2019-05-23 16:14:55 +07:00
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// SPDX-License-Identifier: GPL-2.0-or-later
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2013-06-12 00:38:59 +07:00
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/*
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* A simple sysfs interface for the generic PWM framework
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*
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* Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
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*
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* Based on previous work by Lars Poeschel <poeschel@lemonage.de>
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*/
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#include <linux/device.h>
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#include <linux/mutex.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/kdev_t.h>
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#include <linux/pwm.h>
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struct pwm_export {
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struct device child;
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struct pwm_device *pwm;
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2016-03-31 03:03:27 +07:00
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struct mutex lock;
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2019-05-31 16:55:00 +07:00
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struct pwm_state suspend;
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2013-06-12 00:38:59 +07:00
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};
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static struct pwm_export *child_to_pwm_export(struct device *child)
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{
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return container_of(child, struct pwm_export, child);
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}
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static struct pwm_device *child_to_pwm_device(struct device *child)
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{
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struct pwm_export *export = child_to_pwm_export(child);
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return export->pwm;
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t period_show(struct device *child,
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struct device_attribute *attr,
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char *buf)
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2013-06-12 00:38:59 +07:00
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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2013-06-12 00:38:59 +07:00
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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2020-06-03 05:31:16 +07:00
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return sprintf(buf, "%llu\n", state.period);
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2013-06-12 00:38:59 +07:00
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t period_store(struct device *child,
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struct device_attribute *attr,
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const char *buf, size_t size)
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2013-06-12 00:38:59 +07:00
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{
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2016-03-31 03:03:27 +07:00
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struct pwm_export *export = child_to_pwm_export(child);
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struct pwm_device *pwm = export->pwm;
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2020-06-03 05:31:16 +07:00
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u64 val;
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2013-06-12 00:38:59 +07:00
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int ret;
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2020-06-03 05:31:16 +07:00
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ret = kstrtou64(buf, 0, &val);
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2013-06-12 00:38:59 +07:00
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if (ret)
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return ret;
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2016-03-31 03:03:27 +07:00
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mutex_lock(&export->lock);
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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state.period = val;
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ret = pwm_apply_state(pwm, &state);
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2016-03-31 03:03:27 +07:00
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mutex_unlock(&export->lock);
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2013-06-12 00:38:59 +07:00
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return ret ? : size;
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t duty_cycle_show(struct device *child,
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struct device_attribute *attr,
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char *buf)
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2013-06-12 00:38:59 +07:00
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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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2013-06-12 00:38:59 +07:00
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2020-06-03 05:31:16 +07:00
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return sprintf(buf, "%llu\n", state.duty_cycle);
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2013-06-12 00:38:59 +07:00
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t duty_cycle_store(struct device *child,
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struct device_attribute *attr,
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const char *buf, size_t size)
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2013-06-12 00:38:59 +07:00
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{
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2016-03-31 03:03:27 +07:00
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struct pwm_export *export = child_to_pwm_export(child);
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struct pwm_device *pwm = export->pwm;
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2013-06-12 00:38:59 +07:00
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unsigned int val;
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int ret;
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ret = kstrtouint(buf, 0, &val);
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if (ret)
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return ret;
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2016-03-31 03:03:27 +07:00
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mutex_lock(&export->lock);
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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state.duty_cycle = val;
