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