iio: adc: ab8500-gpadc: Support non-hw-conversion

The hardware conversion mode only exists in the AB8500
version of the chip, as it is lacking in the AB8505 it
will not be in the device tree and we should just not
even try to obtain it.

The driver already contains code to avoid using a
non-existing hardware conversion IRQ at conversion time.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201218222013.383704-1-linus.walleij@linaro.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ab8500-gpadc.c

@@ -1108,10 +1108,14 @@ static int ab8500_gpadc_probe(struct platform_device *pdev)
 		return gpadc->irq_sw;
 	}
 
-	gpadc->irq_hw = platform_get_irq_byname(pdev, "HW_CONV_END");
-	if (gpadc->irq_hw < 0) {
-		dev_err(dev, "failed to get platform hw_conv_end irq\n");
-		return gpadc->irq_hw;
+	if (is_ab8500(gpadc->ab8500)) {
+		gpadc->irq_hw = platform_get_irq_byname(pdev, "HW_CONV_END");
+		if (gpadc->irq_hw < 0) {
+			dev_err(dev, "failed to get platform hw_conv_end irq\n");
+			return gpadc->irq_hw;
+		}
+	} else {
+		gpadc->irq_hw = 0;
 	}
 
 	/* Initialize completion used to notify completion of conversion */
@@ -1128,14 +1132,16 @@ static int ab8500_gpadc_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = devm_request_threaded_irq(dev, gpadc->irq_hw, NULL,
-		ab8500_bm_gpadcconvend_handler,	IRQF_NO_SUSPEND | IRQF_ONESHOT,
-		"ab8500-gpadc-hw", gpadc);
-	if (ret < 0) {
-		dev_err(dev,
-			"Failed to request hw conversion irq: %d\n",
-			gpadc->irq_hw);
-		return ret;
+	if (gpadc->irq_hw) {
+		ret = devm_request_threaded_irq(dev, gpadc->irq_hw, NULL,
+			ab8500_bm_gpadcconvend_handler,	IRQF_NO_SUSPEND | IRQF_ONESHOT,
+			"ab8500-gpadc-hw", gpadc);
+		if (ret < 0) {
+			dev_err(dev,
+				"Failed to request hw conversion irq: %d\n",
+				gpadc->irq_hw);
+			return ret;
+		}
 	}
 
 	/* The VTVout LDO used to power the AB8500 GPADC */