[RFC PATCHv2 0/4] Add DT support for fixed PHYs

Hello,

Here is a second version of the patch set that adds a Device Tree
binding and the related code to support fixed PHYs. Marked as RFC,
this patch set is obviously not intended for merging in 3.12.

Since the first version, the changes have been:

 * Instead of using a 'fixed-link' property inside the Ethernet device
   DT node, with a fairly cryptic succession of integer values, we now
   use a PHY subnode under the Ethernet device DT node, with explicit
   properties to configure the duplex, speed, pause and other PHY
   properties.

 * The PHY address is automatically allocated by the kernel and no
   longer visible in the Device Tree binding.

 * The PHY device is created directly when the network driver calls
   of_phy_connect_fixed_link(), and associated to the PHY DT node,
   which allows the existing of_phy_connect() function to work,
   without the need to use the deprecated of_phy_connect_fixed_link().

The things I am not entirely happy with yet are:

 * The PHY ID is hardcoded to 0xdeadbeef. Ideally, it should be a
   properly reserved vendor/device identifier, but it isn't clear how
   to get one allocated for this purpose.

 * The fixed_phy_register() function in drivers/net/phy/fixed.c has
   some OF references. So ideally, I would have preferred to put this
   code in drivers/of/of_mdio.c, but to call get_phy_device(), we need
   a reference to the mii_bus structure that represents the fixed MDIO
   bus.

 * There is some error management missing in fixed_phy_register(), but
   it can certainly be added easily. This RFC is meant to sort out the
   general idea.

Thanks,

Thomas

Thomas Petazzoni (4):
  net: phy: decouple PHY id and PHY address in fixed PHY driver
  net: phy: extend fixed driver with fixed_phy_register()
  of: provide a binding for fixed link PHYs
  net: mvneta: add support for fixed links

 .../devicetree/bindings/net/fixed-link.txt         | 34 ++++++++++++
 .../bindings/net/marvell-armada-370-neta.txt       |  4 +-
 drivers/net/ethernet/marvell/mvneta.c              | 10 ++--
 drivers/net/phy/fixed.c                            | 63 ++++++++++++++++++----
 drivers/of/of_mdio.c                               | 24 +++++++++
 include/linux/of_mdio.h                            | 15 ++++++
 include/linux/phy_fixed.h                          | 11 ++++
 7 files changed, 145 insertions(+), 16 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/fixed-link.txt

-- 
1.8.1.2

Until now, the fixed_phy_add() function was taking as argument
'phy_id', which was used both as the PHY address on the fake fixed
MDIO bus, and as the PHY id, as available in the MII_PHYSID1 and
MII_PHYSID2 registers. However, those two informations are completely
unrelated.

This patch decouples them. The PHY id of fixed PHYs is hardcoded to be
0xdeadbeef. Ideally, a really reserved value would be nicer, but there
doesn't seem to be an easy of making sure a dummy value can be
assigned to the Linux kernel for such usage.

The PHY address remains passed by the caller of phy_fixed_add().

Signed-off-by: Thomas Petazzoni <redacted>
---
 drivers/net/phy/fixed.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/fixed.c b/drivers/net/phy/fixed.c
index ba55adf..0f02403 100644
--- a/drivers/net/phy/fixed.c
+++ b/drivers/net/phy/fixed.c

@@ -31,7 +31,7 @@ struct fixed_mdio_bus {
 };
 
 struct fixed_phy {
-	int id;
+	int addr;
 	u16 regs[MII_REGS_NUM];
 	struct phy_device *phydev;
 	struct fixed_phy_status status;

@@ -104,8 +104,8 @@ static int fixed_phy_update_regs(struct fixed_phy *fp)
 	if (fp->status.asym_pause)
 		lpa |= LPA_PAUSE_ASYM;
 
-	fp->regs[MII_PHYSID1] = fp->id >> 16;
-	fp->regs[MII_PHYSID2] = fp->id;
+	fp->regs[MII_PHYSID1] = 0xdead;
+	fp->regs[MII_PHYSID2] = 0xbeef;
 
 	fp->regs[MII_BMSR] = bmsr;
 	fp->regs[MII_BMCR] = bmcr;

