[V3 PATCH 12/16] powerpc/pseries/vas: sysfs interface to export capabilities

[Haren Myneni <haren@linux.ibm.com>]

pHyp provides GZIP default and GZIP QoS capabilities which gives
the total number of credits are available in LPAR. This patch
creates sysfs entries and exports LPAR credits, the currently used
and the available credits for each feature.

/sys/kernel/vas/VasCaps/VDefGzip: (default GZIP capabilities)
	avail_lpar_creds /* Available credits to use */
	target_lpar_creds /* Total credits available which can be
			 /* changed with DLPAR operation */
	used_lpar_creds  /* Used credits */

/sys/kernel/vas/VasCaps/VQosGzip (QoS GZIP capabilities)
	avail_lpar_creds
	target_lpar_creds
	used_lpar_creds

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/Makefile    |   2 +-
 arch/powerpc/platforms/pseries/vas-sysfs.c | 173 +++++++++++++++++++++
 arch/powerpc/platforms/pseries/vas.c       |   6 +
 arch/powerpc/platforms/pseries/vas.h       |   2 +
 4 files changed, 182 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/platforms/pseries/vas-sysfs.c

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 4cda0ef87be0..e24093bebc0b 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -30,4 +30,4 @@ obj-$(CONFIG_PPC_SVM)		+= svm.o
 obj-$(CONFIG_FA_DUMP)		+= rtas-fadump.o
 
