1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * c 2001 PPC 64 Team, IBM Corp |
4 | * |
5 | * /dev/nvram driver for PPC64 |
6 | */ |
7 | |
8 | |
9 | #include <linux/types.h> |
10 | #include <linux/errno.h> |
11 | #include <linux/init.h> |
12 | #include <linux/spinlock.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/ctype.h> |
15 | #include <linux/uaccess.h> |
16 | #include <linux/of.h> |
17 | #include <asm/nvram.h> |
18 | #include <asm/rtas.h> |
19 | #include <asm/machdep.h> |
20 | |
21 | /* Max bytes to read/write in one go */ |
22 | #define NVRW_CNT 0x20 |
23 | |
24 | static unsigned int nvram_size; |
25 | static int nvram_fetch, nvram_store; |
26 | static char nvram_buf[NVRW_CNT]; /* assume this is in the first 4GB */ |
27 | static DEFINE_SPINLOCK(nvram_lock); |
28 | |
29 | /* See clobbering_unread_rtas_event() */ |
30 | #define NVRAM_RTAS_READ_TIMEOUT 5 /* seconds */ |
31 | static time64_t last_unread_rtas_event; /* timestamp */ |
32 | |
33 | #ifdef CONFIG_PSTORE |
34 | time64_t last_rtas_event; |
35 | #endif |
36 | |
37 | static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index) |
38 | { |
39 | unsigned int i; |
40 | unsigned long len; |
41 | int done; |
42 | unsigned long flags; |
43 | char *p = buf; |
44 | |
45 | |
46 | if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE) |
47 | return -ENODEV; |
48 | |
49 | if (*index >= nvram_size) |
50 | return 0; |
51 | |
52 | i = *index; |
53 | if (i + count > nvram_size) |
54 | count = nvram_size - i; |
55 | |
56 | spin_lock_irqsave(&nvram_lock, flags); |
57 | |
58 | for (; count != 0; count -= len) { |
59 | len = count; |
60 | if (len > NVRW_CNT) |
61 | len = NVRW_CNT; |
62 | |
63 | if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf), |
64 | len) != 0) || len != done) { |
65 | spin_unlock_irqrestore(lock: &nvram_lock, flags); |
66 | return -EIO; |
67 | } |
68 | |
69 | memcpy(p, nvram_buf, len); |
70 | |
71 | p += len; |
72 | i += len; |
73 | } |
74 | |
75 | spin_unlock_irqrestore(lock: &nvram_lock, flags); |
76 | |
77 | *index = i; |
78 | return p - buf; |
79 | } |
80 | |
81 | static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index) |
82 | { |
83 | unsigned int i; |
84 | unsigned long len; |
85 | int done; |
86 | unsigned long flags; |
87 | const char *p = buf; |
88 | |
89 | if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE) |
90 | return -ENODEV; |
91 | |
92 | if (*index >= nvram_size) |
93 | return 0; |
94 | |
95 | i = *index; |
96 | if (i + count > nvram_size) |
97 | count = nvram_size - i; |
98 | |
99 | spin_lock_irqsave(&nvram_lock, flags); |
100 | |
101 | for (; count != 0; count -= len) { |
102 | len = count; |
103 | if (len > NVRW_CNT) |
104 | len = NVRW_CNT; |
105 | |
106 | memcpy(nvram_buf, p, len); |
107 | |
108 | if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf), |
109 | len) != 0) || len != done) { |
110 | spin_unlock_irqrestore(lock: &nvram_lock, flags); |
111 | return -EIO; |
112 | } |
113 | |
114 | p += len; |
115 | i += len; |
116 | } |
117 | spin_unlock_irqrestore(lock: &nvram_lock, flags); |
118 | |
119 | *index = i; |
120 | return p - buf; |
121 | } |
122 | |
123 | static ssize_t pSeries_nvram_get_size(void) |
124 | { |
125 | return nvram_size ? nvram_size : -ENODEV; |
126 | } |
127 | |
128 | /* nvram_write_error_log |
129 | * |
130 | * We need to buffer the error logs into nvram to ensure that we have |
131 | * the failure information to decode. |
132 | */ |
133 | int nvram_write_error_log(char * buff, int length, |
