1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * PowerNV OPAL in-memory console interface
4 *
5 * Copyright 2014 IBM Corp.
6 */
7
8 #include <asm/io.h>
9 #include <asm/opal.h>
10 #include <linux/debugfs.h>
11 #include <linux/of.h>
12 #include <linux/types.h>
13 #include <asm/barrier.h>
14
15 #include "powernv.h"
16
17 /* OPAL in-memory console. Defined in OPAL source at core/console.c */
18 struct memcons {
19 __be64 magic;
20 #define MEMCONS_MAGIC 0x6630696567726173L
21 __be64 obuf_phys;
22 __be64 ibuf_phys;
23 __be32 obuf_size;
24 __be32 ibuf_size;
25 __be32 out_pos;
26 #define MEMCONS_OUT_POS_WRAP 0x80000000u
27 #define MEMCONS_OUT_POS_MASK 0x00ffffffu
28 __be32 in_prod;
29 __be32 in_cons;
30 };
31
32 static struct memcons *opal_memcons = NULL;
33
memcons_copy(struct memcons * mc,char * to,loff_t pos,size_t count)34 ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count)
35 {
36 const char *conbuf;
37 ssize_t ret;
38 size_t first_read = 0;
39 uint32_t out_pos, avail;
40
41 if (!mc)
42 return -ENODEV;
43
44 out_pos = be32_to_cpu(READ_ONCE(mc->out_pos));
45
46 /* Now we've read out_pos, put a barrier in before reading the new
47 * data it points to in conbuf. */
48 smp_rmb();
49
50 conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
51
52 /* When the buffer has wrapped, read from the out_pos marker to the end
53 * of the buffer, and then read the remaining data as in the un-wrapped
54 * case. */
55 if (out_pos & MEMCONS_OUT_POS_WRAP) {
56
57 out_pos &= MEMCONS_OUT_POS_MASK;
58 avail = be32_to_cpu(mc->obuf_size) - out_pos;
59
60 ret = memory_read_from_buffer(to, count, &pos,
61 conbuf + out_pos, avail);
62
63 if (ret < 0)
64 goto out;
65
66 first_read = ret;
67 to += first_read;
68 count -= first_read;
69 pos -= avail;
70
71 if (count <= 0)
72 goto out;
73 }
74
75 /* Sanity check. The firmware should not do this to us. */
76 if (out_pos > be32_to_cpu(mc->obuf_size)) {
77 pr_err("OPAL: memory console corruption. Aborting read.\n");
78 return -EINVAL;
79 }
80
81 ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos);
82
83 if (ret < 0)
84 goto out;
85
86 ret += first_read;
87 out:
88 return ret;
89 }
90
opal_msglog_copy(char * to,loff_t pos,size_t count)91 ssize_t opal_msglog_copy(char *to, loff_t pos, size_t count)
92 {
93 return memcons_copy(opal_memcons, to, pos, count);
94 }
95
opal_msglog_read(struct file * file,struct kobject * kobj,struct bin_attribute * bin_attr,char * to,loff_t pos,size_t count)96 static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj,
97 struct bin_attribute *bin_attr, char *to,
98 loff_t pos, size_t count)
99 {
100 return opal_msglog_copy(to, pos, count);
101 }
102
103 static struct bin_attribute opal_msglog_attr = {
104 .attr = {.name = "msglog", .mode = 0400},
105 .read = opal_msglog_read
106 };
107
memcons_init(struct device_node * node,const char * mc_prop_name)108 struct memcons *memcons_init(struct device_node *node, const char *mc_prop_name)
109 {
110 u64 mcaddr;
111 struct memcons *mc;
112
113 if (of_property_read_u64(node, mc_prop_name, &mcaddr)) {
114 pr_warn("%s property not found, no message log\n",
115 mc_prop_name);
116 goto out_err;
117 }
118
119 mc = phys_to_virt(mcaddr);
120 if (!mc) {
121 pr_warn("memory console address is invalid\n");
122 goto out_err;
123 }
124
125 if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
126 pr_warn("memory console version is invalid\n");
127 goto out_err;
128 }
129
130 return mc;
131
132 out_err:
133 return NULL;
134 }
135
memcons_get_size(struct memcons * mc)136 u32 memcons_get_size(struct memcons *mc)
137 {
138 return be32_to_cpu(mc->ibuf_size) + be32_to_cpu(mc->obuf_size);
139 }
140
opal_msglog_init(void)141 void __init opal_msglog_init(void)
142 {
143 opal_memcons = memcons_init(opal_node, "ibm,opal-memcons");
144 if (!opal_memcons) {
145 pr_warn("OPAL: memcons failed to load from ibm,opal-memcons\n");
146 return;
147 }
148
149 opal_msglog_attr.size = memcons_get_size(opal_memcons);
150 }
151
opal_msglog_sysfs_init(void)152 void __init opal_msglog_sysfs_init(void)
153 {
154 if (!opal_memcons) {
155 pr_warn("OPAL: message log initialisation failed, not creating sysfs entry\n");
156 return;
157 }
158
159 if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0)
160 pr_warn("OPAL: sysfs file creation failed\n");
161 }
162