[PATCH v4 13/28] cxl/mem: Expose DCD partition capabilities in sysfs

[ira.weiny@intel.com]

From: Navneet Singh <navneet.singh@intel.com>

To properly configure CXL regions on Dynamic Capacity Devices (DCD),
user space will need to know the details of the DC partitions available.

Expose dynamic capacity capabilities through sysfs.

Signed-off-by: Navneet Singh <navneet.singh@intel.com>
Co-developed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
[iweiny: Change .../memX/dc/* to .../memX/dcY/*]
[iweiny: add read only and shareable attributes from DSMAS]
[djiang: Split sysfs docs]
[iweiny: Adjust sysfs doc dates]
[iweiny: Add qos details]
---
 Documentation/ABI/testing/sysfs-bus-cxl |  45 ++++++++++++
 drivers/cxl/core/memdev.c               | 126 ++++++++++++++++++++++++++++++++
 2 files changed, 171 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 3f5627a1210a..b865eefdb74c 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -54,6 +54,51 @@ Description:
 		identically named field in the Identify Memory Device Output
 		Payload in the CXL-2.0 specification.
 
+What:		/sys/bus/cxl/devices/memX/dcY/size
+Date:		December, 2024
+KernelVersion:	v6.13
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Dynamic Capacity (DC) region information.  Devices only
+		export dcY if DCD partition Y is supported.
+		dcY/size is the size of each of those partitions.
+
+What:		/sys/bus/cxl/devices/memX/dcY/read_only
+Date:		December, 2024
+KernelVersion:	v6.13
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Dynamic Capacity (DC) region information.  Devices only
+		export dcY if DCD partition Y is supported.
+		dcY/read_only indicates true if the region is exported
+		read_only from the device.
+
+What:		/sys/bus/cxl/devices/memX/dcY/shareable
+Date:		December, 2024
+KernelVersion:	v6.13
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Dynamic Capacity (DC) region information.  Devices only
+		export dcY if DCD partition Y is supported.
+		dcY/shareable indicates true if the region is exported
+		shareable from the device.
+
+What:		/sys/bus/cxl/devices/memX/dcY/qos_class
+Date:		December, 2024
+KernelVersion:	v6.13
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Dynamic Capacity (DC) region information.  Devices only
+		export dcY if DCD partition Y is supported.  For CXL host
+		platforms that support "QoS Telemmetry" this attribute conveys
+		a comma delimited list of platform specific cookies that
+		identifies a QoS performance class for the persistent partition
+		of the CXL mem device. These class-ids can be compared against
+		a similar "qos_class" published for a root decoder. While it is
+		not required that the endpoints map their local memory-class to
+		a matching platform class, mismatches are not recommended and
+		there are platform specific performance related side-effects
+		that may result. First class-id is displayed.
 
 What:		/sys/bus/cxl/devices/memX/pmem/qos_class
 Date:		May, 2023
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 84fefb76dafa..2565b10a769c 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -2,6 +2,7 @@
 /* Copyright(c) 2020 Intel Corporation. */
 
 #include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/string_choices.h>
 #include <linux/firmware.h>
 #include <linux/device.h>
 #include <linux/slab.h>
@@ -449,6 +450,123 @@ static struct attribute *cxl_memdev_security_attributes[] = {
 	NULL,
 };
 
