gpu: host1x: Provide a proper struct bus_type

Previously the struct bus_type exported by the host1x infrastructure was
only a very basic skeleton. Turn that implementation into a more full-
fledged bus to support proper probe ordering and power management.

Note that the bus infrastructure needs to be available before any of the
drivers can be registered. This is automatically ensured if all drivers
are built as loadable modules (via symbol dependencies). If all drivers
are built-in there are no such guarantees and the link order determines
the initcall ordering. Adjust drivers/gpu/Makefile to make sure that the
host1x bus infrastructure is initialized prior to any of its users (only
drm/tegra currently).

v2: Fix building host1x and tegra-drm as modules
    Reported-by: Dave Airlie <airlied@gmail.com>

Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Mark Zhang <markz@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

5 files changed, 88 insertions, 42 deletions

diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
index 70da9eb52a42..e9ed439a5b65 100644
--- a/drivers/gpu/Makefile
+++ b/drivers/gpu/Makefile
@@ -1,3 +1,6 @@
-obj-y                   += drm/ vga/
+# drm/tegra depends on host1x, so if both drivers are built-in care must be
+# taken to initialize them in the correct order. Link order is the only way
+# to ensure this currently.
 obj-$(CONFIG_TEGRA_HOST1X)      += host1x/
+obj-y                   += drm/ vga/
 obj-$(CONFIG_IMX_IPUV3_CORE)    += ipu-v3/
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index d4f827593dfa..a0c18ae79029 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -912,7 +912,9 @@ static const struct of_device_id host1x_drm_subdevs[] = {
 };
 
 static struct host1x_driver host1x_drm_driver = {
-        .name = "drm",
+        .driver = {
+                .name = "drm",
+        },
         .probe = host1x_drm_probe,
         .remove = host1x_drm_remove,
         .subdevs = host1x_drm_subdevs,
diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index 0b52f0ea8871..4a99c6416e6a 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -72,13 +72,14 @@ static void host1x_subdev_del(struct host1x_subdev *subdev)
 /**
  * host1x_device_parse_dt() - scan device tree and add matching subdevices
  */
-static int host1x_device_parse_dt(struct host1x_device *device)
+static int host1x_device_parse_dt(struct host1x_device *device,
+                                  struct host1x_driver *driver)
 {
         struct device_node *np;
         int err;
 
         for_each_child_of_node(device->dev.parent->of_node, np) {
-                if (of_match_node(device->driver->subdevs, np) &&
+                if (of_match_node(driver->subdevs, np) &&
                     of_device_is_available(np)) {
                         err = host1x_subdev_add(device, np);
                         if (err < 0)
@@ -109,17 +110,12 @@ static void host1x_subdev_register(struct host1x_device *device,
         mutex_unlock(&device->clients_lock);
         mutex_unlock(&device->subdevs_lock);
 
-        /*
-         * When all subdevices have been registered, the composite device is
-         * ready to be probed.
-         */
         if (list_empty(&device->subdevs)) {
-                err = device->driver->probe(device);
+                err = device_add(&device->dev);
                 if (err < 0)
-                        dev_err(&device->dev, "probe failed for %ps: %d\n",
-                                device->driver, err);
+                        dev_err(&device->dev, "failed to add: %d\n", err);
                 else
-                        device->bound = true;
+                        device->registered = true;
         }
 }
 
@@ -127,18 +123,16 @@ static void __host1x_subdev_unregister(struct host1x_device *device,
                                        struct host1x_subdev *subdev)
 {
         struct host1x_client *client = subdev->client;
-        int err;
 
         /*
          * If all subdevices have been activated, we're about to remove the
          * first active subdevice, so unload the driver first.
          */
-        if (list_empty(&device->subdevs) && device->bound) {
-                err = device->driver->remove(device);
-                if (err < 0)
-                        dev_err(&device->dev, "remove failed: %d\n", err);
-
-                device->bound = false;
+        if (list_empty(&device->subdevs)) {
+                if (device->registered) {
+                        device->registered = false;
+                        device_del(&device->dev);
+                }
         }
 
         /*
@@ -265,20 +259,60 @@ static int host1x_del_client(struct host1x *host1x,
         return -ENODEV;
 }
 
-static struct bus_type host1x_bus_type = {
-        .name = "host1x",
-};
+static int host1x_device_match(struct device *dev, struct device_driver *drv)
+{
+        return strcmp(dev_name(dev), drv->name) == 0;
+}
 
-int host1x_bus_init(void)
+static int host1x_device_probe(struct device *dev)
 {
-        return bus_register(&host1x_bus_type);
+        struct host1x_driver *driver = to_host1x_driver(dev->driver);
+        struct host1x_device *device = to_host1x_device(dev);
+
+        if (driver->probe)
+                return driver->probe(device);
+
+        return 0;
 }
 
-void host1x_bus_exit(void)
+static int host1x_device_remove(struct device *dev)
 {
-        bus_unregister(&host1x_bus_type);
+        struct host1x_driver *driver = to_host1x_driver(dev->driver);
+        struct host1x_device *device = to_host1x_device(dev);
+
+        if (driver->remove)
+                return driver->remove(device);
+
+        return 0;
 }
 
