net: Distributed Switch Architecture protocol support

Distributed Switch Architecture is a protocol for managing hardware
switch chips.  It consists of a set of MII management registers and
commands to configure the switch, and an ethernet header format to
signal which of the ports of the switch a packet was received from
or is intended to be sent to.

The switches that this driver supports are typically embedded in
access points and routers, and a typical setup with a DSA switch
looks something like this:

	+-----------+       +-----------+
	|           | RGMII |           |
	|           +-------+           +------ 1000baseT MDI ("WAN")
	|           |       |  6-port   +------ 1000baseT MDI ("LAN1")
	|    CPU    |       |  ethernet +------ 1000baseT MDI ("LAN2")
	|           |MIImgmt|  switch   +------ 1000baseT MDI ("LAN3")
	|           +-------+  w/5 PHYs +------ 1000baseT MDI ("LAN4")
	|           |       |           |
	+-----------+       +-----------+

The switch driver presents each port on the switch as a separate
network interface to Linux, polls the switch to maintain software
link state of those ports, forwards MII management interface
accesses to those network interfaces (e.g. as done by ethtool) to
the switch, and exposes the switch's hardware statistics counters
via the appropriate Linux kernel interfaces.

This initial patch supports the MII management interface register
layout of the Marvell 88E6123, 88E6161 and 88E6165 switch chips, and
supports the "Ethertype DSA" packet tagging format.

(There is no officially registered ethertype for the Ethertype DSA
packet format, so we just grab a random one.  The ethertype to use
is programmed into the switch, and the switch driver uses the value
of ETH_P_EDSA for this, so this define can be changed at any time in
the future if the one we chose is allocated to another protocol or
if Ethertype DSA gets its own officially registered ethertype, and
everything will continue to work.)

