[PATCH 1/2] powerpc/pseries/dlpar: Remove device tree node for DLPAR IO remove

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

For the DLPAR IO REMOVE, the corresponding device tree nodes and
properties have to be removed from the device tree after disable
the device. In the current implementation, the user space (drmgr
tool) remove the device tree nodes by updating /proc/ppc64/ofdt
which needs /dev/mem. But /dev/mem access is restricted under
system lockdown is enabled.

This patch extends the /sys/kernel/dlpar interface and provides
‘dt remove index <drc_index>’ to the user space so that drmgr
tool can remove the corresponding device tree nodes based on DRC
index from the device tree.

Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h        |  1 +
 arch/powerpc/platforms/pseries/dlpar.c | 87 +++++++++++++++++++++++++-
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 065ffd1b2f8a..04406162fc5a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -397,6 +397,7 @@ inline uint16_t pseries_errorlog_length(struct pseries_errorlog *sect)
 #define PSERIES_HP_ELOG_RESOURCE_SLOT	3
 #define PSERIES_HP_ELOG_RESOURCE_PHB	4
 #define PSERIES_HP_ELOG_RESOURCE_PMEM   6
+#define PSERIES_HP_ELOG_RESOURCE_DT	7
 
 #define PSERIES_HP_ELOG_ACTION_ADD	1
 #define PSERIES_HP_ELOG_ACTION_REMOVE	2
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 47f8eabd1bee..993fd3e8f6ea 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -330,6 +330,86 @@ int dlpar_unisolate_drc(u32 drc_index)
 	return 0;
 }
 
+static int changeset_detach_node_recursive(struct of_changeset *ocs,
+					struct device_node *node)
+{
+	struct device_node *child;
+	int rc;
+
+	for_each_child_of_node(node, child) {
+		rc = changeset_detach_node_recursive(ocs, child);
+		if (rc) {
+			of_node_put(child);
+			return rc;
+		}
+	}
+
+	pr_info("%s: %pOF\n", __func__, node);
+	return of_changeset_detach_node(ocs, node);
+}
+
+static int dlpar_hp_dt_remove(u32 drc_index)
+{
+	struct device_node *np;
+	struct of_changeset ocs;
+	u32 index;
+	int rc = 0;
+
+	/*
+	 * Prune all nodes with a matching index.
+	 * TODO Search for sub-nodes that haven't been properly detached yet.
+	 */
+	of_changeset_init(&ocs);
+
+	for_each_node_with_property(np, "ibm,my-drc-index") {
+		rc = of_property_read_u32(np, "ibm,my-drc-index", &index);
+		if (rc) {
+			pr_err("%s: %pOF: of_property_read_u32 %s: %d\n",
+				__func__, np, "ibm,my-drc-index", rc);
+			of_node_put(np);
+			goto out;
+		}
+
+		if (index == drc_index) {
+			rc = changeset_detach_node_recursive(&ocs, np);
+			if (rc) {
+				of_node_put(np);
+				goto out;
+			}
+		}
+	}
+
+	rc = of_changeset_apply(&ocs);
+
+out:
+	of_changeset_destroy(&ocs);
+	return rc;
+}
+
+static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
+{
+	int rc;
+
+	if (phpe->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX)
+		return -EINVAL;
+
+	lock_device_hotplug();
+
+	switch (phpe->action) {
+	case PSERIES_HP_ELOG_ACTION_REMOVE:
+		rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
+		break;
+	default:
+		pr_err("Invalid action (%d) specified\n", phpe->action);
+		rc = -EINVAL;
+		break;
+	}
+
+	unlock_device_hotplug();
+
+	return rc;
+}
+
 int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
 {
 	int rc;
@@ -361,6 +441,9 @@ int handle_dlpar_errorlog(struct pseries_hp_errorlog *hp_elog)
 	case PSERIES_HP_ELOG_RESOURCE_PMEM:
 		rc = dlpar_hp_pmem(hp_elog);
 		break;
+	case PSERIES_HP_ELOG_RESOURCE_DT:
+		rc = dlpar_hp_dt(hp_elog);
+		break;
 
 	default:
 		pr_warn_ratelimited("Invalid resource (%d) specified\n",
@@ -413,6 +496,8 @@ static int dlpar_parse_resource(char **cmd, struct pseries_hp_errorlog *hp_elog)
 		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_MEM;
 	} else if (sysfs_streq(arg, "cpu")) {
 		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_CPU;
+	} else if (sysfs_streq(arg, "dt")) {
+		hp_elog->resource = PSERIES_HP_ELOG_RESOURCE_DT;
 	} else {
 		pr_err("Invalid resource specified.\n");
 		return -EINVAL;
@@ -554,7 +639,7 @@ static ssize_t dlpar_store(const struct class *class, const struct class_attribu
 static ssize_t dlpar_show(const struct class *class, const struct class_attribute *attr,
 			  char *buf)
 {
-	return sprintf(buf, "%s\n", "memory,cpu");
+	return sprintf(buf, "%s\n", "memory,cpu,dt");
 }
 
 static CLASS_ATTR_RW(dlpar);
-- 
2.43.5