[PATCH 4/4] pwm: tegra: Add support to configure pin state in suspends/resume

[Laxman Dewangan]

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.

The tristate (high impedance of PWM pin form Tegra) also define
one of the state of PWM regulator which needs to be configure in
suspend state of system.

Add support to configure the pin state via pinctrl frameworks in
suspend and active state of the system.

Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
---
 drivers/pwm/pwm-tegra.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index e9c4de5..60ed522 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/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>
 
@@ -52,6 +53,9 @@ struct tegra_pwm_chip {
 	void __iomem *regs;
 
 	const struct tegra_pwm_soc *soc;
+	struct pinctrl		*pinctrl;
+	struct pinctrl_state	*suspend_state;
+	struct pinctrl_state	*resume_state;
 };
 
 static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
@@ -215,6 +219,27 @@ static int tegra_pwm_probe(struct platform_device *pdev)
 	pwm->chip.base = -1;
 	pwm->chip.npwm = pwm->soc->num_channels;
 
+	pwm->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (!IS_ERR(pwm->pinctrl)) {
+		pwm->suspend_state = pinctrl_lookup_state(pwm->pinctrl,
+							  "suspend");
+		if (IS_ERR(pwm->suspend_state)) {
+			/* Ignore error other than PROBE_DEFER */
+			ret = PTR_ERR(pwm->suspend_state);
+			if (ret == -EPROBE_DEFER)
+				return ret;
+		}
+
+		pwm->resume_state = pinctrl_lookup_state(pwm->pinctrl,
+							 "resume");
+		if (IS_ERR(pwm->resume_state)) {
+			/* Ignore error other than PROBE_DEFER */
+			ret = PTR_ERR(pwm->resume_state);
+			if (ret == -EPROBE_DEFER)
+				return ret;
+		}
+	}
+
 	ret = pwmchip_add(&pwm->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
@@ -256,6 +281,42 @@ 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)
+{
+	struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
+	int ret;
+
+	if (IS_ERR(pc->pinctrl) || IS_ERR(pc->suspend_state))
+		return 0;
+
+	ret = pinctrl_select_state(pc->pinctrl, pc->suspend_state);
+	if (ret < 0) {
+		dev_err(dev, "Failed to set pin into suspend state:%d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tegra_pwm_resume(struct device *dev)
+{
+	struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
+	int ret;
+
+	if (IS_ERR(pc->pinctrl) || IS_ERR(pc->resume_state))
+		return 0;
+
+	ret = pinctrl_select_state(pc->pinctrl, pc->resume_state);
+	if (ret < 0) {
+		dev_err(dev, "Failed to set pin into resume state:%d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+#endif
+
 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 	.num_channels = 4,
 };
@@ -272,10 +333,15 @@ 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,
-- 
2.1.4