bifrost/r19p0/kernel/drivers/base/memory_group_manager/memory_group_manager.c - manifest_repos/mali-driver - Git at Google

 /*
  *
  * (C) COPYRIGHT 2019 ARM Limited. All rights reserved.
  *
  * This program is free software and is provided to you under the terms of the
  * GNU General Public License version 2 as published by the Free Software
  * Foundation, and any use by you of this program is subject to the terms
  * of such GNU licence.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, you can access it online at
  * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * SPDX-License-Identifier: GPL-2.0
  *
  */

 #include <linux/fs.h>
 #include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/version.h>
 #include <linux/module.h>
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif
 #include <linux/mm.h>
 #include <linux/memory_group_manager.h>

 #if (KERNEL_VERSION(4, 17, 0) > LINUX_VERSION_CODE)
 static inline vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma,
 			unsigned long addr, unsigned long pfn)
 {
 	int err = vm_insert_pfn(vma, addr, pfn);

 	if (unlikely(err == -ENOMEM))
 		return VM_FAULT_OOM;
 	if (unlikely(err < 0 && err != -EBUSY))
 		return VM_FAULT_SIGBUS;

 	return VM_FAULT_NOPAGE;
 }
 #endif

 #if (KERNEL_VERSION(4, 20, 0) > LINUX_VERSION_CODE)
 static inline vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma,
 			unsigned long addr, unsigned long pfn, pgprot_t pgprot)
 {
 	if (pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot))
 		return VM_FAULT_SIGBUS;

 	return vmf_insert_pfn(vma, addr, pfn);
 }
 #endif

 #define IMPORTED_MEMORY_ID (MEMORY_GROUP_MANAGER_NR_GROUPS - 1)

 /**
  * struct mgm_group - Structure to keep track of the number of allocated
  *                    pages per group
  *
  * @size:  The number of allocated small(4KB) pages
  * @lp_size:  The number of allocated large(2MB) pages
  * @insert_pfn: The number of calls to map pages for CPU access.
  * @update_gpu_pte: The number of calls to update GPU page table entries.
  *
  * This structure allows page allocation information to be displayed via
  * debugfs. Display is organized per group with small and large sized pages.
  */
 struct mgm_group {
 	size_t size;
 	size_t lp_size;
 	size_t insert_pfn;
 	size_t update_gpu_pte;
 };

 /**
  * struct mgm_groups - Structure for groups of memory group manager
  *
  * @groups: To keep track of the number of allocated pages of all groups
  * @dev: device attached
  * @mgm_debugfs_root: debugfs root directory of memory group manager
  *
  * This structure allows page allocation information to be displayed via
  * debugfs. Display is organized per group with small and large sized pages.
  */
 struct mgm_groups {
 	struct mgm_group groups[MEMORY_GROUP_MANAGER_NR_GROUPS];
 	struct device *dev;
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *mgm_debugfs_root;
 #endif
 };

 #ifdef CONFIG_DEBUG_FS

 static int mgm_size_get(void *data, u64 *val)
 {
 	struct mgm_group *group = data;

 	*val = group->size;

 	return 0;
 }

 static int mgm_lp_size_get(void *data, u64 *val)
 {
 	struct mgm_group *group = data;

 	*val = group->lp_size;

 	return 0;
 }

 static int mgm_insert_pfn_get(void *data, u64 *val)
 {
 	struct mgm_group *group = data;

 	*val = group->insert_pfn;

 	return 0;
 }

 static int mgm_update_gpu_pte_get(void *data, u64 *val)
 {
 	struct mgm_group *group = data;

 	*val = group->update_gpu_pte;

 	return 0;
 }

 DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_size, mgm_size_get, NULL, "%llu\n");
 DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_lp_size, mgm_lp_size_get, NULL, "%llu\n");

 DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_insert_pfn, mgm_insert_pfn_get, NULL,
 	"%llu\n");

 DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_update_gpu_pte, mgm_update_gpu_pte_get, NULL,
 	"%llu\n");

 static void mgm_term_debugfs(struct mgm_groups *data)
 {
 	debugfs_remove_recursive(data->mgm_debugfs_root);
 }

 #define MGM_DEBUGFS_GROUP_NAME_MAX 10
 static int mgm_initialize_debugfs(struct mgm_groups *mgm_data)
 {
 	int i;
 	struct dentry *e, *g;
 	char debugfs_group_name[MGM_DEBUGFS_GROUP_NAME_MAX];

 	/*
 	 * Create root directory of memory-group-manager
 	 */
 	mgm_data->mgm_debugfs_root =
 		debugfs_create_dir("physical-memory-group-manager", NULL);
 	if (IS_ERR(mgm_data->mgm_debugfs_root)) {
 		dev_err(mgm_data->dev, "fail to create debugfs root directory\n");
 		return -ENODEV;
 	}

 	/*
 	 * Create debugfs files per group
 	 */
 	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
 		scnprintf(debugfs_group_name, MGM_DEBUGFS_GROUP_NAME_MAX,
 				"group_%d", i);
 		g = debugfs_create_dir(debugfs_group_name,
 				mgm_data->mgm_debugfs_root);
 		if (IS_ERR(g)) {
 			dev_err(mgm_data->dev, "fail to create group[%d]\n", i);
 			goto remove_debugfs;
 		}

 		e = debugfs_create_file("size", 0444, g, &mgm_data->groups[i],
 				&fops_mgm_size);
 		if (IS_ERR(e)) {
 			dev_err(mgm_data->dev, "fail to create size[%d]\n", i);
 			goto remove_debugfs;
 		}

 		e = debugfs_create_file("lp_size", 0444, g,
 				&mgm_data->groups[i], &fops_mgm_lp_size);
 		if (IS_ERR(e)) {
 			dev_err(mgm_data->dev,
 				"fail to create lp_size[%d]\n", i);
 			goto remove_debugfs;
 		}

 		e = debugfs_create_file("insert_pfn", 0444, g,
 				&mgm_data->groups[i], &fops_mgm_insert_pfn);
 		if (IS_ERR(e)) {
 			dev_err(mgm_data->dev,
 				"fail to create insert_pfn[%d]\n", i);
 			goto remove_debugfs;
 		}

 		e = debugfs_create_file("update_gpu_pte", 0444, g,
 				&mgm_data->groups[i], &fops_mgm_update_gpu_pte);
 		if (IS_ERR(e)) {
 			dev_err(mgm_data->dev,
 				"fail to create update_gpu_pte[%d]\n", i);
 			goto remove_debugfs;
 		}
 	}

 	return 0;

 remove_debugfs:
 	mgm_term_debugfs(mgm_data);
 	return -ENODEV;
 }

 #else

 static void mgm_term_debugfs(struct mgm_groups *data)
 {
 }

 static int mgm_initialize_debugfs(struct mgm_groups *mgm_data)
 {
 	return 0;
 }

 #endif /* CONFIG_DEBUG_FS */

 #define ORDER_SMALL_PAGE 0
 #define ORDER_LARGE_PAGE 9
 static void update_size(struct memory_group_manager_device *mgm_dev, int
 		group_id, int order, bool alloc)
 {
 	struct mgm_groups *data = mgm_dev->data;

 	switch (order) {
 	case ORDER_SMALL_PAGE:
 		if (alloc)
 			data->groups[group_id].size++;
 		else {
 			WARN_ON(data->groups[group_id].size == 0);
 			data->groups[group_id].size--;
 		}
 	break;

 	case ORDER_LARGE_PAGE:
 		if (alloc)
 			data->groups[group_id].lp_size++;
 		else {
 			WARN_ON(data->groups[group_id].lp_size == 0);
 			data->groups[group_id].lp_size--;
 		}
 	break;

