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libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option

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We currently register a platform device for e820 type-12 memory and
register a nvdimm bus beneath it.  Registering the platform device
triggers the device-core machinery to probe for a driver, but that
search currently comes up empty.  Building the nvdimm-bus registration
into the e820_pmem platform device registration in this way forces
libnvdimm to be built-in.  Instead, convert the built-in portion of
CONFIG_X86_PMEM_LEGACY to simply register a platform device and move the
rest of the logic to the driver for e820_pmem, for the following
reasons:

1/ Letting e820_pmem support be a module allows building and testing
   libnvdimm.ko changes without rebooting

2/ All the normal policy around modules can be applied to e820_pmem
   (unbind to disable and/or blacklisting the module from loading by
   default)

3/ Moving the driver to a generic location and converting it to scan
   "iomem_resource" rather than "e820.map" means any other architecture can
   take advantage of this simple nvdimm resource discovery mechanism by
   registering a resource named "Persistent Memory (legacy)"

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2015-08-19 00:34:34 -04:00
parent 6ec689542b
commit 7a67832c7e
7 changed files with 107 additions and 73 deletions
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86
drivers/nvdimm/e820.c Normal file
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/*
* Copyright (c) 2015, Christoph Hellwig.
* Copyright (c) 2015, Intel Corporation.
*/
#include <linux/platform_device.h>
#include <linux/libnvdimm.h>
#include <linux/module.h>
static const struct attribute_group *e820_pmem_attribute_groups[] = {
&nvdimm_bus_attribute_group,
NULL,
};
static const struct attribute_group *e820_pmem_region_attribute_groups[] = {
&nd_region_attribute_group,
&nd_device_attribute_group,
NULL,
};
static int e820_pmem_remove(struct platform_device *pdev)
{
struct nvdimm_bus *nvdimm_bus = platform_get_drvdata(pdev);
nvdimm_bus_unregister(nvdimm_bus);
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;
nd_desc.attr_groups = e820_pmem_attribute_groups;
nd_desc.provider_name = "e820";
nvdimm_bus = nvdimm_bus_register(dev, &nd_desc);
if (!nvdimm_bus)
goto err;
platform_set_drvdata(pdev, nvdimm_bus);
for (p = iomem_resource.child; p ; p = p->sibling) {
struct nd_region_desc ndr_desc;
if (strncmp(p->name, "Persistent Memory (legacy)", 26) != 0)
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 = NUMA_NO_NODE;
if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
goto err;
}
return 0;
err:
nvdimm_bus_unregister(nvdimm_bus);
dev_err(dev, "failed to register legacy persistent memory ranges\n");
return -ENXIO;
}
static struct platform_driver e820_pmem_driver = {
.probe = e820_pmem_probe,
.remove = e820_pmem_remove,
.driver = {
.name = "e820_pmem",
},
};
static __init int e820_pmem_init(void)
{
return platform_driver_register(&e820_pmem_driver);
}
static __exit void e820_pmem_exit(void)
{
platform_driver_unregister(&e820_pmem_driver);
}
MODULE_ALIAS("platform:e820_pmem*");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Intel Corporation");
module_init(e820_pmem_init);
module_exit(e820_pmem_exit);