[PATCH 0/3] netdev/of/phy: MDIO bus multiplexer support.

[PATCH 0/3] netdev/of/phy: MDIO bus multiplexer support.

[David Daney]

We have several different boards with a multiplexer in the MDIO bus.
There is an MDIO bus controller connected to a switching device with
several child MDIO busses.

Everything is wired up using device tree bindings.

 1/3 - New of_mdio_find_bus() function used to help configuring the
       driver topology.

 2/3 - MDIO bus multiplexer framework.

 3/3 - A driver for a GPIO controlled multiplexer.

I have an additional patch I am working on for an I2C controlled
multiplexer that I will follow up with once this reaches a mergable
state.

David Daney (3):
  netdev/of/phy: New function: of_mdio_find_bus().
  netdev/of/phy: Add MDIO bus multiplexer support.
  netdev/of/phy: Add MDIO bus multiplexer driven by GPIO lines.

 .../devicetree/bindings/net/mdio-mux-gpio.txt      |  127 ++++++++++++++
 Documentation/devicetree/bindings/net/mdio-mux.txt |  132 ++++++++++++++
 drivers/net/phy/Kconfig                            |   17 ++
 drivers/net/phy/Makefile                           |    2 +
 drivers/net/phy/mdio-mux-gpio.c                    |  143 +++++++++++++++
 drivers/net/phy/mdio-mux.c                         |  182 ++++++++++++++++++++
 drivers/net/phy/mdio_bus.c                         |    3 +-
 drivers/of/of_mdio.c                               |   26 +++
 include/linux/mdio-mux.h                           |   18 ++
 include/linux/of_mdio.h                            |    2 +
 include/linux/phy.h                                |    1 +
 11 files changed, 652 insertions(+), 1 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
 create mode 100644 Documentation/devicetree/bindings/net/mdio-mux.txt
 create mode 100644 drivers/net/phy/mdio-mux-gpio.c
 create mode 100644 drivers/net/phy/mdio-mux.c
 create mode 100644 include/linux/mdio-mux.h

-- 
1.7.2.3

[PATCH 1/3] netdev/of/phy: New function: of_mdio_find_bus().

[David Daney]

Add of_mdio_find_bus() which allows an mii_bus to be located given its
associated the device tree node.

This is needed by the follow-on patch to add a driver for MDIO bus
multiplexers.

The of_mdiobus_register() function is modified so that the device tree
node is recorded in the mii_bus.  Then we can find it again by
iterating over all mdio_bus_class devices.

Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
---
 drivers/net/phy/mdio_bus.c |    3 ++-
 drivers/of/of_mdio.c       |   26 ++++++++++++++++++++++++++
 include/linux/of_mdio.h    |    2 ++
 include/linux/phy.h        |    1 +
 4 files changed, 31 insertions(+), 1 deletions(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 6c58da2..227a060 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -70,10 +70,11 @@ static void mdiobus_release(struct device *d)
 	kfree(bus);
 }
 
-static struct class mdio_bus_class = {
+struct class mdio_bus_class = {
 	.name		= "mdio_bus",
 	.dev_release	= mdiobus_release,
 };
+EXPORT_SYMBOL(mdio_bus_class);
 
 /**
  * mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index d35e300..7c28e8c 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -45,6 +45,8 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 		for (i=0; i<PHY_MAX_ADDR; i++)
 			mdio->irq[i] = PHY_POLL;
 
+	mdio->dev.of_node = np;
+
 	/* Register the MDIO bus */
 	rc = mdiobus_register(mdio);
 	if (rc)
@@ -189,3 +191,27 @@ 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);
+
+/**
+ * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
+ * @mdio_np: Pointer to the mii_bus.
+ *
+ * Returns a pointer to the mii_bus, or NULL if none found.
+ *
+ * Because the association of a device_node and mii_bus is made via
+ * of_mdiobus_register(), the mii_bus cannot be found before it is
+ * registered with of_mdiobus_register().
+ *
+ */
+struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np)
+{
+	struct device *d;
+
+	if (!mdio_np)
+		return NULL;
+
+	d = class_find_device(&mdio_bus_class, NULL,  mdio_np, of_phy_match);
+
+	return d ? to_mii_bus(d) : NULL;
+}
+EXPORT_SYMBOL(of_mdio_find_bus);
diff --git a/include/linux/of_mdio.h b/include/linux/of_mdio.h
index 53b94e0..912c27a 100644
--- a/include/linux/of_mdio.h
+++ b/include/linux/of_mdio.h
@@ -22,4 +22,6 @@ extern struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
 					 void (*hndlr)(struct net_device *),
 					 phy_interface_t iface);
 
+extern struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np);
+
 #endif /* __LINUX_OF_MDIO_H */
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 54fc413..e4c3844 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -528,4 +528,5 @@ int __init mdio_bus_init(void);
 void mdio_bus_exit(void);
 
 extern struct bus_type mdio_bus_type;
+extern struct class mdio_bus_class;
 #endif /* __PHY_H */
-- 
1.7.2.3

[PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[David Daney]

This patch adds a somewhat generic framework for MDIO bus
multiplexers.  It is modeled on the I2C multiplexer.

The multiplexer is needed if there are multiple PHYs with the same
address connected to the same MDIO bus adepter, or if there is
insufficient electrical drive capability for all the connected PHY
devices.

Conceptually it could look something like this:

                   ------------------
                   | Control Signal |
                   --------+---------
                           |
 ---------------   --------+------
 | MDIO MASTER |---| Multiplexer |
 ---------------   --+-------+----
                     |       |
                     C       C
                     h       h
                     i       i
                     l       l
                     d       d
                     |       |
     ---------       A       B   ---------
     |       |       |       |   |       |
     | PHY@1 +-------+       +---+ PHY@1 |
     |       |       |       |   |       |
     ---------       |       |   ---------
     ---------       |       |   ---------
     |       |       |       |   |       |
     | PHY@2 +-------+       +---+ PHY@2 |
     |       |                   |       |
     ---------                   ---------

This framework configures the bus topology from device tree data.  The
mechanics of switching the multiplexer is left to device specific
drivers.

The follow-on patch contains a multiplexer driven by GPIO lines.

Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
---
 Documentation/devicetree/bindings/net/mdio-mux.txt |  132 ++++++++++++++
 drivers/net/phy/Kconfig                            |    8 +
 drivers/net/phy/Makefile                           |    1 +
 drivers/net/phy/mdio-mux.c                         |  182 ++++++++++++++++++++
 include/linux/mdio-mux.h                           |   18 ++
 5 files changed, 341 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/mdio-mux.txt
 create mode 100644 drivers/net/phy/mdio-mux.c
 create mode 100644 include/linux/mdio-mux.h

diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
new file mode 100644
index 0000000..a908312
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
@@ -0,0 +1,132 @@
+Common MDIO bus multiplexer/switch properties.
+
+An MDIO bus multiplexer/switch will have several child busses that are
+numbered uniquely in a device dependent manner.  The nodes for an MDIO
+bus multiplexer/switch will have one child node for each child bus.
+
+Required properties:
+- parent-bus : phandle to the parent MDIO bus.
+
+Optional properties:
+- Other properties specific to the multiplexer/switch hardware.
+
+Required properties for child nodes:
+- #address-cells = <1>;
+- #size-cells = <0>;
+- cell-index : The sub-bus number.
+
+
+Example :
+
+	/* The parent MDIO bus. */
+	smi1: mdio@1180000001900 {
+		compatible = "cavium,octeon-3860-mdio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		reg = <0x11800 0x00001900 0x0 0x40>;
+	};
+
+	/*
+	   An NXP sn74cbtlv3253 dual 1-of-4 switch controlled by a
+	   pair of GPIO lines.  Child busses 2 and 3 populated with 4
+	   PHYs each.
+	 */
+	mdio-mux {
+		compatible = "cavium,mdio-mux-sn74cbtlv3253", "cavium,mdio-mux";
+		gpios = <&gpio1 3 0>, <&gpio1 4 0>;
+		parent-bus = <&smi1>;
+
+		mdio@2 {
+			cell-index = <2>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			phy11: ethernet-phy@1 {
+				reg = <1>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy12: ethernet-phy@2 {
+				reg = <2>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy13: ethernet-phy@3 {
+				reg = <3>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy14: ethernet-phy@4 {
+				reg = <4>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+		};
+
+		mdio@3 {
+			cell-index = <3>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			phy21: ethernet-phy@1 {
+				reg = <1>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy22: ethernet-phy@2 {
+				reg = <2>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy23: ethernet-phy@3 {
+				reg = <3>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy24: ethernet-phy@4 {
+				reg = <4>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+		};
+	};
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index a702443..59848bc 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -119,6 +119,14 @@ config MDIO_GPIO
 	  To compile this driver as a module, choose M here: the module
 	  will be called mdio-gpio.
 
+config MDIO_BUS_MUX
+	tristate "Support for MDIO bus multiplexers"
+	help
+	  This module provides a driver framework for MDIO bus
+	  multiplexers which connect one of several child MDIO busses
+	  to a parent bus.  Switching between child busses is done by
+	  device specific drivers.
+
 config MDIO_OCTEON
 	tristate "Support for MDIO buses on Octeon SOCs"
 	depends on  CPU_CAVIUM_OCTEON
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 2333215..0c081d5 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -23,3 +23,4 @@ obj-$(CONFIG_DP83640_PHY)	+= dp83640.o
 obj-$(CONFIG_STE10XP)		+= ste10Xp.o
 obj-$(CONFIG_MICREL_PHY)	+= micrel.o
 obj-$(CONFIG_MDIO_OCTEON)	+= mdio-octeon.o
+obj-$(CONFIG_MDIO_BUS_MUX)	+= mdio-mux.o
diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
new file mode 100644
index 0000000..f9c5826
--- /dev/null
+++ b/drivers/net/phy/mdio-mux.c
@@ -0,0 +1,182 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 Cavium Networks
+ */
+
+#include <linux/platform_device.h>
+#include <linux/of_mdio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <linux/phy.h>
+#include <linux/mdio-mux.h>
+
+#define DRV_VERSION "1.0"
+#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
+
+struct mdio_mux_parent_bus {
+	struct mii_bus *mii_bus;
+	int current_child;
+	int parent_id;
+	void *switch_data;
+	int (*switch_fn)(int current_child, int desired_child, void *data);
+};
+
+struct mdio_mux_child_bus {
+	struct mii_bus *mii_bus;
+	struct mdio_mux_parent_bus *parent;
+	int bus_number;
+	int phy_irq[PHY_MAX_ADDR];
+};
+
+/*
+ * The parent bus' lock is used to order access to the switch_fn.
+ */
+static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
+{
+	struct mdio_mux_child_bus *cb = bus->priv;
+	struct mdio_mux_parent_bus *pb = cb->parent;
+	int r;
+
+	mutex_lock(&pb->mii_bus->mdio_lock);
+	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
+	if (r)
+		goto out;
+
+	pb->current_child = cb->bus_number;
+
+	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
+out:
+	mutex_unlock(&pb->mii_bus->mdio_lock);
+
+	return r;
+}
+
+/*
+ * The parent bus' lock is used to order access to the switch_fn.
+ */
+static int mdio_mux_write(struct mii_bus *bus, int phy_id,
+			  int regnum, u16 val)
+{
+	struct mdio_mux_child_bus *cb = bus->priv;
+	struct mdio_mux_parent_bus *pb = cb->parent;
+
+	int r;
+
+	mutex_lock(&pb->mii_bus->mdio_lock);
+	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
+	if (r)
+		goto out;
+
+	pb->current_child = cb->bus_number;
+
+	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
+out:
+	mutex_unlock(&pb->mii_bus->mdio_lock);
+
+	return r;
+}
+
+static int parent_count;
+
+int mdio_mux_probe(struct platform_device *pdev,
+		   int (*switch_fn)(int cur, int desired, void *data),
+		   void *data)
+{
+	struct device_node *parent_bus_node;
+	struct device_node *child_bus_node;
+	int r, n, ret_val;
+	struct mii_bus *parent_bus;
+	struct mdio_mux_parent_bus *pb;
+	struct mdio_mux_child_bus *cb;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
+
+	if (!parent_bus_node)
+		return -ENODEV;
+
+	parent_bus = of_mdio_find_bus(parent_bus_node);
+
+	pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
+	if (pb == NULL) {
+		ret_val = -ENOMEM;
+		goto err_parent_bus;
+	}
+
+	pb->switch_data = data;
+	pb->switch_fn = switch_fn;
+	pb->current_child = -1;
+	pb->parent_id = parent_count++;
+	pb->mii_bus = parent_bus;
+
+	n = 0;
+	for_each_child_of_node(pdev->dev.of_node, child_bus_node) {
+		u32 v;
+
+		r = of_property_read_u32(child_bus_node, "cell-index", &v);
+		if (r == 0) {
+			cb = devm_kzalloc(&pdev->dev, sizeof(*cb), GFP_KERNEL);
+			if (cb == NULL)
+				break;
+			cb->bus_number = v;
+			cb->parent = pb;
+			cb->mii_bus = mdiobus_alloc();
+			cb->mii_bus->priv = cb;
+
+			cb->mii_bus->irq = cb->phy_irq;
+			cb->mii_bus->name = "mdio_mux";
+			snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
+				 pb->parent_id, v);
+			cb->mii_bus->parent = &pdev->dev;
+			cb->mii_bus->read = mdio_mux_read;
+			cb->mii_bus->write = mdio_mux_write;
+			r = of_mdiobus_register(cb->mii_bus, child_bus_node);
+			if (r) {
+				of_node_put(child_bus_node);
+				devm_kfree(&pdev->dev, cb);
+			} else {
+				n++;
+			}
+
+		} else {
+			of_node_put(child_bus_node);
+		}
+	}
+	if (n) {
+		dev_info(&pdev->dev, "Version " DRV_VERSION "\n");
+		return 0;
+	}
+	ret_val = -ENOMEM;
+	devm_kfree(&pdev->dev, pb);
+err_parent_bus:
+	of_node_put(parent_bus_node);
+	return ret_val;
+}
+EXPORT_SYMBOL(mdio_mux_probe);
+
+static int __devexit mdio_mux_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static int __init mdio_mux_mod_init(void)
+{
+	return 0;
+}
+module_init(mdio_mux_mod_init);
+
+static void __exit mdio_mux_mod_exit(void)
+{
+}
+module_exit(mdio_mux_mod_exit);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mdio-mux.h b/include/linux/mdio-mux.h
new file mode 100644
index 0000000..522992a
--- /dev/null
+++ b/include/linux/mdio-mux.h
@@ -0,0 +1,18 @@
+/*
+ * MDIO bus multiplexer framwork.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 Cavium Networks
+ */
+#ifndef __LINUX_MDIO_MUX_H
+#define __LINUX_MDIO_MUX_H
+#include <linux/platform_device.h>
+
+int mdio_mux_probe(struct platform_device *pdev,
+		   int (*switch_fn) (int cur, int desired, void *data),
+		   void *data);
+
+#endif /* __LINUX_MDIO_MUX_H */
-- 
1.7.2.3