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ret = pwm_apply_state(pwm, &state);
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2016-03-31 03:03:27 +07:00
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mutex_unlock(&export->lock);
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2013-06-12 00:38:59 +07:00
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return ret ? : size;
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t enable_show(struct device *child,
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struct device_attribute *attr,
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char *buf)
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2013-06-12 00:38:59 +07:00
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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2013-06-12 00:38:59 +07:00
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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return sprintf(buf, "%d\n", state.enabled);
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2013-06-12 00:38:59 +07:00
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t enable_store(struct device *child,
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struct device_attribute *attr,
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const char *buf, size_t size)
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2013-06-12 00:38:59 +07:00
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{
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2016-03-31 03:03:27 +07:00
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struct pwm_export *export = child_to_pwm_export(child);
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struct pwm_device *pwm = export->pwm;
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2013-06-12 00:38:59 +07:00
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int val, ret;
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ret = kstrtoint(buf, 0, &val);
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if (ret)
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return ret;
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2016-03-31 03:03:27 +07:00
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mutex_lock(&export->lock);
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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2013-06-12 00:38:59 +07:00
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switch (val) {
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case 0:
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2016-04-15 02:17:43 +07:00
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state.enabled = false;
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2013-06-12 00:38:59 +07:00
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break;
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case 1:
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2016-04-15 02:17:43 +07:00
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state.enabled = true;
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2013-06-12 00:38:59 +07:00
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break;
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default:
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ret = -EINVAL;
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2016-04-15 02:17:43 +07:00
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goto unlock;
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2013-06-12 00:38:59 +07:00
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}
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2016-06-08 08:58:23 +07:00
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ret = pwm_apply_state(pwm, &state);
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2016-03-31 03:03:27 +07:00
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2016-04-15 02:17:43 +07:00
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unlock:
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mutex_unlock(&export->lock);
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2013-06-12 00:38:59 +07:00
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return ret ? : size;
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t polarity_show(struct device *child,
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struct device_attribute *attr,
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char *buf)
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2013-06-12 00:38:59 +07:00
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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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2015-07-20 14:56:05 +07:00
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const char *polarity = "unknown";
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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2013-06-12 00:38:59 +07:00
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2016-04-15 02:17:43 +07:00
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switch (state.polarity) {
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2015-07-20 14:56:05 +07:00
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case PWM_POLARITY_NORMAL:
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polarity = "normal";
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break;
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case PWM_POLARITY_INVERSED:
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polarity = "inversed";
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break;
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}
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return sprintf(buf, "%s\n", polarity);
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2013-06-12 00:38:59 +07:00
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t polarity_store(struct device *child,
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struct device_attribute *attr,
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const char *buf, size_t size)
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2013-06-12 00:38:59 +07:00
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{
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2016-03-31 03:03:27 +07:00
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struct pwm_export *export = child_to_pwm_export(child);
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struct pwm_device *pwm = export->pwm;
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2013-06-12 00:38:59 +07:00
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enum pwm_polarity polarity;
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2016-04-15 02:17:43 +07:00
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struct pwm_state state;
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2013-06-12 00:38:59 +07:00
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int ret;
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if (sysfs_streq(buf, "normal"))
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polarity = PWM_POLARITY_NORMAL;
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else if (sysfs_streq(buf, "inversed"))
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polarity = PWM_POLARITY_INVERSED;
