RE: GMII2RGMII Converter support in macb driver

[Appana Durga Kedareswara Rao <appana.durga.rao@xilinx.com>]

Hi Nicolas Ferre,

> -----Original Message-----
> From: Nicolas Ferre [mailto:nicolas.ferre@atmel.com]
> Sent: Tuesday, April 12, 2016 6:52 PM
> To: Appana Durga Kedareswara Rao <appanad@xilinx.com>;
> netdev@vger.kernel.org; Michal Simek <michals@xilinx.com>
> Cc: Punnaiah Choudary Kalluri <punnaia@xilinx.com>; Harini Katakam
> <harinik@xilinx.com>; Anirudha Sarangi <anirudh@xilinx.com>; Appana Durga
> Kedareswara Rao <appanad@xilinx.com>
> Subject: Re: GMII2RGMII Converter support in macb driver
> 
> Le 12/04/2016 15:03, Appana Durga Kedareswara Rao a écrit :
> > Hi All,
> >
> >
> >
> >
> >
> >                There is a Xilinx custom IP for GMII to RGMII
> > conversion data sheet here
> > (http://www.xilinx.com/support/documentation/ip_documentation/gmii_to_
> > rgmii/v4_0/pg160-gmii-to-rgmii.pdf
> > )
> >
> >
> >
> >
> >
> >                Unlike other Phy's this IP won't support auto
> > negotiation and other features that usually normal Phy's support.
> >
> > This IP has only one register (Control register) which needs to be
> > programmed based on the external phy auto negotiation
> >
> > (Based on the external phy negotiated speed).
> >
> >
> >
> > I am able to make it work for GEM driver by doing the below changes in
> > the driver (drivers/net/ethernet/cadence/macb.c).
> >
> >
> >
> > +#define XEMACPS_GMII2RGMII_FULLDPLX                         BMCR_FULLDPLX
> >
> > +#define XEMACPS_GMII2RGMII_SPEED1000                       BMCR_SPEED1000
> >
> > +#define XEMACPS_GMII2RGMII_SPEED100                         BMCR_SPEED100
> >
> > +#define
> > XEMACPS_GMII2RGMII_REG_NUM                                       0x10
> >
> > +
> >
> > /*
> >
> >   * Graceful stop timeouts in us. We should allow up to
> >
> >   * 1 frame time (10 Mbits/s, full-duplex, ignoring collisions)
> >
> > @@ -311,8 +317,10 @@ static void macb_handle_link_change(struct
> > net_device *dev)
> >
> > {
> >
> >               struct macb *bp = netdev_priv(dev);
> >
> >               struct phy_device *phydev = bp->phy_dev;
> >
> > +             struct phy_device *gmii2rgmii_phydev =
> > + bp->gmii2rgmii_phy_dev;
> >
> >               unsigned long flags;
> >
> >               int status_change = 0;
> >
> > +             u16 gmii2rgmii_reg = 0;
> >
> >                spin_lock_irqsave(&bp->lock, flags);
> >
> > @@ -326,15 +334,27 @@ static void macb_handle_link_change(struct
> > net_device *dev)
> >
> >                                             if (macb_is_gem(bp))
> >
> >                                                            reg &=
> > ~GEM_BIT(GBE);
> >
> > -                                            if (phydev->duplex)
> >
> > +                                           if (phydev->duplex) {
> >
> >                                                            reg |=
> > MACB_BIT(FD);
> >
> > -                                            if (phydev->speed == SPEED_100)
> >
> > +
> > gmii2rgmii_reg |= XEMACPS_GMII2RGMII_FULLDPLX;
> >
> > +                                           }
> >
> > +                                           if (phydev->speed ==
> > SPEED_100) {
> >
> >                                                            reg |=
> > MACB_BIT(SPD);
> >
> > +
> > gmii2rgmii_reg |= XEMACPS_GMII2RGMII_SPEED100;
> >
> > +                                           }
> >
> >                                             if (phydev->speed ==
> > SPEED_1000 &&
> >
> > -                                                bp->caps &
> > MACB_CAPS_GIGABIT_MODE_AVAILABLE)
> >
> > +                                               bp->caps &
> > MACB_CAPS_GIGABIT_MODE_AVAILABLE) {
> >