[PATCH 3/3] netdev/of/phy: Add MDIO bus multiplexer driven by GPIO lines.

[David Daney]

The GPIO pins select which sub bus is connected to the master.

Initially tested with an sn74cbtlv3253 switch device wired into the
MDIO bus.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: "David S. Miller" <davem@davemloft.net>
---
 .../devicetree/bindings/net/mdio-mux-gpio.txt      |  127 +++++++++++++++++
 drivers/net/phy/Kconfig                            |    9 ++
 drivers/net/phy/Makefile                           |    1 +
 drivers/net/phy/mdio-mux-gpio.c                    |  143 ++++++++++++++++++++
 4 files changed, 280 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
 create mode 100644 drivers/net/phy/mdio-mux-gpio.c

diff --git a/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt b/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
new file mode 100644
index 0000000..23406a4
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
@@ -0,0 +1,127 @@
+Properties for an MDIO bus multiplexer/switch controlled by GPIO pins.
+
+This is a special case of a MDIO bus multiplexer.  One or more GPIO
+lines are used to control which child bus is connected.
+
+Required properties in addition to the generic multiplexer properties:
+
+- compatible : Should define the compatible device type for the
+               multiplexer.  Currently "cavium,mdio-mux-sn74cbtlv3253"
+               is defined, others are possible.
+- gpios : GPIO specifiers for each GPIO line.  One or more must be specified.
+
+
+Example :
+
+	/* The parent MDIO bus. */
+	smi1: mdio@1180000001900 {
+		compatible = "cavium,octeon-3860-mdio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		reg = <0x11800 0x00001900 0x0 0x40>;
+	};
+
+	/*
+	   An NXP sn74cbtlv3253 dual 1-of-4 switch controlled by a
+	   pair of GPIO lines.  Child busses 2 and 3 populated with 4
+	   PHYs each.
+	 */
+	mdio-mux {
+		compatible = "cavium,mdio-mux-sn74cbtlv3253", "cavium,mdio-mux";
+		gpios = <&gpio1 3 0>, <&gpio1 4 0>;
+		parent-bus = <&smi1>;
+
+		mdio@2 {
+			cell-index = <2>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			phy11: ethernet-phy@1 {
+				reg = <1>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy12: ethernet-phy@2 {
+				reg = <2>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy13: ethernet-phy@3 {
+				reg = <3>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+			phy14: ethernet-phy@4 {
+				reg = <4>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <10 8>; /* Pin 10, active low */
+			};
+		};
+
+		mdio@3 {
+			cell-index = <3>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			phy21: ethernet-phy@1 {
+				reg = <1>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy22: ethernet-phy@2 {
+				reg = <2>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy23: ethernet-phy@3 {
+				reg = <3>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+			phy24: ethernet-phy@4 {
+				reg = <4>;
+				compatible = "marvell,88e1149r";
+				marvell,reg-init = <3 0x10 0 0x5777>,
+					<3 0x11 0 0x00aa>,
+					<3 0x12 0 0x4105>,
+					<3 0x13 0 0x0a60>;
+				interrupt-parent = <&gpio>;
+				interrupts = <12 8>; /* Pin 12, active low */
+			};
+		};
+	};
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 59848bc..59b3b17 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -127,6 +127,15 @@ config MDIO_BUS_MUX
 	  to a parent bus.  Switching between child busses is done by
 	  device specific drivers.
 
