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// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
/*
* Do XSCOMs through linux debugfs interface
*
* Copyright 2014-2017 IBM Corp.
*/
#define _LARGEFILE64_SOURCE
#include <sys/mman.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <stdint.h>
#include <stdbool.h>
#include <dirent.h>
#include <assert.h>
#include <ctype.h>
#include "xscom.h"
#define XSCOM_BASE_PATH "/sys/kernel/debug/powerpc/scom"
struct xscom_chip {
struct xscom_chip *next;
uint32_t chip_id;
int fd;
};
static struct xscom_chip *xscom_chips;
void xscom_for_each_chip(void (*cb)(uint32_t chip_id))
{
struct xscom_chip *c;
for (c = xscom_chips; c; c = c->next)
cb(c->chip_id);
}
static uint32_t xscom_add_chip(const char *base_path, const char *dname)
{
char nbuf[strlen(base_path) + strlen(dname) + 16];
struct xscom_chip *chip;
int fd;
snprintf(nbuf, sizeof(nbuf), "%s/%s/access", base_path, dname);
fd = open(nbuf, O_RDWR);
if (fd < 0) {
perror("Failed to open SCOM access file");
exit(1);
}
chip = malloc(sizeof(*chip));
assert(chip);
memset(chip, 0, sizeof(*chip));
chip->fd = fd;
chip->chip_id = strtoul(dname, NULL, 16);
chip->next = xscom_chips;
xscom_chips = chip;
return chip->chip_id;
}
static bool xscom_check_dirname(const char *n)
{
while(*n) {
char c = toupper(*(n++));
if ((c < 'A' || c > 'Z') &&
(c < '0' || c > '9'))
return false;
}
return true;
}
static uint32_t xscom_scan_chips(const char *base_path)
{
int i, nfiles;
struct dirent **filelist;
uint32_t lower = 0xffffffff;
nfiles = scandir(base_path, &filelist, NULL, alphasort);
if (nfiles < 0) {
perror("Error accessing sysfs scom directory");
exit(1);
}
if (nfiles == 0) {
fprintf(stderr, "No SCOM dir found in sysfs\n");
exit(1);
}
for (i = 0; i < nfiles; i++) {
struct dirent *d = filelist[i];
uint32_t id;
if (d->d_type != DT_DIR)
continue;
if (!xscom_check_dirname(d->d_name))
continue;
id = xscom_add_chip(base_path, d->d_name);
if (id < lower)
lower = id;
free(d);
}
free(filelist);
return lower;
}
static struct xscom_chip *xscom_find_chip(uint32_t chip_id)
{
struct xscom_chip *c;
for (c = xscom_chips; c; c = c->next)
if (c->chip_id == chip_id)
return c;
return NULL;
}
static uint64_t xscom_mangle_addr(uint64_t addr)
{
uint64_t tmp;
/*
* Shift the top 4 bits (indirect mode) down by 4 bits so we
* don't lose going through the debugfs interfaces.
*/
tmp = (addr & 0xf000000000000000) >> 4;
addr &= 0x00ffffffffffffff;
addr |= tmp;
/* Shift up by 3 for debugfs */
return addr << 3;
}
int xscom_read(uint32_t chip_id, uint64_t addr, uint64_t *val)
{
struct xscom_chip *c = xscom_find_chip(chip_id);
int rc;
if (!c)
return -ENODEV;
addr = xscom_mangle_addr(addr);
lseek64(c->fd, addr, SEEK_SET);
rc = read(c->fd, val, 8);
if (rc < 0)
return -errno;
if (rc != 8)
return -EIO;
return 0;
}
int xscom_write(uint32_t chip_id, uint64_t addr, uint64_t val)
{
struct xscom_chip *c = xscom_find_chip(chip_id);
int rc;
if (!c)
return -ENODEV;
addr = xscom_mangle_addr(addr);
lseek64(c->fd, addr, SEEK_SET);
rc = write(c->fd, &val, 8);
if (rc < 0)
return -errno;
if (rc != 8)
return -EIO;
return 0;
}
int xscom_read_ex(uint32_t ex_target_id, uint64_t addr, uint64_t *val)
{
uint32_t chip_id = ex_target_id >> 4;;
addr |= (ex_target_id & 0xf) << 24;
/* XXX TODO: Special wakeup ? */
return xscom_read(chip_id, addr, val);
}
int xscom_write_ex(uint32_t ex_target_id, uint64_t addr, uint64_t val)
{
uint32_t chip_id = ex_target_id >> 4;;
addr |= (ex_target_id & 0xf) << 24;
/* XXX TODO: Special wakeup ? */
return xscom_write(chip_id, addr, val);
}
bool xscom_readable(uint64_t addr)
{
/* Top nibble 9 indicates form 1 indirect, which is write only */
if (((addr >> 60) & 0xf) == 9)
return false;
return true;
}
uint32_t xscom_init(void)
{
return xscom_scan_chips(XSCOM_BASE_PATH);
}
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