// SPDX-License-Identifier: GPL-2.0-or-later
/*
* c 2001 PPC 64 Team, IBM Corp
*
* /dev/nvram driver for PPC64
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/machdep.h>
/* Max bytes to read/write in one go */
#define NVRW_CNT 0x20
static unsigned int nvram_size;
static int nvram_fetch, nvram_store;
static char nvram_buf[NVRW_CNT]; /* assume this is in the first 4GB */
static DEFINE_SPINLOCK(nvram_lock);
/* See clobbering_unread_rtas_event() */
#define NVRAM_RTAS_READ_TIMEOUT 5 /* seconds */
static time64_t last_unread_rtas_event; /* timestamp */
#ifdef CONFIG_PSTORE
time64_t last_rtas_event;
#endif
static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
unsigned int i;
unsigned long len;
int done;
unsigned long flags;
char *p = buf;
if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
return -ENODEV;
if (*index >= nvram_size)
return 0;
i = *index;
if (i + count > nvram_size)
count = nvram_size - i;
spin_lock_irqsave(&nvram_lock, flags);
for (; count != 0; count -= len) {
len = count;
if (len > NVRW_CNT)
len = NVRW_CNT;
if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
len) != 0) || len != done) {
spin_unlock_irqrestore(&nvram_lock, flags);
return -EIO;
}
memcpy(p, nvram_buf, len);
p += len;
i += len;
}
spin_unlock_irqrestore(&nvram_lock, flags);
*index = i;
return p - buf;
}
static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
{
unsigned int i;
unsigned long len;
int done;
unsigned long flags;
const char *p = buf;
if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
return -ENODEV;
if (*index >= nvram_size)
return 0;
i = *index;
if (i + count > nvram_size)
count = nvram_size - i;
spin_lock_irqsave(&nvram_lock, flags);
for (; count != 0; count -= len) {
len = count;
if (len > NVRW_CNT)
len = NVRW_CNT;
memcpy(nvram_buf, p, len);
if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
len) != 0) || len != done) {
spin_unlock_irqrestore(&nvram_lock, flags);
return -EIO;
}
p += len;
i += len;
}
spin_unlock_irqrestore(&nvram_lock, flags);
*index = i;
return p - buf;
}
static ssize_t pSeries_nvram_get_size(void)
{
return nvram_size ? nvram_size : -ENODEV;
}
/* nvram_write_error_log
*
* We need to buffer the error logs into nvram to ensure that we have
* the failure information to decode.
*/
int nvram_write_error_log(char * buff, int length,
unsigned int err_type, unsigned int error_log_cnt)
{
int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
err_type, error_log_cnt);
if (!rc) {
last_unread_rtas_event = ktime_get_real_seconds();
#ifdef CONFIG_PSTORE
last_rtas_event = ktime_get_real_seconds();
#endif
}
return rc;
}
/* nvram_read_error_log
*
* Reads nvram for error log for at most 'length'
*/
int nvram_read_error_log(char *buff, int length,
unsigned int *err_type, unsigned int *error_log_cnt)
{
return nvram_read_partition(&rtas_log_partition, buff, length,
err_type, error_log_cnt);
}
/* This doesn't actually zero anything, but it sets the event_logged
* word to tell that this event is safely in syslog.
*/
int nvram_clear_error_log(void)
{
loff_t tmp_index;
int clear_word = ERR_FLAG_ALREADY_LOGGED;
int rc;
if (rtas_log_partition.index == -1)
return -1;
tmp_index = rtas_log_partition.index;
rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
if (rc <= 0) {
printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
return rc;
}
last_unread_rtas_event = 0;
return 0;
}
/*
* Are we using the ibm,rtas-log for oops/panic reports? And if so,
* would logging this oops/panic overwrite an RTAS event that rtas_errd
* hasn't had a chance to read and process? Return 1 if so, else 0.
*
* We assume that if rtas_errd hasn't read the RTAS event in
* NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
*/
int clobbering_unread_rtas_event(void)
{
return (oops_log_partition.index == rtas_log_partition.index
&& last_unread_rtas_event
&& ktime_get_real_seconds() - last_unread_rtas_event <=
NVRAM_RTAS_READ_TIMEOUT);
}
static int __init pseries_nvram_init_log_partitions(void)
{
int rc;
/* Scan nvram for partitions */
nvram_scan_partitions();
rc = nvram_init_os_partition(&rtas_log_partition);
nvram_init_oops_partition(rc == 0);
return 0;
}
machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);
int __init pSeries_nvram_init(void)
{
struct device_node *nvram;
const __be32 *nbytes_p;
unsigned int proplen;
nvram = of_find_node_by_type(NULL, "nvram");
if (nvram == NULL)
return -ENODEV;
nbytes_p = of_get_property(nvram, "#bytes", &proplen);
if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
of_node_put(nvram);
return -EIO;
}
nvram_size = be32_to_cpup(nbytes_p);
nvram_fetch = rtas_function_token(RTAS_FN_NVRAM_FETCH);
nvram_store = rtas_function_token(RTAS_FN_NVRAM_STORE);
printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
of_node_put(nvram);
ppc_md.nvram_read = pSeries_nvram_read;
ppc_md.nvram_write = pSeries_nvram_write;
ppc_md.nvram_size = pSeries_nvram_get_size;
return 0;
}
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