drm/tilcdc: panel: Add support for enable GPIO

In order to support the "enable GPIO" available in many panel devices,
this commit adds a proper devicetree binding.

By providing an enable GPIO in the devicetree, the driver can now turn
off and on the panel device, and/or the backlight device. Both the
backlight and the GPIO are optional properties.

Tested-by: Darren Etheridge <detheridge@ti.com>
Tested-by: Johannes Pointner <johannes.pointner@br-automation.com>
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 34 insertions, 5 deletions

diff --git a/Documentation/devicetree/bindings/drm/tilcdc/panel.txt b/Documentation/devicetree/bindings/drm/tilcdc/panel.txt
index 10a06e826b4a..4ab9e2300907 100644
--- a/Documentation/devicetree/bindings/drm/tilcdc/panel.txt
+++ b/Documentation/devicetree/bindings/drm/tilcdc/panel.txt
@@ -20,6 +20,7 @@ Required properties:
 
 Optional properties:
 - backlight: phandle of the backlight device attached to the panel
+- enable-gpios: GPIO pin to enable or disable the panel
 
 Recommended properties:
  - pinctrl-names, pinctrl-0: the pincontrol settings to configure
@@ -33,6 +34,7 @@ Example:
                 pinctrl-names = "default";
                 pinctrl-0 = <&bone_lcd3_cape_lcd_pins>;
                 backlight = <&backlight>;
+                enable-gpios = <&gpio3 19 0>;
 
                 panel-info {
                         ac-bias           = <255>;
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_panel.c b/drivers/gpu/drm/tilcdc/tilcdc_panel.c
index f2a5b23782fa..7a0315855e90 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_panel.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_panel.c
@@ -18,6 +18,7 @@
 #include <linux/pinctrl/pinmux.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
 #include <video/display_timing.h>
 #include <video/of_display_timing.h>
 #include <video/videomode.h>
@@ -29,6 +30,7 @@ struct panel_module {
         struct tilcdc_panel_info *info;
         struct display_timings *timings;
         struct backlight_device *backlight;
+        struct gpio_desc *enable_gpio;
 };
 #define to_panel_module(x) container_of(x, struct panel_module, base)
 
@@ -55,13 +57,17 @@ static void panel_encoder_dpms(struct drm_encoder *encoder, int mode)
 {
         struct panel_encoder *panel_encoder = to_panel_encoder(encoder);
         struct backlight_device *backlight = panel_encoder->mod->backlight;
+        struct gpio_desc *gpio = panel_encoder->mod->enable_gpio;
 
-        if (!backlight)
-                return;
+        if (backlight) {
+                backlight->props.power = mode == DRM_MODE_DPMS_ON ?
+                                         FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
+                backlight_update_status(backlight);
+        }
 
-        backlight->props.power = mode == DRM_MODE_DPMS_ON
-                                     ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
-        backlight_update_status(backlight);
+        if (gpio)
+                gpiod_set_value_cansleep(gpio,
+                                         mode == DRM_MODE_DPMS_ON ? 1 : 0);
 }
 
 static bool panel_encoder_mode_fixup(struct drm_encoder *encoder,
@@ -369,6 +375,25 @@ static int panel_probe(struct platform_device *pdev)
                 dev_info(&pdev->dev, "found backlight\n");
         }
 
+        panel_mod->enable_gpio = devm_gpiod_get(&pdev->dev, "enable");
+        if (IS_ERR(panel_mod->enable_gpio)) {
+                ret = PTR_ERR(panel_mod->enable_gpio);
+                if (ret != -ENOENT) {
+                        dev_err(&pdev->dev, "failed to request enable GPIO\n");
+                        goto fail_backlight;
+                }
+
+                /* Optional GPIO is not here, continue silently. */
+                panel_mod->enable_gpio = NULL;
+        } else {
+                ret = gpiod_direction_output(panel_mod->enable_gpio, 0);
+                if (ret < 0) {
+                        dev_err(&pdev->dev, "failed to setup GPIO\n");
+                        goto fail_backlight;
+                }
+                dev_info(&pdev->dev, "found enable GPIO\n");
+        }
+
         mod = &panel_mod->base;
         pdev->dev.platform_data = mod;
 
@@ -401,6 +426,8 @@ fail_timings:
 
 fail_free:
         tilcdc_module_cleanup(mod);
+
+fail_backlight:
         if (panel_mod->backlight)
                 put_device(&panel_mod->backlight->dev);
         return ret;