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Linux/arch/powerpc/platforms/pseries/nvram.c

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  1 /*
  2  *  c 2001 PPC 64 Team, IBM Corp
  3  *
  4  *      This program is free software; you can redistribute it and/or
  5  *      modify it under the terms of the GNU General Public License
  6  *      as published by the Free Software Foundation; either version
  7  *      2 of the License, or (at your option) any later version.
  8  *
  9  * /dev/nvram driver for PPC64
 10  *
 11  * This perhaps should live in drivers/char
 12  */
 13 
 14 
 15 #include <linux/types.h>
 16 #include <linux/errno.h>
 17 #include <linux/init.h>
 18 #include <linux/spinlock.h>
 19 #include <linux/slab.h>
 20 #include <linux/kmsg_dump.h>
 21 #include <linux/pstore.h>
 22 #include <linux/ctype.h>
 23 #include <asm/uaccess.h>
 24 #include <asm/nvram.h>
 25 #include <asm/rtas.h>
 26 #include <asm/prom.h>
 27 #include <asm/machdep.h>
 28 
 29 /* Max bytes to read/write in one go */
 30 #define NVRW_CNT 0x20
 31 
 32 static unsigned int nvram_size;
 33 static int nvram_fetch, nvram_store;
 34 static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
 35 static DEFINE_SPINLOCK(nvram_lock);
 36 
 37 /* See clobbering_unread_rtas_event() */
 38 #define NVRAM_RTAS_READ_TIMEOUT 5               /* seconds */
 39 static time64_t last_unread_rtas_event;         /* timestamp */
 40 
 41 #ifdef CONFIG_PSTORE
 42 time64_t last_rtas_event;
 43 #endif
 44 
 45 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
 46 {
 47         unsigned int i;
 48         unsigned long len;
 49         int done;
 50         unsigned long flags;
 51         char *p = buf;
 52 
 53 
 54         if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
 55                 return -ENODEV;
 56 
 57         if (*index >= nvram_size)
 58                 return 0;
 59 
 60         i = *index;
 61         if (i + count > nvram_size)
 62                 count = nvram_size - i;
 63 
 64         spin_lock_irqsave(&nvram_lock, flags);
 65 
 66         for (; count != 0; count -= len) {
 67                 len = count;
 68                 if (len > NVRW_CNT)
 69                         len = NVRW_CNT;
 70                 
 71                 if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
 72                                len) != 0) || len != done) {
 73                         spin_unlock_irqrestore(&nvram_lock, flags);
 74                         return -EIO;
 75                 }
 76                 
 77                 memcpy(p, nvram_buf, len);
 78 
 79                 p += len;
 80                 i += len;
 81         }
 82 
 83         spin_unlock_irqrestore(&nvram_lock, flags);
 84         
 85         *index = i;
 86         return p - buf;
 87 }
 88 
 89 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
 90 {
 91         unsigned int i;
 92         unsigned long len;
 93         int done;
 94         unsigned long flags;
 95         const char *p = buf;
 96 
 97         if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
 98                 return -ENODEV;
 99 
100         if (*index >= nvram_size)
101                 return 0;
102 
103         i = *index;
104         if (i + count > nvram_size)
105                 count = nvram_size - i;
106 
107         spin_lock_irqsave(&nvram_lock, flags);
108 
109         for (; count != 0; count -= len) {
110                 len = count;
111                 if (len > NVRW_CNT)
112                         len = NVRW_CNT;
113 
114                 memcpy(nvram_buf, p, len);
115 
116                 if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
117                                len) != 0) || len != done) {
118                         spin_unlock_irqrestore(&nvram_lock, flags);
119                         return -EIO;
120                 }
121                 
122                 p += len;
123                 i += len;
124         }
125         spin_unlock_irqrestore(&nvram_lock, flags);
126         
127         *index = i;
128         return p - buf;
129 }
130 
131 static ssize_t pSeries_nvram_get_size(void)
132 {
133         return nvram_size ? nvram_size : -ENODEV;
134 }
135 
136 /* nvram_write_error_log
137  *
138  * We need to buffer the error logs into nvram to ensure that we have
139  * the failure information to decode.
140  */
141 int nvram_write_error_log(char * buff, int length,
142                           unsigned int err_type, unsigned int error_log_cnt)
143 {
144         int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
145                                                 err_type, error_log_cnt);
146         if (!rc) {
147                 last_unread_rtas_event = ktime_get_real_seconds();
148 #ifdef CONFIG_PSTORE
149                 last_rtas_event = ktime_get_real_seconds();
150 #endif
151         }
152 
153         return rc;
154 }
155 
156 /* nvram_read_error_log
157  *
158  * Reads nvram for error log for at most 'length'
159  */
160 int nvram_read_error_log(char *buff, int length,
161                         unsigned int *err_type, unsigned int *error_log_cnt)
162 {
163         return nvram_read_partition(&rtas_log_partition, buff, length,
164                                                 err_type, error_log_cnt);
165 }
166 
167 /* This doesn't actually zero anything, but it sets the event_logged
168  * word to tell that this event is safely in syslog.
169  */
170 int nvram_clear_error_log(void)
171 {
172         loff_t tmp_index;
173         int clear_word = ERR_FLAG_ALREADY_LOGGED;
174         int rc;
175 
176         if (rtas_log_partition.index == -1)
177                 return -1;
178 
179         tmp_index = rtas_log_partition.index;
180         
181         rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
182         if (rc <= 0) {
183                 printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
184                 return rc;
185         }
186         last_unread_rtas_event = 0;
187 
188         return 0;
189 }
190 
191 /*
192  * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
193  * would logging this oops/panic overwrite an RTAS event that rtas_errd
194  * hasn't had a chance to read and process?  Return 1 if so, else 0.
195  *
196  * We assume that if rtas_errd hasn't read the RTAS event in
197  * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
198  */
199 int clobbering_unread_rtas_event(void)
200 {
201         return (oops_log_partition.index == rtas_log_partition.index
202                 && last_unread_rtas_event
203                 && ktime_get_real_seconds() - last_unread_rtas_event <=
204                                                 NVRAM_RTAS_READ_TIMEOUT);
205 }
206 
207 static int __init pseries_nvram_init_log_partitions(void)
208 {
209         int rc;
210 
211         /* Scan nvram for partitions */
212         nvram_scan_partitions();
213 
214         rc = nvram_init_os_partition(&rtas_log_partition);
215         nvram_init_oops_partition(rc == 0);
216         return 0;
217 }
218 machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);
219 
220 int __init pSeries_nvram_init(void)
221 {
222         struct device_node *nvram;
223         const __be32 *nbytes_p;
224         unsigned int proplen;
225 
226         nvram = of_find_node_by_type(NULL, "nvram");
227         if (nvram == NULL)
228                 return -ENODEV;
229 
230         nbytes_p = of_get_property(nvram, "#bytes", &proplen);
231         if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
232                 of_node_put(nvram);
233                 return -EIO;
234         }
235 
236         nvram_size = be32_to_cpup(nbytes_p);
237 
238         nvram_fetch = rtas_token("nvram-fetch");
239         nvram_store = rtas_token("nvram-store");
240         printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
241         of_node_put(nvram);
242 
243         ppc_md.nvram_read       = pSeries_nvram_read;
244         ppc_md.nvram_write      = pSeries_nvram_write;
245         ppc_md.nvram_size       = pSeries_nvram_get_size;
246 
247         return 0;
248 }
249 
250 

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