On Thu, Jan 22, 2026 at 12:56:42PM +0200, Vladimir Oltean wrote:

This is the standalone variant of drivers/net/dsa/sja1105/sja1105_mdio.c.
Same kind of differences between this driver and the embedded DSA one
apply: regmap is being used for register access, and addresses are
multiplied by 4 with regmap.

In fact this is so generic that there is nothing NXP SJA1110 specific
about it at all, and just instantiates mdio-regmap. I decided to name it
mdio-regmap-simple.c in the style of drivers/mfd/simple-mfd-i2c.c which
has support for various vendor compatible strings.

...

+#include <linux/module.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mdio/mdio-regmap.h>

...

+static const struct mdio_regmap_simple_data nxp_sja1110_base_tx = {
+	.valid_addr = 0,
+	.autoscan = false,
+};

Actually the  { } is enough to initialise that. But if you want to be super
explicit... :-)

...

+static int mdio_regmap_simple_probe(struct platform_device *pdev)
+{
+	const struct mdio_regmap_simple_data *data;
+	struct mdio_regmap_config config = {};
+	struct device *dev = &pdev->dev;
+	struct regmap *regmap;
+	struct mii_bus *bus;
+
+	if (!dev->of_node || !dev->parent)

dev->of_node check is not needed, see below.

+		return -ENODEV;
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap)
+		return -ENODEV;
+
+	data = device_get_match_data(dev);
+
+	config.regmap = regmap;
+	config.parent = dev;
+	config.name = dev_name(dev);
+	/* The resource is optional, provided for finding the registers
+	 * within a device-wide non-MMIO regmap
+	 */
+	config.resource = platform_get_resource(pdev, IORESOURCE_REG, 0);

+	if (data) {

We may always require data to be present. As you use a default one anyway.

+		config.valid_addr = data->valid_addr;
+		config.autoscan = data->autoscan;
+	}

And if it is not provided we will have a crash which is fine. It will just
point that the code was not ever been run on real HW.

+	return PTR_ERR_OR_ZERO(devm_mdio_regmap_register(dev, &config));
+}

...

+static struct platform_driver mdio_regmap_simple_driver = {
+	.probe = mdio_regmap_simple_probe,
+	.driver = {
+		.name = "mdio-regmap-simple",
+		.of_match_table = mdio_regmap_simple_match,
+	},
+};

+

Unneeded blank line.

+module_platform_driver(mdio_regmap_simple_driver);

-- 
With Best Regards,
Andy Shevchenko