Hello Simon,

On Thu, 25 May 2023 13:02:39 +0200
Simon Horman [off-list ref] wrote:

On Thu, May 25, 2023 at 12:11:23PM +0200, Maxime Chevallier wrote:

quoted

There exists several examples today of devices that embed an
ethernet PHY or PCS directly inside an SoC. In this situation,
either the device is controlled through a vendor-specific register
set, or sometimes exposes the standard 802.3 registers that are
typically accessed over MDIO.

As phylib and phylink are designed to use mdiodevices, this driver
allows creating a virtual MDIO bus, that translates mdiodev register
accesses to regmap accesses.

The reason we use regmap is because there are at least 3 such
devices known today, 2 of them are Altera TSE PCS's, memory-mapped,
exposed with a 4-byte stride in stmmac's dwmac-socfpga variant, and
a 2-byte stride in altera-tse. The other one
(nxp,sja1110-base-tx-mdio) is exposed over SPI.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>  

...

quoted

+struct mii_bus *devm_mdio_regmap_register(struct device *dev,
+					  const struct
mdio_regmap_config *config) +{
+	struct mdio_regmap_config *mrc;
+	struct mii_bus *mii;
+	int rc;
+
+	if (!config->parent)
+		return ERR_PTR(-EINVAL);
+
+	mii = devm_mdiobus_alloc_size(config->parent,
sizeof(*mrc));
+	if (!mii)
+		return ERR_PTR(-ENOMEM);
+
+	mrc = mii->priv;
+	memcpy(mrc, config, sizeof(*mrc));
+
+	mrc->regmap = config->regmap;
+	mrc->valid_addr = config->valid_addr;
+
+	mii->name = DRV_NAME;
+	strscpy(mii->id, config->name, MII_BUS_ID_SIZE);
+	mii->parent = config->parent;
+	mii->read = mdio_regmap_read_c22;
+	mii->write = mdio_regmap_write_c22;
+
+	if (config->autoscan)
+		mii->phy_mask = ~BIT(config->valid_addr);
+	else
+		mii->phy_mask = ~0UL;  

Hi Maxime,

phy_mask is a u32.
But 0UL may be either 32 or 64 bits wide.

Right

I think a better approach would be to use U32_MAX.

I guess ~0 would also work, and this would also align with what
fixed-phy and sfp do for their internal MDIO bus.

I'll fix that for next revision

Thanks,

Maxime

quoted

+
+	rc = devm_mdiobus_register(dev, mii);
+	if (rc) {
+		dev_err(config->parent, "Cannot register MDIO
bus![%s] (%d)\n", mii->id, rc);
+		return ERR_PTR(rc);
+	}
+
+	return mii;
+}
+EXPORT_SYMBOL_GPL(devm_mdio_regmap_register);
+
+MODULE_DESCRIPTION("MDIO API over regmap");
+MODULE_AUTHOR("Maxime Chevallier [off-list ref]");
+MODULE_LICENSE("GPL");