 	default:
 		dev_err(data->dev, "Unknown order(%d)\n", order);
 	break;
 	}
 }

 static struct page *example_mgm_alloc_page(
 	struct memory_group_manager_device *mgm_dev, int group_id,
 	gfp_t gfp_mask, unsigned int order)
 {
 	struct mgm_groups *const data = mgm_dev->data;
 	struct page *p;

 	dev_dbg(data->dev, "%s(mgm_dev=%p, group_id=%d gfp_mask=0x%x order=%u\n",
 		__func__, (void *)mgm_dev, group_id, gfp_mask, order);

 	if (WARN_ON(group_id < 0) ||
 		WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
 		return NULL;

 	p = alloc_pages(gfp_mask, order);

 	if (p) {
 		update_size(mgm_dev, group_id, order, true);
 	} else {
 		struct mgm_groups *data = mgm_dev->data;

 		dev_err(data->dev, "alloc_pages failed\n");
 	}

 	return p;
 }

 static void example_mgm_free_page(
 	struct memory_group_manager_device *mgm_dev, int group_id,
 	struct page *page, unsigned int order)
 {
 	struct mgm_groups *const data = mgm_dev->data;

 	dev_dbg(data->dev, "%s(mgm_dev=%p, group_id=%d page=%p order=%u\n",
 		__func__, (void *)mgm_dev, group_id, (void *)page, order);

 	if (WARN_ON(group_id < 0) ||
 		WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
 		return;

 	__free_pages(page, order);

 	update_size(mgm_dev, group_id, order, false);
 }

 static int example_mgm_get_import_memory_id(
 	struct memory_group_manager_device *mgm_dev,
 	struct memory_group_manager_import_data *import_data)
 {
 	struct mgm_groups *const data = mgm_dev->data;

 	dev_dbg(data->dev, "%s(mgm_dev=%p, import_data=%p (type=%d)\n",
 		__func__, (void *)mgm_dev, (void *)import_data,
 		(int)import_data->type);

 	if (!WARN_ON(!import_data)) {
 		WARN_ON(!import_data->u.dma_buf);

 		WARN_ON(import_data->type !=
 				MEMORY_GROUP_MANAGER_IMPORT_TYPE_DMA_BUF);
 	}

 	return IMPORTED_MEMORY_ID;
 }

 static u64 example_mgm_update_gpu_pte(
 	struct memory_group_manager_device *const mgm_dev, int const group_id,
 	int const mmu_level, u64 pte)
 {
 	struct mgm_groups *const data = mgm_dev->data;
 	const u32 pbha_bit_pos = 59; /* bits 62:59 */
 	const u32 pbha_bit_mask = 0xf; /* 4-bit */

 	dev_dbg(data->dev,
 		"%s(mgm_dev=%p, group_id=%d, mmu_level=%d, pte=0x%llx)\n",
 		__func__, (void *)mgm_dev, group_id, mmu_level, pte);

 	if (WARN_ON(group_id < 0) ||
 		WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
 		return pte;

 	pte |= ((u64)group_id & pbha_bit_mask) << pbha_bit_pos;

 	data->groups[group_id].update_gpu_pte++;

 	return pte;
 }

 static vm_fault_t example_mgm_vmf_insert_pfn_prot(
 	struct memory_group_manager_device *const mgm_dev, int const group_id,
 	struct vm_area_struct *const vma, unsigned long const addr,
 	unsigned long const pfn, pgprot_t const prot)
 {
 	struct mgm_groups *const data = mgm_dev->data;
 	vm_fault_t fault;

 	dev_dbg(data->dev,
 		"%s(mgm_dev=%p, group_id=%d, vma=%p, addr=0x%lx, pfn=0x%lx, prot=0x%llx)\n",
 		__func__, (void *)mgm_dev, group_id, (void *)vma, addr, pfn,
 		pgprot_val(prot));

 	if (WARN_ON(group_id < 0) ||
 		WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
 		return VM_FAULT_SIGBUS;

 	fault = vmf_insert_pfn_prot(vma, addr, pfn, prot);

 	if (fault == VM_FAULT_NOPAGE)
 		data->groups[group_id].insert_pfn++;
 	else
 		dev_err(data->dev, "vmf_insert_pfn_prot failed\n");

 	return fault;
 }

 static int mgm_initialize_data(struct mgm_groups *mgm_data)
 {
 	int i;

