cxl/region: Add sysfs attribute for locality attributes of CXL regions

Add read/write latencies and bandwidth sysfs attributes for the enabled CXL
region. The bandwidth is the aggregated bandwidth of all devices that
contribute to the CXL region. The latency is the worst latency of the
device amongst all the devices that contribute to the CXL region.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20240308220055.2172956-11-dave.jiang@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 9a0d2d7621de..d4d39536e6c7 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -30,6 +30,98 @@
 
 static struct cxl_region *to_cxl_region(struct device *dev);
 
+#define __ACCESS_ATTR_RO(_level, _name) {				\
+	.attr	= { .name = __stringify(_name), .mode = 0444 },		\
+	.show	= _name##_access##_level##_show,			\
+}
+
+#define ACCESS_DEVICE_ATTR_RO(level, name)	\
+	struct device_attribute dev_attr_access##level##_##name = __ACCESS_ATTR_RO(level, name)
+
+#define ACCESS_ATTR_RO(level, attrib)					      \
+static ssize_t attrib##_access##level##_show(struct device *dev,	      \
+					  struct device_attribute *attr,      \
+					  char *buf)			      \
+{									      \
+	struct cxl_region *cxlr = to_cxl_region(dev);			      \
+									      \
+	if (cxlr->coord[level].attrib == 0)				      \
+		return -ENOENT;						      \
+									      \
+	return sysfs_emit(buf, "%u\n", cxlr->coord[level].attrib);	      \
+}									      \
+static ACCESS_DEVICE_ATTR_RO(level, attrib)
+
+ACCESS_ATTR_RO(0, read_bandwidth);
+ACCESS_ATTR_RO(0, read_latency);
+ACCESS_ATTR_RO(0, write_bandwidth);
+ACCESS_ATTR_RO(0, write_latency);
+
+#define ACCESS_ATTR_DECLARE(level, attrib)	\
+	(&dev_attr_access##level##_##attrib.attr)
+
+static struct attribute *access0_coordinate_attrs[] = {
+	ACCESS_ATTR_DECLARE(0, read_bandwidth),
+	ACCESS_ATTR_DECLARE(0, write_bandwidth),
+	ACCESS_ATTR_DECLARE(0, read_latency),
+	ACCESS_ATTR_DECLARE(0, write_latency),
+	NULL
+};
+
+ACCESS_ATTR_RO(1, read_bandwidth);
+ACCESS_ATTR_RO(1, read_latency);
+ACCESS_ATTR_RO(1, write_bandwidth);
+ACCESS_ATTR_RO(1, write_latency);
+
+static struct attribute *access1_coordinate_attrs[] = {
+	ACCESS_ATTR_DECLARE(1, read_bandwidth),
+	ACCESS_ATTR_DECLARE(1, write_bandwidth),
+	ACCESS_ATTR_DECLARE(1, read_latency),
+	ACCESS_ATTR_DECLARE(1, write_latency),
+	NULL
+};
+
+#define ACCESS_VISIBLE(level)						\
+static umode_t cxl_region_access##level##_coordinate_visible(		\
+		struct kobject *kobj, struct attribute *a, int n)	\
+{									\
+	struct device *dev = kobj_to_dev(kobj);				\
+	struct cxl_region *cxlr = to_cxl_region(dev);			\
+									\
+	if (a == &dev_attr_access##level##_read_latency.attr &&		\
+	    cxlr->coord[level].read_latency == 0)			\
+		return 0;						\
+									\
+	if (a == &dev_attr_access##level##_write_latency.attr &&	\
+	    cxlr->coord[level].write_latency == 0)			\
+		return 0;						\
+									\
+	if (a == &dev_attr_access##level##_read_bandwidth.attr &&	\
+	    cxlr->coord[level].read_bandwidth == 0)			\
+		return 0;						\
+									\
+	if (a == &dev_attr_access##level##_write_bandwidth.attr &&	\
+	    cxlr->coord[level].write_bandwidth == 0)			\
+		return 0;						\
+									\
+	return a->mode;							\
+}
+
+ACCESS_VISIBLE(0);
+ACCESS_VISIBLE(1);
+
+static const struct attribute_group cxl_region_access0_coordinate_group = {
+	.name = "access0",
+	.attrs = access0_coordinate_attrs,
+	.is_visible = cxl_region_access0_coordinate_visible,
+};
+
+static const struct attribute_group cxl_region_access1_coordinate_group = {
+	.name = "access1",
+	.attrs = access1_coordinate_attrs,
+	.is_visible = cxl_region_access1_coordinate_visible,
+};
+
 static ssize_t uuid_show(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
@@ -2069,6 +2161,8 @@ static const struct attribute_group *region_groups[] = {
 	&cxl_base_attribute_group,
 	&cxl_region_group,
 	&cxl_region_target_group,
+	&cxl_region_access0_coordinate_group,
+	&cxl_region_access1_coordinate_group,
 	NULL,
 };