Re: [PATCH 3/9] powerpc/pseries: Add cpu DLPAR support for drc-info property

From: Tyrel Datwyler <redacted>

Older firmwares provided information about Dynamic Reconfig
Connectors (DRC) through several device tree properties, namely
ibm,drc-types, ibm,drc-indexes, ibm,drc-names, and
ibm,drc-power-domains. New firmwares have the ability to present this
same information in a much condensed format through a device tree
property called ibm,drc-info.

The existing cpu DLPAR hotplug code only understands the older DRC
property format when validating the drc-index of a cpu during a
hotplug add. This updates those code paths to use the ibm,drc-info
property, when present, instead for validation.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
  arch/powerpc/platforms/pseries/hotplug-cpu.c | 101 ++++++++++++++++++++++-----
  1 file changed, 85 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index bbda646..9ba006c 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -407,17 +407,58 @@ static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
  	return found;
  }

+static bool drc_info_valid_index(struct device_node *parent, u32 drc_index)
+{
+	struct property *info;
+	struct of_drc_info drc;
+	const __be32 *value;
+	int count, i, j;
+
+	info = of_find_property(parent, "ibm,drc-info", NULL);
+	if (!info)
+		return false;
+
+	value = of_prop_next_u32(info, NULL, &count);
+
+	/* First value of ibm,drc-info is number of drc-info records */
+	if (value)
+		value++;
+	else
+		return false;
+
+	for (i = 0; i < count; i++) {
+		if (of_read_drc_info_cell(&info, &value, &drc))
+			return false;
+
+		if (strncmp(drc.drc_type, "CPU", 3))
+			break;
+
+		if (drc_index > drc.last_drc_index)
+			continue;
+
+		for (j = 0; j < drc.num_sequential_elems; j++)
+			if (drc_index == (drc.drc_index_start + (drc.sequential_inc * j)))
+					return true;
+	}
+
+	return false;
+}
+
  static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
  {
  	bool found = false;
  	int rc, index;

-	index = 0;
+	if (of_find_property(parent, "ibm,drc-info", NULL))
+		return drc_info_valid_index(parent, drc_index);
+
+	index = 1;

  		if (rc)
  			break;

@@ -720,8 +761,11 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
  static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
  {
  	struct device_node *parent;
+	struct property *info;
  	int cpus_found = 0;
  	int index, rc;
+	int i, j;
+	u32 drc_index;

  	parent = of_find_node_by_path("/cpus");
  	if (!parent) {

@@ -730,24 +774,49 @@ static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
  		return -1;
  	}

-	/* Search the ibm,drc-indexes array for possible CPU drcs to
-	 * add. Note that the format of the ibm,drc-indexes array is
-	 * the number of entries in the array followed by the array
-	 * of drc values so we start looking at index = 1.
-	 */
-	index = 1;
-	while (cpus_found < cpus_to_add) {
-		u32 drc;
+	info = of_find_property(parent, "ibm,drc-info", NULL);
+	if (info) {
+		struct of_drc_info drc;
+		const __be32 *value;
+		int count;

-		rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
-						index++, &drc);
-		if (rc)
-			break;
+		value = of_prop_next_u32(info, NULL, &count);
+		if (value)
+			value++;

-		if (dlpar_cpu_exists(parent, drc))
-			continue;
+		for (i = 0; i < count; i++) {
+			of_read_drc_info_cell(&info, &value, &drc);
+			if (strncmp(drc.drc_type, "CPU", 3))
+				break;
+
+			for (j = 0; j < drc.num_sequential_elems && cpus_found < cpus_to_add; j++) {
+				drc_index = drc.drc_index_start + (drc.sequential_inc * j);
+
+				if (dlpar_cpu_exists(parent, drc_index))
+					continue;
+
+				cpu_drcs[cpus_found++] = drc_index;
+			}
+		}
+	} else {
+		/* Search the ibm,drc-indexes array for possible CPU drcs to
+		 * add. Note that the format of the ibm,drc-indexes array is
+		 * the number of entries in the array followed by the array
+		 * of drc values so we start looking at index = 1.
+		 */
+		index = 1;
+		while (cpus_found < cpus_to_add) {
+			rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
+							index++, &drc_index);
+
+			if (rc)
+				break;

-		cpu_drcs[cpus_found++] = drc;
+			if (dlpar_cpu_exists(parent, drc_index))
+				continue;
+
+			cpu_drcs[cpus_found++] = drc_index;
+		}
  	}

  	of_node_put(parent);