[PATCH 5/5] dmaengine: idxd: add configuration for concurrent batch descriptor processing

[Fenghua Yu]

From: Dave Jiang <dave.jiang@xxxxxxxxx>

Add sysfs knob to allow control of the number of batch descriptors that can
be concurrently processed by an engine in the group as a fraction of the
Maximum Work Descriptors in Progress value specfied in ENGCAP register.
This control knob is part of toggle for QoS control.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Co-developed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 .../ABI/stable/sysfs-driver-dma-idxd          | 12 +++++++
 drivers/dma/idxd/device.c                     |  2 ++
 drivers/dma/idxd/idxd.h                       |  1 +
 drivers/dma/idxd/registers.h                  |  4 ++-
 drivers/dma/idxd/sysfs.c                      | 36 +++++++++++++++++--
 5 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-driver-dma-idxd b/Documentation/ABI/stable/sysfs-driver-dma-idxd
index 02a721a8ea68..8e2c2c405db2 100644
--- a/Documentation/ABI/stable/sysfs-driver-dma-idxd
+++ b/Documentation/ABI/stable/sysfs-driver-dma-idxd
@@ -278,3 +278,15 @@ Description:	Allows control of the number of work descriptors that can be
 		1 (1/2 of max value), 2 (1/4 of the max value), and 3 (1/8 of
 		the max value). It's visible only on platforms that support
 		the capability.
+
+What:		/sys/bus/dsa/devices/group<m>.<n>/batch_progress_limit
+Date:		Sept 14, 2022
+KernelVersion:	6.0.0
+Contact:	dmaengine@xxxxxxxxxxxxxxx
+Description:	Allows control of the number of batch descriptors that can be
+		concurrently processed by an engine in the group as a fraction
+		of the Maximum Batch Descriptors in Progress value specified in
+		the ENGCAP register. The acceptable values are 0 (default),
+		1 (1/2 of max value), 2 (1/4 of the max value), and 3 (1/8 of
+		the max value). It's visible only on platforms that support
+		the capability.
diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 3aa583f70312..7a9f3110552b 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -708,6 +708,7 @@ static void idxd_groups_clear_state(struct idxd_device *idxd)
 			group->tc_b = -1;
 		}
 		group->desc_progress_limit = 0;
+		group->batch_progress_limit = 0;
 	}
 }
 
@@ -930,6 +931,7 @@ static void idxd_group_flags_setup(struct idxd_device *idxd)
 			group->grpcfg.flags.rdbufs_allowed = idxd->max_rdbufs;
 
 		group->grpcfg.flags.desc_progress_limit = group->desc_progress_limit;
+		group->grpcfg.flags.batch_progress_limit = group->batch_progress_limit;
 	}
 }
 
diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 058010be0f87..8035c7982f93 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -96,6 +96,7 @@ struct idxd_group {
 	int tc_a;
 	int tc_b;
 	int desc_progress_limit;
+	int batch_progress_limit;
 };
 
 struct idxd_pmu {
diff --git a/drivers/dma/idxd/registers.h b/drivers/dma/idxd/registers.h
index 2cc2543edd58..fe3b8d04f9db 100644
--- a/drivers/dma/idxd/registers.h
+++ b/drivers/dma/idxd/registers.h
@@ -298,7 +298,9 @@ union group_flags {
 		u64 rdbufs_allowed:8;
 		u64 rsvd3:4;
 		u64 desc_progress_limit:2;
-		u64 rsvd4:30;
+		u64 rsvd4:2;
+		u64 batch_progress_limit:2;
+		u64 rsvd5:26;
 	};
 	u64 bits;
 } __packed;
diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
index 3e655a3a4c7c..88d2cac316fe 100644
--- a/drivers/dma/idxd/sysfs.c
+++ b/drivers/dma/idxd/sysfs.c
@@ -474,6 +474,36 @@ static struct device_attribute dev_attr_group_desc_progress_limit =
 		__ATTR(desc_progress_limit, 0644, group_desc_progress_limit_show,
 		       group_desc_progress_limit_store);
 
+static ssize_t group_batch_progress_limit_show(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	struct idxd_group *group = confdev_to_group(dev);
+
+	return sysfs_emit(buf, "%d\n", group->batch_progress_limit);
+}
+
+static ssize_t group_batch_progress_limit_store(struct device *dev,
+						struct device_attribute *attr,
+						const char *buf, size_t count)
+{
+	struct idxd_group *group = confdev_to_group(dev);
+	int val, rc;
+
+	rc = kstrtoint(buf, 10, &val);
+	if (rc < 0)
+		return -EINVAL;
+
+	if (val & ~GENMASK(1, 0))
+		return -EINVAL;
+
+	group->batch_progress_limit = val;
+	return count;
+}
+
+static struct device_attribute dev_attr_group_batch_progress_limit =
+		__ATTR(batch_progress_limit, 0644, group_batch_progress_limit_show,
+		       group_batch_progress_limit_store);
 static struct attribute *idxd_group_attributes[] = {
 	&dev_attr_group_work_queues.attr,
 	&dev_attr_group_engines.attr,
@@ -486,14 +516,16 @@ static struct attribute *idxd_group_attributes[] = {
 	&dev_attr_group_traffic_class_a.attr,
 	&dev_attr_group_traffic_class_b.attr,
 	&dev_attr_group_desc_progress_limit.attr,
+	&dev_attr_group_batch_progress_limit.attr,
 	NULL,
 };
 
 static bool idxd_group_attr_progress_limit_invisible(struct attribute *attr,
 						     struct idxd_device *idxd)
 {
-	return attr == &dev_attr_group_desc_progress_limit.attr &&
-	       !idxd->hw.group_cap.progress_limit;
+	return (attr == &dev_attr_group_desc_progress_limit.attr ||
+		attr == &dev_attr_group_batch_progress_limit.attr) &&
+		!idxd->hw.group_cap.progress_limit;
 }
 
 static umode_t idxd_group_attr_visible(struct kobject *kobj,
-- 
2.32.0