 obj-$(CONFIG_SUSPEND)		+= suspend.o
-obj-$(CONFIG_PPC_VAS)		+= vas.o
+obj-$(CONFIG_PPC_VAS)		+= vas.o vas-sysfs.o
diff --git a/arch/powerpc/platforms/pseries/vas-sysfs.c b/arch/powerpc/platforms/pseries/vas-sysfs.c
new file mode 100644
index 000000000000..5f01f8ba6806
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/vas-sysfs.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2016-17 IBM Corp.
+ */
+
+#define pr_fmt(fmt) "vas: " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+#include "vas.h"
+
+#ifdef CONFIG_SYSFS
+static struct kobject *pseries_vas_kobj;
+static struct kobject *vas_capabs_kobj;
+
+struct vas_capabs_entry {
+	struct kobject kobj;
+	struct vas_ct_capabs *capabs;
+};
+
+#define to_capabs_entry(entry) container_of(entry, struct vas_capabs_entry, kobj)
+
+static ssize_t avail_lpar_creds_show(struct vas_ct_capabs *capabs, char *buf)
+{
+	int avail_creds = atomic_read(&capabs->target_lpar_creds) -
+			atomic_read(&capabs->used_lpar_creds);
+	return sprintf(buf, "%d\n", avail_creds);
+}
+
+#define sysfs_capbs_entry_read(_name)					\
+static ssize_t _name##_show(struct vas_ct_capabs *capabs, char *buf) 	\
+{									\
+	return sprintf(buf, "%d\n", atomic_read(&capabs->_name));	\
+}
+
+struct vas_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct vas_ct_capabs *, char *);
+	ssize_t (*store)(struct vas_ct_capabs *, const char *, size_t);
+};
+
+#define VAS_ATTR_RO(_name)	\
+	sysfs_capbs_entry_read(_name);		\
+	static struct vas_sysfs_entry _name##_attribute = __ATTR(_name,	\
+				0444, _name##_show, NULL);
+
+VAS_ATTR_RO(target_lpar_creds);
+VAS_ATTR_RO(used_lpar_creds);
+
+static struct vas_sysfs_entry avail_lpar_creds_attribute =
+	__ATTR(avail_lpar_creds, 0444, avail_lpar_creds_show, NULL);
+
+static struct attribute *vas_capab_attrs[] = {
+	&target_lpar_creds_attribute.attr,
+	&used_lpar_creds_attribute.attr,
+	&avail_lpar_creds_attribute.attr,
+	NULL,
+};
+
+static ssize_t vas_type_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct vas_capabs_entry *centry;
+	struct vas_ct_capabs *capabs;
+	struct vas_sysfs_entry *entry;
+
+	centry = to_capabs_entry(kobj);
+	capabs = centry->capabs;
+	entry = container_of(attr, struct vas_sysfs_entry, attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(capabs, buf);
+}
+
+static ssize_t vas_type_store(struct kobject *kobj, struct attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct vas_capabs_entry *centry;
+	struct vas_ct_capabs *capabs;
+	struct vas_sysfs_entry *entry;
+
+	centry = to_capabs_entry(kobj);
+	capabs = centry->capabs;
+	entry = container_of(attr, struct vas_sysfs_entry, attr);
+	if (!entry->store)
+		return -EIO;
+
+	return entry->store(capabs, buf, count);
+}
+
+static void vas_type_release(struct kobject *kobj)
+{
+	struct vas_capabs_entry *centry = to_capabs_entry(kobj);
+	kfree(centry);
+}
+
+static const struct sysfs_ops vas_sysfs_ops = {
+	.show	=	vas_type_show,
+	.store	=	vas_type_store,
+};
+
+static struct kobj_type vas_attr_type = {
+		.release	=	vas_type_release,
+		.sysfs_ops      =       &vas_sysfs_ops,
+		.default_attrs  =       vas_capab_attrs,
+};
+
+/*
+ * Add feature specific capability dir entry.
+ * Ex: VDefGzip or VQosGzip
+ */
+int sysfs_add_vas_capabs(struct vas_ct_capabs *capabs)
+{
+	struct vas_capabs_entry *centry;
+	int ret = 0;
+
+	centry = kzalloc(sizeof(*centry), GFP_KERNEL);
+	if (!centry)
+		return -ENOMEM;
+
+	kobject_init(&centry->kobj, &vas_attr_type);
+	centry->capabs = capabs;
+
+	ret = kobject_add(&centry->kobj, vas_capabs_kobj, "%s",
+			  capabs->name);
+
+	if (ret) {
+		pr_err("VAS: sysfs kobject add / event failed %d\n", ret);
+		kobject_put(&centry->kobj);
+	}
+
+	return ret;
+}
+
+/*
+ * Add VAS and VasCaps (overall capabilities) dir entries.
+ */
+int __init sysfs_pseries_vas_init(struct vas_all_capabs *vas_caps)
+{
+	pseries_vas_kobj = kobject_create_and_add("vas", kernel_kobj);
+	if (!pseries_vas_kobj) {
+		pr_err("Failed to create VAS sysfs entry\n");
+		return -ENOMEM;
+	}
+
+	vas_capabs_kobj = kobject_create_and_add(vas_caps->name,
+						 pseries_vas_kobj);
+	if (!vas_capabs_kobj) {
+		pr_err("Failed to create VAS capabilities kobject\n");
+		kobject_put(pseries_vas_kobj);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+#else
+int sysfs_add_vas_capabs(struct vas_ct_capabs *capabs)
+{
+	return 0;
+}
+
+int __init sysfs_pseries_vas_init(struct vas_all_capabs *vas_caps)
+{
+	return 0;
+}
+#endif
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 2106eca0862a..ac06fa09900c 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -594,6 +594,10 @@ static int get_vas_capabilities(u8 feat, enum vas_cop_feat_type type,
 		}
 	}
 
+	rc = sysfs_add_vas_capabs(capab);
+	if (rc)
+		return rc;
+
 	copypaste_feat = 1;
 
 	return 0;
@@ -629,6 +633,8 @@ static int __init pseries_vas_init(void)
 	capabs_all.descriptor = be64_to_cpu(capabs_be->descriptor);
 	capabs_all.feat_type = be64_to_cpu(capabs_be->feat_type);
 
+	sysfs_pseries_vas_init(&capabs_all);
+
 	ct_capabs_be = kmalloc(sizeof(*ct_capabs_be), GFP_KERNEL);
 	if (!ct_capabs_be) {
 		rc = -ENOMEM;
diff --git a/arch/powerpc/platforms/pseries/vas.h b/arch/powerpc/platforms/pseries/vas.h
index 208682fffa57..e64677f03f08 100644
--- a/arch/powerpc/platforms/pseries/vas.h
+++ b/arch/powerpc/platforms/pseries/vas.h
@@ -93,4 +93,6 @@ struct vas_win_lpar_be {
 	__be64	win_util;	/* Number of bytes processed */
 } __packed __aligned(0x1000);
 
+int sysfs_add_vas_capabs(struct vas_ct_capabs *capabs);
+int __init sysfs_pseries_vas_init(struct vas_all_capabs *vas_caps);
 #endif /* _VAS_H */
-- 
2.18.2