cxl/memdev: Introduce cxl_class_memdev_type

In preparation for memdev's without mailbox related infrastructure,
introduce cxl_class_memdev_type as a superset of a cxl_memdev_type.
Effectively the only difference is that cxl_class_memdev_type exports
common sysfs attributes where cxl_memdev_type has none.

Related to this is all the cxl_mem_probe() paths that assume the presence
of a class device mailbox are updated to skip that requirement.

Co-developed-by: Alejandro Lucero <alucerop@amd.com>
Signed-off-by: Alejandro Lucero <alucerop@amd.com>
Signed-off-by: Dan Williams <djbw@kernel.org>
Tested-by: ALejandro Lucero <alucerop@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/20260519210158.1499795-5-djbw@kernel.org
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

2 files changed, 47 insertions, 14 deletions

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 91c99eeea92c..33a3d2e7b13a 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -574,16 +574,23 @@ void cxl_memdev_update_perf(struct cxl_memdev *cxlmd)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_memdev_update_perf, "CXL");
 
-static const struct device_type cxl_memdev_type = {
+static const struct device_type cxl_class_memdev_type = {
 	.name = "cxl_memdev",
 	.release = cxl_memdev_release,
 	.devnode = cxl_memdev_devnode,
 	.groups = cxl_memdev_attribute_groups,
 };
 
+static const struct device_type cxl_memdev_type = {
+	.name = "cxl_memdev",
+	.release = cxl_memdev_release,
+	.devnode = cxl_memdev_devnode,
+};
+
 bool is_cxl_memdev(const struct device *dev)
 {
-	return dev->type == &cxl_memdev_type;
+	return (dev->type == &cxl_class_memdev_type ||
+		dev->type == &cxl_memdev_type);
 }
 EXPORT_SYMBOL_NS_GPL(is_cxl_memdev, "CXL");
 
@@ -712,7 +719,10 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 	dev->parent = get_device(cxlds->dev);
 	dev->bus = &cxl_bus_type;
 	dev->devt = MKDEV(cxl_mem_major, cxlmd->id);
-	dev->type = &cxl_memdev_type;
+	if (cxlds->type == CXL_DEVTYPE_DEVMEM)
+		dev->type = &cxl_memdev_type;
+	else
+		dev->type = &cxl_class_memdev_type;
 	device_set_pm_not_required(dev);
 	INIT_WORK(&cxlmd->detach_work, detach_memdev);
 
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index fcffe24dcb42..ff858318091f 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -65,6 +65,26 @@ static int cxl_debugfs_poison_clear(void *data, u64 dpa)
 DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
 			 cxl_debugfs_poison_clear, "%llx\n");
 
+static void cxl_memdev_poison_enable(struct cxl_memdev_state *mds,
+				     struct cxl_memdev *cxlmd,
+				     struct dentry *dentry)
+{
+	/*
+	 * Avoid poison debugfs for DEVMEM aka accelerators as they rely on
+	 * cxl_memdev_state.
+	 */
+	if (!mds)
+		return;
+
+	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
+		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_inject_fops);
+
+	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
+		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_clear_fops);
+}
+
 static int cxl_mem_probe(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
@@ -92,12 +112,7 @@ static int cxl_mem_probe(struct device *dev)
 	dentry = cxl_debugfs_create_dir(dev_name(dev));
 	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);
 
-	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
-		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
-				    &cxl_poison_inject_fops);
-	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
-		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
-				    &cxl_poison_clear_fops);
+	cxl_memdev_poison_enable(mds, cxlmd, dentry);
 
 	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
 	if (rc)
@@ -206,16 +221,24 @@ static ssize_t trigger_poison_list_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(trigger_poison_list);
 
-static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
+static bool cxl_poison_attr_visible(struct kobject *kobj, struct attribute *a)
 {
 	struct device *dev = kobj_to_dev(kobj);
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 
-	if (a == &dev_attr_trigger_poison_list.attr)
-		if (!test_bit(CXL_POISON_ENABLED_LIST,
-			      mds->poison.enabled_cmds))
-			return 0;
+	if (!mds ||
+	    !test_bit(CXL_POISON_ENABLED_LIST, mds->poison.enabled_cmds))
+		return false;
+
+	return true;
+}
+
+static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	if (a == &dev_attr_trigger_poison_list.attr &&
+	    !cxl_poison_attr_visible(kobj, a))
+		return 0;
 
 	return a->mode;
 }