mfd: axp20x: Generalise handling without interrupt

At the moment we allow the AXP15060 and the AXP806 PMICs to omit the
interrupt line to the SoC, and we skip registering the PEK (power key)
driver in this case, since that crashes when no IRQ is described in the
DT node.
The IRQ pin potentially not being connected to anything does affect more
PMICs, though, and the PEK driver is not the only one requiring an
interrupt: at least the AC power supply driver crashes in a similar
fashion.

Generalise the handling of AXP MFD devices when the platform tables
describe no interrupt, by allowing each device to specify an alternative
MFD list for this case. If no specific alternative is specified, we go
with the safe default of "just the regulators", which matches the current
situation.

This enables new devices using the AXP313a PMIC, but not connecting the
IRQ pin.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20230828213229.20332-1-andre.przywara@arm.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/axp20x.c

@@ -1133,6 +1133,8 @@ int axp20x_match_device(struct axp20x_dev *axp20x)
 	struct device *dev = axp20x->dev;
 	const struct acpi_device_id *acpi_id;
 	const struct of_device_id *of_id;
+	const struct mfd_cell *cells_no_irq = NULL;
+	int nr_cells_no_irq = 0;
 
 	if (dev->of_node) {
 		of_id = of_match_device(dev->driver->of_match_table, dev);
@@ -1207,14 +1209,15 @@ int axp20x_match_device(struct axp20x_dev *axp20x)
 		 * if there is no interrupt line.
 		 */
 		if (of_property_read_bool(axp20x->dev->of_node,
-					  "x-powers,self-working-mode") &&
-		    axp20x->irq > 0) {
+					  "x-powers,self-working-mode")) {
 			axp20x->nr_cells = ARRAY_SIZE(axp806_self_working_cells);
 			axp20x->cells = axp806_self_working_cells;
 		} else {
 			axp20x->nr_cells = ARRAY_SIZE(axp806_cells);
 			axp20x->cells = axp806_cells;
 		}
+		nr_cells_no_irq = ARRAY_SIZE(axp806_cells);
+		cells_no_irq = axp806_cells;
 		axp20x->regmap_cfg = &axp806_regmap_config;
 		axp20x->regmap_irq_chip = &axp806_regmap_irq_chip;
 		break;
@@ -1238,24 +1241,8 @@ int axp20x_match_device(struct axp20x_dev *axp20x)
 		axp20x->regmap_irq_chip = &axp803_regmap_irq_chip;
 		break;
 	case AXP15060_ID:
-		/*
-		 * Don't register the power key part if there is no interrupt
-		 * line.
-		 *
-		 * Since most use cases of AXP PMICs are Allwinner SOCs, board
-		 * designers follow Allwinner's reference design and connects
-		 * IRQ line to SOC, there's no need for those variants to deal
-		 * with cases that IRQ isn't connected. However, AXP15660 is
-		 * used by some other vendors' SOCs that didn't connect IRQ
-		 * line, we need to deal with this case.
-		 */
-		if (axp20x->irq > 0) {
-			axp20x->nr_cells = ARRAY_SIZE(axp15060_cells);
-			axp20x->cells = axp15060_cells;
-		} else {
-			axp20x->nr_cells = ARRAY_SIZE(axp_regulator_only_cells);
-			axp20x->cells = axp_regulator_only_cells;
-		}
+		axp20x->nr_cells = ARRAY_SIZE(axp15060_cells);
+		axp20x->cells = axp15060_cells;
 		axp20x->regmap_cfg = &axp15060_regmap_config;
 		axp20x->regmap_irq_chip = &axp15060_regmap_irq_chip;
 		break;
@@ -1263,6 +1250,23 @@ int axp20x_match_device(struct axp20x_dev *axp20x)
 		dev_err(dev, "unsupported AXP20X ID %lu\n", axp20x->variant);
 		return -EINVAL;
 	}
+
+	/*
+	 * Use an alternative cell array when no interrupt line is connected,
+	 * since IRQs are required by some drivers.
+	 * The default is the safe "regulator-only", as this works fine without
+	 * an interrupt specified.
+	 */
+	if (axp20x->irq <= 0) {
+		if (cells_no_irq) {
+			axp20x->nr_cells = nr_cells_no_irq;
+			axp20x->cells = cells_no_irq;
+		} else {
+			axp20x->nr_cells = ARRAY_SIZE(axp_regulator_only_cells);
+			axp20x->cells = axp_regulator_only_cells;
+		}
+	}
+
 	dev_info(dev, "AXP20x variant %s found\n",
 		 axp20x_model_names[axp20x->variant]);