thunderbolt: Handle hotplug events

We receive a plug event callback whenever a thunderbolt device is added
or removed. This patch fills in the tb_handle_hotplug method and starts
reacting to these events by adding/removing switches from the hierarchy.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 89 insertions, 2 deletions

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index b31b8cef301d..d6c32e1e2b42 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -195,6 +195,24 @@ static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
                 sw->__unknown1, sw->__unknown4);
 }
 
+struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route)
+{
+        u8 next_port = route; /*
+                               * Routes use a stride of 8 bits,
+                               * eventhough a port index has 6 bits at most.
+                               * */
+        if (route == 0)
+                return sw;
+        if (next_port > sw->config.max_port_number)
+                return 0;
+        if (tb_is_upstream_port(&sw->ports[next_port]))
+                return 0;
+        if (!sw->ports[next_port].remote)
+                return 0;
+        return get_switch_at_route(sw->ports[next_port].remote->sw,
+                                   route >> TB_ROUTE_SHIFT);
+}
+
 /**
  * tb_plug_events_active() - enable/disable plug events on a switch
  *
@@ -249,7 +267,8 @@ void tb_switch_free(struct tb_switch *sw)
                 sw->ports[i].remote = NULL;
         }
 
-        tb_plug_events_active(sw, false);
+        if (!sw->is_unplugged)
+                tb_plug_events_active(sw, false);
 
         kfree(sw->ports);
         kfree(sw);
@@ -333,3 +352,24 @@ err:
         return NULL;
 }
 
+/**
+ * tb_sw_set_unpplugged() - set is_unplugged on switch and downstream switches
+ */
+void tb_sw_set_unpplugged(struct tb_switch *sw)
+{
+        int i;
+        if (sw == sw->tb->root_switch) {
+                tb_sw_WARN(sw, "cannot unplug root switch\n");
+                return;
+        }
+        if (sw->is_unplugged) {
+                tb_sw_WARN(sw, "is_unplugged already set\n");
+                return;
+        }
+        sw->is_unplugged = true;
+        for (i = 0; i <= sw->config.max_port_number; i++) {
+                if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
+                        tb_sw_set_unpplugged(sw->ports[i].remote->sw);
+        }
+}
+
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 3b716fd123f6..1efcacc72104 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -71,11 +71,55 @@ static void tb_handle_hotplug(struct work_struct *work)
 {
         struct tb_hotplug_event *ev = container_of(work, typeof(*ev), work);
         struct tb *tb = ev->tb;
+        struct tb_switch *sw;
+        struct tb_port *port;
         mutex_lock(&tb->lock);
         if (!tb->hotplug_active)
                 goto out; /* during init, suspend or shutdown */
 
-        /* do nothing for now */
+        sw = get_switch_at_route(tb->root_switch, ev->route);
+        if (!sw) {
+                tb_warn(tb,
+                        "hotplug event from non existent switch %llx:%x (unplug: %d)\n",
+                        ev->route, ev->port, ev->unplug);
+                goto out;
+        }
+        if (ev->port > sw->config.max_port_number) {
+                tb_warn(tb,
+                        "hotplug event from non existent port %llx:%x (unplug: %d)\n",
+                        ev->route, ev->port, ev->unplug);
+                goto out;
+        }
+        port = &sw->ports[ev->port];
+        if (tb_is_upstream_port(port)) {
+                tb_warn(tb,
+                        "hotplug event for upstream port %llx:%x (unplug: %d)\n",
+                        ev->route, ev->port, ev->unplug);
+                goto out;
+        }
+        if (ev->unplug) {
+                if (port->remote) {
+                        tb_port_info(port, "unplugged\n");
+                        tb_sw_set_unpplugged(port->remote->sw);
+                        tb_switch_free(port->remote->sw);
+                        port->remote = NULL;
+                } else {
+                        tb_port_info(port,
+                                     "got unplug event for disconnected port, ignoring\n");
+                }
+        } else if (port->remote) {
+                tb_port_info(port,
+                             "got plug event for connected port, ignoring\n");
+        } else {
+                tb_port_info(port, "hotplug: scanning\n");
+                tb_scan_port(port);
+                if (!port->remote) {
+                        tb_port_info(port, "hotplug: no switch found\n");
+                } else if (port->remote->sw->config.depth > 1) {
+                        tb_sw_warn(port->remote->sw,
+                                   "hotplug: chaining not supported\n");
+                }
+        }
 out:
         mutex_unlock(&tb->lock);
         kfree(ev);
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 70a66fef0177..661f1828527a 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -20,6 +20,7 @@ struct tb_switch {
         struct tb_port *ports;
         struct tb *tb;
         int cap_plug_events; /* offset, zero if not found */
+        bool is_unplugged; /* unplugged, will go away */
 };
 
 /**
@@ -160,6 +161,8 @@ void thunderbolt_shutdown_and_free(struct tb *tb);
 
 struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route);
 void tb_switch_free(struct tb_switch *sw);
+void tb_sw_set_unpplugged(struct tb_switch *sw);
+struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route);
 
 int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged);