gpio: dwapb: Get reset control by means of resource managed interface

The reset control interface provides the resource managed version of
the reset_control_get() method. The only thing which needs to be also
automated is the reset lane assertion on the device removal. It can be
implemented by means of the custom action definition. After that the reset
control will be purely managed by the device resources interface.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200730152808.2955-9-Sergey.Semin@baikalelectronics.ruSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-dwapb.c

@@ -621,6 +621,32 @@ static struct dwapb_platform_data *dwapb_gpio_get_pdata(struct device *dev)
 	return pdata;
 }
 
+static void dwapb_assert_reset(void *data)
+{
+	struct dwapb_gpio *gpio = data;
+
+	reset_control_assert(gpio->rst);
+}
+
+static int dwapb_get_reset(struct dwapb_gpio *gpio)
+{
+	int err;
+
+	gpio->rst = devm_reset_control_get_optional_shared(gpio->dev, NULL);
+	if (IS_ERR(gpio->rst)) {
+		dev_err(gpio->dev, "Cannot get reset descriptor\n");
+		return PTR_ERR(gpio->rst);
+	}
+
+	err = reset_control_deassert(gpio->rst);
+	if (err) {
+		dev_err(gpio->dev, "Cannot deassert reset lane\n");
+		return err;
+	}
+
+	return devm_add_action_or_reset(gpio->dev, dwapb_assert_reset, gpio);
+}
+
 static const struct of_device_id dwapb_of_match[] = {
 	{ .compatible = "snps,dw-apb-gpio", .data = (void *)0},
 	{ .compatible = "apm,xgene-gpio-v2", .data = (void *)GPIO_REG_OFFSET_V2},
@@ -660,11 +686,9 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
 	gpio->dev = &pdev->dev;
 	gpio->nr_ports = pdata->nports;
 
-	gpio->rst = devm_reset_control_get_optional_shared(dev, NULL);
-	if (IS_ERR(gpio->rst))
-		return PTR_ERR(gpio->rst);
-
-	reset_control_deassert(gpio->rst);
+	err = dwapb_get_reset(gpio);
+	if (err)
+		return err;
 
 	gpio->ports = devm_kcalloc(&pdev->dev, gpio->nr_ports,
 				   sizeof(*gpio->ports), GFP_KERNEL);
@@ -714,7 +738,6 @@ static int dwapb_gpio_remove(struct platform_device *pdev)
 	struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
 
 	dwapb_gpio_unregister(gpio);
-	reset_control_assert(gpio->rst);
 	clk_bulk_disable_unprepare(DWAPB_NR_CLOCKS, gpio->clks);
 
 	return 0;