[v6,8/9] powerpc/pseries/vas: sysfs interface to export capabilities

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index ee60b59024b4..29b522d2c755 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -29,6 +29,6 @@  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
 
 obj-$(CONFIG_ARCH_HAS_CC_PLATFORM)	+= cc_platform.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..e24d3edb3021
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/vas-sysfs.c
@@ -0,0 +1,226 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2022-23 IBM Corp.
+ */
+
+#define pr_fmt(fmt) "vas: " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.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 *gzip_caps_kobj;
+
+struct vas_caps_entry {
+	struct kobject kobj;
+	struct vas_cop_feat_caps *caps;
+};
+
+#define to_caps_entry(entry) container_of(entry, struct vas_caps_entry, kobj)
+
+#define sysfs_caps_entry_read(_name)					\
+static ssize_t _name##_show(struct vas_cop_feat_caps *caps, char *buf) 	\
+{									\
+	return sprintf(buf, "%d\n", atomic_read(&caps->_name));	\
+}
+
+struct vas_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct vas_cop_feat_caps *, char *);
+	ssize_t (*store)(struct vas_cop_feat_caps *, const char *, size_t);
+};
+
+#define VAS_ATTR_RO(_name)	\
+	sysfs_caps_entry_read(_name);		\
+	static struct vas_sysfs_entry _name##_attribute = __ATTR(_name,	\
+				0444, _name##_show, NULL);
+
+/*
+ * Create sysfs interface:
+ * /sys/devices/vas/vas0/gzip/default_capabilities
+ *	This directory contains the following VAS GZIP capabilities
+ *	for the defaule credit type.
+ * /sys/devices/vas/vas0/gzip/default_capabilities/nr_total_credits
+ *	Total number of default credits assigned to the LPAR which
+ *	can be changed with DLPAR operation.
+ * /sys/devices/vas/vas0/gzip/default_capabilities/nr_used_credits
+ *	Number of credits used by the user space. One credit will
+ *	be assigned for each window open.
+ *
+ * /sys/devices/vas/vas0/gzip/qos_capabilities
+ *	This directory contains the following VAS GZIP capabilities
+ *	for the Quality of Service (QoS) credit type.
+ * /sys/devices/vas/vas0/gzip/qos_capabilities/nr_total_credits
+ *	Total number of QoS credits assigned to the LPAR. The user
+ *	has to define this value using HMC interface. It can be
+ *	changed dynamically by the user.
+ * /sys/devices/vas/vas0/gzip/qos_capabilities/nr_used_credits
+ *	Number of credits used by the user space.
+ */
+
+VAS_ATTR_RO(nr_total_credits);
+VAS_ATTR_RO(nr_used_credits);
+
+static struct attribute *vas_capab_attrs[] = {
+	&nr_total_credits_attribute.attr,
+	&nr_used_credits_attribute.attr,
+	NULL,
+};
+
+static ssize_t vas_type_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct vas_caps_entry *centry;
+	struct vas_cop_feat_caps *caps;
+	struct vas_sysfs_entry *entry;
+
+	centry = to_caps_entry(kobj);
+	caps = centry->caps;
+	entry = container_of(attr, struct vas_sysfs_entry, attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(caps, buf);
+}
+
+static ssize_t vas_type_store(struct kobject *kobj, struct attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct vas_caps_entry *centry;
+	struct vas_cop_feat_caps *caps;
+	struct vas_sysfs_entry *entry;
+
+	centry = to_caps_entry(kobj);
+	caps = centry->caps;
+	entry = container_of(attr, struct vas_sysfs_entry, attr);
+	if (!entry->store)
+		return -EIO;
+
+	return entry->store(caps, buf, count);
+}
+
+static void vas_type_release(struct kobject *kobj)
+{
+	struct vas_caps_entry *centry = to_caps_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,
+};
+
+static char *vas_caps_kobj_name(struct vas_cop_feat_caps *caps,
+				struct kobject **kobj)
+{
+	if (caps->descriptor == VAS_GZIP_QOS_CAPABILITIES) {
+		*kobj = gzip_caps_kobj;
+		return "qos_capabilities";
+	} else if (caps->descriptor == VAS_GZIP_DEFAULT_CAPABILITIES) {
+		*kobj = gzip_caps_kobj;
+		return "default_capabilities";
+	} else
+		return "Unknown";
+}
+
+/*
+ * Add feature specific capability dir entry.
+ * Ex: VDefGzip or VQosGzip
+ */
+int sysfs_add_vas_caps(struct vas_cop_feat_caps *caps)
+{
+	struct vas_caps_entry *centry;
+	struct kobject *kobj = NULL;
+	int ret = 0;
+	char *name;
+
+	centry = kzalloc(sizeof(*centry), GFP_KERNEL);
+	if (!centry)
+		return -ENOMEM;
+
+	kobject_init(&centry->kobj, &vas_attr_type);
+	centry->caps = caps;
+	name  = vas_caps_kobj_name(caps, &kobj);
+
+	if (kobj) {
+		ret = kobject_add(&centry->kobj, kobj, "%s", name);
+
+		if (ret) {
+			pr_err("VAS: sysfs kobject add / event failed %d\n",
+					ret);
+			kobject_put(&centry->kobj);
+		}
+	}
+
+	return ret;
+}
+
+static struct miscdevice vas_miscdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "vas",
+};
+
+/*
+ * Add VAS and VasCaps (overall capabilities) dir entries.
+ */
+int __init sysfs_pseries_vas_init(struct vas_all_caps *vas_caps)
+{
+	int ret;
+
+	ret = misc_register(&vas_miscdev);
+	if (ret < 0) {
+		pr_err("%s: register vas misc device failed\n", __func__);
+		return ret;
+	}
+
+	/*
+	 * The hypervisor does not expose multiple VAS instances, but can
+	 * see multiple VAS instances on PowerNV. So create 'vas0' directory
+	 * on pseries.
+	 */
+	pseries_vas_kobj = kobject_create_and_add("vas0",
+					&vas_miscdev.this_device->kobj);
+	if (!pseries_vas_kobj) {
+		pr_err("Failed to create VAS sysfs entry\n");
+		return -ENOMEM;
+	}
+
+	if ((vas_caps->feat_type & VAS_GZIP_QOS_FEAT_BIT) ||
+		(vas_caps->feat_type & VAS_GZIP_DEF_FEAT_BIT)) {
+		gzip_caps_kobj = kobject_create_and_add("gzip",
+						       pseries_vas_kobj);
+		if (!gzip_caps_kobj) {
+			pr_err("Failed to create VAS GZIP capability entry\n");
+			kobject_put(pseries_vas_kobj);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+#else
+int sysfs_add_vas_caps(struct vas_cop_feat_caps *caps)
+{
+	return 0;
+}
+
+int __init sysfs_pseries_vas_init(struct vas_all_caps *vas_caps)
+{
+	return 0;
+}
+#endif
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 96178dd58adf..ca0ad191229d 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -560,6 +560,10 @@  static int __init get_vas_capabilities(u8 feat, enum vas_cop_feat_type type,
 		}
 	}
 