@@ -115,7 +115,7 @@ static int fixed_phy_update_regs(struct fixed_phy *fp)
 	return 0;
 }
 
-static int fixed_mdio_read(struct mii_bus *bus, int phy_id, int reg_num)
+static int fixed_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
 {
 	struct fixed_mdio_bus *fmb = bus->priv;
 	struct fixed_phy *fp;

@@ -124,7 +124,7 @@ static int fixed_mdio_read(struct mii_bus *bus, int phy_id, int reg_num)
 		return -1;
 
 	list_for_each_entry(fp, &fmb->phys, node) {
-		if (fp->id == phy_id) {
+		if (fp->addr == phy_addr) {
 			/* Issue callback if user registered it. */
 			if (fp->link_update) {
 				fp->link_update(fp->phydev->attached_dev,

@@ -138,7 +138,7 @@ static int fixed_mdio_read(struct mii_bus *bus, int phy_id, int reg_num)
 	return 0xFFFF;
 }
 
-static int fixed_mdio_write(struct mii_bus *bus, int phy_id, int reg_num,
+static int fixed_mdio_write(struct mii_bus *bus, int phy_addr, int reg_num,
 			    u16 val)
 {
 	return 0;

@@ -160,7 +160,7 @@ int fixed_phy_set_link_update(struct phy_device *phydev,
 		return -EINVAL;
 
 	list_for_each_entry(fp, &fmb->phys, node) {
-		if (fp->id == phydev->phy_id) {
+		if (fp->addr == phydev->addr) {
 			fp->link_update = link_update;
 			fp->phydev = phydev;
 			return 0;

@@ -171,7 +171,7 @@ int fixed_phy_set_link_update(struct phy_device *phydev,
 }
 EXPORT_SYMBOL_GPL(fixed_phy_set_link_update);
 
-int fixed_phy_add(unsigned int irq, int phy_id,
+int fixed_phy_add(unsigned int irq, int phy_addr,
 		  struct fixed_phy_status *status)
 {
 	int ret;

@@ -184,9 +184,9 @@ int fixed_phy_add(unsigned int irq, int phy_id,
 
 	memset(fp->regs, 0xFF,  sizeof(fp->regs[0]) * MII_REGS_NUM);
 
-	fmb->irqs[phy_id] = irq;
+	fmb->irqs[phy_addr] = irq;
 
-	fp->id = phy_id;
+	fp->addr = phy_addr;
 	fp->status = *status;
 
 	ret = fixed_phy_update_regs(fp);

-- 
1.8.1.2

The existing fixed_phy_add() function has several drawbacks that
prevents it from being used as is for OF-based declaration of fixed
PHYs:

 * The address of the PHY on the fake bus needs to be passed, while a
   dynamic allocation is desired.

 * Since the phy_device instantiation is post-poned until the next
   mdiobus scan, there is no way to associate the fixed PHY with its
   OF node, which later prevents of_phy_connect() from finding this
   fixed PHY from a given OF node.

To solve this, this commit introduces fixed_phy_register(), which will
allocate an available PHY address, add the PHY using fixed_phy_add()
and instantiate the phy_device structure associated with the provided
OF node.

Signed-off-by: Thomas Petazzoni <redacted>
---
 drivers/net/phy/fixed.c   | 43 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/phy_fixed.h | 11 +++++++++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/net/phy/fixed.c b/drivers/net/phy/fixed.c
index 0f02403..3f9412b 100644
--- a/drivers/net/phy/fixed.c
+++ b/drivers/net/phy/fixed.c

@@ -21,6 +21,7 @@
 #include <linux/phy_fixed.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/of.h>
 
 #define MII_REGS_NUM 29
 

@@ -203,6 +204,48 @@ err_regs:
 }
 EXPORT_SYMBOL_GPL(fixed_phy_add);
 
