348 lines
7.7 KiB
C
348 lines
7.7 KiB
C
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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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};
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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 pwm_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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return sprintf(buf, "%u\n", pwm->period);
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}
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static ssize_t pwm_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_device *pwm = child_to_pwm_device(child);
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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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ret = pwm_config(pwm, pwm->duty_cycle, val);
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return ret ? : size;
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}
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static ssize_t pwm_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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return sprintf(buf, "%u\n", pwm->duty_cycle);
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}
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static ssize_t pwm_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_device *pwm = child_to_pwm_device(child);
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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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ret = pwm_config(pwm, val, pwm->period);
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return ret ? : size;
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}
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static ssize_t pwm_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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int enabled = test_bit(PWMF_ENABLED, &pwm->flags);
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return sprintf(buf, "%d\n", enabled);
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}
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static ssize_t pwm_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_device *pwm = child_to_pwm_device(child);
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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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switch (val) {
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case 0:
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pwm_disable(pwm);
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break;
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case 1:
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ret = pwm_enable(pwm);
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break;
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default:
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ret = -EINVAL;
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break;
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}
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return ret ? : size;
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}
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static ssize_t pwm_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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return sprintf(buf, "%s\n", pwm->polarity ? "inversed" : "normal");
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}
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static ssize_t pwm_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_device *pwm = child_to_pwm_device(child);
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enum pwm_polarity polarity;
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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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ret = pwm_set_polarity(pwm, polarity);
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return ret ? : size;
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}
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static DEVICE_ATTR(period, 0644, pwm_period_show, pwm_period_store);
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static DEVICE_ATTR(duty_cycle, 0644, pwm_duty_cycle_show, pwm_duty_cycle_store);
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static DEVICE_ATTR(enable, 0644, pwm_enable_show, pwm_enable_store);
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static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store);
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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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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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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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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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kfree(export);
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return ret;
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}
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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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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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/* 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 pwm_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(export, 0200, NULL, pwm_export_store);
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static ssize_t pwm_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(unexport, 0200, NULL, pwm_unexport_store);
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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 sprintf(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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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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};
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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 its 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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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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/* for class_find_device() */
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put_device(parent);
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device_unregister(parent);
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}
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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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