+static ssize_t show_size_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+	return sysfs_emit(buf, "%#llx\n", mds->dc_region[pos].decode_len);
+}
+
+static ssize_t show_read_only_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+	return sysfs_emit(buf, "%s\n",
+			  str_false_true(mds->dc_region[pos].read_only));
+}
+
+static ssize_t show_shareable_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+	return sysfs_emit(buf, "%s\n",
+			  str_false_true(mds->dc_region[pos].shareable));
+}
+
+static ssize_t show_qos_class_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+	return sysfs_emit(buf, "%d\n", mds->dc_perf[pos].qos_class);
+}
+
+#define CXL_MEMDEV_DC_ATTR_GROUP(n)						\
+static ssize_t dc##n##_size_show(struct device *dev,				\
+				 struct device_attribute *attr,			\
+				 char *buf)					\
+{										\
+	return show_size_dcN(to_cxl_memdev(dev), buf, (n));			\
+}										\
+struct device_attribute dc##n##_size = {					\
+	.attr	= { .name = "size", .mode = 0444 },				\
+	.show	= dc##n##_size_show,						\
+};										\
+static ssize_t dc##n##_read_only_show(struct device *dev,			\
+				      struct device_attribute *attr,		\
+				      char *buf)				\
+{										\
+	return show_read_only_dcN(to_cxl_memdev(dev), buf, (n));		\
+}										\
+struct device_attribute dc##n##_read_only = {					\
+	.attr	= { .name = "read_only", .mode = 0444 },			\
+	.show	= dc##n##_read_only_show,					\
+};										\
+static ssize_t dc##n##_shareable_show(struct device *dev,			\
+				     struct device_attribute *attr,		\
+				     char *buf)					\
+{										\
+	return show_shareable_dcN(to_cxl_memdev(dev), buf, (n));		\
+}										\
+struct device_attribute dc##n##_shareable = {					\
+	.attr	= { .name = "shareable", .mode = 0444 },			\
+	.show	= dc##n##_shareable_show,					\
+};										\
+static ssize_t dc##n##_qos_class_show(struct device *dev,			\
+				      struct device_attribute *attr,		\
+				      char *buf)				\
+{										\
+	return show_qos_class_dcN(to_cxl_memdev(dev), buf, (n));		\
+}										\
+struct device_attribute dc##n##_qos_class = {					\
+	.attr	= { .name = "qos_class", .mode = 0444 },			\
+	.show	= dc##n##_qos_class_show,					\
+};										\
+static struct attribute *cxl_memdev_dc##n##_attributes[] = {			\
+	&dc##n##_size.attr,							\
+	&dc##n##_read_only.attr,						\
+	&dc##n##_shareable.attr,						\
+	&dc##n##_qos_class.attr,						\
+	NULL,									\
+};										\
+static umode_t cxl_memdev_dc##n##_attr_visible(struct kobject *kobj,		\
+					       struct attribute *a,		\
+					       int pos)				\
+{										\
+	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);	\
+										\
+	/* Not a memory device */						\
+	if (!mds)								\
+		return 0;							\
+	return a->mode;								\
+}										\
+static umode_t cxl_memdev_dc##n##_group_visible(struct kobject *kobj)		\
+{										\
+	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);	\
+										\
+	/* Not a memory device or partition not supported */			\
+	if (!mds || n >= mds->nr_dc_region)					\
+		return false;							\
+	return true;								\
+}										\
+DEFINE_SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n);					\
+static struct attribute_group cxl_memdev_dc##n##_group = {			\
+	.name = "dc"#n,								\
+	.attrs = cxl_memdev_dc##n##_attributes,					\
+	.is_visible = SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n),			\
+}
+CXL_MEMDEV_DC_ATTR_GROUP(0);
+CXL_MEMDEV_DC_ATTR_GROUP(1);
+CXL_MEMDEV_DC_ATTR_GROUP(2);
+CXL_MEMDEV_DC_ATTR_GROUP(3);
+CXL_MEMDEV_DC_ATTR_GROUP(4);
+CXL_MEMDEV_DC_ATTR_GROUP(5);
+CXL_MEMDEV_DC_ATTR_GROUP(6);
+CXL_MEMDEV_DC_ATTR_GROUP(7);
+
 static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
 				  int n)
 {
@@ -525,6 +643,14 @@ static struct attribute_group cxl_memdev_security_attribute_group = {
 };
 
 static const struct attribute_group *cxl_memdev_attribute_groups[] = {
+	&cxl_memdev_dc0_group,
+	&cxl_memdev_dc1_group,
+	&cxl_memdev_dc2_group,
+	&cxl_memdev_dc3_group,
+	&cxl_memdev_dc4_group,
+	&cxl_memdev_dc5_group,
+	&cxl_memdev_dc6_group,
+	&cxl_memdev_dc7_group,
 	&cxl_memdev_attribute_group,
 	&cxl_memdev_ram_attribute_group,
 	&cxl_memdev_pmem_attribute_group,

-- 
2.46.0