[PATCH 01/16] cxl/regs: Add cxl_unmap_component_regs()

[Ben Cheatham <Benjamin.Cheatham@xxxxxxx>]

In order to allocate the MSI/-X interrupt for CXL error isolation the
PCIe portdrv driver needs to map the MMIO-space isolation capability
register that contains the interrupt vector. The CXL core already
provides a function to map registers in this space:
cxl_map_component_regs(). The mappings given this function are managed
by devres. If the isolation registers are left mapped by the PCIe
portdrv driver, the CXL driver will run into a devres conflict when it
goes to map the same registers during probe.

Add cxl_unmap_component_regs() to be called from the PCIe portdrv
driver. This function will unwind the devres allocations done by
cxl_map_component_regs(), which will allow the PCIe portdrv driver to
map the isolation capability register without conflicts.

Factor out the register mapping retrieval code in
cxl_map_component_regs() to be reused by cxl_map/unmap_component_regs().

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@xxxxxxx>
---
 drivers/cxl/core/regs.c | 77 +++++++++++++++++++++++++++++++----------
 drivers/cxl/cxl.h       |  3 ++
 2 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
index b8e767a9571c..da8e668a3b70 100644
--- a/drivers/cxl/core/regs.c
+++ b/drivers/cxl/core/regs.c
@@ -201,40 +201,81 @@ void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_iomap_block, "CXL");
 
-int cxl_map_component_regs(const struct cxl_register_map *map,
+struct mapinfo {
+	const struct cxl_reg_map *rmap;
+	void __iomem **addr;
+};
+
+static int cxl_get_mapinfo(const struct cxl_register_map *map,
 			   struct cxl_component_regs *regs,
-			   unsigned long map_mask)
+			   unsigned long map_mask, struct mapinfo *info)
 {
-	struct device *host = map->host;
-	struct mapinfo {
-		const struct cxl_reg_map *rmap;
-		void __iomem **addr;
-	} mapinfo[] = {
+	struct mapinfo mapinfo[] = {
 		{ &map->component_map.hdm_decoder, &regs->hdm_decoder },
 		{ &map->component_map.ras, &regs->ras },
 	};
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(mapinfo); i++) {
-		struct mapinfo *mi = &mapinfo[i];
-		resource_size_t addr;
-		resource_size_t length;
-
-		if (!mi->rmap->valid)
+		if (!mapinfo[i].rmap->valid)
 			continue;
-		if (!test_bit(mi->rmap->id, &map_mask))
+		if (!test_bit(mapinfo[i].rmap->id, &map_mask))
 			continue;
-		addr = map->resource + mi->rmap->offset;
-		length = mi->rmap->size;
-		*(mi->addr) = devm_cxl_iomap_block(host, addr, length);
-		if (!*(mi->addr))
-			return -ENOMEM;
+
+		*info = mapinfo[i];
+		return 0;
 	}
 
+	return -ENXIO;
+}
+
+int cxl_map_component_regs(const struct cxl_register_map *map,
+			   struct cxl_component_regs *regs,
+			   unsigned long map_mask)
+{
+	struct device *host = map->host;
+	resource_size_t addr, length;
+	struct mapinfo mi;
+	int rc;
+
+	rc = cxl_get_mapinfo(map, regs, map_mask, &mi);
+	if (rc)
+		return rc;
+
+	addr = map->resource + mi.rmap->offset;
+	length = mi.rmap->size;
+	*mi.addr = devm_cxl_iomap_block(host, addr, length);
+	if (!(*mi.addr))
+		return -ENOMEM;
+
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_map_component_regs, "CXL");
 
+int cxl_unmap_component_regs(const struct cxl_register_map *map,
+			     struct cxl_component_regs *regs,
+			     unsigned long map_mask)
+{
+	struct device *host = map->host;
+	resource_size_t addr, length;
+	struct mapinfo mi;
+	int rc;
+
+	rc = cxl_get_mapinfo(map, regs, map_mask, &mi);
+	if (rc)
+		return rc;
+
+	if (!(*mi.addr))
+		return 0;
+
+	addr = map->resource + mi.rmap->offset;
+	length = mi.rmap->size;
+
+	devm_iounmap(host, *mi.addr);
+	devm_release_mem_region(host, addr, length);
+	return 0;
+}
+
 int cxl_map_device_regs(const struct cxl_register_map *map,
 			struct cxl_device_regs *regs)
 {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 51b7058387ef..a0fda305e25b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -300,6 +300,9 @@ void cxl_probe_device_regs(struct device *dev, void __iomem *base,
 int cxl_map_component_regs(const struct cxl_register_map *map,
 			   struct cxl_component_regs *regs,
 			   unsigned long map_mask);
+int cxl_unmap_component_regs(const struct cxl_register_map *map,
+			     struct cxl_component_regs *regs,
+			     unsigned long map_mask);
 int cxl_map_device_regs(const struct cxl_register_map *map,
 			struct cxl_device_regs *regs);
 int cxl_map_pmu_regs(struct cxl_register_map *map, struct cxl_pmu_regs *regs);
-- 
2.34.1