[PATCH 1/2] drm/bridge/sii8620: add external connector handle

[Maciej Purski]

The driver should be switched on if an external connector is plugged and
switched off if it is unplugged. Extcon is optional. If it is not found,
the driver stays in "always-on" mode.

Signed-off-by: Maciej Purski <m.purski at samsung.com>
---
 .../bindings/display/bridge/sil-sii8620.txt        |  4 ++
 drivers/gpu/drm/bridge/sil-sii8620.c               | 83 +++++++++++++++++++++-
 2 files changed, 85 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/sil-sii8620.txt b/Documentation/devicetree/bindings/display/bridge/sil-sii8620.txt
index 9409d9c..1f230bf 100644
--- a/Documentation/devicetree/bindings/display/bridge/sil-sii8620.txt
+++ b/Documentation/devicetree/bindings/display/bridge/sil-sii8620.txt
@@ -10,6 +10,9 @@ Required properties:
 	- clocks, clock-names: specification and name of "xtal" clock
 	- video interfaces: Device node can contain video interface port
 			    node for HDMI encoder according to [1].
+Optional properties:
+	- extcon: phandle to external connector for MHL cable changes
+		  detection
 
 [1]: Documentation/devicetree/bindings/media/video-interfaces.txt
 
@@ -24,6 +27,7 @@ Example:
 		reset-gpio = <&gpv7 0 0>;
 		clocks = <&pmu_system_controller 0>;
 		clock-names = "xtal";
+		extcon = <&muic>;
 
 		port {
 			mhl_to_hdmi: endpoint {
diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
index 2d51a22..5002654 100644
--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -17,6 +17,7 @@
 
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/extcon.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
@@ -78,6 +79,10 @@ struct sii8620 {
 	struct edid *edid;
 	unsigned int gen2_write_burst:1;
 	enum sii8620_mt_state mt_state;
+	struct extcon_dev *extcon;
+	struct notifier_block extcon_nb;
+	struct work_struct extcon_wq;
+	bool extcon_attached;
 	struct list_head mt_queue;
 	struct {
 		int r_size;
@@ -2102,6 +2107,72 @@ static void sii8620_cable_in(struct sii8620 *ctx)
 	enable_irq(to_i2c_client(ctx->dev)->irq);
 }
 
+static void sii8620_cable_out(struct sii8620 *ctx)
+{
+	disable_irq(to_i2c_client(ctx->dev)->irq);
+	sii8620_hw_off(ctx);
+}
+
+static void sii8620_extcon_work(struct work_struct *work)
+{
+	struct sii8620 *ctx =
+		container_of(work, struct sii8620, extcon_wq);
+
+	if (ctx->extcon_attached)
+		sii8620_cable_in(ctx);
+	else
+		sii8620_cable_out(ctx);
+}
+
+static int sii8620_extcon_notifier(struct notifier_block *self,
+			unsigned long event, void *ptr)
+{
+	struct sii8620 *ctx =
+		container_of(self, struct sii8620, extcon_nb);
+
+	ctx->extcon_attached = event;
+	schedule_work(&ctx->extcon_wq);
+
+	return NOTIFY_DONE;
+}
+
+static int sii8620_extcon_init(struct sii8620 *ctx)
+{
+	struct extcon_dev *edev;
+	int ret;
+
+	INIT_WORK(&ctx->extcon_wq, sii8620_extcon_work);
+
+	if (!of_property_read_bool(ctx->dev->of_node, "extcon")) {
+		dev_info(ctx->dev, "no extcon found, switching to 'always on' mode\n");
+		ctx->extcon_attached = true;
+		return 0;
+	}
+
+	edev = extcon_get_edev_by_phandle(ctx->dev, 0);
+	if (IS_ERR(edev)) {
+		if (PTR_ERR(edev) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_err(ctx->dev, "Invalid or missing extcon\n");
+		return PTR_ERR(edev);
+	}
+
+	ctx->extcon_attached = extcon_get_cable_state_(edev, EXTCON_DISP_MHL);
+	dev_info(ctx->dev, "extcon(MHL) = %d\n", ctx->extcon_attached);
+
+	ctx->extcon = edev;
+	ctx->extcon_nb.notifier_call = sii8620_extcon_notifier;
+	ret = devm_extcon_register_notifier(ctx->dev, edev,
+					EXTCON_DISP_MHL, &ctx->extcon_nb);
+
+	if (ret) {
+		dev_err(ctx->dev, "failed to register notifier for MHL\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static inline struct sii8620 *bridge_to_sii8620(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct sii8620, bridge);
@@ -2201,13 +2272,20 @@ static int sii8620_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	ret = sii8620_extcon_init(ctx);
+	if (ret < 0) {
+		dev_err(ctx->dev, "failed to initialize EXTCON\n");
+		return ret;
+	}
+
 	i2c_set_clientdata(client, ctx);
 
 	ctx->bridge.funcs = &sii8620_bridge_funcs;
 	ctx->bridge.of_node = dev->of_node;
 	drm_bridge_add(&ctx->bridge);
 
-	sii8620_cable_in(ctx);
+	if (ctx->extcon_attached)
+		sii8620_cable_in(ctx);
 
 	return 0;
 }
@@ -2216,7 +2294,8 @@ static int sii8620_remove(struct i2c_client *client)
 {
 	struct sii8620 *ctx = i2c_get_clientdata(client);
 
-	disable_irq(to_i2c_client(ctx->dev)->irq);
+	if (!ctx->extcon_attached)
+		sii8620_cable_out(ctx);
 	drm_bridge_remove(&ctx->bridge);
 	sii8620_hw_off(ctx);
 
-- 
2.7.4