libnvdimm: introduce devm_nvdimm_memremap(), convert nfit_spa_map() users

In preparation for generically mapping flush hint addresses for both the
BLK and PMEM use case, provide a generic / reference counted mapping
api.  Given the fact that a dimm may belong to multiple regions (PMEM
and BLK), the flush hint addresses need to be held valid as long as any
region associated with the dimm is active.  This is similar to the
existing BLK-region case where multiple BLK-regions may share an
aperture mapping.  Up-level this shared / reference-counted mapping
capability from the nfit driver to a core nvdimm capability.

This eliminates the need for the nd_blk_region.disable() callback.  Note
that the removal of nfit_spa_map() and related infrastructure is
deferred to a later patch.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit.c

@@ -1616,7 +1616,8 @@ static void __iomem *__nfit_spa_map(struct acpi_nfit_desc *acpi_desc,
  * when all region devices referencing the same mapping are disabled /
  * unbound.
  */
-static void __iomem *nfit_spa_map(struct acpi_nfit_desc *acpi_desc,
+static __maybe_unused void __iomem *nfit_spa_map(
+		struct acpi_nfit_desc *acpi_desc,
 		struct acpi_nfit_system_address *spa, enum spa_map_type type)
 {
 	void __iomem *iomem;
@@ -1669,7 +1670,6 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
 		struct device *dev)
 {
 	struct nvdimm_bus_descriptor *nd_desc = to_nd_desc(nvdimm_bus);
-	struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
 	struct nd_blk_region *ndbr = to_nd_blk_region(dev);
 	struct nfit_flush *nfit_flush;
 	struct nfit_blk_mmio *mmio;
@@ -1697,8 +1697,8 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
 	/* map block aperture memory */
 	nfit_blk->bdw_offset = nfit_mem->bdw->offset;
 	mmio = &nfit_blk->mmio[BDW];
-	mmio->addr.base = nfit_spa_map(acpi_desc, nfit_mem->spa_bdw,
-			SPA_MAP_APERTURE);
+	mmio->addr.base = devm_nvdimm_memremap(dev, nfit_mem->spa_bdw->address,
+                        nfit_mem->spa_bdw->length, ARCH_MEMREMAP_PMEM);
 	if (!mmio->addr.base) {
 		dev_dbg(dev, "%s: %s failed to map bdw\n", __func__,
 				nvdimm_name(nvdimm));
@@ -1720,8 +1720,8 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
 	nfit_blk->cmd_offset = nfit_mem->dcr->command_offset;
 	nfit_blk->stat_offset = nfit_mem->dcr->status_offset;
 	mmio = &nfit_blk->mmio[DCR];
-	mmio->addr.base = nfit_spa_map(acpi_desc, nfit_mem->spa_dcr,
-			SPA_MAP_CONTROL);
+	mmio->addr.base = devm_nvdimm_ioremap(dev, nfit_mem->spa_dcr->address,
+			nfit_mem->spa_dcr->length);
 	if (!mmio->addr.base) {
 		dev_dbg(dev, "%s: %s failed to map dcr\n", __func__,
 				nvdimm_name(nvdimm));
@@ -1748,7 +1748,7 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
 
 	nfit_flush = nfit_mem->nfit_flush;
 	if (nfit_flush && nfit_flush->flush->hint_count != 0) {
-		nfit_blk->nvdimm_flush = devm_ioremap_nocache(dev,
+		nfit_blk->nvdimm_flush = devm_nvdimm_ioremap(dev,
 				nfit_flush->flush->hint_address[0], 8);
 		if (!nfit_blk->nvdimm_flush)
 			return -ENOMEM;

drivers/nvdimm/Kconfig

 menuconfig LIBNVDIMM
 	tristate "NVDIMM (Non-Volatile Memory Device) Support"
 	depends on PHYS_ADDR_T_64BIT
+	depends on HAS_IOMEM
 	depends on BLK_DEV
 	help
 	  Generic support for non-volatile memory devices including
@@ -19,7 +20,6 @@ if LIBNVDIMM
 config BLK_DEV_PMEM
 	tristate "PMEM: Persistent memory block device support"
 	default LIBNVDIMM
-	depends on HAS_IOMEM
 	select ND_BTT if BTT
 	select ND_PFN if NVDIMM_PFN
 	help

drivers/nvdimm/core.c

@@ -20,6 +20,7 @@
 #include <linux/ndctl.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/io.h>
 #include "nd-core.h"
 #include "nd.h"
 
@@ -57,6 +58,127 @@ bool is_nvdimm_bus_locked(struct device *dev)
 }
 EXPORT_SYMBOL(is_nvdimm_bus_locked);
 
