LXR linux/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
  28static struct device_node *pmem_node;
  29
  30static 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
  68static 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
 106int 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
 142static const struct of_device_id drc_pmem_match[] = {
 143        { .type = "ibm,persistent-memory", },
 144        {}
 145};
 146
 147static 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}
 168machine_arch_initcall(pseries, pseries_pmem_init);
 169