cxl/mem: Split creation from mapping in probe

Add a new function specifically for mapping the register blocks and
offsets within. The new function can be used more generically for other
register block identifiers.

No functional change is meant to be introduced in this patch with the
exception of a dev_err printed when the device register block isn't
found.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20210407222625.320177-3-ben.widawsky@intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/pci.c

@@ -925,22 +925,40 @@ static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm)
 	return 0;
 }
 
-static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev, u32 reg_lo,
-				      u32 reg_hi)
+static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct cxl_mem *cxlm;
-	void __iomem *regs;
-	u64 offset;
-	u8 bar;
-	int rc;
 
 	cxlm = devm_kzalloc(dev, sizeof(*cxlm), GFP_KERNEL);
 	if (!cxlm) {
 		dev_err(dev, "No memory available\n");
-		return NULL;
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_init(&cxlm->mbox_mutex);
+	cxlm->pdev = pdev;
+	cxlm->enabled_cmds =
+		devm_kmalloc_array(dev, BITS_TO_LONGS(cxl_cmd_count),
+				   sizeof(unsigned long),
+				   GFP_KERNEL | __GFP_ZERO);
+	if (!cxlm->enabled_cmds) {
+		dev_err(dev, "No memory available for bitmap\n");
+		return ERR_PTR(-ENOMEM);
 	}
 
+	return cxlm;
+}
+
+static int cxl_mem_map_regblock(struct cxl_mem *cxlm, u32 reg_lo, u32 reg_hi)
+{
+	struct pci_dev *pdev = cxlm->pdev;
+	struct device *dev = &pdev->dev;
+	void __iomem *regs;
+	u64 offset;
+	u8 bar;
+	int rc;
+
 	offset = ((u64)reg_hi << 32) | (reg_lo & CXL_REGLOC_ADDR_MASK);
 	bar = FIELD_GET(CXL_REGLOC_BIR_MASK, reg_lo);
 
@@ -948,30 +966,20 @@ static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev, u32 reg_lo,
 	if (pci_resource_len(pdev, bar) < offset) {
 		dev_err(dev, "BAR%d: %pr: too small (offset: %#llx)\n", bar,
 			&pdev->resource[bar], (unsigned long long)offset);
-		return NULL;
+		return -ENXIO;
 	}
 
 	rc = pcim_iomap_regions(pdev, BIT(bar), pci_name(pdev));
 	if (rc) {
 		dev_err(dev, "failed to map registers\n");
-		return NULL;
+		return rc;
 	}
 	regs = pcim_iomap_table(pdev)[bar];
 
-	mutex_init(&cxlm->mbox_mutex);
-	cxlm->pdev = pdev;
 	cxlm->base = regs + offset;
-	cxlm->enabled_cmds =
-		devm_kmalloc_array(dev, BITS_TO_LONGS(cxl_cmd_count),
-				   sizeof(unsigned long),
-				   GFP_KERNEL | __GFP_ZERO);
-	if (!cxlm->enabled_cmds) {
-		dev_err(dev, "No memory available for bitmap\n");
-		return NULL;
-	}
 
 	dev_dbg(dev, "Mapped CXL Memory Device resource\n");
-	return cxlm;
+	return 0;
 }
 
 static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
@@ -1417,14 +1425,18 @@ static int cxl_mem_identify(struct cxl_mem *cxlm)
 static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	struct device *dev = &pdev->dev;
-	struct cxl_mem *cxlm = NULL;
 	u32 regloc_size, regblocks;
+	struct cxl_mem *cxlm;
 	int rc, regloc, i;
 
 	rc = pcim_enable_device(pdev);
 	if (rc)
 		return rc;
 
+	cxlm = cxl_mem_create(pdev);
+	if (IS_ERR(cxlm))
+		return PTR_ERR(cxlm);
+
 	regloc = cxl_mem_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC_OFFSET);
 	if (!regloc) {
 		dev_err(dev, "register location dvsec not found\n");
@@ -1449,13 +1461,17 @@ static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		reg_type = FIELD_GET(CXL_REGLOC_RBI_MASK, reg_lo);
 
 		if (reg_type == CXL_REGLOC_RBI_MEMDEV) {
-			cxlm = cxl_mem_create(pdev, reg_lo, reg_hi);
+			rc = cxl_mem_map_regblock(cxlm, reg_lo, reg_hi);
+			if (rc)
+				return rc;
 			break;
 		}
 	}
 
-	if (!cxlm)
-		return -ENODEV;
+	if (i == regblocks) {
+		dev_err(dev, "Missing register locator for device registers\n");
+		return -ENXIO;
+	}
 
 	rc = cxl_mem_setup_regs(cxlm);
 	if (rc)