 	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
 		mgm_data->groups[i].size = 0;
 		mgm_data->groups[i].lp_size = 0;
 		mgm_data->groups[i].insert_pfn = 0;
 		mgm_data->groups[i].update_gpu_pte = 0;
 	}

 	return mgm_initialize_debugfs(mgm_data);
 }

 static void mgm_term_data(struct mgm_groups *data)
 {
 	int i;

 	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
 		if (data->groups[i].size != 0)
 			dev_warn(data->dev,
 				"%zu 0-order pages in group(%d) leaked\n",
 				data->groups[i].size, i);
 		if (data->groups[i].lp_size != 0)
 			dev_warn(data->dev,
 				"%zu 9 order pages in group(%d) leaked\n",
 				data->groups[i].lp_size, i);
 	}

 	mgm_term_debugfs(data);
 }

 static int memory_group_manager_probe(struct platform_device *pdev)
 {
 	struct memory_group_manager_device *mgm_dev;
 	struct mgm_groups *mgm_data;

 	mgm_dev = kzalloc(sizeof(*mgm_dev), GFP_KERNEL);
 	if (!mgm_dev)
 		return -ENOMEM;

 	mgm_dev->owner = THIS_MODULE;
 	mgm_dev->ops.mgm_alloc_page = example_mgm_alloc_page;
 	mgm_dev->ops.mgm_free_page = example_mgm_free_page;
 	mgm_dev->ops.mgm_get_import_memory_id =
 			example_mgm_get_import_memory_id;
 	mgm_dev->ops.mgm_vmf_insert_pfn_prot = example_mgm_vmf_insert_pfn_prot;
 	mgm_dev->ops.mgm_update_gpu_pte = example_mgm_update_gpu_pte;

 	mgm_data = kzalloc(sizeof(*mgm_data), GFP_KERNEL);
 	if (!mgm_data) {
 		kfree(mgm_dev);
 		return -ENOMEM;
 	}

 	mgm_dev->data = mgm_data;
 	mgm_data->dev = &pdev->dev;

 	if (mgm_initialize_data(mgm_data)) {
 		kfree(mgm_data);
 		kfree(mgm_dev);
 		return -ENOENT;
 	}

 	platform_set_drvdata(pdev, mgm_dev);
 	dev_info(&pdev->dev, "Memory group manager probed successfully\n");

 	return 0;
 }

 static int memory_group_manager_remove(struct platform_device *pdev)
 {
 	struct memory_group_manager_device *mgm_dev =
 		platform_get_drvdata(pdev);
 	struct mgm_groups *mgm_data = mgm_dev->data;

 	mgm_term_data(mgm_data);
 	kfree(mgm_data);

 	kfree(mgm_dev);

 	dev_info(&pdev->dev, "Memory group manager removed successfully\n");

 	return 0;
 }

 static const struct of_device_id memory_group_manager_dt_ids[] = {
 	{ .compatible = "arm,physical-memory-group-manager" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, memory_group_manager_dt_ids);

 static struct platform_driver memory_group_manager_driver = {
 	.probe = memory_group_manager_probe,
 	.remove = memory_group_manager_remove,
 	.driver = {
 		.name = "physical-memory-group-manager",
 		.owner = THIS_MODULE,
 		.of_match_table = of_match_ptr(memory_group_manager_dt_ids),
 		/*
 		 * Prevent the mgm_dev from being unbound and freed, as other's
 		 * may have pointers to it and would get confused, or crash, if
 		 * it suddenly disappear.
 		 */
 		.suppress_bind_attrs = true,
 	}
 };

 module_platform_driver(memory_group_manager_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("ARM Ltd.");
 MODULE_VERSION("1.0");
	/*
	*
	* (C) COPYRIGHT 2019 ARM Limited. All rights reserved.
	*
	* This program is free software and is provided to you under the terms of the
	* GNU General Public License version 2 as published by the Free Software
	* Foundation, and any use by you of this program is subject to the terms
	* of such GNU licence.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, you can access it online at
	* http://www.gnu.org/licenses/gpl-2.0.html.
	*
	* SPDX-License-Identifier: GPL-2.0
	*
	*/