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Nicolas Pitre <nico@marvell.com>
Tested-by: Byron Bradley <byron.bbradley@gmail.com>
Tested-by: Tim Ellis <tim.ellis@mac.com>
Tested-by: Peter van Valderen <linux@ddcrew.com>
Tested-by: Dirk Teurlings <dirk@upexia.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 369 insertions, 0 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
new file mode 100644
index 000000000000..6cc5be2ec7f1
--- /dev/null
+++ b/net/dsa/dsa.c
@@ -0,0 +1,369 @@
+/*
+ * net/dsa/dsa.c - Hardware switch handling
+ * Copyright (c) 2008 Marvell Semiconductor
+ *
+ * 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.
+ */
+
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+#include <net/dsa.h>
+#include "dsa_priv.h"
+
+char dsa_driver_version[] = "0.1";
+
+
+/* switch driver registration ***********************************************/
+static DEFINE_MUTEX(dsa_switch_drivers_mutex);
+static LIST_HEAD(dsa_switch_drivers);
+
+void register_switch_driver(struct dsa_switch_driver *drv)
+{
+        mutex_lock(&dsa_switch_drivers_mutex);
+        list_add_tail(&drv->list, &dsa_switch_drivers);
+        mutex_unlock(&dsa_switch_drivers_mutex);
+}
+
+void unregister_switch_driver(struct dsa_switch_driver *drv)
+{
+        mutex_lock(&dsa_switch_drivers_mutex);
+        list_del_init(&drv->list);
+        mutex_unlock(&dsa_switch_drivers_mutex);
+}
+
+static struct dsa_switch_driver *
+dsa_switch_probe(struct mii_bus *bus, int sw_addr, char **_name)
+{
+        struct dsa_switch_driver *ret;
+        struct list_head *list;
+        char *name;
+
+        ret = NULL;
+        name = NULL;
+
+        mutex_lock(&dsa_switch_drivers_mutex);
+        list_for_each(list, &dsa_switch_drivers) {
+                struct dsa_switch_driver *drv;
+
+                drv = list_entry(list, struct dsa_switch_driver, list);
+
+                name = drv->probe(bus, sw_addr);
+                if (name != NULL) {
+                        ret = drv;
+                        break;
+                }
+        }
+        mutex_unlock(&dsa_switch_drivers_mutex);
+
+        *_name = name;
+
+        return ret;
+}
+
+
+/* basic switch operations **************************************************/
+static struct dsa_switch *
+dsa_switch_setup(struct device *parent, struct dsa_platform_data *pd,
+                 struct mii_bus *bus, struct net_device *dev)
+{
+        struct dsa_switch *ds;
+        int ret;
+        struct dsa_switch_driver *drv;
+        char *name;
+        int i;
+
+        /*
+         * Probe for switch model.
+         */
+        drv = dsa_switch_probe(bus, pd->sw_addr, &name);
+        if (drv == NULL) {
+                printk(KERN_ERR "%s: could not detect attached switch\n",
+                       dev->name);
+                return ERR_PTR(-EINVAL);
+        }
+        printk(KERN_INFO "%s: detected a %s switch\n", dev->name, name);
+
+
+        /*
+         * Allocate and initialise switch state.
+         */
+        ds = kzalloc(sizeof(*ds) + drv->priv_size, GFP_KERNEL);
+        if (ds == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        ds->pd = pd;
+        ds->master_netdev = dev;
+        ds->master_mii_bus = bus;
+
+        ds->drv = drv;
+        ds->tag_protocol = drv->tag_protocol;
+
+
+        /*
+         * Validate supplied switch configuration.
+         */
+        ds->cpu_port = -1;
+        for (i = 0; i < DSA_MAX_PORTS; i++) {
+                char *name;
+
+                name = pd->port_names[i];
+                if (name == NULL)
+                        continue;
+
+                if (!strcmp(name, "cpu")) {
+                        if (ds->cpu_port != -1) {
+                                printk(KERN_ERR "multiple cpu ports?!\n");
+                                ret = -EINVAL;
+                                goto out;
+                        }
+                        ds->cpu_port = i;
+                } else {
+                        ds->valid_port_mask |= 1 << i;
+                }
+        }
+
+        if (ds->cpu_port == -1) {
+                printk(KERN_ERR "no cpu port?!\n");
+                ret = -EINVAL;
+                goto out;
+        }
+
+
+        /*
+         * If we use a tagging format that doesn't have an ethertype
+         * field, make sure that all packets from this point on get
+         * sent to the tag format's receive function.  (Which will
+         * discard received packets until we set ds->ports[] below.)
+         */
+        wmb();
+        dev->dsa_ptr = (void *)ds;
+
+
+        /*
+         * Do basic register setup.
+         */
+        ret = drv->setup(ds);
+        if (ret < 0)
+                goto out;
+
+        ret = drv->set_addr(ds, dev->dev_addr);
+        if (ret < 0)
+                goto out;
+
+        ds->slave_mii_bus = mdiobus_alloc();
+        if (ds->slave_mii_bus == NULL) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        dsa_slave_mii_bus_init(ds);
+
+        ret = mdiobus_register(ds->slave_mii_bus);
+        if (ret < 0)
+                goto out_free;
+
+
+        /*
+         * Create network devices for physical switch ports.
+         */
+        wmb();
+        for (i = 0; i < DSA_MAX_PORTS; i++) {
