Re: [PATCH v3] net: phy: add driver for Motorcomm yt8511 phy

[Heiner Kallweit <hkallweit1@gmail.com>]

On 14.05.2021 13:58, Peter Geis wrote:
> Add a driver for the Motorcomm yt8511 phy that will be used in the
> production Pine64 rk3566-quartz64 development board.
> It supports gigabit transfer speeds, rgmii, and 125mhz clk output.
> 
> Signed-off-by: Peter Geis <pgwipeout@gmail.com>
> ---
> Changes v3:
> - Add rgmii mode selection support
> 
> Changes v2:
> - Change to __phy_modify
> - Handle return errors
> - Remove unnecessary &
> 
>  MAINTAINERS                 |   6 ++
>  drivers/net/phy/Kconfig     |   6 ++
>  drivers/net/phy/Makefile    |   1 +
>  drivers/net/phy/motorcomm.c | 121 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 134 insertions(+)
>  create mode 100644 drivers/net/phy/motorcomm.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 601b5ae0368a..2a2e406238fc 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12388,6 +12388,12 @@ F:	Documentation/userspace-api/media/drivers/meye*
>  F:	drivers/media/pci/meye/
>  F:	include/uapi/linux/meye.h
>  
> +MOTORCOMM PHY DRIVER
> +M:	Peter Geis <pgwipeout@gmail.com>
> +L:	netdev@vger.kernel.org
> +S:	Maintained
> +F:	drivers/net/phy/motorcomm.c
> +
>  MOXA SMARTIO/INDUSTIO/INTELLIO SERIAL CARD
>  S:	Orphan
>  F:	Documentation/driver-api/serial/moxa-smartio.rst
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 288bf405ebdb..16db9f8037b5 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -229,6 +229,12 @@ config MICROSEMI_PHY
>  	help
>  	  Currently supports VSC8514, VSC8530, VSC8531, VSC8540 and VSC8541 PHYs
>  
> +config MOTORCOMM_PHY
> +	tristate "Motorcomm PHYs"
> +	help
> +	  Enables support for Motorcomm network PHYs.
> +	  Currently supports the YT8511 gigabit PHY.
> +
>  config NATIONAL_PHY
>  	tristate "National Semiconductor PHYs"
>  	help
> diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
> index bcda7ed2455d..37ffbc6e3c87 100644
> --- a/drivers/net/phy/Makefile
> +++ b/drivers/net/phy/Makefile
> @@ -70,6 +70,7 @@ obj-$(CONFIG_MICREL_PHY)	+= micrel.o
>  obj-$(CONFIG_MICROCHIP_PHY)	+= microchip.o
>  obj-$(CONFIG_MICROCHIP_T1_PHY)	+= microchip_t1.o
>  obj-$(CONFIG_MICROSEMI_PHY)	+= mscc/
> +obj-$(CONFIG_MOTORCOMM_PHY)	+= motorcomm.o
>  obj-$(CONFIG_NATIONAL_PHY)	+= national.o
>  obj-$(CONFIG_NXP_C45_TJA11XX_PHY)	+= nxp-c45-tja11xx.o
>  obj-$(CONFIG_NXP_TJA11XX_PHY)	+= nxp-tja11xx.o
> diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> new file mode 100644
> index 000000000000..b85f10efa28e
> --- /dev/null
> +++ b/drivers/net/phy/motorcomm.c
> @@ -0,0 +1,121 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Driver for Motorcomm PHYs
> + *
> + * Author: Peter Geis <pgwipeout@gmail.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/phy.h>
> +
> +#define PHY_ID_YT8511		0x0000010a

This PHY ID looks weird, the OUI part is empty.
Looking here http://standards-oui.ieee.org/cid/cid.txt
it seems Motorcomm has been assigned at least a CID.
An invalid OUI leaves a good chance for a PHY ID conflict.

