8b7b02f945
Anything coming from sysfs has a newline at the end. Cut it off before
comparing the strings.
Fixes: 20ab67608a ("power: add environment capability probing")
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>
Tested-by: Lihong Ma <lihongx.ma@intel.com>
Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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* Copyright(c) 2020 Intel Corporation
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*/
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include "power_common.h"
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#define POWER_SYSFILE_SCALING_DRIVER \
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"/sys/devices/system/cpu/cpu%u/cpufreq/scaling_driver"
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int
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cpufreq_check_scaling_driver(const char *driver_name)
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{
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unsigned int lcore_id = 0; /* always check core 0 */
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char fullpath[PATH_MAX];
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char readbuf[PATH_MAX];
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size_t end_idx;
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char *s;
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FILE *f;
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/*
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* Check if scaling driver matches what we expect.
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*/
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snprintf(fullpath, sizeof(fullpath), POWER_SYSFILE_SCALING_DRIVER,
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lcore_id);
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f = fopen(fullpath, "r");
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/* if there's no driver at all, bail out */
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if (f == NULL)
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return 0;
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s = fgets(readbuf, sizeof(readbuf), f);
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/* don't need it any more */
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fclose(f);
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/* if we can't read it, consider unsupported */
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if (s == NULL)
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return 0;
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/* when read from sysfs, driver name has an extra newline at the end */
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end_idx = strnlen(readbuf, sizeof(readbuf));
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if (end_idx > 0 && readbuf[end_idx - 1] == '\n') {
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end_idx--;
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readbuf[end_idx] = '\0';
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}
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/* does the driver name match? */
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if (strncmp(readbuf, driver_name, sizeof(readbuf)) != 0)
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return 0;
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/*
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* We might have a situation where the driver is supported, but we don't
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* have permissions to do frequency scaling. This error should not be
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* handled here, so consider the system to support scaling for now.
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*/
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return 1;
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}
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