1 files changed, 95 insertions, 0 deletions
diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c
new file mode 100644
index 0000000000..f9e1a76a04
--- /dev/null
+++ b/drivers/dax/hmem/device.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/platform_device.h>
+#include <linux/memregion.h>
+#include <linux/module.h>
+#include <linux/dax.h>
+#include <linux/mm.h>
+
+static bool nohmem;
+module_param_named(disable, nohmem, bool, 0444);
+
+static bool platform_initialized;
+static DEFINE_MUTEX(hmem_resource_lock);
+static struct resource hmem_active = {
+	.name = "HMEM devices",
+	.start = 0,
+	.end = -1,
+	.flags = IORESOURCE_MEM,
+};
+
+int walk_hmem_resources(struct device *host, walk_hmem_fn fn)
+{
+	struct resource *res;
+	int rc = 0;
+
+	mutex_lock(&hmem_resource_lock);
+	for (res = hmem_active.child; res; res = res->sibling) {
+		rc = fn(host, (int) res->desc, res);
+		if (rc)
+			break;
+	}
+	mutex_unlock(&hmem_resource_lock);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(walk_hmem_resources);
+
+static void __hmem_register_resource(int target_nid, struct resource *res)
+{
+	struct platform_device *pdev;
+	struct resource *new;
+	int rc;
+
+	new = __request_region(&hmem_active, res->start, resource_size(res), "",
+			       0);
+	if (!new) {
+		pr_debug("hmem range %pr already active\n", res);
+		return;
+	}
+
+	new->desc = target_nid;
+
+	if (platform_initialized)
+		return;
+
+	pdev = platform_device_alloc("hmem_platform", 0);
+	if (!pdev) {
+		pr_err_once("failed to register device-dax hmem_platform device\n");
+		return;
+	}
+
+	rc = platform_device_add(pdev);
+	if (rc)
+		platform_device_put(pdev);
+	else
+		platform_initialized = true;
+}
+
+void hmem_register_resource(int target_nid, struct resource *res)
+{
+	if (nohmem)
+		return;
+
+	mutex_lock(&hmem_resource_lock);
+	__hmem_register_resource(target_nid, res);
+	mutex_unlock(&hmem_resource_lock);
+}
+
+static __init int hmem_register_one(struct resource *res, void *data)
+{
+	hmem_register_resource(phys_to_target_node(res->start), res);
+
+	return 0;
+}
+
+static __init int hmem_init(void)
+{
+	walk_iomem_res_desc(IORES_DESC_SOFT_RESERVED,
+			IORESOURCE_MEM, 0, -1, NULL, hmem_register_one);
+	return 0;
+}
+
+/*
+ * As this is a fallback for address ranges unclaimed by the ACPI HMAT
+ * parsing it must be at an initcall level greater than hmat_init().
+ */
+device_initcall(hmem_init);