Input: mpr121 - add polling mode

In case the interrupt line is not available, polling can be used
to read out the state of the keys. Period of the polling needs to
be configured by the poll-interval DT property.
Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml

@@ -17,6 +17,10 @@ description: |
 allOf:
   - $ref: input.yaml#
 
+anyOf:
+  - required: [ interrupts ]
+  - required: [ poll-interval ]
+
 properties:
   compatible:
     const: fsl,mpr121-touchkey
@@ -41,12 +45,12 @@ properties:
 required:
   - compatible
   - reg
-  - interrupts
   - vdd-supply
   - linux,keycodes
 
 examples:
   - |
+    // Example with interrupts
     #include "dt-bindings/input/input.h"
     i2c {
         #address-cells = <1>;
@@ -64,3 +68,22 @@ examples:
                              <KEY_8>, <KEY_9>, <KEY_A>, <KEY_B>;
         };
     };
+
+  - |
+    // Example with polling
+    #include "dt-bindings/input/input.h"
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        mpr121@5a {
+            compatible = "fsl,mpr121-touchkey";
+            reg = <0x5a>;
+            poll-interval = <20>;
+            autorepeat;
+            vdd-supply = <&ldo4_reg>;
+            linux,keycodes = <KEY_0>, <KEY_1>, <KEY_2>, <KEY_3>,
+                             <KEY_4>, <KEY_5>, <KEY_6>, <KEY_7>,
+                             <KEY_8>, <KEY_9>, <KEY_A>, <KEY_B>;
+        };
+    };

Documentation/devicetree/bindings/input/input.yaml

@@ -24,6 +24,10 @@ properties:
           minimum: 0
           maximum: 0xff
 
+  poll-interval:
+    description: Poll interval time in milliseconds.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
   power-off-time-sec:
     description:
       Duration in seconds which the key should be kept pressed for device to

drivers/input/keyboard/mpr121_touchkey.c

@@ -54,6 +54,9 @@
 /* MPR121 has 12 keys */
 #define MPR121_MAX_KEY_COUNT		12
 
+#define MPR121_MIN_POLL_INTERVAL	10
+#define MPR121_MAX_POLL_INTERVAL	200
+
 struct mpr121_touchkey {
 	struct i2c_client	*client;
 	struct input_dev	*input_dev;
@@ -115,11 +118,11 @@ static struct regulator *mpr121_vdd_supply_init(struct device *dev)
 	return vdd_supply;
 }
 
-static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
+static void mpr_touchkey_report(struct input_dev *dev)
 {
-	struct mpr121_touchkey *mpr121 = dev_id;
-	struct i2c_client *client = mpr121->client;
+	struct mpr121_touchkey *mpr121 = input_get_drvdata(dev);
 	struct input_dev *input = mpr121->input_dev;
+	struct i2c_client *client = mpr121->client;
 	unsigned long bit_changed;
 	unsigned int key_num;
 	int reg;
@@ -127,14 +130,14 @@ static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
 	reg = i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_1_ADDR);
 	if (reg < 0) {
 		dev_err(&client->dev, "i2c read error [%d]\n", reg);
-		goto out;
+		return;
 	}
 
 	reg <<= 8;
 	reg |= i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_0_ADDR);
 	if (reg < 0) {
 		dev_err(&client->dev, "i2c read error [%d]\n", reg);
-		goto out;
+		return;
 	}
 
 	reg &= TOUCH_STATUS_MASK;
@@ -155,8 +158,14 @@ static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
 
 	}
 	input_sync(input);
+}
+
+static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
+{
+	struct mpr121_touchkey *mpr121 = dev_id;
+
+	mpr_touchkey_report(mpr121->input_dev);
 
-out:
 	return IRQ_HANDLED;
 }
 
@@ -229,14 +238,10 @@ static int mpr_touchkey_probe(struct i2c_client *client,
 	int vdd_uv;
 	struct mpr121_touchkey *mpr121;
 	struct input_dev *input_dev;
+	u32 poll_interval = 0;
 	int error;
 	int i;
 
-	if (!client->irq) {
-		dev_err(dev, "irq number should not be zero\n");
-		return -EINVAL;
-	}
-
 	vdd_supply = mpr121_vdd_supply_init(dev);
 	if (IS_ERR(vdd_supply))
 		return PTR_ERR(vdd_supply);
@@ -274,6 +279,7 @@ static int mpr_touchkey_probe(struct i2c_client *client,
 	if (device_property_read_bool(dev, "autorepeat"))
 		__set_bit(EV_REP, input_dev->evbit);
 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
+	input_set_drvdata(input_dev, mpr121);
 
 	input_dev->keycode = mpr121->keycodes;
 	input_dev->keycodesize = sizeof(mpr121->keycodes[0]);
@@ -288,13 +294,40 @@ static int mpr_touchkey_probe(struct i2c_client *client,
 		return error;
 	}
 
-	error = devm_request_threaded_irq(dev, client->irq, NULL,
-					  mpr_touchkey_interrupt,
-					  IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
-					  dev->driver->name, mpr121);
-	if (error) {
-		dev_err(dev, "Failed to register interrupt\n");
-		return error;
+	device_property_read_u32(dev, "poll-interval", &poll_interval);
+
+	if (client->irq) {
+		error = devm_request_threaded_irq(dev, client->irq, NULL,
+						  mpr_touchkey_interrupt,
+						  IRQF_TRIGGER_FALLING |
+						  IRQF_ONESHOT,
+						  dev->driver->name, mpr121);
+		if (error) {
+			dev_err(dev, "Failed to register interrupt\n");
+			return error;
+		}
+	} else if (poll_interval) {
+		if (poll_interval < MPR121_MIN_POLL_INTERVAL)
+			return -EINVAL;
+
+		if (poll_interval > MPR121_MAX_POLL_INTERVAL)
+			return -EINVAL;
+
+		error = input_setup_polling(input_dev, mpr_touchkey_report);
+		if (error) {
+			dev_err(dev, "Failed to setup polling\n");
+			return error;
+		}
+
+		input_set_poll_interval(input_dev, poll_interval);
+		input_set_min_poll_interval(input_dev,
+					    MPR121_MIN_POLL_INTERVAL);
+		input_set_max_poll_interval(input_dev,
+					    MPR121_MAX_POLL_INTERVAL);
+	} else {
+		dev_err(dev,
+			"invalid IRQ number and polling not configured\n");
+		return -EINVAL;
 	}
 
 	error = input_register_device(input_dev);