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