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 = 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
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);
168
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