	#include <linux/fs.h>
	#include <linux/of.h>
	#include <linux/slab.h>
	#include <linux/platform_device.h>
	#include <linux/version.h>
	#include <linux/module.h>
	#ifdef CONFIG_DEBUG_FS
	#include <linux/debugfs.h>
	#endif
	#include <linux/mm.h>
	#include <linux/memory_group_manager.h>

	#if (KERNEL_VERSION(4, 17, 0) > LINUX_VERSION_CODE)
	static inline vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma,
	unsigned long addr, unsigned long pfn)
	{
	int err = vm_insert_pfn(vma, addr, pfn);

	if (unlikely(err == -ENOMEM))
	return VM_FAULT_OOM;
	if (unlikely(err < 0 && err != -EBUSY))
	return VM_FAULT_SIGBUS;

	return VM_FAULT_NOPAGE;
	}
	#endif

	#if (KERNEL_VERSION(4, 20, 0) > LINUX_VERSION_CODE)
	static inline vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma,
	unsigned long addr, unsigned long pfn, pgprot_t pgprot)
	{
	if (pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot))
	return VM_FAULT_SIGBUS;

	return vmf_insert_pfn(vma, addr, pfn);
	}
	#endif

	#define IMPORTED_MEMORY_ID (MEMORY_GROUP_MANAGER_NR_GROUPS - 1)

	/**
	* struct mgm_group - Structure to keep track of the number of allocated
	* pages per group
	*
	* @size: The number of allocated small(4KB) pages
	* @lp_size: The number of allocated large(2MB) pages
	* @insert_pfn: The number of calls to map pages for CPU access.
	* @update_gpu_pte: The number of calls to update GPU page table entries.
	*
	* This structure allows page allocation information to be displayed via
	* debugfs. Display is organized per group with small and large sized pages.
	*/
	struct mgm_group {
	size_t size;
	size_t lp_size;
	size_t insert_pfn;
	size_t update_gpu_pte;
	};

	/**
	* struct mgm_groups - Structure for groups of memory group manager
	*
	* @groups: To keep track of the number of allocated pages of all groups
	* @dev: device attached
	* @mgm_debugfs_root: debugfs root directory of memory group manager
	*
	* This structure allows page allocation information to be displayed via
	* debugfs. Display is organized per group with small and large sized pages.
	*/
	struct mgm_groups {
	struct mgm_group groups[MEMORY_GROUP_MANAGER_NR_GROUPS];
	struct device *dev;
	#ifdef CONFIG_DEBUG_FS
	struct dentry *mgm_debugfs_root;
	#endif
	};

	#ifdef CONFIG_DEBUG_FS

	static int mgm_size_get(void data, u64 val)
	{
	struct mgm_group *group = data;

	*val = group->size;

	return 0;
	}

	static int mgm_lp_size_get(void data, u64 val)
	{
	struct mgm_group *group = data;

	*val = group->lp_size;

	return 0;
	}

	static int mgm_insert_pfn_get(void data, u64 val)
	{
	struct mgm_group *group = data;

	*val = group->insert_pfn;

	return 0;
	}

	static int mgm_update_gpu_pte_get(void data, u64 val)
	{
	struct mgm_group *group = data;

	*val = group->update_gpu_pte;

	return 0;
	}

	DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_size, mgm_size_get, NULL, "%llu\n");
	DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_lp_size, mgm_lp_size_get, NULL, "%llu\n");

	DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_insert_pfn, mgm_insert_pfn_get, NULL,
	"%llu\n");

	DEFINE_SIMPLE_ATTRIBUTE(fops_mgm_update_gpu_pte, mgm_update_gpu_pte_get, NULL,
	"%llu\n");

	static void mgm_term_debugfs(struct mgm_groups *data)
	{
	debugfs_remove_recursive(data->mgm_debugfs_root);
	}

	#define MGM_DEBUGFS_GROUP_NAME_MAX 10
	static int mgm_initialize_debugfs(struct mgm_groups *mgm_data)
	{
	int i;
	struct dentry e, g;
	char debugfs_group_name[MGM_DEBUGFS_GROUP_NAME_MAX];

	/*
	* Create root directory of memory-group-manager
	*/
	mgm_data->mgm_debugfs_root =
	debugfs_create_dir("physical-memory-group-manager", NULL);
	if (IS_ERR(mgm_data->mgm_debugfs_root)) {
	dev_err(mgm_data->dev, "fail to create debugfs root directory\n");
	return -ENODEV;
	}

	/*
	* Create debugfs files per group
	*/
	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
	scnprintf(debugfs_group_name, MGM_DEBUGFS_GROUP_NAME_MAX,
	"group_%d", i);
	g = debugfs_create_dir(debugfs_group_name,
	mgm_data->mgm_debugfs_root);
	if (IS_ERR(g)) {
	dev_err(mgm_data->dev, "fail to create group[%d]\n", i);
	goto remove_debugfs;
	}

	e = debugfs_create_file("size", 0444, g, &mgm_data->groups[i],
	&fops_mgm_size);
	if (IS_ERR(e)) {
	dev_err(mgm_data->dev, "fail to create size[%d]\n", i);
	goto remove_debugfs;
	}

	e = debugfs_create_file("lp_size", 0444, g,
	&mgm_data->groups[i], &fops_mgm_lp_size);
	if (IS_ERR(e)) {
	dev_err(mgm_data->dev,
	"fail to create lp_size[%d]\n", i);
	goto remove_debugfs;
	}

	e = debugfs_create_file("insert_pfn", 0444, g,
	&mgm_data->groups[i], &fops_mgm_insert_pfn);
	if (IS_ERR(e)) {
	dev_err(mgm_data->dev,
	"fail to create insert_pfn[%d]\n", i);
	goto remove_debugfs;
	}

	e = debugfs_create_file("update_gpu_pte", 0444, g,
	&mgm_data->groups[i], &fops_mgm_update_gpu_pte);
	if (IS_ERR(e)) {
	dev_err(mgm_data->dev,
	"fail to create update_gpu_pte[%d]\n", i);
	goto remove_debugfs;
	}
	}

	return 0;

	remove_debugfs:
	mgm_term_debugfs(mgm_data);
	return -ENODEV;
	}

	#else

	static void mgm_term_debugfs(struct mgm_groups *data)
	{
	}

	static int mgm_initialize_debugfs(struct mgm_groups *mgm_data)
	{
	return 0;
	}

	#endif /* CONFIG_DEBUG_FS */

	#define ORDER_SMALL_PAGE 0
	#define ORDER_LARGE_PAGE 9
	static void update_size(struct memory_group_manager_device *mgm_dev, int
	group_id, int order, bool alloc)
	{
	struct mgm_groups *data = mgm_dev->data;

	switch (order) {
	case ORDER_SMALL_PAGE:
	if (alloc)
	data->groups[group_id].size++;
	else {
	WARN_ON(data->groups[group_id].size == 0);
	data->groups[group_id].size--;
	}
	break;

	case ORDER_LARGE_PAGE:
	if (alloc)
	data->groups[group_id].lp_size++;
	else {
	WARN_ON(data->groups[group_id].lp_size == 0);
	data->groups[group_id].lp_size--;
	}
	break;

