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(&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(&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(&nvram_lock, flags);
111 			return -EIO;
112 		}
113 
114 		p += len;
115 		i += len;
116 	}
117 	spin_unlock_irqrestore(&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, "nvram");
219 	if (nvram == NULL)
220 		return -ENODEV;
221 
222 	nbytes_p = of_get_property(nvram, "#bytes", &proplen);
223 	if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
224 		of_node_put(nvram);
225 		return -EIO;
226 	}
227 
228 	nvram_size = be32_to_cpup(nbytes_p);
229 
230 	nvram_fetch = rtas_token("nvram-fetch");
231 	nvram_store = rtas_token("nvram-store");
232 	printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
233 	of_node_put(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