> +
> +#define YT8511_PAGE_SELECT	0x1e
> +#define YT8511_PAGE		0x1f
> +#define YT8511_EXT_CLK_GATE	0x0c
> +#define YT8511_EXT_SLEEP_CTRL	0x27
> +
> +/* 2b00 25m from pll
> + * 2b01 25m from xtl *default*
> + * 2b10 62.m from pll
> + * 2b11 125m from pll
> + */
> +#define YT8511_CLK_125M		(BIT(2) | BIT(1))
> +
> +/* RX Delay enabled = 1.8ns 1000T, 8ns 10/100T */
> +#define YT8511_DELAY_RX		BIT(0)
> +
> +/* TX Delay is bits 7:4, default 0x5
> + * Delay = 150ps * N - 250ps, Default = 500ps
> + */
> +#define YT8511_DELAY_TX		(0x5 << 4)
> +
> +static int yt8511_read_page(struct phy_device *phydev)
> +{
> +	return __phy_read(phydev, YT8511_PAGE_SELECT);
> +};
> +
> +static int yt8511_write_page(struct phy_device *phydev, int page)
> +{
> +	return __phy_write(phydev, YT8511_PAGE_SELECT, page);
> +};
> +
> +static int yt8511_config_init(struct phy_device *phydev)
> +{
> +	int ret, oldpage, val;
> +
> +	/* set clock mode to 125mhz */
> +	oldpage = phy_select_page(phydev, YT8511_EXT_CLK_GATE);
> +	if (oldpage < 0)
> +		goto err_restore_page;
> +
> +	ret = __phy_modify(phydev, YT8511_PAGE, 0, YT8511_CLK_125M);
> +	if (ret < 0)
> +		goto err_restore_page;
> +
> +	/* set rgmii delay mode */
> +	val = __phy_read(phydev, YT8511_PAGE);
> +
> +	switch (phydev->interface) {
> +	case PHY_INTERFACE_MODE_RGMII:
> +		val &= ~(YT8511_DELAY_RX | YT8511_DELAY_TX);
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII_ID:
> +		val |= YT8511_DELAY_RX | YT8511_DELAY_TX;
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII_RXID:
> +		val &= ~(YT8511_DELAY_TX);
> +		val |= YT8511_DELAY_RX;
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII_TXID:
> +		val &= ~(YT8511_DELAY_RX);
> +		val |= YT8511_DELAY_TX;
> +		break;
> +	default: /* leave everything alone in other modes */
> +		break;
> +	}
> +
> +	ret = __phy_write(phydev, YT8511_PAGE, val);
> +	if (ret < 0)
> +		goto err_restore_page;
> +
> +	/* disable auto sleep */
> +	ret = __phy_write(phydev, YT8511_PAGE_SELECT, YT8511_EXT_SLEEP_CTRL);
> +	if (ret < 0)
> +		goto err_restore_page;
> +	ret = __phy_modify(phydev, YT8511_PAGE, BIT(15), 0);
> +	if (ret < 0)
> +		goto err_restore_page;
> +
> +err_restore_page:
> +	return phy_restore_page(phydev, oldpage, ret);
> +}
> +
> +static struct phy_driver motorcomm_phy_drvs[] = {
> +	{
> +		PHY_ID_MATCH_EXACT(PHY_ID_YT8511),
> +		.name		= "YT8511 Gigabit Ethernet",
> +		.config_init	= yt8511_config_init,
> +		.get_features	= genphy_read_abilities,
> +		.config_aneg	= genphy_config_aneg,
> +		.read_status	= genphy_read_status,

These three genphy callbacks are fallbacks anyway.
So you don't have to set them.

> +		.suspend	= genphy_suspend,
> +		.resume		= genphy_resume,
> +		.read_page	= yt8511_read_page,
> +		.write_page	= yt8511_write_page,
> +	},
> +};
> +
> +module_phy_driver(motorcomm_phy_drvs);
> +
> +MODULE_DESCRIPTION("Motorcomm PHY driver");
> +MODULE_AUTHOR("Peter Geis");
> +MODULE_LICENSE("GPL");
> +
> +static const struct mdio_device_id __maybe_unused motorcomm_tbl[] = {
> +	{ PHY_ID_MATCH_EXACT(PHY_ID_YT8511) },
> +	{ /* sentinal */ }
> +};
> +
> +MODULE_DEVICE_TABLE(mdio, motorcomm_tbl);
>