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else
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return -EINVAL;
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2016-03-31 03:03:27 +07:00
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mutex_lock(&export->lock);
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2016-04-15 02:17:43 +07:00
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pwm_get_state(pwm, &state);
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state.polarity = polarity;
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ret = pwm_apply_state(pwm, &state);
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2016-03-31 03:03:27 +07:00
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mutex_unlock(&export->lock);
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2013-06-12 00:38:59 +07:00
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return ret ? : size;
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}
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2016-06-08 16:21:25 +07:00
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static ssize_t capture_show(struct device *child,
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struct device_attribute *attr,
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char *buf)
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{
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struct pwm_device *pwm = child_to_pwm_device(child);
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struct pwm_capture result;
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int ret;
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ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ));
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if (ret)
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return ret;
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return sprintf(buf, "%u %u\n", result.period, result.duty_cycle);
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}
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2015-10-27 04:32:37 +07:00
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static DEVICE_ATTR_RW(period);
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static DEVICE_ATTR_RW(duty_cycle);
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static DEVICE_ATTR_RW(enable);
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static DEVICE_ATTR_RW(polarity);
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2016-06-08 16:21:25 +07:00
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static DEVICE_ATTR_RO(capture);
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2013-06-12 00:38:59 +07:00
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static struct attribute *pwm_attrs[] = {
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&dev_attr_period.attr,
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&dev_attr_duty_cycle.attr,
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&dev_attr_enable.attr,
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&dev_attr_polarity.attr,
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2016-06-08 16:21:25 +07:00
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&dev_attr_capture.attr,
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2013-06-12 00:38:59 +07:00
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NULL
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};
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2013-12-04 17:29:53 +07:00
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ATTRIBUTE_GROUPS(pwm);
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2013-06-12 00:38:59 +07:00
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static void pwm_export_release(struct device *child)
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{
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struct pwm_export *export = child_to_pwm_export(child);
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kfree(export);
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}
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static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
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{
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struct pwm_export *export;
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2018-10-01 20:23:57 +07:00
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char *pwm_prop[2];
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2013-06-12 00:38:59 +07:00
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int ret;
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if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
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return -EBUSY;
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export = kzalloc(sizeof(*export), GFP_KERNEL);
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if (!export) {
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clear_bit(PWMF_EXPORTED, &pwm->flags);
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return -ENOMEM;
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}
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export->pwm = pwm;
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2016-03-31 03:03:27 +07:00
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mutex_init(&export->lock);
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2013-06-12 00:38:59 +07:00
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export->child.release = pwm_export_release;
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export->child.parent = parent;
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export->child.devt = MKDEV(0, 0);
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2013-12-04 17:29:53 +07:00
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export->child.groups = pwm_groups;
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2013-06-12 00:38:59 +07:00
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dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
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ret = device_register(&export->child);
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if (ret) {
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clear_bit(PWMF_EXPORTED, &pwm->flags);
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2018-03-08 16:57:37 +07:00
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put_device(&export->child);
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export = NULL;
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2013-06-12 00:38:59 +07:00
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return ret;
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}
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2018-10-01 20:23:57 +07:00
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pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);
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pwm_prop[1] = NULL;
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kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
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kfree(pwm_prop[0]);
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2013-06-12 00:38:59 +07:00