+static int phy_fixed_addr;
+static DEFINE_SPINLOCK(phy_fixed_addr_lock);
+
+int fixed_phy_register(unsigned int irq,
+		       struct fixed_phy_status *status,
+		       struct device_node *np)
+{
+	struct fixed_mdio_bus *fmb = &platform_fmb;
+	struct phy_device *phy;
+	int phy_addr;
+	int ret;
+
+	/* Get the next available PHY address, up to PHY_MAX_ADDR */
+	spin_lock(&phy_fixed_addr_lock);
+	if (phy_fixed_addr == PHY_MAX_ADDR) {
+		spin_unlock(&phy_fixed_addr_lock);
+		return -ENOSPC;
+	}
+	phy_addr = phy_fixed_addr++;
+	spin_unlock(&phy_fixed_addr_lock);
+
+	ret = fixed_phy_add(PHY_POLL, phy_addr, status);
+	if (ret < 0)
+		return ret;
+
+	phy = get_phy_device(fmb->mii_bus, phy_addr, false);
+	if (!phy || IS_ERR(phy))
+		return -EINVAL;
+
+	of_node_get(np);
+	phy->dev.of_node = np;
+
+	ret = phy_device_register(phy);
+	if (ret) {
+		phy_device_free(phy);
+		of_node_put(np);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int __init fixed_mdio_bus_init(void)
 {
 	struct fixed_mdio_bus *fmb = &platform_fmb;

diff --git a/include/linux/phy_fixed.h b/include/linux/phy_fixed.h
index 509d8f5..902e8a1 100644
--- a/include/linux/phy_fixed.h
+++ b/include/linux/phy_fixed.h

@@ -9,15 +9,26 @@ struct fixed_phy_status {
 	int asym_pause;
 };
 
+struct device_node;
+
 #ifdef CONFIG_FIXED_PHY
 extern int fixed_phy_add(unsigned int irq, int phy_id,
 			 struct fixed_phy_status *status);
+extern int fixed_phy_register(unsigned int irq,
+			      struct fixed_phy_status *status,
+			      struct device_node *np);
 #else
 static inline int fixed_phy_add(unsigned int irq, int phy_id,
 				struct fixed_phy_status *status)
 {
 	return -ENODEV;
 }
+extern int fixed_phy_register(unsigned int irq,
+			      struct fixed_phy_status *status,
+			      struct device_node *np)
+{
+	return -ENODEV;
+}
 #endif /* CONFIG_FIXED_PHY */
 
 /*

-- 
1.8.1.2

Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device. For those situations, a Device Tree
binding allows to describe a "fixed link" using a special PHY node.

This patch adds:

 * A documentation for the fixed PHY Device Tree binding.

 * An of_phy_is_fixed_link() function that an Ethernet driver can call
   on its PHY phandle to find out whether it's a fixed link PHY or
   not. It should typically be used to know if
   of_phy_register_fixed_link() should be called.

 * An of_phy_register_fixed_link() function that instantiates the
   fixed PHY into the PHY subsystem, so that when the driver calls
   of_phy_connect(), the PHY device associated to the OF node will be
   found.

Signed-off-by: Thomas Petazzoni <redacted>
---
 .../devicetree/bindings/net/fixed-link.txt         | 34 ++++++++++++++++++++++
 drivers/of/of_mdio.c                               | 24 +++++++++++++++
 include/linux/of_mdio.h                            | 15 ++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/fixed-link.txt

diff --git a/Documentation/devicetree/bindings/net/fixed-link.txt b/Documentation/devicetree/bindings/net/fixed-link.txt
new file mode 100644
index 0000000..9f2a1a50
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/fixed-link.txt

@@ -0,0 +1,34 @@
+Fixed link Device Tree binding
+------------------------------
+
+Some Ethernet MACs have a "fixed link", and are not connected to a
+normal MDIO-managed PHY device. For those situations, a Device Tree
+binding allows to describe a "fixed link".
+
+Such a fixed link situation is described by creating a PHY node as a
+sub-node of an Ethernet device, with the following properties:
+
+* 'fixed-link' (boolean, mandatory), to indicate that this PHY is a
+  fixed link PHY.
+* 'speed' (integer, mandatory), to indicate the link speed. Accepted
+  values are 10, 100 and 1000
+* 'full-duplex' (boolean, optional), to indicate that full duplex is
+  used. When absent, half duplex is assumed.
+* 'pause' (boolean, optional), to indicate that pause should be
+  enabled.
+* 'asym-pause' (boolean, optional), to indicate that asym_pause should
+  be enabled.
+
+Example:
+
+ethernet@0 {
+	...
+	phy = <&phy0>;
+	phy0: phy@0 {
+	      fixed-link;
+	      speed = <1000>;
+	      full-duplex;
+	};
+	...
+};
+

