RE: [PATCH v6 3/3] net: phy: Add gmiitorgmii converter support

[Appana Durga Kedareswara Rao]

Hi Andrew,

Thanks for the review...

> 
> > +static int xgmiitorgmii_read_status(struct phy_device *phydev) {
> > +   struct gmii2rgmii *priv = phydev->priv;
> > +   u16 val = 0;
> > +
> > +   priv->phy_drv->read_status(phydev);
> 
> This can return an error, in which case phydev->speed should not be trusted.

Will fix...

> 
> I've not thought locking all the way through yet. I don't think you need a 
> lock
> here, but i need to think about it.

Ok...

> 
> > +
> > +   val = mdiobus_read(phydev->mdio.bus, priv->addr,
> > +XILINX_GMII2RGMII_REG);
> 
> You should check for an error here.
> 
> > +   val &= XILINX_GMII2RGMII_SPEED_MASK;
> > +
> > +   if (phydev->speed == SPEED_1000)
> > +   val |= BMCR_SPEED1000;
> > +   else if (phydev->speed == SPEED_100)
> > +   val |= BMCR_SPEED100;
> > +   else
> > +   val |= BMCR_SPEED10;
> 
> What happens if for example the PHY is an aquantia and has negotiated
> SPEED_2500? Some Marvell PHYs can also do odd speeds, like 200Mbps.
> You probably want to return an error, rather than silently have things go 
> wrong.

Will fix...

> 
> > +
> > +   mdiobus_write(phydev->mdio.bus, priv->addr,
> XILINX_GMII2RGMII_REG,
> > +val);
> 
> This can also return an error.

Will fix...

> 
> > +   return 0;
> > +}
> > +
> > +int xgmiitorgmii_probe(struct mdio_device *mdiodev) {
> > +   struct device *dev = >dev;
> > +   struct device_node *np = dev->of_node, *phy_node;
> > +   struct gmii2rgmii *priv;
> > +
> > +   priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +   if (!priv)
> > +   return -ENOMEM;
> > +
> > +   phy_node = of_parse_phandle(np, "phy-handle", 0);
> > +   if (IS_ERR(phy_node)) {
> > +   dev_err(dev, "Couldn't parse phy-handle\n");
> > +   return -ENODEV;
> > +   }
> > +
> > +   priv->phy_dev = of_phy_find_device(phy_node);
> > +   if (!priv->phy_dev) {
> > +   dev_info(dev, "Couldn't find phydev\n");
> > +   return -EPROBE_DEFER;
> > +   }
> > +
> > +   priv->addr = mdiodev->addr;
> > +   priv->phy_drv = priv->phy_dev->drv;
> > +   memcpy(>conv_phy_drv, priv->phy_dev->drv,
> > +  sizeof(struct phy_driver));
> > +   priv->conv_phy_drv.read_status = xgmiitorgmii_read_status;
> > +   priv->phy_dev->priv = priv;
> > +   priv->phy_dev->drv = >conv_phy_drv;
> 
> So from this point onward, the phy driver depends on the memory allocated by
> this driver. If this driver goes away, freeing its memory, the next call to
> read_status() is going to have a problem.
> 
> Also, i think this assignment should take the phy lock, just to be safe.

Ok will fix

> 
> There also needs to be some thought into what happens if the phy driver is
> unloaded. Should this driver take a reference on the phy driver to prevent 
> that?

Ok will increment the reference count of the external phy device...


Regards,
Kedar.

> 
>Andrew

Re: [PATCH v6 3/3] net: phy: Add gmiitorgmii converter support

[Andrew Lunn]

> +static int xgmiitorgmii_read_status(struct phy_device *phydev)
> +{
> + struct gmii2rgmii *priv = phydev->priv;
> + u16 val = 0;
> +
> + priv->phy_drv->read_status(phydev);

This can return an error, in which case phydev->speed should not be
trusted.

I've not thought locking all the way through yet. I don't think you
need a lock here, but i need to think about it.

> +
> + val = mdiobus_read(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG);

You should check for an error here.

> + val &= XILINX_GMII2RGMII_SPEED_MASK;
> +
> + if (phydev->speed == SPEED_1000)
> + val |= BMCR_SPEED1000;
> + else if (phydev->speed == SPEED_100)
> + val |= BMCR_SPEED100;
> + else
> + val |= BMCR_SPEED10;

What happens if for example the PHY is an aquantia and has negotiated
SPEED_2500? Some Marvell PHYs can also do odd speeds, like 200Mbps.
You probably want to return an error, rather than silently have things
go wrong.

> +
> + mdiobus_write(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG, val);

This can also return an error.

> + return 0;
> +}
> +
> +int xgmiitorgmii_probe(struct mdio_device *mdiodev)
> +{
> + struct device *dev = >dev;
> + struct device_node *np = dev->of_node, *phy_node;
> + struct gmii2rgmii *priv;
> +
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + phy_node = of_parse_phandle(np, "phy-handle", 0);
> + if (IS_ERR(phy_node)) {
> + dev_err(dev, "Couldn't parse phy-handle\n");
> + return -ENODEV;
> + }
> +
> + priv->phy_dev = of_phy_find_device(phy_node);
> + if (!priv->phy_dev) {
> + dev_info(dev, "Couldn't find phydev\n");
> + return -EPROBE_DEFER;
> + }
> +
> + priv->addr = mdiodev->addr;
> + priv->phy_drv = priv->phy_dev->drv;
> + memcpy(>conv_phy_drv, priv->phy_dev->drv,
> +sizeof(struct phy_driver));
> + priv->conv_phy_drv.read_status = xgmiitorgmii_read_status;
> + priv->phy_dev->priv = priv;
> + priv->phy_dev->drv = >conv_phy_drv;

So from this point onward, the phy driver depends on the memory
allocated by this driver. If this driver goes away, freeing its
memory, the next call to read_status() is going to have a problem.

