drm/tilcdc: adopt pinctrl support

Update tilcdc driver to set the state of the pins to:
- "default on resume
- "sleep" on suspend

By optionally putting the pins into sleep state in the suspend callback
we can accomplish two things.
- minimize current leakage from pins and thus save power,
- prevent the IP from driving pins output in an uncontrolled manner,
which may happen if the power domain drops the domain regulator.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/tilcdc/tilcdc_drv.c

@@ -18,6 +18,8 @@
 /* LCDC DRM driver, based on da8xx-fb */
 
 #include <linux/component.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/suspend.h>
 
 #include "tilcdc_drv.h"
 #include "tilcdc_regs.h"
@@ -585,6 +587,9 @@ static int tilcdc_pm_suspend(struct device *dev)
 		if (registers[i].save && (priv->rev >= registers[i].rev))
 			priv->saved_register[n++] = tilcdc_read(ddev, registers[i].reg);
 
+	/* Select sleep pin state */
+	pinctrl_pm_select_sleep_state(dev);
+
 	return 0;
 }
 
@@ -594,6 +599,9 @@ static int tilcdc_pm_resume(struct device *dev)
 	struct tilcdc_drm_private *priv = ddev->dev_private;
 	unsigned i, n = 0;
 
+	/* Select default pin state */
+	pinctrl_pm_select_default_state(dev);
+
 	/* Restore register state: */
 	for (i = 0; i < ARRAY_SIZE(registers); i++)
 		if (registers[i].save && (priv->rev >= registers[i].rev))