pwm: tegra: Add support to configure pin state in suspends/resume

In some of NVIDIA Tegra's platform, PWM controller is used to
control the PWM controlled regulators. PWM signal is connected to
the VID pin of the regulator where duty cycle of PWM signal decide
the voltage level of the regulator output.

When system enters suspend, some PWM client/slave regulator devices
require the PWM output to be tristated.

Add support to configure the pin state via pinctrl frameworks in
suspend and active state of the system.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-tegra.c

@@ -29,6 +29,7 @@
 #include <linux/of_device.h>
 #include <linux/pwm.h>
 #include <linux/platform_device.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/slab.h>
 #include <linux/reset.h>
 
@@ -255,6 +256,18 @@ static int tegra_pwm_remove(struct platform_device *pdev)
 	return pwmchip_remove(&pc->chip);
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int tegra_pwm_suspend(struct device *dev)
+{
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int tegra_pwm_resume(struct device *dev)
+{
+	return pinctrl_pm_select_default_state(dev);
+}
+#endif
+
 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 	.num_channels = 4,
 };
@@ -271,10 +284,15 @@ static const struct of_device_id tegra_pwm_of_match[] = {
 
 MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
 
+static const struct dev_pm_ops tegra_pwm_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(tegra_pwm_suspend, tegra_pwm_resume)
+};
+
 static struct platform_driver tegra_pwm_driver = {
 	.driver = {
 		.name = "tegra-pwm",
 		.of_match_table = tegra_pwm_of_match,
+		.pm = &tegra_pwm_pm_ops,
 	},
 	.probe = tegra_pwm_probe,
 	.remove = tegra_pwm_remove,