134 | unsigned int err_type, unsigned int error_log_cnt) |
135 | { |
136 | int rc = nvram_write_os_partition(&rtas_log_partition, buff, length, |
137 | err_type, error_log_cnt); |
138 | if (!rc) { |
139 | last_unread_rtas_event = ktime_get_real_seconds(); |
140 | #ifdef CONFIG_PSTORE |
141 | last_rtas_event = ktime_get_real_seconds(); |
142 | #endif |
143 | } |
144 | |
145 | return rc; |
146 | } |
147 | |
148 | /* nvram_read_error_log |
149 | * |
150 | * Reads nvram for error log for at most 'length' |
151 | */ |
152 | int nvram_read_error_log(char *buff, int length, |
153 | unsigned int *err_type, unsigned int *error_log_cnt) |
154 | { |
155 | return nvram_read_partition(&rtas_log_partition, buff, length, |
156 | err_type, error_log_cnt); |
157 | } |
158 | |
159 | /* This doesn't actually zero anything, but it sets the event_logged |
160 | * word to tell that this event is safely in syslog. |
161 | */ |
162 | int nvram_clear_error_log(void) |
163 | { |
164 | loff_t tmp_index; |
165 | int clear_word = ERR_FLAG_ALREADY_LOGGED; |
166 | int rc; |
167 | |
168 | if (rtas_log_partition.index == -1) |
169 | return -1; |
170 | |
171 | tmp_index = rtas_log_partition.index; |
172 | |
173 | rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index); |
174 | if (rc <= 0) { |
175 | printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n" , rc); |
176 | return rc; |
177 | } |
178 | last_unread_rtas_event = 0; |
179 | |
180 | return 0; |
181 | } |
182 | |
183 | /* |
184 | * Are we using the ibm,rtas-log for oops/panic reports? And if so, |
185 | * would logging this oops/panic overwrite an RTAS event that rtas_errd |
186 | * hasn't had a chance to read and process? Return 1 if so, else 0. |
187 | * |
188 | * We assume that if rtas_errd hasn't read the RTAS event in |
189 | * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to. |
190 | */ |
191 | int clobbering_unread_rtas_event(void) |
192 | { |
193 | return (oops_log_partition.index == rtas_log_partition.index |
194 | && last_unread_rtas_event |
195 | && ktime_get_real_seconds() - last_unread_rtas_event <= |
196 | NVRAM_RTAS_READ_TIMEOUT); |
197 | } |
198 | |
199 | static int __init pseries_nvram_init_log_partitions(void) |
200 | { |
201 | int rc; |
202 | |
203 | /* Scan nvram for partitions */ |
204 | nvram_scan_partitions(); |
205 | |
206 | rc = nvram_init_os_partition(&rtas_log_partition); |
207 | nvram_init_oops_partition(rc == 0); |
208 | return 0; |
209 | } |
210 | machine_arch_initcall(pseries, pseries_nvram_init_log_partitions); |
211 | |
212 | int __init pSeries_nvram_init(void) |
213 | { |
214 | struct device_node *nvram; |
215 | const __be32 *nbytes_p; |
216 | unsigned int proplen; |
217 | |
218 | nvram = of_find_node_by_type(NULL, type: "nvram" ); |
219 | if (nvram == NULL) |
220 | return -ENODEV; |
221 | |
222 | nbytes_p = of_get_property(node: nvram, name: "#bytes" , lenp: &proplen); |
223 | if (nbytes_p == NULL || proplen != sizeof(unsigned int)) { |
224 | of_node_put(node: nvram); |
225 | return -EIO; |
226 | } |
227 | |
228 | nvram_size = be32_to_cpup(p: nbytes_p); |
229 | |
230 | nvram_fetch = rtas_function_token(RTAS_FN_NVRAM_FETCH); |
231 | nvram_store = rtas_function_token(RTAS_FN_NVRAM_STORE); |
232 | printk(KERN_INFO "PPC64 nvram contains %d bytes\n" , nvram_size); |
233 | of_node_put(node: nvram); |
234 | |
235 | ppc_md.nvram_read = pSeries_nvram_read; |
236 | ppc_md.nvram_write = pSeries_nvram_write; |
237 | ppc_md.nvram_size = pSeries_nvram_get_size; |
238 | |
239 | return 0; |
240 | } |
241 | |
242 | |