[PATCH 2/2] powerpc/pseries/dlpar: Add device tree nodes for DLPAR IO add

[Haren Myneni]

For the DLPAR IO ADD, the corresponding device tree nodes and
properties will be added to the device tree after enable the
device. The user space (drmgr tool) uses configure_connector
RTAS call with the DRC index to retrieve the corresponding
device nodes but this RTAS call needs /dev/mem access. Also
updates the device tree by writing to /proc/ppc64/ofdt.
Under system lockdown, /dev/mem access is restricted which means
the user space can not issue configure_connector RTAS call and
also can not access to /proc/ppc64/ofdt.

This patch extends the /sys/kernel/dlpar interface and provides
‘dt add index <drc_index>’ to the user space. The drmgr tool uses
this interface to update the device tree whenever the device is
added. This interface retrieves device tree nodes for the
corresponding DRC index using configure_connector RTAS call and
adds new device nodes / properties to the device tree.

Signed-off-by: Scott Cheloha <cheloha at linux.ibm.com>
Signed-off-by: Haren Myneni <haren at linux.ibm.com>
---
 arch/powerpc/platforms/pseries/dlpar.c | 134 +++++++++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 993fd3e8f6ea..fb34d5859da8 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -23,6 +23,7 @@
 #include <linux/uaccess.h>
 #include <asm/rtas.h>
 #include <asm/rtas-work-area.h>
+#include <asm/prom.h>
 
 static struct workqueue_struct *pseries_hp_wq;
 
@@ -264,6 +265,22 @@ int dlpar_detach_node(struct device_node *dn)
 
 	return 0;
 }
+static int dlpar_changeset_attach_cc_nodes(struct of_changeset *ocs,
+					struct device_node *dn)
+{
+	int rc;
+
+	pr_info("%s: %pOF\n", __func__, dn);
+
+	rc = of_changeset_attach_node(ocs, dn);
+
+	if (!rc && dn->child)
+		rc = dlpar_changeset_attach_cc_nodes(ocs, dn->child);
+	if (!rc && dn->sibling)
+		rc = dlpar_changeset_attach_cc_nodes(ocs, dn->sibling);
+
+	return rc;
+}
 
 #define DR_ENTITY_SENSE		9003
 #define DR_ENTITY_PRESENT	1
@@ -330,6 +347,120 @@ int dlpar_unisolate_drc(u32 drc_index)
 	return 0;
 }
 
+static struct device_node *
+get_device_node_with_drc_index(u32 index)
+{
+	struct device_node *np = NULL;
+	u32 node_index;
+	int rc;
+
+	for_each_node_with_property(np, "ibm,my-drc-index") {
+		rc = of_property_read_u32(np, "ibm,my-drc-index",
+					     &node_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);
+			return NULL;
+		}
+
+		if (index == node_index)
+			break;
+	}
+
+	return np;
+}
+
+static struct device_node *
+get_device_node_with_drc_info(u32 index)
+{
+	struct device_node *np = NULL;
+	struct of_drc_info drc;
+	struct property *info;
+	const __be32 *value;
+	u32 node_index;
+	int i, j, count;
+
+	for_each_node_with_property(np, "ibm,drc-info") {
+		info = of_find_property(np, "ibm,drc-info", NULL);
+		if (info == NULL) {
+			/* XXX can this happen? */
+			of_node_put(np);
+			return NULL;
+		}
+		value = of_prop_next_u32(info, NULL, &count);
+		if (value == NULL)
+			continue;
+		value++;
+		for (i = 0; i < count; i++) {
+			if (of_read_drc_info_cell(&info, &value, &drc))
+				break;
+			if (index > drc.last_drc_index)
+				continue;
+			node_index = drc.drc_index_start;
+			for (j = 0; j < drc.num_sequential_elems; j++) {
+				if (index == node_index)
+					return np;
+				node_index += drc.sequential_inc;
+			}
+		}
+	}
+
+	return NULL;
+}
+
+static int dlpar_hp_dt_add(u32 index)
+{
+	struct device_node *np, *nodes;
+	struct of_changeset ocs;
+	int rc;
+
+	/*
+	 * Do not add device node(s) if already exists in the
+	 * device tree.
+	 */
+	np = get_device_node_with_drc_index(index);
+	if (np) {
+		pr_err("%s: Adding device node for index (%d), but "
+				"already exists in the device tree\n",
+				__func__, index);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	np = get_device_node_with_drc_info(index);
+
+	if (!np)
+		return -EIO;
+
+	pr_info("%s: %pOF\n", __func__, np);
+
+	/* Next, configure the connector. */
+	nodes = dlpar_configure_connector(cpu_to_be32(index), np);
+	if (!nodes) {
+		rc = -EIO;
+		goto out;
+	}
+
+	/*
+	 * Add the new nodes from dlpar_configure_connector() onto
+	 * the device-tree.
+	 */
+	of_changeset_init(&ocs);
+	rc = dlpar_changeset_attach_cc_nodes(&ocs, nodes);
+
+	if (!rc)
+		rc = of_changeset_apply(&ocs);
+	else
+		dlpar_free_cc_nodes(nodes);
+
+	of_changeset_destroy(&ocs);
+
+out:
+	of_node_put(np);
+	return rc;
+}
+
 static int changeset_detach_node_recursive(struct of_changeset *ocs,
 					struct device_node *node)
 {
@@ -396,6 +527,9 @@ static int dlpar_hp_dt(struct pseries_hp_errorlog *phpe)
 	lock_device_hotplug();
 
 	switch (phpe->action) {
+	case PSERIES_HP_ELOG_ACTION_ADD:
+		rc = dlpar_hp_dt_add(phpe->_drc_u.drc_index);
+		break;
 	case PSERIES_HP_ELOG_ACTION_REMOVE:
 		rc = dlpar_hp_dt_remove(phpe->_drc_u.drc_index);
 		break;
-- 
2.43.5