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Commit 7a67832c authored by Dan Williams's avatar Dan Williams
Browse files

libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option 



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: default avatarDan Williams <dan.j.williams@intel.com>
parent 6ec68954

arch/x86/Kconfig

+5 −1
Original line number Diff line number Diff line
@@ -1426,10 +1426,14 @@ config ILLEGAL_POINTER_VALUE 


source "mm/Kconfig"



config X86_PMEM_LEGACY_DEVICE

	bool



config X86_PMEM_LEGACY

	bool "Support non-standard NVDIMMs and ADR protected memory"

	tristate "Support non-standard NVDIMMs and ADR protected memory"

	depends on PHYS_ADDR_T_64BIT

	depends on BLK_DEV

	select X86_PMEM_LEGACY_DEVICE

	select LIBNVDIMM

	help

	  Treat memory marked using the non-standard e820 type of 12 as used

arch/x86/include/uapi/asm/e820.h

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ 
/*

 * This is a non-standardized way to represent ADR or NVDIMM regions that

 * persist over a reboot.  The kernel will ignore their special capabilities

 * unless the CONFIG_X86_PMEM_LEGACY=y option is set.

 * unless the CONFIG_X86_PMEM_LEGACY option is set.

 *

 * ( Note that older platforms also used 6 for the same type of memory,

 *   but newer versions switched to 12 as 6 was assigned differently.  Some

arch/x86/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -92,7 +92,7 @@ obj-$(CONFIG_KVM_GUEST) += kvm.o kvmclock.o 
obj-$(CONFIG_PARAVIRT)		+= paravirt.o paravirt_patch_$(BITS).o

obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= paravirt-spinlocks.o

obj-$(CONFIG_PARAVIRT_CLOCK)	+= pvclock.o

obj-$(CONFIG_X86_PMEM_LEGACY)	+= pmem.o

obj-$(CONFIG_X86_PMEM_LEGACY_DEVICE) += pmem.o



obj-$(CONFIG_PCSPKR_PLATFORM)	+= pcspeaker.o

arch/x86/kernel/pmem.c

+8 −71
Original line number Diff line number Diff line
@@ -3,80 +3,17 @@ 
 * Copyright (c) 2015, Intel Corporation.

 */

#include <linux/platform_device.h>

#include <linux/libnvdimm.h>

#include <linux/module.h>

#include <asm/e820.h>



static void e820_pmem_release(struct device *dev)

{

	struct nvdimm_bus *nvdimm_bus = dev->platform_data;



	if (nvdimm_bus)

		nvdimm_bus_unregister(nvdimm_bus);

}



static struct platform_device e820_pmem = {

	.name = "e820_pmem",

	.id = -1,

	.dev = {

		.release = e820_pmem_release,

	},

};



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 __init int register_e820_pmem(void)

{

	static struct nvdimm_bus_descriptor nd_desc;

	struct device *dev = &e820_pmem.dev;

	struct nvdimm_bus *nvdimm_bus;

	int rc, i;



	rc = platform_device_register(&e820_pmem);

	if (rc)

		return rc;

	struct platform_device *pdev;



	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;

	dev->platform_data = nvdimm_bus;



	for (i = 0; i < e820.nr_map; i++) {

		struct e820entry *ei = &e820.map[i];

		struct resource res = {

			.flags	= IORESOURCE_MEM,

			.start	= ei->addr,

			.end	= ei->addr + ei->size - 1,

		};

		struct nd_region_desc ndr_desc;



		if (ei->type != E820_PRAM)

			continue;



		memset(&ndr_desc, 0, sizeof(ndr_desc));

		ndr_desc.res = &res;

		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:

	dev_err(dev, "failed to register legacy persistent memory ranges\n");

	platform_device_unregister(&e820_pmem);

	return -ENXIO;

	/*

	 * See drivers/nvdimm/e820.c for the implementation, this is

	 * simply here to trigger the module to load on demand.

	 */

	pdev = platform_device_alloc("e820_pmem", -1);

	return platform_device_add(pdev);

}

device_initcall(register_e820_pmem);

drivers/nvdimm/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ obj-$(CONFIG_LIBNVDIMM) += libnvdimm.o 
obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o

obj-$(CONFIG_ND_BTT) += nd_btt.o

obj-$(CONFIG_ND_BLK) += nd_blk.o

obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o



nd_pmem-y := pmem.o
@@ -9,6 +10,8 @@ nd_btt-y := btt.o 


nd_blk-y := blk.o



nd_e820-y := e820.o



libnvdimm-y := core.o

libnvdimm-y += bus.o

libnvdimm-y += dimm_devs.o