gpu: nvgpu: track classes using dynamic linked list

Remove devnode_class pointer from struct nvgpu_os_linux and replace it
by a list head.

Add new structure nvgpu_class to store class related meta-data and
create it dynamically in nvgpu_create_class().
Add new function nvgpu_prepare_dev_node_class_list() to prepare list of
all classes that are required for each GPU.

For now there is only one class per GPU, but in MIG mode multiple
classes will be created with one class per instance.

Update gk20a_user_init() to loop through list of classes and create
dev nodes for each class.
gk20a_user_deinit() frees up the linked list.

Jira NVGPU-5648

Change-Id: I891a55c0ce1c2ff9db094564529b3f569df9735c
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2428501
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/gpu/nvgpu/os/linux/ioctl.c

@@ -243,17 +243,13 @@ void gk20a_user_deinit(struct device *dev)
 {
 	struct gk20a *g = gk20a_from_dev(dev);
 	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
-	struct class *class = l->devnode_class;
 	struct nvgpu_cdev *cdev, *n;
-
-	if (class == NULL) {
-		return;
-	}
+	struct nvgpu_class *class, *p;
 
 	nvgpu_list_for_each_entry_safe(cdev, n, &l->cdev_list_head, nvgpu_cdev, list_entry) {
 		nvgpu_list_del(&cdev->list_entry);
 
-		device_destroy(class, cdev->cdev.dev);
+		device_destroy(cdev->class, cdev->cdev.dev);
 		cdev_del(&cdev->cdev);
 
 		nvgpu_kfree(g, cdev);
@@ -261,11 +257,63 @@ void gk20a_user_deinit(struct device *dev)
 
 	if (l->cdev_region) {
 		unregister_chrdev_region(l->cdev_region, l->num_cdevs);
+		l->num_cdevs = 0;
 	}
 
-	class_destroy(class);
-	l->devnode_class = NULL;
-	l->num_cdevs = 0;
+	nvgpu_list_for_each_entry_safe(class, p, &l->class_list_head, nvgpu_class, list_entry) {
+		nvgpu_list_del(&class->list_entry);
+
+		class_destroy(class->class);
+		nvgpu_kfree(g, class);
+	}
+}
+
+struct nvgpu_class *nvgpu_create_class(struct gk20a *g, const char *class_name)
+{
+	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
+	struct nvgpu_class *class;
+
+	class = nvgpu_kzalloc(g, sizeof(*class));
+	if (class == NULL) {
+		return NULL;
+	}
+
+	class->class = class_create(THIS_MODULE, class_name);
+	if (IS_ERR(class->class)) {
+		nvgpu_err(g, "failed to create class");
+		nvgpu_kfree(g, class);
+		return NULL;
+	}
+
+	nvgpu_init_list_node(&class->list_entry);
+	nvgpu_list_add_tail(&class->list_entry, &l->class_list_head);
+
+	return class;
+}
+
+int nvgpu_prepare_dev_node_class_list(struct gk20a *g, u32 *num_classes)
+{
+	struct nvgpu_class *class;
+	u32 count = 0U;
+
+	if (g->pci_class != 0U) {
+		class = nvgpu_create_class(g, "nvidia-pci-gpu");
+		if (class == NULL) {
+			return -ENOMEM;
+		}
+		class->class->devnode = nvgpu_pci_devnode;
+		count++;
+	} else {
+		class = nvgpu_create_class(g, "nvidia-gpu");
+		if (class == NULL) {
+			return -ENOMEM;
+		}
+		class->class->devnode = NULL;
+		count++;
+	}
+
+	*num_classes = count;
+	return 0;
 }
 
 int gk20a_user_init(struct device *dev)
@@ -274,37 +322,31 @@ int gk20a_user_init(struct device *dev)
 	dev_t devno;
 	struct gk20a *g = gk20a_from_dev(dev);
 	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
-	struct class *class;
-	u32 num_cdevs;
+	struct nvgpu_class *class;
+	u32 num_cdevs, total_cdevs;
+	u32 num_classes;
 	struct nvgpu_cdev *cdev;
 	u32 cdev_index;
 