Also, i think this assignment should take the phy lock, just to be
safe.

There also needs to be some thought into what happens if the phy
driver is unloaded. Should this driver take a reference on the phy
driver to prevent that?

   Andrew

[PATCH v6 3/3] net: phy: Add gmiitorgmii converter support

[Kedareswara rao Appana]

This patch adds support for gmiitorgmii converter.

The GMII to RGMII IP core provides the Reduced Gigabit Media
Independent Interface (RGMII) between Ethernet physical media
Devices and the Gigabit Ethernet controller. This core can
Switch dynamically between the three different speed modes of
Operation by configuring the converter register through mdio write.

MDIO interface is used to set operating speed of Ethernet MAC.

This converter sits between the MAC and the external phy
MAC <==> GMII2RGMII <==> RGMII_PHY

Signed-off-by: Kedareswara rao Appana 
---
Thanks a lot Andrew for your inputs.
Changes for v6:
--> Don't force phy to default enabled as suggested by Florian.
--> Fix Mask value as suggested by Florian.
--> Used mdio_module_driver as suggested by Florian.
--> Remove switch case and used if-else conditions for phy speed
checking as suggested by Florian.
Changes for v5:
--> Fixed return values in the probe as suggested by punnaiah.
--> Added a mask for the converter speed as suggested by punnaiah.
Changes for v4:
--> Updated phydev speed for all 3 speeds as suggested by zhuyj.
Changes for v3:
--> Updated the driver as suggested by Andrew.
Changes for v2:
--> Passed struct xphy pointer directly to the fix_mac_speed
API as suggested by the Florian.
--> Added checks for the phy-node fail case as suggested
by the Florian

 drivers/net/phy/Kconfig |   7 +++
 drivers/net/phy/Makefile|   1 +
 drivers/net/phy/xilinx_gmii2rgmii.c | 109 
 3 files changed, 117 insertions(+)
 create mode 100644 drivers/net/phy/xilinx_gmii2rgmii.c

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 1b534ea..d66133bf 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -312,6 +312,13 @@ config MICROSEMI_PHY
 ---help---
   Currently supports the VSC8531 and VSC8541 PHYs
 
+config XILINX_GMII2RGMII
+   tristate "Xilinx GMII2RGMII converter driver"
+   ---help---
+ This driver support xilinx GMII to RGMII IP core it provides
+ the Reduced Gigabit Media Independent Interface(RGMII) between
+ Ethernet physical media devices and the Gigabit Ethernet controller.
+
 endif # PHYLIB
 
 config MICREL_KS8995MA
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index a713bd4..73d65ce 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -50,3 +50,4 @@ obj-$(CONFIG_MDIO_BCM_IPROC)  += mdio-bcm-iproc.o
 obj-$(CONFIG_INTEL_XWAY_PHY)   += intel-xway.o
 obj-$(CONFIG_MDIO_HISI_FEMAC)  += mdio-hisi-femac.o
 obj-$(CONFIG_MDIO_XGENE)   += mdio-xgene.o
+obj-$(CONFIG_XILINX_GMII2RGMII) += xilinx_gmii2rgmii.o
diff --git a/drivers/net/phy/xilinx_gmii2rgmii.c 
b/drivers/net/phy/xilinx_gmii2rgmii.c
new file mode 100644
index 000..8e980ad
--- /dev/null
+++ b/drivers/net/phy/xilinx_gmii2rgmii.c
@@ -0,0 +1,109 @@
+/* Xilinx GMII2RGMII Converter driver
+ *
+ * Copyright (C) 2016 Xilinx, Inc.
+ *
+ * Author: Kedareswara rao Appana 
+ *
+ * Description:
+ * This driver is developed for Xilinx GMII2RGMII Converter
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#define XILINX_GMII2RGMII_REG  0x10
+#define XILINX_GMII2RGMII_SPEED_MASK   (BMCR_SPEED1000 | BMCR_SPEED100)
+
+struct gmii2rgmii {
+   struct phy_device *phy_dev;
+   struct phy_driver *phy_drv;
+   struct phy_driver conv_phy_drv;
+   int addr;
+};
+
+static int xgmiitorgmii_read_status(struct phy_device *phydev)
+{
+   struct gmii2rgmii *priv = phydev->priv;
+   u16 val = 0;
+
+   priv->phy_drv->read_status(phydev);
+
+   val = mdiobus_read(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG);
+   val &= XILINX_GMII2RGMII_SPEED_MASK;
+
+   if (phydev->speed == SPEED_1000)
+   val |= BMCR_SPEED1000;
+   else if (phydev->speed == SPEED_100)
+   val |= BMCR_SPEED100;
+   else
+   val |= BMCR_SPEED10;
+
+   mdiobus_write(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG, val);
+
+   return 0;
+}
+
+int xgmiitorgmii_probe(struct mdio_device *mdiodev)
+{
+   struct device *dev = >dev;
+   struct device_node *np = dev->of_node, *phy_node;
+   struct gmii2rgmii *priv;
+
+   priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+   if (!priv)
+   return -ENOMEM;
+
+   phy_node = of_parse_phandle(np, "phy-handle", 0);
+   if