powerpc/pseries: Add cpu DLPAR support for drc-info property

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1573449697-5448-4-git-send-email-tyreld@linux.ibm.com

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 8ab24bd..3e8cbfe 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -465,17 +465,67 @@ 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;
+       u32 index;
+       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;
+
+               index = drc.drc_index_start;
+               for (j = 0; j < drc.num_sequential_elems; j++) {
+                       if (drc_index == index)
+                               return true;
+
+                       index += drc.sequential_inc;
+               }
+       }
+
+       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);
+
+       /* 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 (!found) {
                u32 drc;
 
                rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
                                                index++, &drc);
+
                if (rc)
                        break;
 
@@ -718,19 +768,52 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
        return rc;
 }
 
-static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
+static int find_drc_info_cpus_to_add(struct device_node *cpus,
+                                    struct property *info,
+                                    u32 *cpu_drcs, u32 cpus_to_add)
 {
-       struct device_node *parent;
+       struct of_drc_info drc;
+       const __be32 *value;
+       u32 count, drc_index;
        int cpus_found = 0;
-       int index, rc;
+       int i, j;
 
-       parent = of_find_node_by_path("/cpus");
-       if (!parent) {
-               pr_warn("Could not find CPU root node in device tree\n");
-               kfree(cpu_drcs);
+       if (!info)
                return -1;
+
+       value = of_prop_next_u32(info, NULL, &count);
+       if (value)
+               value++;
+
+       for (i = 0; i < count; i++) {
+               of_read_drc_info_cell(&info, &value, &drc);
+               if (strncmp(drc.drc_type, "CPU", 3))
+                       break;
+
+               drc_index = drc.drc_index_start;
+               for (j = 0; j < drc.num_sequential_elems; j++) {
+                       if (dlpar_cpu_exists(cpus, drc_index))
+                               continue;
+
+                       cpu_drcs[cpus_found++] = drc_index;
+
+                       if (cpus_found == cpus_to_add)
+                               return cpus_found;
+
+                       drc_index += drc.sequential_inc;
+               }
        }
 
+       return cpus_found;
+}
+
+static int find_drc_index_cpus_to_add(struct device_node *cpus,
+                                     u32 *cpu_drcs, u32 cpus_to_add)
+{
+       int cpus_found = 0;
+       int index, rc;
+       u32 drc_index;
+
        /* 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
@@ -738,25 +821,25 @@ static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
         */
        index = 1;
        while (cpus_found < cpus_to_add) {
-               u32 drc;
+               rc = of_property_read_u32_index(cpus, "ibm,drc-indexes",
+                                               index++, &drc_index);
 
-               rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
-                                               index++, &drc);
                if (rc)
                        break;
 
-               if (dlpar_cpu_exists(parent, drc))
+               if (dlpar_cpu_exists(cpus, drc_index))
                        continue;
 
-               cpu_drcs[cpus_found++] = drc;
+               cpu_drcs[cpus_found++] = drc_index;
        }
 
-       of_node_put(parent);
        return cpus_found;
 }
 
 static int dlpar_cpu_add_by_count(u32 cpus_to_add)
 {
+       struct device_node *parent;
+       struct property *info;
        u32 *cpu_drcs;
        int cpus_added = 0;
        int cpus_found;
@@ -768,7 +851,21 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add)
        if (!cpu_drcs)
                return -EINVAL;
 
-       cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
+       parent = of_find_node_by_path("/cpus");
+       if (!parent) {
+               pr_warn("Could not find CPU root node in device tree\n");
+               kfree(cpu_drcs);
+               return -1;
+       }
+
+       info = of_find_property(parent, "ibm,drc-info", NULL);
+       if (info)
+               cpus_found = find_drc_info_cpus_to_add(parent, info, cpu_drcs, cpus_to_add);
+       else
+               cpus_found = find_drc_index_cpus_to_add(parent, cpu_drcs, cpus_to_add);
+
+       of_node_put(parent);
+
        if (cpus_found < cpus_to_add) {
                pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
                        cpus_found, cpus_to_add);