+config MDIO_BUS_MUX_GPIO
+	tristate "Support for GPIO controlled MDIO bus multiplexers"
+	depends on MDIO_BUS_MUX && GENERIC_GPIO
+	help
+	  This module provides a driver for MDIO bus multiplexers that
+	  are controlled via GPIO lines.  The multiplexer connects one of
+	  several child MDIO busses to a parent bus.  Child bus
+	  selection is under the control of GPIO lines.
+
 config MDIO_OCTEON
 	tristate "Support for MDIO buses on Octeon SOCs"
 	depends on  CPU_CAVIUM_OCTEON
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 0c081d5..d1a1927 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_STE10XP)		+= ste10Xp.o
 obj-$(CONFIG_MICREL_PHY)	+= micrel.o
 obj-$(CONFIG_MDIO_OCTEON)	+= mdio-octeon.o
 obj-$(CONFIG_MDIO_BUS_MUX)	+= mdio-mux.o
+obj-$(CONFIG_MDIO_BUS_MUX_GPIO)	+= mdio-mux-gpio.o
diff --git a/drivers/net/phy/mdio-mux-gpio.c b/drivers/net/phy/mdio-mux-gpio.c
new file mode 100644
index 0000000..3cdad35
--- /dev/null
+++ b/drivers/net/phy/mdio-mux-gpio.c
@@ -0,0 +1,143 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 Cavium Networks
+ */
+
+#include <linux/platform_device.h>
+#include <linux/of_mdio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/gfp.h>
+#include <linux/phy.h>
+#include <linux/mdio-mux.h>
+#include <linux/of_gpio.h>
+
+#define DRV_VERSION "1.0"
+#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"
+
+#define MDIO_MUX_GPIO_MAX_BITS 8
+
+struct mdio_mux_gpio_state {
+	int gpio[MDIO_MUX_GPIO_MAX_BITS];
+	unsigned int num_gpios;
+};
+
+static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
+				   void *data)
+{
+	int change;
+	unsigned int n;
+	struct mdio_mux_gpio_state *s = data;
+
+	if (current_child == desired_child)
+		return 0;
+
+	change = current_child == -1 ? -1 : current_child ^ desired_child;
+
+	for (n = 0; n < s->num_gpios; n++) {
+		if (change & 1)
+			gpio_set_value_cansleep(s->gpio[n],
+						(desired_child & 1) != 0);
+		change >>= 1;
+		desired_child >>= 1;
+	}
+
+	return 0;
+}
+
+static int __devinit mdio_mux_gpio_probe(struct platform_device *pdev)
+{
+	enum of_gpio_flags f;
+	struct mdio_mux_gpio_state *s;
+	unsigned int num_gpios;
+	unsigned int n;
+	int r;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	num_gpios = of_gpio_count(pdev->dev.of_node);
+	if (num_gpios == 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
+		return -ENODEV;
+
+	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	s->num_gpios = num_gpios;
+
+	for (n = 0; n < num_gpios; ) {
+		int gpio = of_get_named_gpio_flags(pdev->dev.of_node,
+						   "gpios", n, &f);
+		s->gpio[n] = gpio;
+		if (gpio < 0) {
+			r = -ENODEV;
+			goto err;
+		}
+
+		n++;
+
+		r = gpio_request(gpio, "mdio_mux_gpio");
+		if (r)
+			goto err;
+
+		r = gpio_direction_output(gpio, 0);
+		if (r)
+			goto err;
+	}
+
+	r = mdio_mux_probe(pdev, mdio_mux_gpio_switch_fn, s);
+
+	if (r == 0)
+		return 0;
+err:
+	while (n) {
+		n--;
+		gpio_free(s->gpio[n]);
+	}
+	devm_kfree(&pdev->dev, s);
+	return r;
+}
+
+static int __devexit mdio_mux_gpio_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static struct of_device_id mdio_mux_gpio_match[] = {
+	{
+		.compatible = "cavium,mdio-mux-sn74cbtlv3253",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, mdio_mux_match);
+
+static struct platform_driver mdio_mux_gpio_driver = {
+	.driver = {
+		.name		= "mdio-mux-gpio",
+		.owner		= THIS_MODULE,
+		.of_match_table = mdio_mux_gpio_match,
+	},
+	.probe		= mdio_mux_gpio_probe,
+	.remove		= __devexit_p(mdio_mux_gpio_remove),
+};
+
+static int __init mdio_mux_gpio_mod_init(void)
+{
+	return platform_driver_register(&mdio_mux_gpio_driver);
+}
+late_initcall(mdio_mux_gpio_mod_init);
+
+static void __exit mdio_mux_gpio_mod_exit(void)
+{
+	platform_driver_unregister(&mdio_mux_gpio_driver);
+}
+module_exit(mdio_mux_gpio_mod_exit);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");
-- 
1.7.2.3

Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[Andy Fleming]

On Wed, Aug 31, 2011 at 3:01 PM, David Daney <david.daney@cavium.com> wrote:
> This patch adds a somewhat generic framework for MDIO bus
> multiplexers.  It is modeled on the I2C multiplexer.
>
> The multiplexer is needed if there are multiple PHYs with the same
> address connected to the same MDIO bus adepter, or if there is
> insufficient electrical drive capability for all the connected PHY
> devices.
>
> Conceptually it could look something like this:
>
>                   ------------------
>                   | Control Signal |
>                   --------+---------
>                           |
>  ---------------   --------+------
>  | MDIO MASTER |---| Multiplexer |
>  ---------------   --+-------+----
>                     |       |
>                     C       C
>                     h       h
>                     i       i
>                     l       l
>                     d       d
>                     |       |
>     ---------       A       B   ---------
>     |       |       |       |   |       |
>     | PHY@1 +-------+       +---+ PHY@1 |
>     |       |       |       |   |       |
>     ---------       |       |   ---------
>     ---------       |       |   ---------
>     |       |       |       |   |       |
>     | PHY@2 +-------+       +---+ PHY@2 |
>     |       |                   |       |
>     ---------                   ---------
>
> This framework configures the bus topology from device tree data.  The
> mechanics of switching the multiplexer is left to device specific
> drivers.
>
> The follow-on patch contains a multiplexer driven by GPIO lines.


It's amazing how various companies' board designers have come up with
the same brain-dead PHY topologies. We (Freescale) have some similar
code in our tree, but it's not this generically applicable.

>
> Signed-off-by: David Daney <david.daney@cavium.com>
> Cc: Grant Likely <grant.likely@secretlab.ca>
> Cc: "David S. Miller" <davem@davemloft.net>

Looks good to me.