+                struct net_device *slave_dev;
+
+                if (!(ds->valid_port_mask & (1 << i)))
+                        continue;
+
+                slave_dev = dsa_slave_create(ds, parent, i, pd->port_names[i]);
+                if (slave_dev == NULL) {
+                        printk(KERN_ERR "%s: can't create dsa slave "
+                               "device for port %d(%s)\n",
+                               dev->name, i, pd->port_names[i]);
+                        continue;
+                }
+
+                ds->ports[i] = slave_dev;
+        }
+
+        return ds;
+
+out_free:
+        mdiobus_free(ds->slave_mii_bus);
+out:
+        dev->dsa_ptr = NULL;
+        kfree(ds);
+        return ERR_PTR(ret);
+}
+
+static void dsa_switch_destroy(struct dsa_switch *ds)
+{
+}
+
+
+/* link polling *************************************************************/
+static void dsa_link_poll_work(struct work_struct *ugly)
+{
+        struct dsa_switch *ds;
+
+        ds = container_of(ugly, struct dsa_switch, link_poll_work);
+
+        ds->drv->poll_link(ds);
+        mod_timer(&ds->link_poll_timer, round_jiffies(jiffies + HZ));
+}
+
+static void dsa_link_poll_timer(unsigned long _ds)
+{
+        struct dsa_switch *ds = (void *)_ds;
+
+        schedule_work(&ds->link_poll_work);
+}
+
+
+/* platform driver init and cleanup *****************************************/
+static int dev_is_class(struct device *dev, void *class)
+{
+        if (dev->class != NULL && !strcmp(dev->class->name, class))
+                return 1;
+
+        return 0;
+}
+
+static struct device *dev_find_class(struct device *parent, char *class)
+{
+        if (dev_is_class(parent, class)) {
+                get_device(parent);
+                return parent;
+        }
+
+        return device_find_child(parent, class, dev_is_class);
+}
+
+static struct mii_bus *dev_to_mii_bus(struct device *dev)
+{
+        struct device *d;
+
+        d = dev_find_class(dev, "mdio_bus");
+        if (d != NULL) {
+                struct mii_bus *bus;
+
+                bus = to_mii_bus(d);
+                put_device(d);
+
+                return bus;
+        }
+
+        return NULL;
+}
+
+static struct net_device *dev_to_net_device(struct device *dev)
+{
+        struct device *d;
+
+        d = dev_find_class(dev, "net");
+        if (d != NULL) {
+                struct net_device *nd;
+
+                nd = to_net_dev(d);
+                dev_hold(nd);
+                put_device(d);
+
+                return nd;
+        }
+
+        return NULL;
+}
+
+static int dsa_probe(struct platform_device *pdev)
+{
+        static int dsa_version_printed;
+        struct dsa_platform_data *pd = pdev->dev.platform_data;
+        struct net_device *dev;
+        struct mii_bus *bus;
+        struct dsa_switch *ds;
+
+        if (!dsa_version_printed++)
+                printk(KERN_NOTICE "Distributed Switch Architecture "
+                        "driver version %s\n", dsa_driver_version);
+
+        if (pd == NULL || pd->mii_bus == NULL || pd->netdev == NULL)
+                return -EINVAL;
+
+        bus = dev_to_mii_bus(pd->mii_bus);
+        if (bus == NULL)
+                return -EINVAL;
+
+        dev = dev_to_net_device(pd->netdev);
+        if (dev == NULL)
+                return -EINVAL;
+
+        if (dev->dsa_ptr != NULL) {
+                dev_put(dev);
+                return -EEXIST;
+        }
+
+        ds = dsa_switch_setup(&pdev->dev, pd, bus, dev);
+        if (IS_ERR(ds)) {
+                dev_put(dev);
+                return PTR_ERR(ds);
+        }
+
+        if (ds->drv->poll_link != NULL) {
+                INIT_WORK(&ds->link_poll_work, dsa_link_poll_work);
+                init_timer(&ds->link_poll_timer);
+                ds->link_poll_timer.data = (unsigned long)ds;
+                ds->link_poll_timer.function = dsa_link_poll_timer;
+                ds->link_poll_timer.expires = round_jiffies(jiffies + HZ);
+                add_timer(&ds->link_poll_timer);
+        }
+
+        platform_set_drvdata(pdev, ds);
+
+        return 0;
+}
+
+static int dsa_remove(struct platform_device *pdev)
+{
+        struct dsa_switch *ds = platform_get_drvdata(pdev);
+
+        if (ds->drv->poll_link != NULL)
+                del_timer_sync(&ds->link_poll_timer);
+
+        flush_scheduled_work();
+
+        dsa_switch_destroy(ds);
+
+        return 0;
+}
+
+static void dsa_shutdown(struct platform_device *pdev)
+{
+}
+
+static struct platform_driver dsa_driver = {
+        .probe          = dsa_probe,
+        .remove         = dsa_remove,
+        .shutdown       = dsa_shutdown,
+        .driver = {
+                .name   = "dsa",
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init dsa_init_module(void)
+{
+        return platform_driver_register(&dsa_driver);
+}
+module_init(dsa_init_module);
+
+static void __exit dsa_cleanup_module(void)
+{
+        platform_driver_unregister(&dsa_driver);
+}
+module_exit(dsa_cleanup_module);
+
+MODULE_AUTHOR("Lennert Buytenhek <buytenh@wantstofly.org>")
+MODULE_DESCRIPTION("Driver for Distributed Switch Architecture switch chips");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:dsa");