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authorDavid Daney <david.daney@cavium.com>2012-05-02 15:16:38 +0000
committerDavid S. Miller <davem@davemloft.net>2012-05-07 22:58:09 -0400
commit0ca2997d145268e6b4ef000692061849cdab8348 (patch)
treedeeca7985f029cae477945e988816889c986e263 /drivers/net/phy/mdio-mux.c
parent251060220021283eef3652145a41f5b26db97ce5 (diff)
downloadlinux-0ca2997d145268e6b4ef000692061849cdab8348.tar.bz2
netdev/of/phy: Add MDIO bus multiplexer support.
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@cavium.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/phy/mdio-mux.c')
-rw-r--r--drivers/net/phy/mdio-mux.c192
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
new file mode 100644
index 000000000000..39ea0674dcde
--- /dev/null
+++ b/drivers/net/phy/mdio-mux.c
@@ -0,0 +1,192 @@
+/*
+ * 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, 2012 Cavium, Inc.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/mdio-mux.h>
+#include <linux/of_mdio.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define DRV_VERSION "1.0"
+#define DRV_DESCRIPTION "MDIO bus multiplexer driver"
+
+struct mdio_mux_child_bus;
+
+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);
+
+ /* List of our children linked through their next fields. */
+ struct mdio_mux_child_bus *children;
+};
+
+struct mdio_mux_child_bus {
+ struct mii_bus *mii_bus;
+ struct mdio_mux_parent_bus *parent;
+ struct mdio_mux_child_bus *next;
+ 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_init(struct device *dev,
+ int (*switch_fn)(int cur, int desired, void *data),
+ void **mux_handle,
+ void *data)
+{
+ struct device_node *parent_bus_node;
+ struct device_node *child_bus_node;
+ int r, ret_val;
+ struct mii_bus *parent_bus;
+ struct mdio_mux_parent_bus *pb;
+ struct mdio_mux_child_bus *cb;
+
+ if (!dev->of_node)
+ return -ENODEV;
+
+ parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
+
+ if (!parent_bus_node)
+ return -ENODEV;
+
+ parent_bus = of_mdio_find_bus(parent_bus_node);
+ if (parent_bus == NULL) {
+ ret_val = -EPROBE_DEFER;
+ goto err_parent_bus;
+ }
+
+ pb = devm_kzalloc(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;
+
+ ret_val = -ENODEV;
+ for_each_child_of_node(dev->of_node, child_bus_node) {
+ u32 v;
+
+ r = of_property_read_u32(child_bus_node, "reg", &v);
+ if (r)
+ continue;
+
+ cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
+ if (cb == NULL) {
+ dev_err(dev,
+ "Error: Failed to allocate memory for child\n");
+ ret_val = -ENOMEM;
+ 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 = 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) {
+ mdiobus_free(cb->mii_bus);
+ devm_kfree(dev, cb);
+ } else {
+ of_node_get(child_bus_node);
+ cb->next = pb->children;
+ pb->children = cb;
+ }
+ }
+ if (pb->children) {
+ *mux_handle = pb;
+ dev_info(dev, "Version " DRV_VERSION "\n");
+ return 0;
+ }
+err_parent_bus:
+ of_node_put(parent_bus_node);
+ return ret_val;
+}
+EXPORT_SYMBOL_GPL(mdio_mux_init);
+
+void mdio_mux_uninit(void *mux_handle)
+{
+ struct mdio_mux_parent_bus *pb = mux_handle;
+ struct mdio_mux_child_bus *cb = pb->children;
+
+ while (cb) {
+ mdiobus_unregister(cb->mii_bus);
+ mdiobus_free(cb->mii_bus);
+ cb = cb->next;
+ }
+}
+EXPORT_SYMBOL_GPL(mdio_mux_uninit);
+
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");