Re: [PATCH net-next v2 2/2] net: phy: add DAPU Telecom DAP8210R(I) Gigabit Ethernet PHY driver

[Maxime Chevallier]

Hi,

On 7/16/26 13:38, Artem Shimko wrote:
> Add a new PHY driver for the DAPU Telecom DAP8211R(I) Gigabit
> Ethernet PHY, which is commonly used in enterprise and industrial
> networking applications.
> 
> The driver implements extended register access via indirect addressing
> through corresponding registers, and provides comprehensive device tree
> support for RGMII delay configuration. The rx-internal-delay-ps and
> tx-internal-delay-ps properties allow precise tuning of clock delays in
> 150 ps steps from 0 to 2250 ps. Additionally, the optional
> dapu,tx-inverted-clk flag enables 180-degree TX clock phase shift for
> boards where signal integrity or MAC requirements necessitate clock
> inversion.
> 
> Signed-off-by: Artem Shimko <a.shimko.dev@xxxxxxxxx>
> ---
>  drivers/net/phy/Kconfig    |  10 ++
>  drivers/net/phy/Makefile   |   1 +
>  drivers/net/phy/dap8211r.c | 281 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 292 insertions(+)
>  create mode 100644 drivers/net/phy/dap8211r.c
> 
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 099f25dceabb..4576f707ac94 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -237,6 +237,16 @@ config DAVICOM_PHY
>  	help
>  	  Currently supports dm9161e and dm9131
>  
> +config DAP8211R_PHY
> +	tristate "DAPU Telecom DAP8211R(I) Gigabit Ethernet PHY"
> +	depends on OF
> +	help
> +	  Support for the DAPU Telecom DAP8211R(I) Gigabit Ethernet PHY.
> +	  This PHY is designed for enterprise and industrial networking
> +	  applications, supporting 10/100/1000 Mbps operation.
> +	  RGMII with: configurable TX/RX clock delays, optional flag to enable
> +	  180-degree TX clock phase shift and internal packet generator.
> +
>  config ICPLUS_PHY
>  	tristate "ICPlus PHYs"
>  	help
> diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
> index de660ae94945..ad35733eb4bb 100644
> --- a/drivers/net/phy/Makefile
> +++ b/drivers/net/phy/Makefile
> @@ -53,6 +53,7 @@ obj-$(CONFIG_BROADCOM_PHY)	+= broadcom.o
>  obj-$(CONFIG_CICADA_PHY)	+= cicada.o
>  obj-$(CONFIG_CORTINA_PHY)	+= cortina.o
>  obj-$(CONFIG_DAVICOM_PHY)	+= davicom.o
> +obj-$(CONFIG_DAP8211R_PHY)	+= dap8211r.o
>  obj-$(CONFIG_DP83640_PHY)	+= dp83640.o
>  obj-$(CONFIG_DP83822_PHY)	+= dp83822.o
>  obj-$(CONFIG_DP83848_PHY)	+= dp83848.o
> diff --git a/drivers/net/phy/dap8211r.c b/drivers/net/phy/dap8211r.c
> new file mode 100644
> index 000000000000..e1e6a322ef0c
> --- /dev/null
> +++ b/drivers/net/phy/dap8211r.c
> @@ -0,0 +1,281 @@
> +// SPDX-License-Identifier: GPL
> +/*
> + * Driver for the DAPU Telecom DAP8211R(I) Gigabit Ethernet PHY.
> + *
> + * Specifications:
> + *   - IEEE 802.3 10BASE-Te, 100BASE-TX, 1000BASE-T
> + *   - IEEE 802.3az-2010 Energy Efficient Ethernet
> + *   - IEEE 1588 SyncE support
> + *   - RGMII
> + *
> + * Author: Artem Shimko <a.shimko.dev@xxxxxxxxx>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/errno.h>
> +#include <linux/ethtool.h>
> +#include <linux/kernel.h>
> +#include <linux/mii.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/of.h>
> +#include <linux/phy.h>
> +