Acked-by: Andy Fleming <afleming@freescale.com>

Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[Kumar Gala]

> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
> new file mode 100644
> index 0000000..a908312
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
> @@ -0,0 +1,132 @@
> +Common MDIO bus multiplexer/switch properties.
> +
> +An MDIO bus multiplexer/switch will have several child busses that are
> +numbered uniquely in a device dependent manner.  The nodes for an MDIO
> +bus multiplexer/switch will have one child node for each child bus.
> +
> +Required properties:
> +- parent-bus : phandle to the parent MDIO bus.

Should probably be mdio-parent-bus

> +
> +Optional properties:
> +- Other properties specific to the multiplexer/switch hardware.
> +
> +Required properties for child nodes:
> +- #address-cells = <1>;
> +- #size-cells = <0>;
> +- cell-index : The sub-bus number.

What does sub-bus number mean?

> +
> +
> +Example :

[snip]

> diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
> new file mode 100644
> index 0000000..f9c5826
> --- /dev/null
> +++ b/drivers/net/phy/mdio-mux.c
> @@ -0,0 +1,182 @@
> +/*
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + *
> + * Copyright (C) 2011 Cavium Networks
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/of_mdio.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/gfp.h>
> +#include <linux/phy.h>
> +#include <linux/mdio-mux.h>
> +
> +#define DRV_VERSION "1.0"
> +#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
> +
> +struct mdio_mux_parent_bus {
> +	struct mii_bus *mii_bus;
> +	int current_child;
> +	int parent_id;
> +	void *switch_data;
> +	int (*switch_fn)(int current_child, int desired_child, void *data);
> +};
> +
> +struct mdio_mux_child_bus {
> +	struct mii_bus *mii_bus;
> +	struct mdio_mux_parent_bus *parent;
> +	int bus_number;
> +	int phy_irq[PHY_MAX_ADDR];
> +};
> +
> +/*
> + * The parent bus' lock is used to order access to the switch_fn.
> + */
> +static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
> +{
> +	struct mdio_mux_child_bus *cb = bus->priv;
> +	struct mdio_mux_parent_bus *pb = cb->parent;
> +	int r;
> +
> +	mutex_lock(&pb->mii_bus->mdio_lock);
> +	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
> +	if (r)
> +		goto out;
> +
> +	pb->current_child = cb->bus_number;
> +
> +	r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
> +out:
> +	mutex_unlock(&pb->mii_bus->mdio_lock);
> +
> +	return r;
> +}
> +
> +/*
> + * The parent bus' lock is used to order access to the switch_fn.
> + */
> +static int mdio_mux_write(struct mii_bus *bus, int phy_id,
> +			  int regnum, u16 val)
> +{
> +	struct mdio_mux_child_bus *cb = bus->priv;
> +	struct mdio_mux_parent_bus *pb = cb->parent;
> +
> +	int r;
> +
> +	mutex_lock(&pb->mii_bus->mdio_lock);
> +	r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
> +	if (r)
> +		goto out;
> +
> +	pb->current_child = cb->bus_number;
> +
> +	r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
> +out:
> +	mutex_unlock(&pb->mii_bus->mdio_lock);
> +
> +	return r;
> +}
> +
> +static int parent_count;
> +
> +int mdio_mux_probe(struct platform_device *pdev,
> +		   int (*switch_fn)(int cur, int desired, void *data),
> +		   void *data)
> +{
> +	struct device_node *parent_bus_node;
> +	struct device_node *child_bus_node;
> +	int r, n, ret_val;
> +	struct mii_bus *parent_bus;
> +	struct mdio_mux_parent_bus *pb;
> +	struct mdio_mux_child_bus *cb;
> +
> +	if (!pdev->dev.of_node)
> +		return -ENODEV;
> +
> +	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
> +
> +	if (!parent_bus_node)
> +		return -ENODEV;
> +
> +	parent_bus = of_mdio_find_bus(parent_bus_node);


So what happens if the parent bus probe happens after the mux probe?

> +
> +	pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
> +	if (pb == NULL) {
> +		ret_val = -ENOMEM;
> +		goto err_parent_bus;
> +	}
> +
> +	pb->switch_data = data;
> +	pb->switch_fn = switch_fn;
> +	pb->current_child = -1;
> +	pb->parent_id = parent_count++;
> +	pb->mii_bus = parent_bus;
> +
> +	n = 0;
> +	for_each_child_of_node(pdev->dev.of_node, child_bus_node) {
> +		u32 v;
> +
> +		r = of_property_read_u32(child_bus_node, "cell-index", &v);
> +		if (r == 0) {
> +			cb = devm_kzalloc(&pdev->dev, sizeof(*cb), GFP_KERNEL);
> +			if (cb == NULL)
> +				break;
> +			cb->bus_number = v;
> +			cb->parent = pb;
> +			cb->mii_bus = mdiobus_alloc();
> +			cb->mii_bus->priv = cb;
> +
> +			cb->mii_bus->irq = cb->phy_irq;
> +			cb->mii_bus->name = "mdio_mux";
> +			snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
> +				 pb->parent_id, v);
> +			cb->mii_bus->parent = &pdev->dev;
> +			cb->mii_bus->read = mdio_mux_read;
> +			cb->mii_bus->write = mdio_mux_write;
> +			r = of_mdiobus_register(cb->mii_bus, child_bus_node);
> +			if (r) {
> +				of_node_put(child_bus_node);
> +				devm_kfree(&pdev->dev, cb);
> +			} else {
> +				n++;
> +			}
> +
> +		} else {
> +			of_node_put(child_bus_node);
> +		}
> +	}
> +	if (n) {
> +		dev_info(&pdev->dev, "Version " DRV_VERSION "\n");
> +		return 0;
> +	}
> +	ret_val = -ENOMEM;
> +	devm_kfree(&pdev->dev, pb);
> +err_parent_bus:
> +	of_node_put(parent_bus_node);
> +	return ret_val;
> +}
> +EXPORT_SYMBOL(mdio_mux_probe);
> +
> +static int __devexit mdio_mux_remove(struct platform_device *pdev)
> +{
> +	return 0;
> +}
> +
> +static int __init mdio_mux_mod_init(void)
> +{
> +	return 0;
> +}
> +module_init(mdio_mux_mod_init);
> +
> +static void __exit mdio_mux_mod_exit(void)
> +{
> +}
> +module_exit(mdio_mux_mod_exit);
> +
> +MODULE_DESCRIPTION(DRV_DESCRIPTION);
> +MODULE_VERSION(DRV_VERSION);
> +MODULE_AUTHOR("David Daney");
> +MODULE_LICENSE("GPL");

Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[David Daney]

On 09/13/2011 04:07 PM, Kumar Gala wrote:
>
>> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
>> new file mode 100644
>> index 0000000..a908312
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
>> @@ -0,0 +1,132 @@
>> +Common MDIO bus multiplexer/switch properties.
>> +
>> +An MDIO bus multiplexer/switch will have several child busses that are
>> +numbered uniquely in a device dependent manner.  The nodes for an MDIO
>> +bus multiplexer/switch will have one child node for each child bus.
>> +
>> +Required properties:
>> +- parent-bus : phandle to the parent MDIO bus.
>
> Should probably be mdio-parent-bus

Why?  We know it is MDIO.

