[PATCH] Input: tca6416-keypad - Add OF support for driver instantiation

["Tomáš Juřena" <jurenatomas@gmail.com>]

From: Tomas Jurena <jurenatomas@gmail.com>

Adds support for instantiating the tca6416-keypad driver via
Device Tree. If no platform data is present, the driver can now be
probed based on OF bindings.

A corresponding Device Tree binding document is added at:
  Documentation/devicetree/bindings/input/tca6416-keypad.yaml

This allows the driver to be used in systems that rely solely on the
Device Tree for hardware description, such as embedded ARM platforms.

Tested on Toradex Ixora 1.3A board and Apalis imx8 SOM.

Signed-off-by: Tomas Jurena <jurenatomas@gmail.com>
---
 .../bindings/input/tca6416-keypad.yaml        | 87 ++++++++++++++++++
 drivers/input/keyboard/tca6416-keypad.c       | 88 +++++++++++++++++--
 2 files changed, 170 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/input/tca6416-keypad.yaml

diff --git a/Documentation/devicetree/bindings/input/tca6416-keypad.yaml b/Documentation/devicetree/bindings/input/tca6416-keypad.yaml
new file mode 100644
index 000000000000..f050403c4dbe
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/tca6416-keypad.yaml
@@ -0,0 +1,87 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/tca6416-keypad.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI TCA6416 keypad
+
+maintainers:
+
+description: |
+  Texas Instruments TCA6416 IO expander as a keypad input device.
+
+allOf:
+  - $ref: input.yaml#
+
+properties:
+  compatible:
+    enum:
+      - ti,tca6416_keys
+      - ti,tca6408_keys
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  linux,gpio-keymap:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description: |
+      Array of gpio keys provided by the driver instance. Each entry is a
+      bitfield holding configuration of the input key. The bitfield looks like
+      this:
+      +------------------------------------------------------------+
+      | Bits     | 31:18    |         17 | 16:14 | 13:10    | 9:0  |
+      | Function | reserved | active_low | type  | reserved | code |
+      +------------------------------------------------------------+
+      code - Linux key code
+      type - EV_KEY or EV_SW
+      active_low - Key is active in low state
+
+  linux,keycodes:
+    minItems: 1
+    maxItems: 16
+
+  autorepeat:
+    type: boolean
+    description: |
+      Enables the Linux input system's autorepeat feature on the input device.
+
+  polling:
+    type: boolean
+    description: |
+      Forces driver to use polling mode instead of IRQ.
+
+  pinmask:
+    description: |
+      Allows to disable certain keys. By default are all inputs enabled.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      keypad@21 {
+        compatible = "ti,tca6416_keys";
+        reg = <0x21>;
+        interrupt-parent = <&gpio>;
+        interrupts = <26 IRQ_TYPE_EDGE_FALLING>;
+        linux,gpio-keymap = <
+                            0x24290, // active low, EV_KEY, 0, KEY_MACRO1
+                            0x24291, // active low, EV_KEY, 1, KEY_MACRO2
+                            0x24292, // active low, EV_KEY, 2, KEY_MACRO3
+        >;
+      };
+    };
+
+...
diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c
index fbc674d7b9f0..8910498cf266 100644
--- a/drivers/input/keyboard/tca6416-keypad.c
+++ b/drivers/input/keyboard/tca6416-keypad.c
@@ -17,6 +17,7 @@
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/tca6416_keypad.h>
+#include <linux/bitfield.h>
 
 #define TCA6416_INPUT          0
 #define TCA6416_OUTPUT         1
@@ -24,6 +25,7 @@
 #define TCA6416_DIRECTION      3
 
 #define TCA6416_POLL_INTERVAL	100 /* msec */
+#define TCA6416_MAX_IO_SIZE 16 /* maximum number of inputs */
 
 static const struct i2c_device_id tca6416_id[] = {
 	{ "tca6416-keys", 16, },
@@ -173,9 +175,67 @@ static int tca6416_setup_registers(struct tca6416_keypad_chip *chip)
 	return 0;
 }
 