> +#define DAP8211R_PHY_ID			0x0008011B
> +#define DAP8211R_PHY_ID_MASK		0xFFFFFFFF
> +
> +#define DAP8211R_EXT_ADD		0x1E
> +#define DAP8211R_EXT_DATA		0x1F
> +
> +#define DAP8211R_PHY_CON		0xA001
> +#define DAP8211R_PHY_SW_RST		BIT(15)
> +
> +#define DAP8211R_RGMII_CON		0xA003
> +#define DAP8211R_RGMII_TX_DEL_MASK	GENMASK(3, 0)
> +#define DAP8211R_RGMII_RX_DEL_MASK	GENMASK(13, 10)
> +#define DAP8211R_RGMII_CLK_INVERT	BIT(14)
> +
> +/* Default RGMII delay: 13 * 150 == 1.95ns */
> +#define DAP8211R_DEFAULT_DELAY_SEL	0xD
> +
> +struct dap8211r_delay_config {
> +	u32 ps;
> +	u8 sel;
> +};
> +
> +static const struct dap8211r_delay_config delay_config[] = {
> +	{   0, 0},
> +	{ 150, 1},
> +	{ 300, 2},
> +	{ 450, 3},
> +	{ 600, 4},
> +	{ 750, 5},
> +	{ 900, 6},
> +	{1050, 7},
> +	{1200, 8},
> +	{1350, 9},
> +	{1500, 10},
> +	{1650, 11},
> +	{1800, 12},
> +	{1950, 13},
> +	{2100, 14},
> +	{2250, 15},
> +};
> +
> +#define DAP8211R_DELAY_COUNT	ARRAY_SIZE(delay_config)
> +
> +/**
> + * dap8211r_delay_ps_to_sel() - Convert ps to register value (exact match only)
> + * @ps: Delay in picoseconds
> + *
> + * Converts a delay value in picoseconds to the corresponding register value
> + * for RGMII delay configuration. The PHY supports specific values from
> + * 0 to 2250 ps in 150 ps steps.
> + *
> + * Return: Register value (0-15) on success, -EINVAL if @ps is not supported.
> + */
> +
> +static int dap8211r_delay_ps_to_sel(u32 ps)
> +{
> +	for (int i = 0; i < DAP8211R_DELAY_COUNT; i++)
> +		if (ps == delay_config[i].ps)
> +			return delay_config[i].sel;
> +
> +	return -EINVAL;
> +}
> +
> +/**
> + * dap8211r_read_ext() - Read extended register
> + * @phydev: PHY device structure
> + * @reg: Extended register address
> + *
> + * Reads a PHY extended register using the indirect access method.
> + * The caller must hold the MDIO bus lock.
> + *
> + * Return: Register value on success, or negative error code
> + */
> +static int dap8211r_read_ext(struct phy_device *phydev, u16 reg)
> +{
> +	int ret;
> +
> +	phy_lock_mdio_bus(phydev);
> +	ret = __phy_write(phydev, DAP8211R_EXT_ADD, reg);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = __phy_read(phydev, DAP8211R_EXT_DATA);
> +out:
> +	phy_unlock_mdio_bus(phydev);
> +	return ret;
> +}
> +
> +/**
> + * dap8211r_modify_ext() - Modify extended register bits
> + * @phydev: PHY device structure
> + * @reg: Extended register address
> + * @mask: Bit mask of bits to clear
> + * @set: Bit mask of bits to set
> + *
> + * Modifies a PHY extended register using the indirect access method.
> + * New value = (old value & ~mask) | set.
> + * The caller must hold the MDIO bus lock.
> + *
> + * Return: 0 on success, or negative error code
> + */
> +static int dap8211r_modify_ext(struct phy_device *phydev, u16 reg, u16 mask, u16 set)
> +{
> +	int ret;
> +
> +	phy_lock_mdio_bus(phydev);
> +	ret = __phy_write(phydev, DAP8211R_EXT_ADD, reg);
> +	if (ret < 0)
> +		goto out;
> +
> +	ret = __phy_modify(phydev, DAP8211R_EXT_DATA, mask, set);
> +out:
> +	phy_unlock_mdio_bus(phydev);
> +	return ret;
> +}
> +
> +/**
> + * dap8211r_get_rgmii_delay() - Get RGMII delay from DT
> + * @phydev: PHY device
> + * @prop_name: DT property name
