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![Andy Shevchenko](/assets/img/avatar_default.png)
While the uses in this code are unproblematic, it's generally safer for sysfs outputs to use the new sysfs_emit() helper instead of raw calls to sprintf() and friends. This also has the benefit of annotating the uses, which makes them easier to audit and potentially use them to generate sysfs documentation from them. This patch replaces existing sprintf() calls straightforwardly with the new helper. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
529 lines
11 KiB
C
529 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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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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struct mutex lock;
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struct pwm_state suspend;
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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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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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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return sysfs_emit(buf, "%llu\n", state.period);
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}
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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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{
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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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struct pwm_state state;
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u64 val;
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int ret;
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ret = kstrtou64(buf, 0, &val);
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if (ret)
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return ret;
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mutex_lock(&export->lock);
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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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mutex_unlock(&export->lock);
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return ret ? : size;
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}
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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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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return sysfs_emit(buf, "%llu\n", state.duty_cycle);
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}
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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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{
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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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struct pwm_state state;
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u64 val;
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int ret;
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ret = kstrtou64(buf, 0, &val);
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if (ret)
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return ret;
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mutex_lock(&export->lock);
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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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mutex_unlock(&export->lock);
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return ret ? : size;
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}
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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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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return sysfs_emit(buf, "%d\n", state.enabled);
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}
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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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{
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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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struct pwm_state state;
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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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mutex_lock(&export->lock);
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pwm_get_state(pwm, &state);
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switch (val) {
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case 0:
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state.enabled = false;
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break;
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case 1:
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state.enabled = true;
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break;
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default:
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ret = -EINVAL;
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goto unlock;
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}
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ret = pwm_apply_state(pwm, &state);
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unlock:
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mutex_unlock(&export->lock);
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return ret ? : size;
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}
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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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{
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const struct pwm_device *pwm = child_to_pwm_device(child);
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const char *polarity = "unknown";
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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switch (state.polarity) {
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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 sysfs_emit(buf, "%s\n", polarity);
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}
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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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{
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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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enum pwm_polarity polarity;
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struct pwm_state state;
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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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mutex_lock(&export->lock);
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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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mutex_unlock(&export->lock);
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return ret ? : size;
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}
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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 sysfs_emit(buf, "%u %u\n", result.period, result.duty_cycle);
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}
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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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static DEVICE_ATTR_RO(capture);
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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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&dev_attr_capture.attr,
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NULL
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};
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ATTRIBUTE_GROUPS(pwm);
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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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char *pwm_prop[2];
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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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mutex_init(&export->lock);
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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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export->child.groups = pwm_groups;
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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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put_device(&export->child);
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export = NULL;
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return ret;
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}
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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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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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char *pwm_prop[2];
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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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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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/* 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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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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{
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struct pwm_chip *chip = dev_get_drvdata(parent);
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struct pwm_device *pwm;
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unsigned int hwpwm;
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int ret;
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ret = kstrtouint(buf, 0, &hwpwm);
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if (ret < 0)
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return ret;
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if (hwpwm >= chip->npwm)
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return -ENODEV;
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pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
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if (IS_ERR(pwm))
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return PTR_ERR(pwm);
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ret = pwm_export_child(parent, pwm);
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if (ret < 0)
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pwm_put(pwm);
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return ret ? : len;
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}
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static DEVICE_ATTR_WO(export);
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static ssize_t unexport_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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{