> >                                                            reg |=
> > GEM_BIT(GBE);
> >
> > +
> > gmii2rgmii_reg |= XEMACPS_GMII2RGMII_SPEED1000;
> >
> > +                                           }
> >
> >                                              macb_or_gem_writel(bp,
> > NCFGR, reg);
> >
> > +                                           if (gmii2rgmii_phydev !=
> > + NULL) {
> >
> > +
> > macb_mdio_write(bp->mii_bus,
> >
> > +
> > + gmii2rgmii_phydev->addr,
> >
> > +
> > + XEMACPS_GMII2RGMII_REG_NUM,
> >
> > +
> > + gmii2rgmii_reg);
> >
> > +                                           }
> >
> >                                              bp->speed =
> > phydev->speed;
> >
> >                                             bp->duplex =
> > phydev->duplex;
> >
> > @@ -382,6 +402,19 @@ static int macb_mii_probe(struct net_device *dev)
> >
> >               int phy_irq;
> >
> >               int ret;
> >
> > +             if (bp->gmii2rgmii_phy_node) {
> >
> > +                            phydev = of_phy_attach(bp->dev,
> >
> > +
> > + bp->gmii2rgmii_phy_node,
> >
> > +
> > + 0,
> > 0);
> >
> > +                            if (!phydev) {
> >
> > +                                           dev_err(&bp->pdev->dev, "%s:
> > no gmii to rgmii converter found\n",
> >
> > +                                           dev->name);
> >
> > +                                           return -1;
> >
> > +                            }
> >
> > +                            bp->gmii2rgmii_phy_dev = phydev;
> >
> > +             } else
> >
> > +                            bp->gmii2rgmii_phy_dev = NULL;
> >
> > +
> >
> >               phydev = phy_find_first(bp->mii_bus);
> >
> >               if (!phydev) {
> >
> >                              netdev_err(dev, "no PHY found\n");
> >
> > @@ -402,6 +435,8 @@ static int macb_mii_probe(struct net_device *dev)
> >
> >
> >  bp->phy_interface);
> >
> >               if (ret) {
> >
> >                              netdev_err(dev, "Could not attach to
> > PHY\n");
> >
> > +                            if (bp->gmii2rgmii_phy_dev)
> >
> > +
> > phy_disconnect(bp->gmii2rgmii_phy_dev);
> >
> >                              return ret;
> >
> >               }
> >
> > @@ -3368,6 +3403,9 @@ static int macb_probe(struct platform_device
> > *pdev)
> >
> >                              bp->phy_interface = err;
> >
> >               }
> >
> > +             bp->gmii2rgmii_phy_node =
> > of_parse_phandle(bp->pdev->dev.of_node,
> >
> > +
> > "gmii2rgmii-phy-handle", 0);
> >
> > +
> >
> >               macb_reset_phy(pdev);
> >
> >                /* IP specific init */
> >
> > @@ -3422,6 +3460,8 @@ static int macb_remove(struct platform_device
> > *pdev)
> >
> >                              bp = netdev_priv(dev);
> >
> >                              if (bp->phy_dev)
> >
> >
> > phy_disconnect(bp->phy_dev);
> >
> > +                            if (bp->gmii2rgmii_phy_dev)
> >
> > +
> > phy_disconnect(bp->gmii2rgmii_phy_dev);
> >
> >
> >
> > But doing above changes making driver looks odd.
> >
> > could you please suggest any better option to add support for this IP
> > in the macb driver?
> 
> Appana,
> 
> I certainly can't prototype the solution based on your datasheet and the code
> sent... do a sensible proposal, then we can evaluate.

Thanks for the quick response will come up with a sensible proposal soon...

Regards,
Kedar.

> 
> As the IP is separated from the Eth controller, make it a separate driver (an
> emulated phy one for instance... even if I don't know if it makes sense).
> 
> I don't know if others have already made such an adaptation layer between
> GMII to RGMII but I'm pretty sure it can't be inserted into the macb driver.
> 
> Bye,
> --
> Nicolas Ferre