cxl/region: Factor out interleave granularity setup

Region creation based on Type3 devices can be triggered from user space
allowing memory combination through interleaving.

In preparation for kernel driven region creation, that is Type2 drivers
triggering region creation backed with its advertised CXL memory, factor
out a common helper from the user-sysfs region setup for interleave
granularity.

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260228173603.1125109-4-alejandro.lucero-palau@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: alucerop

drivers/cxl/core/region.c

@@ -559,21 +559,14 @@ static ssize_t interleave_granularity_show(struct device *dev,
 	return sysfs_emit(buf, "%d\n", p->interleave_granularity);
 }
 
-static ssize_t interleave_granularity_store(struct device *dev,
-					    struct device_attribute *attr,
-					    const char *buf, size_t len)
+static int set_interleave_granularity(struct cxl_region *cxlr, int val)
 {
-	struct cxl_region *cxlr = to_cxl_region(dev);
 	struct cxl_root_decoder *cxlrd = cxlr->cxlrd;
 	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
 	struct cxl_region_params *p = &cxlr->params;
-	int rc, val;
+	int rc;
 	u16 ig;
 
-	rc = kstrtoint(buf, 0, &val);
-	if (rc)
-		return rc;
-
 	rc = granularity_to_eig(val, &ig);
 	if (rc)
 		return rc;
@@ -589,14 +582,33 @@ static ssize_t interleave_granularity_store(struct device *dev,
 	if (cxld->interleave_ways > 1 && val != cxld->interleave_granularity)
 		return -EINVAL;
 
-	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
-	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
-		return rc;
+	lockdep_assert_held_write(&cxl_rwsem.region);
 
 	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE)
 		return -EBUSY;
 
 	p->interleave_granularity = val;
+	return 0;
+}
+
+static ssize_t interleave_granularity_store(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t len)
+{
+	struct cxl_region *cxlr = to_cxl_region(dev);
+	int rc, val;
+
+	rc = kstrtoint(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	ACQUIRE(rwsem_write_kill, rwsem)(&cxl_rwsem.region);
+	if ((rc = ACQUIRE_ERR(rwsem_write_kill, &rwsem)))
+		return rc;
+
+	rc = set_interleave_granularity(cxlr, val);
+	if (rc)
+		return rc;
 
 	return len;
 }