libnvdimm, e820: Register all pmem resources

There is currently a mismatch between the resources that will trigger
the e820_pmem driver to register/load and the resources that will
actually be surfaced as pmem ranges. register_e820_pmem() uses
walk_iomem_res_desc() which includes children and siblings. In contrast,
e820_pmem_probe() only considers top level resources. For example the
following resource tree results in the driver being loaded, but no
resources being registered:

    398000000000-39bfffffffff : PCI Bus 0000:ae
      39be00000000-39bf07ffffff : PCI Bus 0000:af
        39be00000000-39beffffffff : 0000:af:00.0
          39be10000000-39beffffffff : Persistent Memory (legacy)

Fix this up to allow definitions of "legacy" pmem ranges anywhere in
system-physical address space. Not that it is a recommended or safe to
define a pmem range in PCI space, but it is useful for debug /
experimentation, and the restriction on being a top-level resource was
arbitrary.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 23 insertions, 19 deletions

diff --git a/drivers/nvdimm/e820.c b/drivers/nvdimm/e820.c
index 6f9a6ffd7cde..521eaf53a52a 100644
--- a/drivers/nvdimm/e820.c
+++ b/drivers/nvdimm/e820.c
@@ -38,12 +38,27 @@ static int e820_range_to_nid(resource_size_t addr)
 }
 #endif
 
+static int e820_register_one(struct resource *res, void *data)
+{
+        struct nd_region_desc ndr_desc;
+        struct nvdimm_bus *nvdimm_bus = data;
+
+        memset(&ndr_desc, 0, sizeof(ndr_desc));
+        ndr_desc.res = res;
+        ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
+        ndr_desc.numa_node = e820_range_to_nid(res->start);
+        set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
+        if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
+                return -ENXIO;
+        return 0;
+}
+
 static int e820_pmem_probe(struct platform_device *pdev)
 {
         static struct nvdimm_bus_descriptor nd_desc;
         struct device *dev = &pdev->dev;
         struct nvdimm_bus *nvdimm_bus;
-        struct resource *p;
+        int rc = -ENXIO;
 
         nd_desc.attr_groups = e820_pmem_attribute_groups;
         nd_desc.provider_name = "e820";
@@ -53,27 +68,15 @@ static int e820_pmem_probe(struct platform_device *pdev)
                 goto err;
         platform_set_drvdata(pdev, nvdimm_bus);
 
-        for (p = iomem_resource.child; p ; p = p->sibling) {
-                struct nd_region_desc ndr_desc;
-
-                if (p->desc != IORES_DESC_PERSISTENT_MEMORY_LEGACY)
-                        continue;
-
-                memset(&ndr_desc, 0, sizeof(ndr_desc));
-                ndr_desc.res = p;
-                ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
-                ndr_desc.numa_node = e820_range_to_nid(p->start);
-                set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
-                if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
-                        goto err;
-        }
-
+        rc = walk_iomem_res_desc(IORES_DESC_PERSISTENT_MEMORY_LEGACY,
+                        IORESOURCE_MEM, 0, -1, nvdimm_bus, e820_register_one);
+        if (rc)
+                goto err;
         return 0;
-
- err:
+err:
         nvdimm_bus_unregister(nvdimm_bus);
         dev_err(dev, "failed to register legacy persistent memory ranges\n");
-        return -ENXIO;
+        return rc;
 }
 
 static struct platform_driver e820_pmem_driver = {
diff --git a/kernel/resource.c b/kernel/resource.c
index 2af6c03858b9..b85f59e8a4b8 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -448,6 +448,7 @@ int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
 
         return __walk_iomem_res_desc(&res, desc, false, arg, func);
 }
+EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
 
 /*
  * This function calls the @func callback against all memory ranges of type