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
 27static struct device_node *pmem_node;
 28
 29static 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
 67static 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
105int 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 = be32_to_cpu(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
141static const struct of_device_id drc_pmem_match[] = {
142	{ .type = "ibm,persistent-memory", },
143	{}
144};
145
146static 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}
167machine_arch_initcall(pseries, pseries_pmem_init);