-	if (g->pci_class != 0U) {
-		class = class_create(THIS_MODULE, "nvidia-pci-gpu");
-		if (IS_ERR(class)) {
-			dev_err(dev, "failed to create class");
-			return PTR_ERR(class);
-		}
-		class->devnode = nvgpu_pci_devnode;
-	} else {
-		class = class_create(THIS_MODULE, "nvidia-gpu");
-		if (IS_ERR(class)) {
-			dev_err(dev, "failed to create class");
-			return PTR_ERR(class);
-		}
-		class->devnode = NULL;
+	nvgpu_init_list_node(&l->cdev_list_head);
+	nvgpu_init_list_node(&l->class_list_head);
+
+	err = nvgpu_prepare_dev_node_class_list(g, &num_classes);
+	if (err != 0) {
+		return err;
 	}
 
 	num_cdevs = sizeof(dev_node_list) / sizeof(dev_node_list[0]);
-	err = alloc_chrdev_region(&devno, 0, num_cdevs, dev_name(dev));
+	total_cdevs = num_cdevs * num_classes;
+
+	err = alloc_chrdev_region(&devno, 0, total_cdevs, dev_name(dev));
 	if (err) {
 		dev_err(dev, "failed to allocate devno\n");
 		goto fail;
 	}
 	l->cdev_region = devno;
 
-	nvgpu_init_list_node(&l->cdev_list_head);
-
+	nvgpu_list_for_each_entry(class, &l->class_list_head, nvgpu_class, list_entry) {
 		for (cdev_index = 0; cdev_index < num_cdevs; cdev_index++) {
 			cdev = nvgpu_kzalloc(g, sizeof(*cdev));
 			if (cdev == NULL) {
@@ -312,20 +354,22 @@ int gk20a_user_init(struct device *dev)
 				goto fail;
 			}
 
-		err = gk20a_create_device(dev, devno++, dev_node_list[cdev_index].name,
+			err = gk20a_create_device(dev, devno++,
+					dev_node_list[cdev_index].name,
 					&cdev->cdev, &cdev->node,
 					dev_node_list[cdev_index].fops,
-					  class);
+					class->class);
 			if (err) {
 				goto fail;
 			}
 
+			cdev->class = class->class;
 			nvgpu_init_list_node(&cdev->list_entry);
 			nvgpu_list_add(&cdev->list_entry, &l->cdev_list_head);
 		}
+	}
 
-	l->num_cdevs = num_cdevs;
-	l->devnode_class = class;
+	l->num_cdevs = total_cdevs;
 
 	return 0;
 fail:

drivers/gpu/nvgpu/os/linux/os_linux.h

@@ -76,6 +76,7 @@ struct dgpu_thermal_alert {
 struct nvgpu_cdev {
 	struct cdev cdev;
 	struct device *node;
+	struct class *class;
 	struct nvgpu_list_node list_entry;
 };
 
@@ -86,13 +87,25 @@ nvgpu_cdev_from_list_entry(struct nvgpu_list_node *node)
 		((uintptr_t)node - offsetof(struct nvgpu_cdev, list_entry));
 };
 
+struct nvgpu_class {
+	struct class *class;
+	struct nvgpu_list_node list_entry;
+};
+
+static inline struct nvgpu_class *
+nvgpu_class_from_list_entry(struct nvgpu_list_node *node)
+{
+	return (struct nvgpu_class *)
+		((uintptr_t)node - offsetof(struct nvgpu_class, list_entry));
+};
+
 struct nvgpu_os_linux {
 	struct gk20a g;
 	struct device *dev;
 	struct dgpu_thermal_alert thermal_alert;
 	struct nvgpu_interrupts interrupts;
-	struct class *devnode_class;
 
+	struct nvgpu_list_node class_list_head;
 	struct nvgpu_list_node cdev_list_head;
 	u32 num_cdevs;