1// SPDX-License-Identifier: GPL-2.0
2#include <linux/platform_device.h>
3#include <linux/memregion.h>
4#include <linux/module.h>
5#include <linux/dax.h>
6#include <linux/mm.h>
7
8static bool nohmem;
9module_param_named(disable, nohmem, bool, 0444);
10
11static bool platform_initialized;
12static DEFINE_MUTEX(hmem_resource_lock);
13static struct resource hmem_active = {
14	.name = "HMEM devices",
15	.start = 0,
16	.end = -1,
17	.flags = IORESOURCE_MEM,
18};
19
20int walk_hmem_resources(struct device *host, walk_hmem_fn fn)
21{
22	struct resource *res;
23	int rc = 0;
24
25	mutex_lock(&hmem_resource_lock);
26	for (res = hmem_active.child; res; res = res->sibling) {
27		rc = fn(host, (int) res->desc, res);
28		if (rc)
29			break;
30	}
31	mutex_unlock(&hmem_resource_lock);
32	return rc;
33}
34EXPORT_SYMBOL_GPL(walk_hmem_resources);
35
36static void __hmem_register_resource(int target_nid, struct resource *res)
37{
38	struct platform_device *pdev;
39	struct resource *new;
40	int rc;
41
42	new = __request_region(&hmem_active, res->start, resource_size(res), "",
43			       0);
44	if (!new) {
45		pr_debug("hmem range %pr already active\n", res);
46		return;
47	}
48
49	new->desc = target_nid;
50
51	if (platform_initialized)
52		return;
53
54	pdev = platform_device_alloc("hmem_platform", 0);
55	if (!pdev) {
56		pr_err_once("failed to register device-dax hmem_platform device\n");
57		return;
58	}
59
60	rc = platform_device_add(pdev);
61	if (rc)
62		platform_device_put(pdev);
63	else
64		platform_initialized = true;
65}
66
67void hmem_register_resource(int target_nid, struct resource *res)
68{
69	if (nohmem)
70		return;
71
72	mutex_lock(&hmem_resource_lock);
73	__hmem_register_resource(target_nid, res);
74	mutex_unlock(&hmem_resource_lock);
75}
76
77static __init int hmem_register_one(struct resource *res, void *data)
78{
79	hmem_register_resource(phys_to_target_node(res->start), res);
80
81	return 0;
82}
83
84static __init int hmem_init(void)
85{
86	walk_iomem_res_desc(IORES_DESC_SOFT_RESERVED,
87			IORESOURCE_MEM, 0, -1, NULL, hmem_register_one);
88	return 0;
89}
90
91/*
92 * As this is a fallback for address ranges unclaimed by the ACPI HMAT
93 * parsing it must be at an initcall level greater than hmat_init().
94 */
95device_initcall(hmem_init);
96