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

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