Serial bus multiplexing is not a concept limited to MDIO.  We would want 
to use "parent-bus" for some I2C multiplexers as well.

>
>> +
>> +Optional properties:
>> +- Other properties specific to the multiplexer/switch hardware.
>> +
>> +Required properties for child nodes:
>> +- #address-cells =<1>;
>> +- #size-cells =<0>;
>> +- cell-index : The sub-bus number.
>
> What does sub-bus number mean?

There are N child buses (or sub-buses) coming out of the multiplexer. 
The cell-index is used as a handle or identifier for each of these.

The concrete example in Patch 3/3 is a multiplexer with four child 
buses.  The happen to have cell-indexes of 0, 1, 2 and 3.

In the GPIO case of patch 3/3, these directly correspond the the state 
of the two GPIO pins controlling the multiplexer.  The driver then uses 
the cell-index property to determine the state of the GPIO to connect 
any given child.

It is possible that the documentation part of the patch could be made 
more clear about this.

>
>> +
>> +
>> +Example :
>
[...]
>> +
>> +int mdio_mux_probe(struct platform_device *pdev,
>> +		   int (*switch_fn)(int cur, int desired, void *data),
>> +		   void *data)
>> +{
>> +	struct device_node *parent_bus_node;
>> +	struct device_node *child_bus_node;
>> +	int r, n, ret_val;
>> +	struct mii_bus *parent_bus;
>> +	struct mdio_mux_parent_bus *pb;
>> +	struct mdio_mux_child_bus *cb;
>> +
>> +	if (!pdev->dev.of_node)
>> +		return -ENODEV;
>> +
>> +	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
>> +
>> +	if (!parent_bus_node)
>> +		return -ENODEV;
>> +
>> +	parent_bus = of_mdio_find_bus(parent_bus_node);
>
>
> So what happens if the parent bus probe happens after the mux probe?
>

The whole house of cards collapses.

Grant Likely has a patch to deal with this by retrying the probing,  but 
as far as I know, it has not been merged yet.

Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[Kumar Gala]

On Sep 13, 2011, at 6:23 PM, David Daney wrote:

> On 09/13/2011 04:07 PM, Kumar Gala wrote:
>> 
>>> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>> new file mode 100644
>>> index 0000000..a908312
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>> @@ -0,0 +1,132 @@
>>> +Common MDIO bus multiplexer/switch properties.
>>> +
>>> +An MDIO bus multiplexer/switch will have several child busses that are
>>> +numbered uniquely in a device dependent manner.  The nodes for an MDIO
>>> +bus multiplexer/switch will have one child node for each child bus.
>>> +
>>> +Required properties:
>>> +- parent-bus : phandle to the parent MDIO bus.
>> 
>> Should probably be mdio-parent-bus
> 
> Why?  We know it is MDIO.
> 
> Serial bus multiplexing is not a concept limited to MDIO.  We would want to use "parent-bus" for some I2C multiplexers as well.

>From many years of dealing with device trees.  We typically don't name things overlay generically unless they will be used over and over again as a common idiom (like reg, interrupt, etc.).

We don't really use 'bus' generically today.

> 
>> 
>>> +
>>> +Optional properties:
>>> +- Other properties specific to the multiplexer/switch hardware.
>>> +
>>> +Required properties for child nodes:
>>> +- #address-cells =<1>;
>>> +- #size-cells =<0>;
>>> +- cell-index : The sub-bus number.
>> 
>> What does sub-bus number mean?
> 
> There are N child buses (or sub-buses) coming out of the multiplexer. The cell-index is used as a handle or identifier for each of these.
> 
> The concrete example in Patch 3/3 is a multiplexer with four child buses.  The happen to have cell-indexes of 0, 1, 2 and 3.
> 
> In the GPIO case of patch 3/3, these directly correspond the the state of the two GPIO pins controlling the multiplexer.  The driver then uses the cell-index property to determine the state of the GPIO to connect any given child.
> 
> It is possible that the documentation part of the patch could be made more clear about this.
> 
>> 
>>> +
>>> +
>>> +Example :
>> 
> [...]
>>> +
>>> +int mdio_mux_probe(struct platform_device *pdev,
>>> +		   int (*switch_fn)(int cur, int desired, void *data),
>>> +		   void *data)
>>> +{
>>> +	struct device_node *parent_bus_node;
>>> +	struct device_node *child_bus_node;
>>> +	int r, n, ret_val;
>>> +	struct mii_bus *parent_bus;
>>> +	struct mdio_mux_parent_bus *pb;
>>> +	struct mdio_mux_child_bus *cb;
>>> +
>>> +	if (!pdev->dev.of_node)
>>> +		return -ENODEV;
>>> +
>>> +	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
>>> +
>>> +	if (!parent_bus_node)
>>> +		return -ENODEV;
>>> +
>>> +	parent_bus = of_mdio_find_bus(parent_bus_node);
>> 
>> 
>> So what happens if the parent bus probe happens after the mux probe?
>> 
> 
> The whole house of cards collapses.
> 
> Grant Likely has a patch to deal with this by retrying the probing,  but as far as I know, it has not been merged yet.

- k

Device tree property names for MDIO bus multiplexer. Was: Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[David Daney]

Well, I would really like to get an official maintainer's take on the 
name of the parent MDIO bus property.  Prehaps Grant or Rob could opine 
on the matter.

Sooner would be better than later as I am about to start shipping boards 
with this burnt into the bootloader.  If it needs changing, I could do 
it in the next couple of days, but after that it escapes into the wild.