+/* Configuration bitmap
+ * | 31:18    |         17 | 16:14 | 13:10    | 9:0  |
+ * | reserved | active_low | type  | reserved | code |
+ */
+#define CFG_CODE GENMASK(9, 0)
+#define CFG_TYPE GENMASK(16, 14)
+#define CFG_ACTIVE_LOW BIT(17)
+
+static struct tca6416_keys_platform_data *
+tca6416_parse_properties(struct device *dev, uint8_t io_size)
+{
+	static const char keymap_property[] = "linux,gpio-keymap";
+	struct tca6416_keys_platform_data *pdata;
+	u32 keymap[TCA6416_MAX_IO_SIZE];
+	struct tca6416_button *buttons;
+	int ret, i;
+	u8 pin;
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return NULL;
+
+	ret = device_property_count_u32(dev, keymap_property);
+	if (ret <= 0)
+		return NULL;
+
+	pdata->nbuttons = ret;
+	if (pdata->nbuttons > io_size)
+		pdata->nbuttons = io_size;
+
+	ret = device_property_read_u32_array(dev, keymap_property, keymap,
+					     pdata->nbuttons);
+	if (ret)
+		return NULL;
+
+	buttons = devm_kcalloc(dev, pdata->nbuttons, sizeof(*buttons),
+			       GFP_KERNEL);
+	if (!buttons)
+		return NULL;
+
+	for (i = 0; i < pdata->nbuttons; i++) {
+		buttons[i].code = FIELD_GET(CFG_CODE, keymap[i]);
+		buttons[i].type = FIELD_GET(CFG_TYPE, keymap[i]);
+		buttons[i].active_low = FIELD_GET(CFG_ACTIVE_LOW, keymap[i]);
+		/* enable all inputs by default */
+		pdata->pinmask |= BIT(i);
+	}
+
+	pdata->buttons = buttons;
+
+	pdata->rep = device_property_read_bool(dev, "autorepeat");
+	/* we can ignore the result as by default all inputs are enabled */
+	device_property_read_u16(dev, "pinmask", &pdata->pinmask);
+	pdata->use_polling = device_property_read_bool(dev, "polling");
+
+	return pdata;
+}
+
 static int tca6416_keypad_probe(struct i2c_client *client)
 {
-	const struct i2c_device_id *id = i2c_client_get_device_id(client);
+	uint8_t io_size = (uintptr_t)i2c_get_match_data(client);
 	struct tca6416_keys_platform_data *pdata;
 	struct tca6416_keypad_chip *chip;
 	struct input_dev *input;
@@ -190,9 +250,13 @@ static int tca6416_keypad_probe(struct i2c_client *client)
 	}
 
 	pdata = dev_get_platdata(&client->dev);
-	if (!pdata) {
-		dev_dbg(&client->dev, "no platform data\n");
-		return -EINVAL;
+	if (!pdata && dev_fwnode(&client->dev)) {
+		pdata = tca6416_parse_properties(&client->dev, io_size);
+		if (!pdata) {
+			dev_err(&client->dev,
+				"Failed to parse device configuration from properties\n");
+			return -EINVAL;
+		}
 	}
 
 	chip = devm_kzalloc(&client->dev,
@@ -207,7 +271,7 @@ static int tca6416_keypad_probe(struct i2c_client *client)
 
 	chip->client = client;
 	chip->input = input;
-	chip->io_size = id->driver_data;
+	chip->io_size = io_size;
 	chip->pinmask = pdata->pinmask;
 	chip->use_polling = pdata->use_polling;
 
@@ -279,9 +343,23 @@ static int tca6416_keypad_probe(struct i2c_client *client)
 	return 0;
 }
 
+static const struct of_device_id tca6416_of_match[] = {
+	{
+		.compatible = "ti,tca6416_keys",
+		.data = (void *)16,
+	},
+	{
+		.compatible = "ti,tca6408_keys",
+		.data = (void *)8,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, tca6416_of_match);
+
 static struct i2c_driver tca6416_keypad_driver = {
 	.driver = {
 		.name	= "tca6416-keypad",
+		.of_match_table = tca6416_of_match,
 	},
 	.probe		= tca6416_keypad_probe,
 	.id_table	= tca6416_id,
-- 
2.34.1