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struct pwm_chip *chip = dev_get_drvdata(parent);
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unsigned int hwpwm;
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int ret;
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ret = kstrtouint(buf, 0, &hwpwm);
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if (ret < 0)
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return ret;
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if (hwpwm >= chip->npwm)
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return -ENODEV;
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ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
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return ret ? : len;
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}
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static DEVICE_ATTR_WO(unexport);
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static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
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char *buf)
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{
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const struct pwm_chip *chip = dev_get_drvdata(parent);
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return sysfs_emit(buf, "%u\n", chip->npwm);
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}
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static DEVICE_ATTR_RO(npwm);
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static struct attribute *pwm_chip_attrs[] = {
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&dev_attr_export.attr,
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&dev_attr_unexport.attr,
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&dev_attr_npwm.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(pwm_chip);
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/* takes export->lock on success */
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static struct pwm_export *pwm_class_get_state(struct device *parent,
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struct pwm_device *pwm,
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struct pwm_state *state)
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{
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struct device *child;
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struct pwm_export *export;
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if (!test_bit(PWMF_EXPORTED, &pwm->flags))
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return NULL;
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child = device_find_child(parent, pwm, pwm_unexport_match);
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if (!child)
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return NULL;
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export = child_to_pwm_export(child);
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put_device(child); /* for device_find_child() */
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mutex_lock(&export->lock);
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pwm_get_state(pwm, state);
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return export;
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}
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static int pwm_class_apply_state(struct pwm_export *export,
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struct pwm_device *pwm,
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struct pwm_state *state)
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{
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int ret = pwm_apply_state(pwm, state);
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/* release lock taken in pwm_class_get_state */
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mutex_unlock(&export->lock);
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return ret;
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}
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static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm)
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{
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struct pwm_chip *chip = dev_get_drvdata(parent);
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unsigned int i;
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int ret = 0;
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for (i = 0; i < npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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struct pwm_state state;
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struct pwm_export *export;
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export = pwm_class_get_state(parent, pwm, &state);
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if (!export)
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continue;
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state.enabled = export->suspend.enabled;
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ret = pwm_class_apply_state(export, pwm, &state);
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if (ret < 0)
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break;
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}
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return ret;
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}
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static int pwm_class_suspend(struct device *parent)
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{
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struct pwm_chip *chip = dev_get_drvdata(parent);
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unsigned int i;
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int ret = 0;
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for (i = 0; i < chip->npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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struct pwm_state state;
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struct pwm_export *export;
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export = pwm_class_get_state(parent, pwm, &state);
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if (!export)
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continue;
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export->suspend = state;
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state.enabled = false;
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ret = pwm_class_apply_state(export, pwm, &state);
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if (ret < 0) {
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/*
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* roll back the PWM devices that were disabled by
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* this suspend function.
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*/
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pwm_class_resume_npwm(parent, i);
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break;
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}
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}
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return ret;
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}
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static int pwm_class_resume(struct device *parent)
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{
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struct pwm_chip *chip = dev_get_drvdata(parent);
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return pwm_class_resume_npwm(parent, chip->npwm);
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}
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static DEFINE_SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume);
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static struct class pwm_class = {
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.name = "pwm",
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.owner = THIS_MODULE,
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.dev_groups = pwm_chip_groups,
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.pm = pm_sleep_ptr(&pwm_class_pm_ops),
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};
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static int pwmchip_sysfs_match(struct device *parent, const void *data)
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{
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return dev_get_drvdata(parent) == data;
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}
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void pwmchip_sysfs_export(struct pwm_chip *chip)
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{
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struct device *parent;
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/*
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* If device_create() fails the pwm_chip is still usable by
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* the kernel it's just not exported.
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*/
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parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
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"pwmchip%d", chip->base);
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if (IS_ERR(parent)) {
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dev_warn(chip->dev,
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"device_create failed for pwm_chip sysfs export\n");
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}
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}
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void pwmchip_sysfs_unexport(struct pwm_chip *chip)
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{
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struct device *parent;
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unsigned int i;
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parent = class_find_device(&pwm_class, NULL, chip,
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pwmchip_sysfs_match);
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if (!parent)
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return;
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for (i = 0; i < chip->npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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if (test_bit(PWMF_EXPORTED, &pwm->flags))
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pwm_unexport_child(parent, pwm);
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}
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put_device(parent);
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device_unregister(parent);
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}
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static int __init pwm_sysfs_init(void)
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{
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return class_register(&pwm_class);
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}
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subsys_initcall(pwm_sysfs_init);
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