Input: sun4i-a10-lradc-keys - add support for A83T

Allwinner A83T SoC has a low res adc like the one in Allwinner A10 SoC,
however, the A10 SoC's vref of lradc internally is divided by 2/3 and
the A83T SoC's vref of lradc internally is divided by 3/4, thus add
a hardware variant for it to be compatible with various devices.
Signed-off-by: Ziping Chen <techping.chan@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt

@@ -2,12 +2,14 @@ Allwinner sun4i low res adc attached tablet keys
 ------------------------------------------------
 
 Required properties:
- - compatible: "allwinner,sun4i-a10-lradc-keys"
+ - compatible: should be one of the following string:
+		"allwinner,sun4i-a10-lradc-keys"
+		"allwinner,sun8i-a83t-r-lradc"
  - reg: mmio address range of the chip
  - interrupts: interrupt to which the chip is connected
  - vref-supply: powersupply for the lradc reference voltage
 
-Each key is represented as a sub-node of "allwinner,sun4i-a10-lradc-keys":
+Each key is represented as a sub-node of the compatible mentioned above:
 
 Required subnode-properties:
 	- label: Descriptive name of the key.

drivers/input/keyboard/sun4i-lradc-keys.c

@@ -46,6 +46,7 @@
 #define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
 #define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
 #define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
+#define HOLD_KEY_EN(x)		((x) << 7)
 #define HOLD_EN(x)		((x) << 6)
 #define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
 #define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
@@ -63,6 +64,25 @@
 #define	CHAN0_KEYDOWN_IRQ	BIT(1)
 #define CHAN0_DATA_IRQ		BIT(0)
 
+/* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
+ * @divisor_numerator:		The numerator of lradc Vref internally divisor
+ * @divisor_denominator:	The denominator of lradc Vref internally divisor
+ */
+struct lradc_variant {
+	u8 divisor_numerator;
+	u8 divisor_denominator;
+};
+
+static const struct lradc_variant lradc_variant_a10 = {
+	.divisor_numerator = 2,
+	.divisor_denominator = 3
+};
+
+static const struct lradc_variant r_lradc_variant_a83t = {
+	.divisor_numerator = 3,
+	.divisor_denominator = 4
+};
+
 struct sun4i_lradc_keymap {
 	u32 voltage;
 	u32 keycode;
@@ -74,6 +94,7 @@ struct sun4i_lradc_data {
 	void __iomem *base;
 	struct regulator *vref_supply;
 	struct sun4i_lradc_keymap *chan0_map;
+	const struct lradc_variant *variant;
 	u32 chan0_map_count;
 	u32 chan0_keycode;
 	u32 vref;
@@ -128,9 +149,9 @@ static int sun4i_lradc_open(struct input_dev *dev)
 	if (error)
 		return error;
 
-	/* lradc Vref internally is divided by 2/3 */
-	lradc->vref = regulator_get_voltage(lradc->vref_supply) * 2 / 3;
-
+	lradc->vref = regulator_get_voltage(lradc->vref_supply) *
+		      lradc->variant->divisor_numerator /
+		      lradc->variant->divisor_denominator;
 	/*
 	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
 	 * stabilize on press, wait (1 + 1) * 4 ms for key release
@@ -222,6 +243,12 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 	if (error)
 		return error;
 
+	lradc->variant = of_device_get_match_data(&pdev->dev);
+	if (!lradc->variant) {
+		dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
+		return -EINVAL;
+	}
+
 	lradc->vref_supply = devm_regulator_get(dev, "vref");
 	if (IS_ERR(lradc->vref_supply))
 		return PTR_ERR(lradc->vref_supply);
@@ -265,7 +292,10 @@ static int sun4i_lradc_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id sun4i_lradc_of_match[] = {
-	{ .compatible = "allwinner,sun4i-a10-lradc-keys", },
+	{ .compatible = "allwinner,sun4i-a10-lradc-keys",
+		.data = &lradc_variant_a10 },
+	{ .compatible = "allwinner,sun8i-a83t-r-lradc",
+		.data = &r_lradc_variant_a83t },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);