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return 0;
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}
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static int pwm_unexport_match(struct device *child, void *data)
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{
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return child_to_pwm_device(child) == data;
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}
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static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
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{
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struct device *child;
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2018-10-01 20:23:57 +07:00
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char *pwm_prop[2];
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2013-06-12 00:38:59 +07:00
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if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
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return -ENODEV;
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child = device_find_child(parent, pwm, pwm_unexport_match);
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if (!child)
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return -ENODEV;
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2018-10-01 20:23:57 +07:00
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pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);
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pwm_prop[1] = NULL;
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kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
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kfree(pwm_prop[0]);
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2013-06-12 00:38:59 +07:00
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/* for device_find_child() */
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put_device(child);
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device_unregister(child);
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pwm_put(pwm);
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return 0;
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}
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2015-10-27 04:32:37 +07:00
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static ssize_t export_store(struct device *parent,
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struct device_attribute *attr,
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const char *buf, size_t len)
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2013-06-12 00:38:59 +07:00
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{
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|
|
struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
struct pwm_device *pwm;
|
|
|
|
unsigned int hwpwm;
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
ret = kstrtouint(buf, 0, &hwpwm);
|
|
|
|
if (ret < 0)
|
|
|
|
return ret;
|
|
|
|
|
|
|
|
if (hwpwm >= chip->npwm)
|
|
|
|
return -ENODEV;
|
|
|
|
|
|
|
|
pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
|
|
|
|
if (IS_ERR(pwm))
|
|
|
|
return PTR_ERR(pwm);
|
|
|
|
|
|
|
|
ret = pwm_export_child(parent, pwm);
|
|
|
|
if (ret < 0)
|
|
|
|
pwm_put(pwm);
|
|
|
|
|
|
|
|
return ret ? : len;
|
|
|
|
}
|
2015-10-27 04:32:37 +07:00
|
|
|
static DEVICE_ATTR_WO(export);
|
2013-06-12 00:38:59 +07:00
|
|
|
|
2015-10-27 04:32:37 +07:00
|
|
|
static ssize_t unexport_store(struct device *parent,
|
|
|
|
struct device_attribute *attr,
|
|
|
|
const char *buf, size_t len)
|
2013-06-12 00:38:59 +07:00
|
|
|
{
|
|
|
|
struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
unsigned int hwpwm;
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
ret = kstrtouint(buf, 0, &hwpwm);
|
|
|
|
if (ret < 0)
|
|
|
|
return ret;
|
|
|
|
|
|
|
|
if (hwpwm >= chip->npwm)
|
|
|
|
return -ENODEV;
|
|
|
|
|
|
|
|
ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
|
|
|
|
|
|
|
|
return ret ? : len;
|
|
|
|
}
|
2015-10-27 04:32:37 +07:00
|
|
|
static DEVICE_ATTR_WO(unexport);
|
2013-06-12 00:38:59 +07:00
|
|
|
|
2013-07-25 05:05:39 +07:00
|
|
|
static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
|
|
|
|
char *buf)
|
2013-06-12 00:38:59 +07:00
|
|
|
{
|
|
|
|
const struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
|
|
|
|
return sprintf(buf, "%u\n", chip->npwm);
|
|
|
|
}
|
2013-07-25 05:05:39 +07:00
|
|
|
static DEVICE_ATTR_RO(npwm);
|
2013-06-12 00:38:59 +07:00
|
|
|
|
2013-07-25 05:05:39 +07:00
|
|
|
static struct attribute *pwm_chip_attrs[] = {
|
|
|
|
&dev_attr_export.attr,
|
|
|
|
&dev_attr_unexport.attr,
|
|
|
|
&dev_attr_npwm.attr,
|
|
|
|
NULL,
|
2013-06-12 00:38:59 +07:00
|
|
|
};
|
2013-07-25 05:05:39 +07:00
|
|
|
ATTRIBUTE_GROUPS(pwm_chip);
|
2013-06-12 00:38:59 +07:00
|
|
|
|
2019-05-31 16:55:00 +07:00
|
|
|
/* takes export->lock on success */
|
|
|
|
static struct pwm_export *pwm_class_get_state(struct device *parent,
|
|
|
|
struct pwm_device *pwm,
|
|
|
|
struct pwm_state *state)
|
|
|
|
{
|
|
|
|
struct device *child;
|
|
|
|
struct pwm_export *export;
|
|
|
|
|
|
|
|
if (!test_bit(PWMF_EXPORTED, &pwm->flags))
|
|
|
|
return NULL;
|
|
|
|
|
|
|
|
child = device_find_child(parent, pwm, pwm_unexport_match);
|
|
|
|
if (!child)
|
|
|
|
return NULL;
|
|
|
|
|
|
|
|
export = child_to_pwm_export(child);
|
|
|
|
put_device(child); /* for device_find_child() */
|
|
|
|
|
|
|
|
mutex_lock(&export->lock);
|
|
|
|
pwm_get_state(pwm, state);
|
|
|
|
|
|
|
|
return export;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int pwm_class_apply_state(struct pwm_export *export,
|
|
|
|
struct pwm_device *pwm,
|
|
|
|
struct pwm_state *state)
|
|
|
|
{
|
|
|
|
int ret = pwm_apply_state(pwm, state);
|
|
|
|
|
|
|
|
/* release lock taken in pwm_class_get_state */
|
|
|
|
mutex_unlock(&export->lock);
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm)
|
|
|
|
{
|
|
|
|
struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
unsigned int i;
|
|
|
|
int ret = 0;
|
|
|
|
|
|
|
|
for (i = 0; i < npwm; i++) {
|
|
|
|
struct pwm_device *pwm = &chip->pwms[i];
|
|
|
|
struct pwm_state state;
|
|
|
|
struct pwm_export *export;
|
|
|
|
|
|
|
|
export = pwm_class_get_state(parent, pwm, &state);
|
|
|
|
if (!export)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
state.enabled = export->suspend.enabled;
|
|
|
|
ret = pwm_class_apply_state(export, pwm, &state);
|
|
|
|
if (ret < 0)
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int __maybe_unused pwm_class_suspend(struct device *parent)
|
|
|
|
{
|
|
|
|
struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
unsigned int i;
|
|
|
|
int ret = 0;
|
|
|
|
|
|
|
|
for (i = 0; i < chip->npwm; i++) {
|
|
|
|
struct pwm_device *pwm = &chip->pwms[i];
|
|
|
|
struct pwm_state state;
|
|
|
|
struct pwm_export *export;
|
|
|
|
|
|
|
|
export = pwm_class_get_state(parent, pwm, &state);
|
|
|
|
if (!export)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
export->suspend = state;
|
|
|
|
state.enabled = false;
|
|
|
|
ret = pwm_class_apply_state(export, pwm, &state);
|
|
|
|
if (ret < 0) {
|
|
|
|
/*
|
|
|
|
* roll back the PWM devices that were disabled by
|
|
|
|
* this suspend function.
