Re: [RFC PATCHv2 3/4] of: provide a binding for fixed link PHYs
From: Grant Likely <hidden>
Date: 2013-09-18 04:29:23
Also in:
linux-arm-kernel, linux-devicetree
On Fri, 6 Sep 2013 17:18:20 +0200, Thomas Petazzoni [off-list ref] wrote:
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 <thomas.petazzoni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
Hi Thomas, The implemenation in this series looks like it is in good shape, so I'll restrict my comments to be binding...
quoted hunk
--- .../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.txtdiff --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.
I understand what you're trying to do here, but it causes a troublesome leakage of implementation detail into the binding, making the whole thing look very odd. This binding tries to make a fixed link look exactly like a real PHY even to the point of including a phandle to the phy. But having a phandle to a node which is *always* a direct child of the MAC node is redundant and a rather looney. Yes, doing it that way makes it easy for of_phy_find_device() to be transparent for fixed link, but that should *not* drive bindings, especially when that makes the binding really rather weird. Second, this new binding doesn't provide anything over and above the existing fixed-link binding. It may not be pretty, but it is estabilshed. That said, I do agree that the current Linux implementation is not good because it cannot handle a fixed-link property transparently. That's a deficiency in the Linux implementation and it should be fixed. of_phy_connect() currently requires the phy phandle to be passed in. Part of the reason it was done this way is that some drivers connect to multiple 'phys'. A soulition could be to make the phy handle optional. If it is empty then go looking for either a phy-device or fixed-link property. Otherwise use the provided node. g.
quoted hunk
+ +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); +#endifdiff --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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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