+static void host1x_device_shutdown(struct device *dev)
+{
+        struct host1x_driver *driver = to_host1x_driver(dev->driver);
+        struct host1x_device *device = to_host1x_device(dev);
+
+        if (driver->shutdown)
+                driver->shutdown(device);
+}
+
+static const struct dev_pm_ops host1x_device_pm_ops = {
+        .suspend = pm_generic_suspend,
+        .resume = pm_generic_resume,
+        .freeze = pm_generic_freeze,
+        .thaw = pm_generic_thaw,
+        .poweroff = pm_generic_poweroff,
+        .restore = pm_generic_restore,
+};
+
+struct bus_type host1x_bus_type = {
+        .name = "host1x",
+        .match = host1x_device_match,
+        .probe = host1x_device_probe,
+        .remove = host1x_device_remove,
+        .shutdown = host1x_device_shutdown,
+        .pm = &host1x_device_pm_ops,
+};
+
 static void __host1x_device_del(struct host1x_device *device)
 {
         struct host1x_subdev *subdev, *sd;
@@ -347,6 +381,8 @@ static int host1x_device_add(struct host1x *host1x,
         if (!device)
                 return -ENOMEM;
 
+        device_initialize(&device->dev);
+
         mutex_init(&device->subdevs_lock);
         INIT_LIST_HEAD(&device->subdevs);
         INIT_LIST_HEAD(&device->active);
@@ -357,18 +393,14 @@ static int host1x_device_add(struct host1x *host1x,
 
         device->dev.coherent_dma_mask = host1x->dev->coherent_dma_mask;
         device->dev.dma_mask = &device->dev.coherent_dma_mask;
+        dev_set_name(&device->dev, "%s", driver->driver.name);
         device->dev.release = host1x_device_release;
-        dev_set_name(&device->dev, "%s", driver->name);
         device->dev.bus = &host1x_bus_type;
         device->dev.parent = host1x->dev;
 
-        err = device_register(&device->dev);
-        if (err < 0)
-                return err;
-
-        err = host1x_device_parse_dt(device);
+        err = host1x_device_parse_dt(device, driver);
         if (err < 0) {
-                device_unregister(&device->dev);
+                kfree(device);
                 return err;
         }
 
@@ -399,7 +431,12 @@ static int host1x_device_add(struct host1x *host1x,
 static void host1x_device_del(struct host1x *host1x,
                               struct host1x_device *device)
 {
-        device_unregister(&device->dev);
+        if (device->registered) {
+                device->registered = false;
+                device_del(&device->dev);
+        }
+
+        put_device(&device->dev);
 }
 
 static void host1x_attach_driver(struct host1x *host1x,
@@ -474,7 +511,8 @@ int host1x_unregister(struct host1x *host1x)
         return 0;
 }
 
-int host1x_driver_register(struct host1x_driver *driver)
+int host1x_driver_register_full(struct host1x_driver *driver,
+                                struct module *owner)
 {
         struct host1x *host1x;
 
@@ -491,9 +529,12 @@ int host1x_driver_register(struct host1x_driver *driver)
 
         mutex_unlock(&devices_lock);
 
-        return 0;
+        driver->driver.bus = &host1x_bus_type;
+        driver->driver.owner = owner;
+
+        return driver_register(&driver->driver);
 }
-EXPORT_SYMBOL(host1x_driver_register);
+EXPORT_SYMBOL(host1x_driver_register_full);
 
 void host1x_driver_unregister(struct host1x_driver *driver)
 {
diff --git a/drivers/gpu/host1x/bus.h b/drivers/gpu/host1x/bus.h
index 4099e99212c8..88fb1c4aac68 100644
--- a/drivers/gpu/host1x/bus.h
+++ b/drivers/gpu/host1x/bus.h
@@ -18,10 +18,10 @@
 #ifndef HOST1X_BUS_H
 #define HOST1X_BUS_H
 
+struct bus_type;
 struct host1x;
 
-int host1x_bus_init(void);
-void host1x_bus_exit(void);
+extern struct bus_type host1x_bus_type;
 
 int host1x_register(struct host1x *host1x);
 int host1x_unregister(struct host1x *host1x);
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index 2529908d304b..53d3d1d45b48 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -216,7 +216,7 @@ static int __init tegra_host1x_init(void)
 {
         int err;
 
-        err = host1x_bus_init();
+        err = bus_register(&host1x_bus_type);
         if (err < 0)
                 return err;
 
@@ -233,7 +233,7 @@ static int __init tegra_host1x_init(void)
 unregister_host1x:
         platform_driver_unregister(&tegra_host1x_driver);
 unregister_bus:
-        host1x_bus_exit();
+        bus_unregister(&host1x_bus_type);
         return err;
 }
 module_init(tegra_host1x_init);
@@ -242,7 +242,7 @@ static void __exit tegra_host1x_exit(void)
 {
         platform_driver_unregister(&tegra_mipi_driver);
         platform_driver_unregister(&tegra_host1x_driver);
-        host1x_bus_exit();
+        bus_unregister(&host1x_bus_type);
 }
 module_exit(tegra_host1x_exit);