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

http://github.com/mirrors/linux
C | 241 lines | 163 code | 49 blank | 29 comment | 40 complexity | b588e6e0684167a3ab78efec528b6aaa MD5 | raw file
  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 <asm/nvram.h>
 17#include <asm/rtas.h>
 18#include <asm/prom.h>
 19#include <asm/machdep.h>
 20
 21/* Max bytes to read/write in one go */
 22#define NVRW_CNT 0x20
 23
 24static unsigned int nvram_size;
 25static int nvram_fetch, nvram_store;
 26static char nvram_buf[NVRW_CNT];	/* assume this is in the first 4GB */
 27static DEFINE_SPINLOCK(nvram_lock);
 28
 29/* See clobbering_unread_rtas_event() */
 30#define NVRAM_RTAS_READ_TIMEOUT 5		/* seconds */
 31static time64_t last_unread_rtas_event;		/* timestamp */
 32
 33#ifdef CONFIG_PSTORE
 34time64_t last_rtas_event;
 35#endif
 36
 37static 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
 81static 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
123static 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 */
133int 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 */
152int 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 */
162int 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 */
191int 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
199static 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}
210machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);
211
212int __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