|
|
|
|
*/
|
|
|
|
pwm_class_resume_npwm(parent, i);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int __maybe_unused pwm_class_resume(struct device *parent)
|
|
|
|
{
|
|
|
|
struct pwm_chip *chip = dev_get_drvdata(parent);
|
|
|
|
|
|
|
|
return pwm_class_resume_npwm(parent, chip->npwm);
|
|
|
|
}
|
|
|
|
|
|
|
|
static SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume);
|
|
|
|
|
2013-06-12 00:38:59 +07:00
|
|
|
static struct class pwm_class = {
|
2015-07-20 14:58:09 +07:00
|
|
|
.name = "pwm",
|
|
|
|
.owner = THIS_MODULE,
|
|
|
|
.dev_groups = pwm_chip_groups,
|
2019-05-31 16:55:00 +07:00
|
|
|
.pm = &pwm_class_pm_ops,
|
2013-06-12 00:38:59 +07:00
|
|
|
};
|
|
|
|
|
|
|
|
static int pwmchip_sysfs_match(struct device *parent, const void *data)
|
|
|
|
{
|
|
|
|
return dev_get_drvdata(parent) == data;
|
|
|
|
}
|
|
|
|
|
|
|
|
void pwmchip_sysfs_export(struct pwm_chip *chip)
|
|
|
|
{
|
|
|
|
struct device *parent;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If device_create() fails the pwm_chip is still usable by
|
2019-03-12 16:25:47 +07:00
|
|
|
* the kernel it's just not exported.
|
2013-06-12 00:38:59 +07:00
|
|
|
*/
|
|
|
|
parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
|
|
|
|
"pwmchip%d", chip->base);
|
|
|
|
if (IS_ERR(parent)) {
|
|
|
|
dev_warn(chip->dev,
|
|
|
|
"device_create failed for pwm_chip sysfs export\n");
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
void pwmchip_sysfs_unexport(struct pwm_chip *chip)
|
2016-08-10 04:57:46 +07:00
|
|
|
{
|
|
|
|
struct device *parent;
|
|
|
|
unsigned int i;
|
|
|
|
|
|
|
|
parent = class_find_device(&pwm_class, NULL, chip,
|
|
|
|
pwmchip_sysfs_match);
|
|
|
|
if (!parent)
|
|
|
|
return;
|
|
|
|
|
|
|
|
for (i = 0; i < chip->npwm; i++) {
|
|
|
|
struct pwm_device *pwm = &chip->pwms[i];
|
|
|
|
|
|
|
|
if (test_bit(PWMF_EXPORTED, &pwm->flags))
|
|
|
|
pwm_unexport_child(parent, pwm);
|
|
|
|
}
|
2016-11-01 17:46:39 +07:00
|
|
|
|
|
|
|
put_device(parent);
|
pwm: Fix deadlock warning when removing PWM device
This patch fixes deadlock warning if removing PWM device
when CONFIG_PROVE_LOCKING is enabled.
This issue can be reproceduced by the following steps on
the R-Car H3 Salvator-X board if the backlight is disabled:
# cd /sys/class/pwm/pwmchip0
# echo 0 > export
# ls
device export npwm power pwm0 subsystem uevent unexport
# cd device/driver
# ls
bind e6e31000.pwm uevent unbind
# echo e6e31000.pwm > unbind
[ 87.659974] ======================================================
[ 87.666149] WARNING: possible circular locking dependency detected
[ 87.672327] 5.0.0 #7 Not tainted
[ 87.675549] ------------------------------------------------------
[ 87.681723] bash/2986 is trying to acquire lock:
[ 87.686337] 000000005ea0e178 (kn->count#58){++++}, at: kernfs_remove_by_name_ns+0x50/0xa0
[ 87.694528]
[ 87.694528] but task is already holding lock:
[ 87.700353] 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c
[ 87.707405]
[ 87.707405] which lock already depends on the new lock.