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index d5a57a9..0507f8f 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c

@@ -14,6 +14,7 @@
 #include <linux/netdevice.h>
 #include <linux/err.h>
 #include <linux/phy.h>
+#include <linux/phy_fixed.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_mdio.h>

@@ -247,3 +248,26 @@ struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
 	return IS_ERR(phy) ? NULL : phy;
 }
 EXPORT_SYMBOL(of_phy_connect_fixed_link);
+
+#if defined(CONFIG_FIXED_PHY)
+bool of_phy_is_fixed_link(struct device_node *np)
+{
+	return of_property_read_bool(np, "fixed-link");
+}
+EXPORT_SYMBOL(of_phy_is_fixed_link);
+
+int of_phy_register_fixed_link(struct device_node *np)
+{
+	struct fixed_phy_status status = {};
+
+	status.link = 1;
+	status.duplex = of_property_read_bool(np, "full-duplex");
+	if (of_property_read_u32(np, "speed", &status.speed))
+		return -EINVAL;
+	status.pause = of_property_read_bool(np, "pause");
+	status.asym_pause = of_property_read_bool(np, "asym-pause");
+
+	return fixed_phy_register(PHY_POLL, &status, np);
+}
+EXPORT_SYMBOL(of_phy_register_fixed_link);
+#endif

diff --git a/include/linux/of_mdio.h b/include/linux/of_mdio.h
index 8163107..2f535ee 100644
--- a/include/linux/of_mdio.h
+++ b/include/linux/of_mdio.h

@@ -57,4 +57,19 @@ static inline struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np)
 }
 #endif /* CONFIG_OF */
 
+#if defined(CONFIG_OF) && defined(CONFIG_FIXED_PHY)
+extern int of_phy_register_fixed_link(struct device_node *np);
+extern bool of_phy_is_fixed_link(struct device_node *np);
+#else
+static inline int of_phy_register_fixed_link(struct device_node *np)
+{
+	return -ENOSYS;
+}
+static inline bool of_phy_is_fixed_link(struct device_node *np)
+{
+	return false;
+}
+#endif
+
+
 #endif /* __LINUX_OF_MDIO_H */

-- 
1.8.1.2

Following the introduction of of_phy_register_fixed_link(), this patch
introduces fixed link support in the mvneta driver, for Marvell Armada
370/XP SOCs.

Signed-off-by: Thomas Petazzoni <redacted>
---
 .../devicetree/bindings/net/marvell-armada-370-neta.txt        |  4 ++--
 drivers/net/ethernet/marvell/mvneta.c                          | 10 ++++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/marvell-armada-370-neta.txt b/Documentation/devicetree/bindings/net/marvell-armada-370-neta.txt
index 859a6fa..4d07d4e 100644
--- a/Documentation/devicetree/bindings/net/marvell-armada-370-neta.txt
+++ b/Documentation/devicetree/bindings/net/marvell-armada-370-neta.txt

@@ -4,8 +4,8 @@ Required properties:
 - compatible: should be "marvell,armada-370-neta".
 - reg: address and length of the register set for the device.
 - interrupts: interrupt for the device
-- phy: A phandle to a phy node defining the PHY address (as the reg
-  property, a single integer).
+- phy: A phandle to the PHY node describing the PHY to which this
+  Ethernet controller is connected to.
 - phy-mode: The interface between the SoC and the PHY (a string that
   of_get_phy_mode() can understand)
 - clocks: a pointer to the reference clock for this device.