+	rc = sysfs_add_vas_caps(caps);
+	if (rc)
+		return rc;
+
 	copypaste_feat = true;
 
 	return 0;
@@ -844,6 +848,8 @@  static int __init pseries_vas_init(void)
 	caps_all.descriptor = be64_to_cpu(hv_caps->descriptor);
 	caps_all.feat_type = be64_to_cpu(hv_caps->feat_type);
 
+	sysfs_pseries_vas_init(&caps_all);
+
 	hv_cop_caps = kmalloc(sizeof(*hv_cop_caps), GFP_KERNEL);
 	if (!hv_cop_caps) {
 		rc = -ENOMEM;
diff --git a/arch/powerpc/platforms/pseries/vas.h b/arch/powerpc/platforms/pseries/vas.h
index 701363cfd7c1..f1bdb776021e 100644
--- a/arch/powerpc/platforms/pseries/vas.h
+++ b/arch/powerpc/platforms/pseries/vas.h
@@ -30,6 +30,9 @@ 
 #define VAS_COPY_PASTE_USER_MODE	0x00000001
 #define VAS_COP_OP_USER_MODE		0x00000010
 
+#define VAS_GZIP_QOS_CAPABILITIES	0x56516F73477A6970
+#define VAS_GZIP_DEFAULT_CAPABILITIES	0x56446566477A6970
+
 /*
  * Co-processor feature - GZIP QoS windows or GZIP default windows
  */
@@ -125,4 +128,7 @@  struct pseries_vas_window {
 	char *name;
 	int fault_virq;
 };
+
+int sysfs_add_vas_caps(struct vas_cop_feat_caps *caps);
+int __init sysfs_pseries_vas_init(struct vas_all_caps *vas_caps);
 #endif /* _VAS_H */