @@ static int omap8250_resume(struct device *dev)
 {
 	struct omap8250_priv *priv = dev_get_drvdata(dev);
 	struct uart_8250_port *up = serial8250_get_port(priv->line);
+	struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
 	int err;
 
 	if (uart_console(&up->port) && console_suspend_enabled) {
-		err = pm_runtime_force_resume(dev);
-		if (err)
-			return err;
+		if (console_suspend_enabled) {
+			err = pm_runtime_force_resume(dev);
+			if (err)
+				return err;
+		} else
+			genpd->flags = genpd_flags_console;
 	}
 
 	serial8250_resume_port(priv->line);