Thanks in advance,
David Daney


On 09/14/2011 01:42 PM, Kumar Gala wrote:
>
> On Sep 13, 2011, at 6:23 PM, David Daney wrote:
>
>> On 09/13/2011 04:07 PM, Kumar Gala wrote:
>>>
>>>> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>>> new file mode 100644
>>>> index 0000000..a908312
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>>> @@ -0,0 +1,132 @@
>>>> +Common MDIO bus multiplexer/switch properties.
>>>> +
>>>> +An MDIO bus multiplexer/switch will have several child busses that are
>>>> +numbered uniquely in a device dependent manner.  The nodes for an MDIO
>>>> +bus multiplexer/switch will have one child node for each child bus.
>>>> +
>>>> +Required properties:
>>>> +- parent-bus : phandle to the parent MDIO bus.
>>>
>>> Should probably be mdio-parent-bus
>>
>> Why?  We know it is MDIO.
>>
>> Serial bus multiplexing is not a concept limited to MDIO.  We would want to use "parent-bus" for some I2C multiplexers as well.
>
>> From many years of dealing with device trees.  We typically don't name things overlay generically unless they will be used over and over again as a common idiom (like reg, interrupt, etc.).
>
> We don't really use 'bus' generically today.
>
>>
>>>
>>>> +
>>>> +Optional properties:
>>>> +- Other properties specific to the multiplexer/switch hardware.
>>>> +
>>>> +Required properties for child nodes:
>>>> +- #address-cells =<1>;
>>>> +- #size-cells =<0>;
>>>> +- cell-index : The sub-bus number.
>>>
>>> What does sub-bus number mean?
>>
>> There are N child buses (or sub-buses) coming out of the multiplexer. The cell-index is used as a handle or identifier for each of these.
>>
>> The concrete example in Patch 3/3 is a multiplexer with four child buses.  The happen to have cell-indexes of 0, 1, 2 and 3.
>>
>> In the GPIO case of patch 3/3, these directly correspond the the state of the two GPIO pins controlling the multiplexer.  The driver then uses the cell-index property to determine the state of the GPIO to connect any given child.
>>
>> It is possible that the documentation part of the patch could be made more clear about this.
>>
>>>
>>>> +
>>>> +
>>>> +Example :
>>>
>> [...]
>>>> +
>>>> +int mdio_mux_probe(struct platform_device *pdev,
>>>> +		   int (*switch_fn)(int cur, int desired, void *data),
>>>> +		   void *data)
>>>> +{
>>>> +	struct device_node *parent_bus_node;
>>>> +	struct device_node *child_bus_node;
>>>> +	int r, n, ret_val;
>>>> +	struct mii_bus *parent_bus;
>>>> +	struct mdio_mux_parent_bus *pb;
>>>> +	struct mdio_mux_child_bus *cb;
>>>> +
>>>> +	if (!pdev->dev.of_node)
>>>> +		return -ENODEV;
>>>> +
>>>> +	parent_bus_node = of_parse_phandle(pdev->dev.of_node, "parent-bus", 0);
>>>> +
>>>> +	if (!parent_bus_node)
>>>> +		return -ENODEV;
>>>> +
>>>> +	parent_bus = of_mdio_find_bus(parent_bus_node);
>>>
>>>
>>> So what happens if the parent bus probe happens after the mux probe?
>>>
>>
>> The whole house of cards collapses.
>>
>> Grant Likely has a patch to deal with this by retrying the probing,  but as far as I know, it has not been merged yet.
>
> - k--
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: Device tree property names for MDIO bus multiplexer. Was: Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[Grant Likely]

[-- Attachment #1.1: Type: text/plain, Size: 4562 bytes --]

On Sep 14, 2011 3:40 PM, "David Daney" <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org> wrote:
>
> Well, I would really like to get an official maintainer's take on the name
of the parent MDIO bus property.  Prehaps Grant or Rob could opine on the
matter.
>
> Sooner would be better than later as I am about to start shipping boards
with this burnt into the bootloader.  If it needs changing, I could do it in
the next couple of days, but after that it escapes into the wild.

Considering that the parent bus should be either implicit in the node
topology, or if not then part of something like an i2c controlled bus
multiplexer, I don't think this is even remotely a big deal. Each bus
multiplexer will still likely have it's own binding, and therefore her to
make its own decision.

That said, in the interest of commonality, I think mdio-parent-bus would be
just fine.  parent-bus is probably too generic.

g.

>
> Thanks in advance,
> David Daney
>
>
> On 09/14/2011 01:42 PM, Kumar Gala wrote:
>>
>>
>> On Sep 13, 2011, at 6:23 PM, David Daney wrote:
>>
>>> On 09/13/2011 04:07 PM, Kumar Gala wrote:
>>>>
>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt
b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>>>> new file mode 100644
>>>>> index 0000000..a908312
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
>>>>> @@ -0,0 +1,132 @@
>>>>> +Common MDIO bus multiplexer/switch properties.
>>>>> +
>>>>> +An MDIO bus multiplexer/switch will have several child busses that
are
>>>>> +numbered uniquely in a device dependent manner.  The nodes for an
MDIO
>>>>> +bus multiplexer/switch will have one child node for each child bus.
>>>>> +
>>>>> +Required properties:
>>>>> +- parent-bus : phandle to the parent MDIO bus.
>>>>
>>>>
>>>> Should probably be mdio-parent-bus
>>>
>>>
>>> Why?  We know it is MDIO.
>>>
>>> Serial bus multiplexing is not a concept limited to MDIO.  We would want
to use "parent-bus" for some I2C multiplexers as well.
>>
>>
>>> From many years of dealing with device trees.  We typically don't name
things overlay generically unless they will be used over and over again as a
common idiom (like reg, interrupt, etc.).
>>
>>
>> We don't really use 'bus' generically today.
>>
>>>
>>>>
>>>>> +
>>>>> +Optional properties:
>>>>> +- Other properties specific to the multiplexer/switch hardware.
>>>>> +
>>>>> +Required properties for child nodes:
>>>>> +- #address-cells =<1>;
>>>>> +- #size-cells =<0>;
>>>>> +- cell-index : The sub-bus number.
>>>>
>>>>
>>>> What does sub-bus number mean?
>>>
>>>
>>> There are N child buses (or sub-buses) coming out of the multiplexer.
The cell-index is used as a handle or identifier for each of these.
>>>
>>> The concrete example in Patch 3/3 is a multiplexer with four child
buses.  The happen to have cell-indexes of 0, 1, 2 and 3.
>>>
>>> In the GPIO case of patch 3/3, these directly correspond the the state
of the two GPIO pins controlling the multiplexer.  The driver then uses the
cell-index property to determine the state of the GPIO to connect any given
child.
>>>
>>> It is possible that the documentation part of the patch could be made
more clear about this.
>>>
>>>>
>>>>> +
>>>>> +
>>>>> +Example :
>>>>
>>>>
>>> [...]
>>>>>
>>>>> +
>>>>> +int mdio_mux_probe(struct platform_device *pdev,
>>>>> +                  int (*switch_fn)(int cur, int desired, void *data),
>>>>> +                  void *data)
>>>>> +{
>>>>> +       struct device_node *parent_bus_node;
>>>>> +       struct device_node *child_bus_node;
>>>>> +       int r, n, ret_val;
>>>>> +       struct mii_bus *parent_bus;
>>>>> +       struct mdio_mux_parent_bus *pb;
>>>>> +       struct mdio_mux_child_bus *cb;
>>>>> +
>>>>> +       if (!pdev->dev.of_node)
>>>>> +               return -ENODEV;
>>>>> +
>>>>> +       parent_bus_node = of_parse_phandle(pdev->dev.of_node,
"parent-bus", 0);
>>>>> +
>>>>> +       if (!parent_bus_node)
>>>>> +               return -ENODEV;
>>>>> +
>>>>> +       parent_bus = of_mdio_find_bus(parent_bus_node);
>>>>
>>>>
>>>>
>>>> So what happens if the parent bus probe happens after the mux probe?
>>>>
>>>
>>> The whole house of cards collapses.
>>>
>>> Grant Likely has a patch to deal with this by retrying the probing,  but
as far as I know, it has not been merged yet.
>>
>>
>> - k--
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>

