Re: [PATCH net-next v2 1/4] net: mdio: Introduce a regmap-based mdio driver

From
Simon Horman <hidden>
Date
2023-05-25 11:03:33
Also in
linux-arm-kernel, lkml
Reply to
Maxime Chevallier, 2023-05-25
On Thu, May 25, 2023 at 12:11:23PM +0200, Maxime Chevallier wrote:
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 hunk ↗ jump to hunk
+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.

I think a better approach would be to use U32_MAX.
quoted hunk ↗ jump to hunk
+
+	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 <maxime.chevallier@bootlin.com>");
+MODULE_LICENSE("GPL");
Thread (10 messages) 10 messages, 3 authors, last reply 2023-05-25
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