	default:
	dev_err(data->dev, "Unknown order(%d)\n", order);
	break;
	}
	}

	static struct page *example_mgm_alloc_page(
	struct memory_group_manager_device *mgm_dev, int group_id,
	gfp_t gfp_mask, unsigned int order)
	{
	struct mgm_groups *const data = mgm_dev->data;
	struct page *p;

	dev_dbg(data->dev, "%s(mgm_dev=%p, group_id=%d gfp_mask=0x%x order=%u\n",
	__func__, (void *)mgm_dev, group_id, gfp_mask, order);

	if (WARN_ON(group_id < 0) \|\|
	WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
	return NULL;

	p = alloc_pages(gfp_mask, order);

	if (p) {
	update_size(mgm_dev, group_id, order, true);
	} else {
	struct mgm_groups *data = mgm_dev->data;

	dev_err(data->dev, "alloc_pages failed\n");
	}

	return p;
	}

	static void example_mgm_free_page(
	struct memory_group_manager_device *mgm_dev, int group_id,
	struct page *page, unsigned int order)
	{
	struct mgm_groups *const data = mgm_dev->data;

	dev_dbg(data->dev, "%s(mgm_dev=%p, group_id=%d page=%p order=%u\n",
	__func__, (void )mgm_dev, group_id, (void )page, order);

	if (WARN_ON(group_id < 0) \|\|
	WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
	return;

	__free_pages(page, order);

	update_size(mgm_dev, group_id, order, false);
	}

	static int example_mgm_get_import_memory_id(
	struct memory_group_manager_device *mgm_dev,
	struct memory_group_manager_import_data *import_data)
	{
	struct mgm_groups *const data = mgm_dev->data;

	dev_dbg(data->dev, "%s(mgm_dev=%p, import_data=%p (type=%d)\n",
	__func__, (void )mgm_dev, (void )import_data,
	(int)import_data->type);

	if (!WARN_ON(!import_data)) {
	WARN_ON(!import_data->u.dma_buf);

	WARN_ON(import_data->type !=
	MEMORY_GROUP_MANAGER_IMPORT_TYPE_DMA_BUF);
	}

	return IMPORTED_MEMORY_ID;
	}

	static u64 example_mgm_update_gpu_pte(
	struct memory_group_manager_device *const mgm_dev, int const group_id,
	int const mmu_level, u64 pte)
	{
	struct mgm_groups *const data = mgm_dev->data;
	const u32 pbha_bit_pos = 59; /* bits 62:59 */
	const u32 pbha_bit_mask = 0xf; /* 4-bit */

	dev_dbg(data->dev,
	"%s(mgm_dev=%p, group_id=%d, mmu_level=%d, pte=0x%llx)\n",
	__func__, (void *)mgm_dev, group_id, mmu_level, pte);

	if (WARN_ON(group_id < 0) \|\|
	WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
	return pte;

	pte \|= ((u64)group_id & pbha_bit_mask) << pbha_bit_pos;

	data->groups[group_id].update_gpu_pte++;

	return pte;
	}

	static vm_fault_t example_mgm_vmf_insert_pfn_prot(
	struct memory_group_manager_device *const mgm_dev, int const group_id,
	struct vm_area_struct *const vma, unsigned long const addr,
	unsigned long const pfn, pgprot_t const prot)
	{
	struct mgm_groups *const data = mgm_dev->data;
	vm_fault_t fault;

	dev_dbg(data->dev,
	"%s(mgm_dev=%p, group_id=%d, vma=%p, addr=0x%lx, pfn=0x%lx, prot=0x%llx)\n",
	__func__, (void )mgm_dev, group_id, (void )vma, addr, pfn,
	pgprot_val(prot));

	if (WARN_ON(group_id < 0) \|\|
	WARN_ON(group_id >= MEMORY_GROUP_MANAGER_NR_GROUPS))
	return VM_FAULT_SIGBUS;

	fault = vmf_insert_pfn_prot(vma, addr, pfn, prot);

	if (fault == VM_FAULT_NOPAGE)
	data->groups[group_id].insert_pfn++;
	else
	dev_err(data->dev, "vmf_insert_pfn_prot failed\n");

	return fault;
	}

	static int mgm_initialize_data(struct mgm_groups *mgm_data)
	{
	int i;