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Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[Grant Likely]

[-- Attachment #1.1: Type: text/plain, Size: 3530 bytes --]

On Aug 31, 2011 2:01 PM, "David Daney" <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org> wrote:
>
> This patch adds a somewhat generic framework for MDIO bus
> multiplexers.  It is modeled on the I2C multiplexer.
>
> The multiplexer is needed if there are multiple PHYs with the same
> address connected to the same MDIO bus adepter, or if there is
> insufficient electrical drive capability for all the connected PHY
> devices.
>
> Conceptually it could look something like this:
>
>                   ------------------
>                   | Control Signal |
>                   --------+---------
>                           |
>  ---------------   --------+------
>  | MDIO MASTER |---| Multiplexer |
>  ---------------   --+-------+----
>                     |       |
>                     C       C
>                     h       h
>                     i       i
>                     l       l
>                     d       d
>                     |       |
>     ---------       A       B   ---------
>     |       |       |       |   |       |
>     | PHY@1 +-------+       +---+ PHY@1 |
>     |       |       |       |   |       |
>     ---------       |       |   ---------
>     ---------       |       |   ---------
>     |       |       |       |   |       |
>     | PHY@2 +-------+       +---+ PHY@2 |
>     |       |                   |       |
>     ---------                   ---------
>
> This framework configures the bus topology from device tree data.  The
> mechanics of switching the multiplexer is left to device specific
> drivers.
>
> The follow-on patch contains a multiplexer driven by GPIO lines.
>
> Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
> Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
> ---
>  Documentation/devicetree/bindings/net/mdio-mux.txt |  132 ++++++++++++++
>  drivers/net/phy/Kconfig                            |    8 +
>  drivers/net/phy/Makefile                           |    1 +
>  drivers/net/phy/mdio-mux.c                         |  182
++++++++++++++++++++
>  include/linux/mdio-mux.h                           |   18 ++
>  5 files changed, 341 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/net/mdio-mux.txt
>  create mode 100644 drivers/net/phy/mdio-mux.c
>  create mode 100644 include/linux/mdio-mux.h
>
> diff --git a/Documentation/devicetree/bindings/net/mdio-mux.txt
b/Documentation/devicetree/bindings/net/mdio-mux.txt
> new file mode 100644
> index 0000000..a908312
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
> @@ -0,0 +1,132 @@
> +Common MDIO bus multiplexer/switch properties.
> +
> +An MDIO bus multiplexer/switch will have several child busses that are
> +numbered uniquely in a device dependent manner.  The nodes for an MDIO
> +bus multiplexer/switch will have one child node for each child bus.
> +
> +Required properties:
> +- parent-bus : phandle to the parent MDIO bus.

As discussed, I like mdio-parent-bus.

> +
> +Optional properties:
> +- Other properties specific to the multiplexer/switch hardware.
> +
> +Required properties for child nodes:
> +- #address-cells = <1>;
> +- #size-cells = <0>;
> +- cell-index : The sub-bus number.

Use reg, not cell-index. That is what it is there for. And add the
appropriate #address/size-cells in the parent.

I've not reviewed the implementation, but with the changes. I'm okay with
the binding.

g.

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Re: [PATCH 2/3] netdev/of/phy: Add MDIO bus multiplexer support.

[David Daney]

On 09/14/2011 05:51 PM, Grant Likely wrote:
>
>
> On Aug 31, 2011 2:01 PM, "David Daney" <david.daney@cavium.com 
> <mailto:david.daney@cavium.com>> wrote:
> >
> > This patch adds a somewhat generic framework for MDIO bus
> > multiplexers.  It is modeled on the I2C multiplexer.
> >
>
[...]
>
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/mdio-mux.txt
> > @@ -0,0 +1,132 @@
> > +Common MDIO bus multiplexer/switch properties.
> > +
> > +An MDIO bus multiplexer/switch will have several child busses that are
> > +numbered uniquely in a device dependent manner.  The nodes for an MDIO
> > +bus multiplexer/switch will have one child node for each child bus.
> > +
> > +Required properties:
> > +- parent-bus : phandle to the parent MDIO bus.
>
> As discussed, I like mdio-parent-bus.
>
> > +
> > +Optional properties:
> > +- Other properties specific to the multiplexer/switch hardware.
> > +
> > +Required properties for child nodes:
> > +- #address-cells = <1>;
> > +- #size-cells = <0>;
> > +- cell-index : The sub-bus number.
>
> Use reg, not cell-index. That is what it is there for. And add the 
> appropriate #address/size-cells in the parent.
>
> I've not reviewed the implementation, but with the changes. I'm okay 
> with the binding.
>

Thanks for the prompt reply Grant.

I will rework this with the binding changes and send a new version soon.

David Daney