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
8 static bool nohmem;
9 module_param_named(disable, nohmem, bool, 0444);
10
11 static bool platform_initialized;
12 static DEFINE_MUTEX(hmem_resource_lock);
13 static struct resource hmem_active = {
14 .name = "HMEM devices",
15 .start = 0,
16 .end = -1,
17 .flags = IORESOURCE_MEM,
18 };
19
walk_hmem_resources(struct device * host,walk_hmem_fn fn)20 int 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 }
34 EXPORT_SYMBOL_GPL(walk_hmem_resources);
35
__hmem_register_resource(int target_nid,struct resource * res)36 static 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
hmem_register_resource(int target_nid,struct resource * res)67 void 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
hmem_register_one(struct resource * res,void * data)77 static __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
hmem_init(void)84 static __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 */
95 device_initcall(hmem_init);
96