cxl/pci: Map registers based on capabilities

The information required to map registers based on capabilities is
contained within the bars themselves.  This means the bar must be mapped
to read the information needed and then unmapped to map the individual
parts of the BAR based on capabilities.

Change cxl_setup_device_regs() to return a new cxl_register_map, change
the name to cxl_probe_device_regs().  Allocate and place
cxl_register_maps on a list while processing all of the specified
register blocks.

After probing all the register blocks go back and map smaller registers
blocks based on their capabilities and dispose of the cxl_register_maps.

NOTE: pci_iomap() is not managed automatically via pcim_enable_device()
so be careful to call pci_iounmap() correctly.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20210604005036.4187184-1-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 90 insertions, 21 deletions

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 33fc6e1634e3..3ffd5fad74b4 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -6,6 +6,7 @@
 #include <linux/module.h>
 #include <linux/sizes.h>
 #include <linux/mutex.h>
+#include <linux/list.h>
 #include <linux/cdev.h>
 #include <linux/idr.h>
 #include <linux/pci.h>
@@ -936,7 +937,7 @@ static void __iomem *cxl_mem_map_regblock(struct cxl_mem *cxlm,
 		return IOMEM_ERR_PTR(-ENXIO);
 	}
 
-	addr = pcim_iomap(pdev, bar, 0);
+	addr = pci_iomap(pdev, bar, 0);
 	if (!addr) {
 		dev_err(dev, "failed to map registers\n");
 		return addr;
@@ -945,7 +946,12 @@ static void __iomem *cxl_mem_map_regblock(struct cxl_mem *cxlm,
 	dev_dbg(dev, "Mapped CXL Memory Device resource bar %u @ %#llx\n",
 		bar, offset);
 
-	return pcim_iomap_table(pdev)[bar] + offset;
+	return addr;
+}
+
+static void cxl_mem_unmap_regblock(struct cxl_mem *cxlm, void __iomem *base)
+{
+	pci_iounmap(cxlm->pdev, base);
 }
 
 static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
@@ -971,6 +977,52 @@ static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
 	return 0;
 }
 
+static int cxl_probe_regs(struct cxl_mem *cxlm, void __iomem *base,
+			  struct cxl_register_map *map)
+{
+	struct pci_dev *pdev = cxlm->pdev;
+	struct device *dev = &pdev->dev;
+	struct cxl_device_reg_map *dev_map;
+
+	switch (map->reg_type) {
+	case CXL_REGLOC_RBI_MEMDEV:
+		dev_map = &map->device_map;
+		cxl_probe_device_regs(dev, base, dev_map);
+		if (!dev_map->status.valid || !dev_map->mbox.valid ||
+		    !dev_map->memdev.valid) {
+			dev_err(dev, "registers not found: %s%s%s\n",
+				!dev_map->status.valid ? "status " : "",
+				!dev_map->mbox.valid ? "status " : "",
+				!dev_map->memdev.valid ? "status " : "");
+			return -ENXIO;
+		}
+
+		dev_dbg(dev, "Probing device registers...\n");
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int cxl_map_regs(struct cxl_mem *cxlm, struct cxl_register_map *map)
+{
+	struct pci_dev *pdev = cxlm->pdev;
+	struct device *dev = &pdev->dev;
+
+	switch (map->reg_type) {
+	case CXL_REGLOC_RBI_MEMDEV:
+		cxl_map_device_regs(pdev, &cxlm->regs.device_regs, map);
+		dev_dbg(dev, "Probing device registers...\n");
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 static void cxl_decode_register_block(u32 reg_lo, u32 reg_hi,
 				      u8 *bar, u64 *offset, u8 *reg_type)
 {
@@ -991,12 +1043,14 @@ static void cxl_decode_register_block(u32 reg_lo, u32 reg_hi,
  */
 static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 {
-	struct cxl_regs *regs = &cxlm->regs;
 	struct pci_dev *pdev = cxlm->pdev;
 	struct device *dev = &pdev->dev;
 	u32 regloc_size, regblocks;
 	void __iomem *base;
 	int regloc, i;
+	struct cxl_register_map *map, *n;
+	LIST_HEAD(register_maps);
+	int ret = 0;
 
 	regloc = cxl_mem_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC_OFFSET);
 	if (!regloc) {
@@ -1020,7 +1074,14 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		u64 offset;
 		u8 bar;
 
-		/* "register low and high" contain other bits */
+		map = kzalloc(sizeof(*map), GFP_KERNEL);
+		if (!map) {
+			ret = -ENOMEM;
+			goto free_maps;
+		}
+
+		list_add(&map->list, &register_maps);
+
 		pci_read_config_dword(pdev, regloc, &reg_lo);
 		pci_read_config_dword(pdev, regloc + 4, &reg_hi);
 
@@ -1030,30 +1091,38 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		dev_dbg(dev, "Found register block in bar %u @ 0x%llx of type %u\n",
 			bar, offset, reg_type);
 
-		if (reg_type == CXL_REGLOC_RBI_MEMDEV) {
-			base = cxl_mem_map_regblock(cxlm, bar, offset);
-			if (!base)
-				return -ENOMEM;
-			break;
+		base = cxl_mem_map_regblock(cxlm, bar, offset);
+		if (!base) {
+			ret = -ENOMEM;
+			goto free_maps;
 		}
-	}
 
-	if (i == regblocks) {
-		dev_err(dev, "Missing register locator for device registers\n");
-		return -ENXIO;
+		map->barno = bar;
+		map->block_offset = offset;
+		map->reg_type = reg_type;
+
+		ret = cxl_probe_regs(cxlm, base + offset, map);
+
+		/* Always unmap the regblock regardless of probe success */
+		cxl_mem_unmap_regblock(cxlm, base);
+
+		if (ret)
+			goto free_maps;
 	}
 
-	cxl_setup_device_regs(dev, base, &regs->device_regs);
+	list_for_each_entry(map, &register_maps, list) {
+		ret = cxl_map_regs(cxlm, map);
+		if (ret)
+			goto free_maps;
+	}
 
-	if (!regs->status || !regs->mbox || !regs->memdev) {
-		dev_err(dev, "registers not found: %s%s%s\n",
-			!regs->status ? "status " : "",
-			!regs->mbox ? "mbox " : "",
-			!regs->memdev ? "memdev" : "");
-		return -ENXIO;
+free_maps:
+	list_for_each_entry_safe(map, n, &register_maps, list) {
+		list_del(&map->list);
+		kfree(map);
 	}
 
-	return 0;
+	return ret;
 }
 
 static struct cxl_memdev *to_cxl_memdev(struct device *dev)