> + * @is_id: If phy mode is PHY_INTERFACE_MODE_RGMII_[TXID,RXID,ID]
> + *
> + * Reads the RGMII delay from the device tree. If the property is not
> + * specified, the default delay (1950ps) is used.
> + *
> + * Return: Register value (0-15) on success, negative error code on failure.
> + *	   -EINVAL: Property not specified and is_id is false.
> + */
> +static int dap8211r_get_rgmii_delay(struct phy_device *phydev, const char *prop_name, bool is_id)
> +{
> +	struct device_node *np = phydev->mdio.dev.of_node;
> +	u32 ps = 0;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, prop_name, &ps);
> +	if (ret == -EINVAL)
> +		return (is_id) ? DAP8211R_DEFAULT_DELAY_SEL : ret;
> +	if (ret < 0)
> +		return ret;
> +
> +	return dap8211r_delay_ps_to_sel(ps);
> +}
> +
> +/**
> + * dap8211r_config_init() - Initialize PHY
> + * @phydev: PHY device structure
> + *
> + * Configures the PHY during initialization:
> + * - RGMII delays based on interface mode
> + * - TX clock invertion
> + * - Software reset to apply settings (low active, self clear)
> + *
> + * Return: 0 on success, or negative error code
> + */
> +static int dap8211r_config_init(struct phy_device *phydev)
> +{
> +	struct device_node *phydev_node = phydev->mdio.dev.of_node;
> +	u16 mask = 0, set = 0;
> +	int ret, retries = 10;
> +
> +	switch (phydev->interface) {
> +	case PHY_INTERFACE_MODE_RGMII:
> +		ret = dap8211r_get_rgmii_delay(phydev, "rx-internal-delay-ps", false);
> +		if (ret >= 0) {
> +			set = FIELD_PREP(DAP8211R_RGMII_RX_DEL_MASK, ret);
> +			mask = DAP8211R_RGMII_RX_DEL_MASK;
> +		} else if ((ret < 0) && (ret != -EINVAL)) {
> +			return ret;
> +		}
> +
> +		ret = dap8211r_get_rgmii_delay(phydev, "tx-internal-delay-ps", false);
> +		if (ret >= 0) {
> +			set |= FIELD_PREP(DAP8211R_RGMII_TX_DEL_MASK, ret);
> +			mask |= DAP8211R_RGMII_TX_DEL_MASK;
> +		} else if ((ret < 0) && (ret != -EINVAL)) {
> +			return ret;
> +		}
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII_RXID:
> +		ret = dap8211r_get_rgmii_delay(phydev, "rx-internal-delay-ps", true);
> +		if (ret < 0)
> +			return ret;
> +
> +		set = FIELD_PREP(DAP8211R_RGMII_RX_DEL_MASK, ret);
> +		mask = DAP8211R_RGMII_RX_DEL_MASK;
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII_ID:
> +		ret = dap8211r_get_rgmii_delay(phydev, "rx-internal-delay-ps", true);
> +		if (ret < 0)
> +			return ret;
> +
> +		set = FIELD_PREP(DAP8211R_RGMII_RX_DEL_MASK, ret);
> +		mask = DAP8211R_RGMII_RX_DEL_MASK;
> +		fallthrough;
> +	case PHY_INTERFACE_MODE_RGMII_TXID:
> +		ret = dap8211r_get_rgmii_delay(phydev, "tx-internal-delay-ps", true);
> +		if (ret < 0)
> +			return ret;
> +
> +		set |= FIELD_PREP(DAP8211R_RGMII_TX_DEL_MASK, ret);
> +		mask |= DAP8211R_RGMII_TX_DEL_MASK;
> +		break;
> +	default:
> +		phydev_err(phydev, "Unsupported interface: %d\n",
> +			   phydev->interface);
> +		return -EINVAL;
> +	}

You can simplify the whole delay parsing a log by using phy_get_internal_delay().
It will give you the index of the delay from the delay table you have :)

https://elixir.bootlin.com/linux/v7.1.3/source/drivers/net/phy/phy_device.c#L3085

You can take a look at the few drivers that use it (mscc, dp83869) for reference

Maxime