dax/hmem: Move hmem device registration to dax_hmem.ko

In preparation for the CXL region driver to take over the responsibility
of registering device-dax instances for CXL regions, move the
registration of "hmem" devices to dax_hmem.ko.

Previously the builtin component of this enabling
(drivers/dax/hmem/device.o) would register platform devices for each
address range and trigger the dax_hmem.ko module to load and attach
device-dax instances to those devices. Now, the ranges are collected
from the HMAT and EFI memory map walking, but the device creation is
deferred. A new "hmem_platform" device is created which triggers
dax_hmem.ko to load and register the platform devices.

Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/167602002771.1924368.5653558226424530127.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 104 insertions, 1 deletions

diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 5025a8c9850b..e7bdff3132fa 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -3,6 +3,7 @@
 #include <linux/memregion.h>
 #include <linux/module.h>
 #include <linux/pfn_t.h>
+#include <linux/dax.h>
 #include "../bus.h"
 
 static bool region_idle;
@@ -43,8 +44,110 @@ static struct platform_driver dax_hmem_driver = {
 	},
 };
 
-module_platform_driver(dax_hmem_driver);
+static void release_memregion(void *data)
+{
+	memregion_free((long) data);
+}
+
+static void release_hmem(void *pdev)
+{
+	platform_device_unregister(pdev);
+}
+
+static int hmem_register_device(struct device *host, int target_nid,
+				const struct resource *res)
+{
+	struct platform_device *pdev;
+	struct memregion_info info;
+	long id;
+	int rc;
+
+	rc = region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
+			       IORES_DESC_SOFT_RESERVED);
+	if (rc != REGION_INTERSECTS)
+		return 0;
+
+	id = memregion_alloc(GFP_KERNEL);
+	if (id < 0) {
+		dev_err(host, "memregion allocation failure for %pr\n", res);
+		return -ENOMEM;
+	}
+	rc = devm_add_action_or_reset(host, release_memregion, (void *) id);
+	if (rc)
+		return rc;
+
+	pdev = platform_device_alloc("hmem", id);
+	if (!pdev) {
+		dev_err(host, "device allocation failure for %pr\n", res);
+		return -ENOMEM;
+	}
+
+	pdev->dev.numa_node = numa_map_to_online_node(target_nid);
+	info = (struct memregion_info) {
+		.target_node = target_nid,
+		.range = {
+			.start = res->start,
+			.end = res->end,
+		},
+	};
+	rc = platform_device_add_data(pdev, &info, sizeof(info));
+	if (rc < 0) {
+		dev_err(host, "memregion_info allocation failure for %pr\n",
+		       res);
+		goto out_put;
+	}
+
+	rc = platform_device_add(pdev);
+	if (rc < 0) {
+		dev_err(host, "%s add failed for %pr\n", dev_name(&pdev->dev),
+			res);
+		goto out_put;
+	}
+
+	return devm_add_action_or_reset(host, release_hmem, pdev);
+
+out_put:
+	platform_device_put(pdev);
+	return rc;
+}
+
+static int dax_hmem_platform_probe(struct platform_device *pdev)
+{
+	return walk_hmem_resources(&pdev->dev, hmem_register_device);
+}
+
+static struct platform_driver dax_hmem_platform_driver = {
+	.probe = dax_hmem_platform_probe,
+	.driver = {
+		.name = "hmem_platform",
+	},
+};
+
+static __init int dax_hmem_init(void)
+{
+	int rc;
+
+	rc = platform_driver_register(&dax_hmem_platform_driver);
+	if (rc)
+		return rc;
+
+	rc = platform_driver_register(&dax_hmem_driver);
+	if (rc)
+		platform_driver_unregister(&dax_hmem_platform_driver);
+
+	return rc;
+}
+
+static __exit void dax_hmem_exit(void)
+{
+	platform_driver_unregister(&dax_hmem_driver);
+	platform_driver_unregister(&dax_hmem_platform_driver);
+}
+
+module_init(dax_hmem_init);
+module_exit(dax_hmem_exit);
 
 MODULE_ALIAS("platform:hmem*");
+MODULE_ALIAS("platform:hmem_platform*");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Intel Corporation");