[ 87.707405]
[ 87.715574]
[ 87.715574] the existing dependency chain (in reverse order) is:
[ 87.723048]
[ 87.723048] -> #1 (pwm_lock){+.+.}:
[ 87.728017] __mutex_lock+0x70/0x7e4
[ 87.732108] mutex_lock_nested+0x1c/0x24
[ 87.736547] pwm_request_from_chip.part.6+0x34/0x74
[ 87.741940] pwm_request_from_chip+0x20/0x40
[ 87.746725] export_store+0x6c/0x1f4
[ 87.750820] dev_attr_store+0x18/0x28
[ 87.754998] sysfs_kf_write+0x54/0x64
[ 87.759175] kernfs_fop_write+0xe4/0x1e8
[ 87.763615] __vfs_write+0x40/0x184
[ 87.767619] vfs_write+0xa8/0x19c
[ 87.771448] ksys_write+0x58/0xbc
[ 87.775278] __arm64_sys_write+0x18/0x20
[ 87.779721] el0_svc_common+0xd0/0x124
[ 87.783986] el0_svc_compat_handler+0x1c/0x24
[ 87.788858] el0_svc_compat+0x8/0x18
[ 87.792947]
[ 87.792947] -> #0 (kn->count#58){++++}:
[ 87.798260] lock_acquire+0xc4/0x22c
[ 87.802353] __kernfs_remove+0x258/0x2c4
[ 87.806790] kernfs_remove_by_name_ns+0x50/0xa0
[ 87.811836] remove_files.isra.1+0x38/0x78
[ 87.816447] sysfs_remove_group+0x48/0x98
[ 87.820971] sysfs_remove_groups+0x34/0x4c
[ 87.825583] device_remove_attrs+0x6c/0x7c
[ 87.830197] device_del+0x11c/0x33c
[ 87.834201] device_unregister+0x14/0x2c
[ 87.838638] pwmchip_sysfs_unexport+0x40/0x4c
[ 87.843509] pwmchip_remove+0xf4/0x13c
[ 87.847773] rcar_pwm_remove+0x28/0x34
[ 87.852039] platform_drv_remove+0x24/0x64
[ 87.856651] device_release_driver_internal+0x18c/0x21c
[ 87.862391] device_release_driver+0x14/0x1c
[ 87.867175] unbind_store+0xe0/0x124
[ 87.871265] drv_attr_store+0x20/0x30
[ 87.875442] sysfs_kf_write+0x54/0x64
[ 87.879618] kernfs_fop_write+0xe4/0x1e8
[ 87.884055] __vfs_write+0x40/0x184
[ 87.888057] vfs_write+0xa8/0x19c
[ 87.891887] ksys_write+0x58/0xbc
[ 87.895716] __arm64_sys_write+0x18/0x20
[ 87.900154] el0_svc_common+0xd0/0x124
[ 87.904417] el0_svc_compat_handler+0x1c/0x24
[ 87.909289] el0_svc_compat+0x8/0x18
[ 87.913378]
[ 87.913378] other info that might help us debug this:
[ 87.913378]
[ 87.921374] Possible unsafe locking scenario:
[ 87.921374]
[ 87.927286] CPU0 CPU1
[ 87.931808] ---- ----
[ 87.936331] lock(pwm_lock);
[ 87.939293] lock(kn->count#58);
[ 87.945120] lock(pwm_lock);
[ 87.950599] lock(kn->count#58);
[ 87.953908]
[ 87.953908] *** DEADLOCK ***
[ 87.953908]
[ 87.959821] 4 locks held by bash/2986:
[ 87.963563] #0: 00000000ace7bc30 (sb_writers#6){.+.+}, at: vfs_write+0x188/0x19c
[ 87.971044] #1: 00000000287991b2 (&of->mutex){+.+.}, at: kernfs_fop_write+0xb4/0x1e8
[ 87.978872] #2: 00000000f739d016 (&dev->mutex){....}, at: device_release_driver_internal+0x40/0x21c
[ 87.988001] #3: 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c
[ 87.995481]
[ 87.995481] stack backtrace:
[ 87.999836] CPU: 0 PID: 2986 Comm: bash Not tainted 5.0.0 #7
[ 88.005489] Hardware name: Renesas Salvator-X board based on r8a7795 ES1.x (DT)
[ 88.012791] Call trace:
[ 88.015235] dump_backtrace+0x0/0x190
[ 88.018891] show_stack+0x14/0x1c