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index b017818..6da1516 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c

@@ -2711,10 +2711,12 @@ static int mvneta_probe(struct platform_device *pdev)
 	}
 
 	phy_node = of_parse_phandle(dn, "phy", 0);
-	if (!phy_node) {
-		dev_err(&pdev->dev, "no associated PHY\n");
-		err = -ENODEV;
-		goto err_free_irq;
+	if (of_phy_is_fixed_link(phy_node)) {
+		err = of_phy_register_fixed_link(phy_node);
+		if (err < 0) {
+			dev_err(&pdev->dev, "cannot register fixed PHY\n");
+			goto err_free_irq;
+		}
 	}
 
 	phy_mode = of_get_phy_mode(dn);

-- 
1.8.1.2

Hello Thomas,

Le vendredi 6 septembre 2013 17:18:17 Thomas Petazzoni a écrit :

Hello,

Here is a second version of the patch set that adds a Device Tree
binding and the related code to support fixed PHYs. Marked as RFC,
this patch set is obviously not intended for merging in 3.12.

Thanks a lot for continuing on this work, I really like the state of it now.

Since the first version, the changes have been:

 * Instead of using a 'fixed-link' property inside the Ethernet device
   DT node, with a fairly cryptic succession of integer values, we now
   use a PHY subnode under the Ethernet device DT node, with explicit
   properties to configure the duplex, speed, pause and other PHY
   properties.

 * The PHY address is automatically allocated by the kernel and no
   longer visible in the Device Tree binding.

 * The PHY device is created directly when the network driver calls
   of_phy_connect_fixed_link(), and associated to the PHY DT node,
   which allows the existing of_phy_connect() function to work,
   without the need to use the deprecated of_phy_connect_fixed_link().

The things I am not entirely happy with yet are:

 * The PHY ID is hardcoded to 0xdeadbeef. Ideally, it should be a
   properly reserved vendor/device identifier, but it isn't clear how
   to get one allocated for this purpose.

Right, we should try to get something better, but we obviously cannot use an 
already allocated OUI for this. Can we ask the Linux foundation or a Linux-
friendly company to allocate one maybe?

 * The fixed_phy_register() function in drivers/net/phy/fixed.c has
   some OF references. So ideally, I would have preferred to put this
   code in drivers/of/of_mdio.c, but to call get_phy_device(), we need
   a reference to the mii_bus structure that represents the fixed MDIO
   bus.

This is not a big deal, not everything in drivers/ is consistent with this, 
and making the fixed MDIO bus globally accessible does not sound too great.

 * There is some error management missing in fixed_phy_register(), but
   it can certainly be added easily. This RFC is meant to sort out the
   general idea.

Do you think you could add these to got beyond the RFC state? The patchset as 
it currently is fine with me if you can address these.
-- 
Florian

Dear Florian Fainelli,

On Fri, 06 Sep 2013 21:42:42 +0100, Florian Fainelli wrote:

quoted

Here is a second version of the patch set that adds a Device Tree
binding and the related code to support fixed PHYs. Marked as RFC,
this patch set is obviously not intended for merging in 3.12.

Thanks a lot for continuing on this work, I really like the state of it now.

Thanks for your feedback.

quoted

Since the first version, the changes have been:

 * Instead of using a 'fixed-link' property inside the Ethernet device
   DT node, with a fairly cryptic succession of integer values, we now
   use a PHY subnode under the Ethernet device DT node, with explicit
   properties to configure the duplex, speed, pause and other PHY
   properties.

 * The PHY address is automatically allocated by the kernel and no
   longer visible in the Device Tree binding.

 * The PHY device is created directly when the network driver calls
   of_phy_connect_fixed_link(), and associated to the PHY DT node,
   which allows the existing of_phy_connect() function to work,
   without the need to use the deprecated of_phy_connect_fixed_link().

The things I am not entirely happy with yet are:

 * The PHY ID is hardcoded to 0xdeadbeef. Ideally, it should be a
   properly reserved vendor/device identifier, but it isn't clear how
   to get one allocated for this purpose.

Right, we should try to get something better, but we obviously cannot use an 
already allocated OUI for this. Can we ask the Linux foundation or a Linux-
friendly company to allocate one maybe?

