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>

drivers/cxl/core.c

@@ -3,6 +3,7 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/pci.h>
 #include "cxl.h"
 
 /**
@@ -13,18 +14,20 @@
  */
 
 /**
- * cxl_setup_device_regs() - Detect CXL Device register blocks
+ * cxl_probe_device_regs() - Detect CXL Device register blocks
  * @dev: Host device of the @base mapping
  * @base: Mapping of CXL 2.0 8.2.8 CXL Device Register Interface
- * @regs: Base pointers for device register blocks (see CXL_DEVICE_REGS())
+ * @map: Map object describing the register block information found
+ *
+ * Probe for device register information and return it in map object.
  */
-void cxl_setup_device_regs(struct device *dev, void __iomem *base,
+void cxl_probe_device_regs(struct device *dev, void __iomem *base,
-			   struct cxl_device_regs *regs)
+			   struct cxl_device_reg_map *map)
 {
 	int cap, cap_count;
 	u64 cap_array;
 
-	*regs = (struct cxl_device_regs) { 0 };
+	*map = (struct cxl_device_reg_map){ 0 };
 
 	cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
 	if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
@@ -34,30 +37,36 @@ void cxl_setup_device_regs(struct device *dev, void __iomem *base,
 	cap_count = FIELD_GET(CXLDEV_CAP_ARRAY_COUNT_MASK, cap_array);
 
 	for (cap = 1; cap <= cap_count; cap++) {
-		void __iomem *register_block;
+		u32 offset, length;
-		u32 offset;
 		u16 cap_id;
 
 		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
 				   readl(base + cap * 0x10));
 		offset = readl(base + cap * 0x10 + 0x4);
-		register_block = base + offset;
+		length = readl(base + cap * 0x10 + 0x8);
 
 		switch (cap_id) {
 		case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
 			dev_dbg(dev, "found Status capability (0x%x)\n", offset);
-			regs->status = register_block;
+
+			map->status.valid = true;
+			map->status.offset = offset;
+			map->status.size = length;
 			break;
 		case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
 			dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
-			regs->mbox = register_block;
+			map->mbox.valid = true;
+			map->mbox.offset = offset;
+			map->mbox.size = length;
 			break;
 		case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
 			dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
 			break;
 		case CXLDEV_CAP_CAP_ID_MEMDEV:
 			dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
-			regs->memdev = register_block;
+			map->memdev.valid = true;
+			map->memdev.offset = offset;
+			map->memdev.size = length;
 			break;
 		default:
 			if (cap_id >= 0x8000)
@@ -68,7 +77,48 @@ void cxl_setup_device_regs(struct device *dev, void __iomem *base,
 		}
 	}
 }
-EXPORT_SYMBOL_GPL(cxl_setup_device_regs);
+EXPORT_SYMBOL_GPL(cxl_probe_device_regs);
+
+int cxl_map_device_regs(struct pci_dev *pdev,
+			struct cxl_device_regs *regs,
+			struct cxl_register_map *map)
+{
+	struct device *dev = &pdev->dev;
+	resource_size_t phys_addr;
+
+	phys_addr = pci_resource_start(pdev, map->barno);
+	phys_addr += map->block_offset;
+
+	if (map->device_map.status.valid) {
+		resource_size_t addr;
+		resource_size_t length;
+
+		addr = phys_addr + map->device_map.status.offset;
+		length = map->device_map.status.size;
+		regs->status = devm_ioremap(dev, addr, length);
+	}
+
+	if (map->device_map.mbox.valid) {
+		resource_size_t addr;
+		resource_size_t length;
+
+		addr = phys_addr + map->device_map.mbox.offset;
+		length = map->device_map.mbox.size;
+		regs->mbox = devm_ioremap(dev, addr, length);
+	}
+
+	if (map->device_map.memdev.valid) {
+		resource_size_t addr;
+		resource_size_t length;
+
+		addr = phys_addr + map->device_map.memdev.offset;
+		length = map->device_map.memdev.size;
+		regs->memdev = devm_ioremap(dev, addr, length);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cxl_map_device_regs);
 
 struct bus_type cxl_bus_type = {
 	.name = "cxl",

drivers/cxl/cxl.h

@@ -53,9 +53,7 @@ struct cxl_device_regs {
 /*
  * Note, the anonymous union organization allows for per
  * register-block-type helper routines, without requiring block-type
- * agnostic code to include the prefix. I.e.
+ * agnostic code to include the prefix.
- * cxl_setup_device_regs(&cxlm->regs.dev) vs readl(cxlm->regs.mbox).
- * The specificity reads naturally from left-to-right.
  */
 struct cxl_regs {
 	union {
@@ -66,8 +64,33 @@ struct cxl_regs {
 	};
 };
 
-void cxl_setup_device_regs(struct device *dev, void __iomem *base,
+struct cxl_reg_map {
-			   struct cxl_device_regs *regs);
+	bool valid;
+	unsigned long offset;
+	unsigned long size;
+};
+
+struct cxl_device_reg_map {
+	struct cxl_reg_map status;
+	struct cxl_reg_map mbox;
+	struct cxl_reg_map memdev;
+};
+
+struct cxl_register_map {
+	struct list_head list;
+	u64 block_offset;
+	u8 reg_type;
+	u8 barno;
+	union {
+		struct cxl_device_reg_map device_map;
+	};
+};
+
+void cxl_probe_device_regs(struct device *dev, void __iomem *base,
+			   struct cxl_device_reg_map *map);
+int cxl_map_device_regs(struct pci_dev *pdev,
+			struct cxl_device_regs *regs,
+			struct cxl_register_map *map);
 
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */

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);
-			base = cxl_mem_map_regblock(cxlm, bar, offset);
+		if (!base) {
-			if (!base)
+			ret = -ENOMEM;
-				return -ENOMEM;
+			goto free_maps;
-			break;
 		}
+
+		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;
 	}
 
-	if (i == regblocks) {
+	list_for_each_entry(map, &register_maps, list) {
-		dev_err(dev, "Missing register locator for device registers\n");
+		ret = cxl_map_regs(cxlm, map);
-		return -ENXIO;
+		if (ret)
+			goto free_maps;
 	}
 
-	cxl_setup_device_regs(dev, base, &regs->device_regs);
+free_maps:
-
+	list_for_each_entry_safe(map, n, &register_maps, list) {
-	if (!regs->status || !regs->mbox || !regs->memdev) {
+		list_del(&map->list);
-		dev_err(dev, "registers not found: %s%s%s\n",
+		kfree(map);
-			!regs->status ? "status " : "",
-			!regs->mbox ? "mbox " : "",
-			!regs->memdev ? "memdev" : "");
-		return -ENXIO;
 	}
 
-	return 0;
+	return ret;
 }
 
 static struct cxl_memdev *to_cxl_memdev(struct device *dev)