[ 88.022204] dump_stack+0xb0/0xec
[ 88.025514] print_circular_bug.isra.32+0x1d0/0x2e0
[ 88.030385] __lock_acquire+0x1318/0x1864
[ 88.034388] lock_acquire+0xc4/0x22c
[ 88.037958] __kernfs_remove+0x258/0x2c4
[ 88.041874] kernfs_remove_by_name_ns+0x50/0xa0
[ 88.046398] remove_files.isra.1+0x38/0x78
[ 88.050487] sysfs_remove_group+0x48/0x98
[ 88.054490] sysfs_remove_groups+0x34/0x4c
[ 88.058580] device_remove_attrs+0x6c/0x7c
[ 88.062671] device_del+0x11c/0x33c
[ 88.066154] device_unregister+0x14/0x2c
[ 88.070070] pwmchip_sysfs_unexport+0x40/0x4c
[ 88.074421] pwmchip_remove+0xf4/0x13c
[ 88.078163] rcar_pwm_remove+0x28/0x34
[ 88.081906] platform_drv_remove+0x24/0x64
[ 88.085996] device_release_driver_internal+0x18c/0x21c
[ 88.091215] device_release_driver+0x14/0x1c
[ 88.095478] unbind_store+0xe0/0x124
[ 88.099048] drv_attr_store+0x20/0x30
[ 88.102704] sysfs_kf_write+0x54/0x64
[ 88.106359] kernfs_fop_write+0xe4/0x1e8
[ 88.110275] __vfs_write+0x40/0x184
[ 88.113757] vfs_write+0xa8/0x19c
[ 88.117065] ksys_write+0x58/0xbc
[ 88.120374] __arm64_sys_write+0x18/0x20
[ 88.124291] el0_svc_common+0xd0/0x124
[ 88.128034] el0_svc_compat_handler+0x1c/0x24
[ 88.132384] el0_svc_compat+0x8/0x18
The sysfs unexport in pwmchip_remove() is completely asymmetric
to what we do in pwmchip_add_with_polarity() and commit 0733424c9ba9
("pwm: Unexport children before chip removal") is a strong indication
that this was wrong to begin with. We should just move
pwmchip_sysfs_unexport() where it belongs, which is right after
pwmchip_sysfs_unexport_children(). In that case, we do not need
separate functions anymore either.
We also really want to remove sysfs irrespective of whether or not
the chip will be removed as a result of pwmchip_remove(). We can only
assume that the driver will be gone after that, so we shouldn't leave
any dangling sysfs files around.
This warning disappears if we move pwmchip_sysfs_unexport() to
the top of pwmchip_remove(), pwmchip_sysfs_unexport_children().
That way it is also outside of the pwm_lock section, which indeed
doesn't seem to be needed.
Moving the pwmchip_sysfs_export() call outside of that section also
seems fine and it'd be perfectly symmetric with pwmchip_remove() again.
So, this patch fixes them.
Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com>
[shimoda: revise the commit log and code]
Fixes: 76abbdde2d95 ("pwm: Add sysfs interface")
Fixes: 0733424c9ba9 ("pwm: Unexport children before chip removal")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Hoan Nguyen An <na-hoan@jinso.co.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-03-19 17:40:08 +07:00
|
|
|
device_unregister(parent);
|
2016-08-10 04:57:46 +07:00
|
|
|
}
|
|
|
|
|
2013-06-12 00:38:59 +07:00
|
|
|
static int __init pwm_sysfs_init(void)
|
|
|
|
{
|
|
|
|
return class_register(&pwm_class);
|
|
|
|
}
|
|
|
|
subsys_initcall(pwm_sysfs_init);
|