arch/powerpc/platforms/pseries/pmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Handles hot and cold plug of persistent memory regions on pseries.
   5  */
   6
   7 #define pr_fmt(fmt)     "pseries-pmem: " fmt
   8
   9 #include <linux/kernel.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/delay.h>
  12 #include <linux/sched.h>        /* for idle_task_exit */
  13 #include <linux/sched/hotplug.h>
  14 #include <linux/cpu.h>
  15 #include <linux/of.h>
  16 #include <linux/of_platform.h>
  17 #include <linux/slab.h>
  18 #include <asm/prom.h>
  19 #include <asm/rtas.h>
  20 #include <asm/firmware.h>
  21 #include <asm/machdep.h>
  22 #include <asm/vdso_datapage.h>
  23 #include <asm/plpar_wrappers.h>
  24 #include <asm/topology.h>
  25
  26 #include "pseries.h"
  27
  28 static struct device_node *pmem_node;
  29
  30 static ssize_t pmem_drc_add_node(u32 drc_index)
  31 {
  32         struct device_node *dn;
  33         int rc;
  34
  35         pr_debug("Attempting to add pmem node, drc index: %x\n", drc_index);
  36
  37         rc = dlpar_acquire_drc(drc_index);
  38         if (rc) {
  39                 pr_err("Failed to acquire DRC, rc: %d, drc index: %x\n",
  40                         rc, drc_index);
  41                 return -EINVAL;
  42         }
  43
  44         dn = dlpar_configure_connector(cpu_to_be32(drc_index), pmem_node);
  45         if (!dn) {
  46                 pr_err("configure-connector failed for drc %x\n", drc_index);
  47                 dlpar_release_drc(drc_index);
  48                 return -EINVAL;
  49         }
  50
  51         /* NB: The of reconfig notifier creates platform device from the node */
  52         rc = dlpar_attach_node(dn, pmem_node);
  53         if (rc) {
  54                 pr_err("Failed to attach node %pOF, rc: %d, drc index: %x\n",
  55                         dn, rc, drc_index);
  56
  57                 if (dlpar_release_drc(drc_index))
  58                         dlpar_free_cc_nodes(dn);
  59
  60                 return rc;
  61         }
  62
  63         pr_info("Successfully added %pOF, drc index: %x\n", dn, drc_index);
  64
  65         return 0;
  66 }
  67
  68 static ssize_t pmem_drc_remove_node(u32 drc_index)
  69 {
  70         struct device_node *dn;
  71         uint32_t index;
  72         int rc;
  73
  74         for_each_child_of_node(pmem_node, dn) {
  75                 if (of_property_read_u32(dn, "ibm,my-drc-index", &index))
  76                         continue;
  77                 if (index == drc_index)
  78                         break;
  79         }
  80
  81         if (!dn) {
  82                 pr_err("Attempting to remove unused DRC index %x\n", drc_index);
  83                 return -ENODEV;
  84         }
  85
  86         pr_debug("Attempting to remove %pOF, drc index: %x\n", dn, drc_index);
  87
  88         /* * NB: tears down the ibm,pmemory device as a side-effect */
  89         rc = dlpar_detach_node(dn);
  90         if (rc)
  91                 return rc;
  92
  93         rc = dlpar_release_drc(drc_index);
  94         if (rc) {
  95                 pr_err("Failed to release drc (%x) for CPU %pOFn, rc: %d\n",
  96                         drc_index, dn, rc);
  97                 dlpar_attach_node(dn, pmem_node);
  98                 return rc;
  99         }
 100
 101         pr_info("Successfully removed PMEM with drc index: %x\n", drc_index);
 102
 103         return 0;
 104 }
 105
 106 int dlpar_hp_pmem(struct pseries_hp_errorlog *hp_elog)
 107 {
 108         u32 drc_index;
 109         int rc;
 110
 111         /* slim chance, but we might get a hotplug event while booting */
 112         if (!pmem_node)
 113                 pmem_node = of_find_node_by_type(NULL, "ibm,persistent-memory");
 114         if (!pmem_node) {
 115                 pr_err("Hotplug event for a pmem device, but none exists\n");
 116                 return -ENODEV;
 117         }
 118
 119         if (hp_elog->id_type != PSERIES_HP_ELOG_ID_DRC_INDEX) {
 120                 pr_err("Unsupported hotplug event type %d\n",
 121                                 hp_elog->id_type);
 122                 return -EINVAL;
 123         }
 124
 125         drc_index = hp_elog->_drc_u.drc_index;
 126
 127         lock_device_hotplug();
 128
 129         if (hp_elog->action == PSERIES_HP_ELOG_ACTION_ADD) {
 130                 rc = pmem_drc_add_node(drc_index);
 131         } else if (hp_elog->action == PSERIES_HP_ELOG_ACTION_REMOVE) {
 132                 rc = pmem_drc_remove_node(drc_index);
 133         } else {
 134                 pr_err("Unsupported hotplug action (%d)\n", hp_elog->action);
 135                 rc = -EINVAL;
 136         }
 137
 138         unlock_device_hotplug();
 139         return rc;
 140 }
 141
 142 static const struct of_device_id drc_pmem_match[] = {
 143         { .type = "ibm,persistent-memory", },
 144         {}
 145 };
 146
 147 static int pseries_pmem_init(void)
 148 {
 149         /*
 150          * Only supported on POWER8 and above.
 151          */
 152         if (!cpu_has_feature(CPU_FTR_ARCH_207S))
 153                 return 0;
 154
 155         pmem_node = of_find_node_by_type(NULL, "ibm,persistent-memory");
 156         if (!pmem_node)
 157                 return 0;
 158
 159         /*
 160          * The generic OF bus probe/populate handles creating platform devices
 161          * from the child (ibm,pmemory) nodes. The generic code registers an of
 162          * reconfig notifier to handle the hot-add/remove cases too.
 163          */
 164         of_platform_bus_probe(pmem_node, drc_pmem_match, NULL);
 165
 166         return 0;
 167 }
 168 machine_arch_initcall(pseries, pseries_pmem_init);