	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
	mgm_data->groups[i].size = 0;
	mgm_data->groups[i].lp_size = 0;
	mgm_data->groups[i].insert_pfn = 0;
	mgm_data->groups[i].update_gpu_pte = 0;
	}

	return mgm_initialize_debugfs(mgm_data);
	}

	static void mgm_term_data(struct mgm_groups *data)
	{
	int i;

	for (i = 0; i < MEMORY_GROUP_MANAGER_NR_GROUPS; i++) {
	if (data->groups[i].size != 0)
	dev_warn(data->dev,
	"%zu 0-order pages in group(%d) leaked\n",
	data->groups[i].size, i);
	if (data->groups[i].lp_size != 0)
	dev_warn(data->dev,
	"%zu 9 order pages in group(%d) leaked\n",
	data->groups[i].lp_size, i);
	}

	mgm_term_debugfs(data);
	}

	static int memory_group_manager_probe(struct platform_device *pdev)
	{
	struct memory_group_manager_device *mgm_dev;
	struct mgm_groups *mgm_data;

	mgm_dev = kzalloc(sizeof(*mgm_dev), GFP_KERNEL);
	if (!mgm_dev)
	return -ENOMEM;

	mgm_dev->owner = THIS_MODULE;
	mgm_dev->ops.mgm_alloc_page = example_mgm_alloc_page;
	mgm_dev->ops.mgm_free_page = example_mgm_free_page;
	mgm_dev->ops.mgm_get_import_memory_id =
	example_mgm_get_import_memory_id;
	mgm_dev->ops.mgm_vmf_insert_pfn_prot = example_mgm_vmf_insert_pfn_prot;
	mgm_dev->ops.mgm_update_gpu_pte = example_mgm_update_gpu_pte;

	mgm_data = kzalloc(sizeof(*mgm_data), GFP_KERNEL);
	if (!mgm_data) {
	kfree(mgm_dev);
	return -ENOMEM;
	}

	mgm_dev->data = mgm_data;
	mgm_data->dev = &pdev->dev;

	if (mgm_initialize_data(mgm_data)) {
	kfree(mgm_data);
	kfree(mgm_dev);
	return -ENOENT;
	}

	platform_set_drvdata(pdev, mgm_dev);
	dev_info(&pdev->dev, "Memory group manager probed successfully\n");

	return 0;
	}

	static int memory_group_manager_remove(struct platform_device *pdev)
	{
	struct memory_group_manager_device *mgm_dev =
	platform_get_drvdata(pdev);
	struct mgm_groups *mgm_data = mgm_dev->data;

	mgm_term_data(mgm_data);
	kfree(mgm_data);

	kfree(mgm_dev);

	dev_info(&pdev->dev, "Memory group manager removed successfully\n");

	return 0;
	}

	static const struct of_device_id memory_group_manager_dt_ids[] = {
	{ .compatible = "arm,physical-memory-group-manager" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, memory_group_manager_dt_ids);

	static struct platform_driver memory_group_manager_driver = {
	.probe = memory_group_manager_probe,
	.remove = memory_group_manager_remove,
	.driver = {
	.name = "physical-memory-group-manager",
	.owner = THIS_MODULE,
	.of_match_table = of_match_ptr(memory_group_manager_dt_ids),
	/*
	* Prevent the mgm_dev from being unbound and freed, as other's
	* may have pointers to it and would get confused, or crash, if
	* it suddenly disappear.
	*/
	.suppress_bind_attrs = true,
	}
	};

	module_platform_driver(memory_group_manager_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("ARM Ltd.");
	MODULE_VERSION("1.0");