[PATCH v3 10/10] powerpc/pseries/vas: Write 'target_creds' for QoS credits change

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

PowerVM support two types of credits - Default (uses normal priority
FIFO) and Qality of service (QoS uses high priproty FIFO). The user
decides the number of QoS credits and sets this value with HMC
interface. With the core add/removal, this value can be changed in HMC
which invokes drmgr to communicate to the kernel.

This patch adds an interface so that drmgr command can write the new
target QoS credits in sysfs. But the kernel gets the new QoS
capabilities from the hypervisor whenever target_creds is updated
to make sure sync with the values in the hypervisor.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/vas-sysfs.c | 34 +++++++++++++++++++++-
 arch/powerpc/platforms/pseries/vas.c       |  2 +-
 arch/powerpc/platforms/pseries/vas.h       |  1 +
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/vas-sysfs.c b/arch/powerpc/platforms/pseries/vas-sysfs.c
index f7609cdef8f8..66f1a0224811 100644
--- a/arch/powerpc/platforms/pseries/vas-sysfs.c
+++ b/arch/powerpc/platforms/pseries/vas-sysfs.c
@@ -36,6 +36,34 @@ static ssize_t avail_creds_show(struct vas_cop_feat_caps *caps, char *buf)
 	return sprintf(buf, "%d\n", avail_creds);
 }
 
+/*
+ * This function is used to get the notification from the drmgr when
+ * QoS credits are changed as part of DLPAR core add/removal. Though
+ * receiving the total QoS credits here, get the official QoS
+ * capabilities from the hypervisor.
+ */
+static ssize_t target_creds_store(struct vas_cop_feat_caps *caps,
+				       const char *buf, size_t count)
+{
+	int err;
+	u16 creds;
+
+	/*
+	 * Nothing to do for default credit type.
+	 */
+	if (caps->win_type == VAS_GZIP_DEF_FEAT_TYPE)
+		return -EOPNOTSUPP;
+
+	err = kstrtou16(buf, 0, &creds);
+	if (!err)
+		err = vas_reconfig_capabilties(caps->win_type);
+
+	if (err)
+		return -EINVAL;
+
+	return count;
+}
+
 #define sysfs_capbs_entry_read(_name)					\
 static ssize_t _name##_show(struct vas_cop_feat_caps *caps, char *buf) 	\
 {									\
@@ -52,8 +80,12 @@ struct vas_sysfs_entry {
 	sysfs_capbs_entry_read(_name);		\
 	static struct vas_sysfs_entry _name##_attribute = __ATTR(_name,	\
 				0444, _name##_show, NULL);
+#define VAS_ATTR(_name)							\
+	sysfs_capbs_entry_read(_name);					\
+	static struct vas_sysfs_entry _name##_attribute = __ATTR(_name, \
+				0644, _name##_show, _name##_store)
 
-VAS_ATTR_RO(target_creds);
+VAS_ATTR(target_creds);
 VAS_ATTR_RO(used_creds);
 
 static struct vas_sysfs_entry avail_creds_attribute =
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 32098e4a2786..3400f4fc6609 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -722,7 +722,7 @@ static int reconfig_close_windows(struct vas_caps *vcap, int excess_creds)
  * changes. Reconfig window configurations based on the credits
  * availability from this new capabilities.
  */
-static int vas_reconfig_capabilties(u8 type)
+int vas_reconfig_capabilties(u8 type)
 {
 	struct hv_vas_cop_feat_caps *hv_caps;
 	struct vas_cop_feat_caps *caps;
diff --git a/arch/powerpc/platforms/pseries/vas.h b/arch/powerpc/platforms/pseries/vas.h
index bc393bd74030..4cf1d0ef66a5 100644
--- a/arch/powerpc/platforms/pseries/vas.h
+++ b/arch/powerpc/platforms/pseries/vas.h
@@ -125,5 +125,6 @@ struct pseries_vas_window {
 };
 
 int sysfs_add_vas_caps(struct vas_cop_feat_caps *caps);
+int vas_reconfig_capabilties(u8 type);
 int __init sysfs_pseries_vas_init(struct vas_all_caps *vas_caps);
 #endif /* _VAS_H */
-- 
2.27.0