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
pmem_drc_add_node(u32 drc_index)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
pmem_drc_remove_node(u32 drc_index)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
dlpar_hp_pmem(struct pseries_hp_errorlog * hp_elog)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
pseries_pmem_init(void)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);
169