+struct nvdimm_map {
+	struct nvdimm_bus *nvdimm_bus;
+	struct list_head list;
+	resource_size_t offset;
+	unsigned long flags;
+	size_t size;
+	union {
+		void *mem;
+		void __iomem *iomem;
+	};
+	struct kref kref;
+};
+
+static struct nvdimm_map *find_nvdimm_map(struct device *dev,
+		resource_size_t offset)
+{
+	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+	struct nvdimm_map *nvdimm_map;
+
+	list_for_each_entry(nvdimm_map, &nvdimm_bus->mapping_list, list)
+		if (nvdimm_map->offset == offset)
+			return nvdimm_map;
+	return NULL;
+}
+
+static struct nvdimm_map *alloc_nvdimm_map(struct device *dev,
+		resource_size_t offset, size_t size, unsigned long flags)
+{
+	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
+	struct nvdimm_map *nvdimm_map;
+
+	nvdimm_map = kzalloc(sizeof(*nvdimm_map), GFP_KERNEL);
+	if (!nvdimm_map)
+		return NULL;
+
+	INIT_LIST_HEAD(&nvdimm_map->list);
+	nvdimm_map->nvdimm_bus = nvdimm_bus;
+	nvdimm_map->offset = offset;
+	nvdimm_map->flags = flags;
+	nvdimm_map->size = size;
+	kref_init(&nvdimm_map->kref);
+
+	if (!request_mem_region(offset, size, dev_name(&nvdimm_bus->dev)))
+		goto err_request_region;
+
+	if (flags)
+		nvdimm_map->mem = memremap(offset, size, flags);
+	else
+		nvdimm_map->iomem = ioremap(offset, size);
+
+	if (!nvdimm_map->mem)
+		goto err_map;
+
+	dev_WARN_ONCE(dev, !is_nvdimm_bus_locked(dev), "%s: bus unlocked!",
+			__func__);
+	list_add(&nvdimm_map->list, &nvdimm_bus->mapping_list);
+
+	return nvdimm_map;
+
+ err_map:
+	release_mem_region(offset, size);
+ err_request_region:
+	kfree(nvdimm_map);
+	return NULL;
+}
+
+static void nvdimm_map_release(struct kref *kref)
+{
+	struct nvdimm_bus *nvdimm_bus;
+	struct nvdimm_map *nvdimm_map;
+
+	nvdimm_map = container_of(kref, struct nvdimm_map, kref);
+	nvdimm_bus = nvdimm_map->nvdimm_bus;
+
+	dev_dbg(&nvdimm_bus->dev, "%s: %pa\n", __func__, &nvdimm_map->offset);
+	list_del(&nvdimm_map->list);
+	if (nvdimm_map->flags)
+		memunmap(nvdimm_map->mem);
+	else
+		iounmap(nvdimm_map->iomem);
+	release_mem_region(nvdimm_map->offset, nvdimm_map->size);
+	kfree(nvdimm_map);
+}
+
+static void nvdimm_map_put(void *data)
+{
+	struct nvdimm_map *nvdimm_map = data;
+	struct nvdimm_bus *nvdimm_bus = nvdimm_map->nvdimm_bus;
+
+	nvdimm_bus_lock(&nvdimm_bus->dev);
+	kref_put(&nvdimm_map->kref, nvdimm_map_release);
+	nvdimm_bus_unlock(&nvdimm_bus->dev);
+}
+
+/**
+ * devm_nvdimm_memremap - map a resource that is shared across regions
+ * @dev: device that will own a reference to the shared mapping
+ * @offset: physical base address of the mapping
+ * @size: mapping size
+ * @flags: memremap flags, or, if zero, perform an ioremap instead
+ */
+void *devm_nvdimm_memremap(struct device *dev, resource_size_t offset,
+		size_t size, unsigned long flags)
+{
+	struct nvdimm_map *nvdimm_map;
+
+	nvdimm_bus_lock(dev);
+	nvdimm_map = find_nvdimm_map(dev, offset);
+	if (!nvdimm_map)
+		nvdimm_map = alloc_nvdimm_map(dev, offset, size, flags);
+	else
+		kref_get(&nvdimm_map->kref);
+	nvdimm_bus_unlock(dev);
+
+	if (devm_add_action_or_reset(dev, nvdimm_map_put, nvdimm_map))
+		return NULL;
+
+	return nvdimm_map->mem;
+}
+EXPORT_SYMBOL_GPL(devm_nvdimm_memremap);
+
 u64 nd_fletcher64(void *addr, size_t len, bool le)
 {
 	u32 *buf = addr;
@@ -335,6 +457,7 @@ struct nvdimm_bus *__nvdimm_bus_register(struct device *parent,
 	if (!nvdimm_bus)
 		return NULL;
 	INIT_LIST_HEAD(&nvdimm_bus->list);
+	INIT_LIST_HEAD(&nvdimm_bus->mapping_list);
 	INIT_LIST_HEAD(&nvdimm_bus->poison_list);
 	init_waitqueue_head(&nvdimm_bus->probe_wait);
 	nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);

drivers/nvdimm/nd-core.h

@@ -31,6 +31,7 @@ struct nvdimm_bus {
 	struct device dev;
 	int id, probe_active;
 	struct list_head poison_list;
+	struct list_head mapping_list;
 	struct mutex reconfig_mutex;
 };
 

include/linux/libnvdimm.h

@@ -99,6 +99,15 @@ struct nd_region_desc {
 	unsigned long flags;
 };
 
+struct device;
+void *devm_nvdimm_memremap(struct device *dev, resource_size_t offset,
+		size_t size, unsigned long flags);
+static inline void __iomem *devm_nvdimm_ioremap(struct device *dev,
+		resource_size_t offset, size_t size)
+{
+	return (void __iomem *) devm_nvdimm_memremap(dev, offset, size, 0);
+}
+
 struct nvdimm_bus;
 struct module;
 struct device;