According to http://standards.ieee.org/develop/regauth/oui/oui.txt, the
Linux Foundation doesn't seem to own any OUI. Should we simply be
contacting some random companies in this list?

quoted

 * The fixed_phy_register() function in drivers/net/phy/fixed.c has
   some OF references. So ideally, I would have preferred to put this
   code in drivers/of/of_mdio.c, but to call get_phy_device(), we need
   a reference to the mii_bus structure that represents the fixed MDIO
   bus.

This is not a big deal, not everything in drivers/ is consistent with this, 
and making the fixed MDIO bus globally accessible does not sound too great.

Indeed.

quoted

 * There is some error management missing in fixed_phy_register(), but
   it can certainly be added easily. This RFC is meant to sort out the
   general idea.

Do you think you could add these to got beyond the RFC state? The patchset as 
it currently is fine with me if you can address these.

Sure, it shouldn't be too difficult.

In the mean time, I'm interested in hearing comments from other people,
especially from the Device Tree bindings maintainers: while the
internal implementation details can always be fixed later on, the DT
binding should obviously get an approval from the DT maintainers.

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

On Fri, Sep 06, 2013 at 05:18:17PM +0200, Thomas Petazzoni wrote:

Hello,

Here is a second version of the patch set that adds a Device Tree
binding and the related code to support fixed PHYs. Marked as RFC,
this patch set is obviously not intended for merging in 3.12.

Since the first version, the changes have been:

 * Instead of using a 'fixed-link' property inside the Ethernet device
   DT node, with a fairly cryptic succession of integer values, we now
   use a PHY subnode under the Ethernet device DT node, with explicit
   properties to configure the duplex, speed, pause and other PHY
   properties.

 * The PHY address is automatically allocated by the kernel and no
   longer visible in the Device Tree binding.

 * The PHY device is created directly when the network driver calls
   of_phy_connect_fixed_link(), and associated to the PHY DT node,
   which allows the existing of_phy_connect() function to work,
   without the need to use the deprecated of_phy_connect_fixed_link().

The things I am not entirely happy with yet are:

 * The PHY ID is hardcoded to 0xdeadbeef. Ideally, it should be a
   properly reserved vendor/device identifier, but it isn't clear how
   to get one allocated for this purpose.

 * The fixed_phy_register() function in drivers/net/phy/fixed.c has
   some OF references. So ideally, I would have preferred to put this
   code in drivers/of/of_mdio.c, but to call get_phy_device(), we need
   a reference to the mii_bus structure that represents the fixed MDIO
   bus.

 * There is some error management missing in fixed_phy_register(), but
   it can certainly be added easily. This RFC is meant to sort out the
   general idea.

+1 for the general idea. This really looks good now. I've not much more
to say. Maybe someone from the devicetree corner has a few words for the
binding?

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Hello Thomas,

2013/9/6 Thomas Petazzoni [off-list ref]:

+Some Ethernet MACs have a "fixed link", and are not connected to a
+normal MDIO-managed PHY device. For those situations, a Device Tree
+binding allows to describe a "fixed link".
+
+Such a fixed link situation is described by creating a PHY node as a
+sub-node of an Ethernet device, with the following properties:
+
+* 'fixed-link' (boolean, mandatory), to indicate that this PHY is a
+  fixed link PHY.
+* 'speed' (integer, mandatory), to indicate the link speed. Accepted
+  values are 10, 100 and 1000

'max-speed' might be better here to match ePAPR v1.1 (if we do care,
'speed') works for me too.

+* 'full-duplex' (boolean, optional), to indicate that full duplex is
+  used. When absent, half duplex is assumed.
+* 'pause' (boolean, optional), to indicate that pause should be
+  enabled.
+* 'asym-pause' (boolean, optional), to indicate that asym_pause should
+  be enabled.

We also need to add a property: 'connection-type' which can be any of
'mii', 'rgmii' etc... When operating Ethernet devices with Ethernet
devices connected back to back, it might be required to configure the
Ethernet MAC with an appropriate connection type.

Note that I picked 'connection-type' here because this the ePAPR v1.1
terminology. Now the good thing is that it is a new "feature" wrt. the
old binding.