// SPDX-License-Identifier: GPL-2.0-or-later /* * A simple sysfs interface for the generic PWM framework * * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com> * * Based on previous work by Lars Poeschel <poeschel@lemonage.de> */ #include <linux/device.h> #include <linux/mutex.h> #include <linux/err.h> #include <linux/slab.h> #include <linux/kdev_t.h> #include <linux/pwm.h> struct pwm_export { struct device child; struct pwm_device *pwm; struct mutex lock; struct pwm_state suspend; }; static struct pwm_export *child_to_pwm_export(struct device *child) { return container_of(child, struct pwm_export, child); } static struct pwm_device *child_to_pwm_device(struct device *child) { struct pwm_export *export = child_to_pwm_export(child); return export->pwm; } static ssize_t period_show(struct device *child, struct device_attribute *attr, char *buf) { const struct pwm_device *pwm = child_to_pwm_device(child); struct pwm_state state; pwm_get_state(pwm, &state); return sprintf(buf, "%llu\n", state.period); } static ssize_t period_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { struct pwm_export *export = child_to_pwm_export(child); struct pwm_device *pwm = export->pwm; struct pwm_state state; u64 val; int ret; ret = kstrtou64(buf, 0, &val); if (ret) return ret; mutex_lock(&export->lock); pwm_get_state(pwm, &state); state.period = val; ret = pwm_apply_state(pwm, &state); mutex_unlock(&export->lock); return ret ? : size; } static ssize_t duty_cycle_show(struct device *child, struct device_attribute *attr, char *buf) { const struct pwm_device *pwm = child_to_pwm_device(child); struct pwm_state state; pwm_get_state(pwm, &state); return sprintf(buf, "%llu\n", state.duty_cycle); } static ssize_t duty_cycle_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { struct pwm_export *export = child_to_pwm_export(child); struct pwm_device *pwm = export->pwm; struct pwm_state state; u64 val; int ret; ret = kstrtou64(buf, 0, &val); if (ret) return ret; mutex_lock(&export->lock); pwm_get_state(pwm, &state); state.duty_cycle = val; ret = pwm_apply_state(pwm, &state); mutex_unlock(&export->lock); return ret ? : size; } static ssize_t enable_show(struct device *child, struct device_attribute *attr, char *buf) { const struct pwm_device *pwm = child_to_pwm_device(child); struct pwm_state state; pwm_get_state(pwm, &state); return sprintf(buf, "%d\n", state.enabled); } static ssize_t enable_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { struct pwm_export *export = child_to_pwm_export(child); struct pwm_device *pwm = export->pwm; struct pwm_state state; int val, ret; ret = kstrtoint(buf, 0, &val); if (ret) return ret; mutex_lock(&export->lock); pwm_get_state(pwm, &state); switch (val) { case 0: state.enabled = false; break; case 1: state.enabled = true; break; default: ret = -EINVAL; goto unlock; } ret = pwm_apply_state(pwm, &state); unlock: mutex_unlock(&export->lock); return ret ? : size; } static ssize_t polarity_show(struct device *child, struct device_attribute *attr, char *buf) { const struct pwm_device *pwm = child_to_pwm_device(child); const char *polarity = "unknown"; struct pwm_state state; pwm_get_state(pwm, &state); switch (state.polarity) { case PWM_POLARITY_NORMAL: polarity = "normal"; break; case PWM_POLARITY_INVERSED: polarity = "inversed"; break; } return sprintf(buf, "%s\n", polarity); } static ssize_t polarity_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { struct pwm_export *export = child_to_pwm_export(child); struct pwm_device *pwm = export->pwm; enum pwm_polarity polarity; struct pwm_state state; int ret; if (sysfs_streq(buf, "normal")) polarity = PWM_POLARITY_NORMAL; else if (sysfs_streq(buf, "inversed")) polarity = PWM_POLARITY_INVERSED; else return -EINVAL; mutex_lock(&export->lock); pwm_get_state(pwm, &state); state.polarity = polarity; ret = pwm_apply_state(pwm, &state); mutex_unlock(&export->lock); return ret ? : size; } static ssize_t capture_show(struct device *child, struct device_attribute *attr, char *buf) { struct pwm_device *pwm = child_to_pwm_device(child); struct pwm_capture result; int ret; ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ)); if (ret) return ret; return sprintf(buf, "%u %u\n", result.period, result.duty_cycle); } static DEVICE_ATTR_RW(period); static DEVICE_ATTR_RW(duty_cycle); static DEVICE_ATTR_RW(enable); static DEVICE_ATTR_RW(polarity); static DEVICE_ATTR_RO(capture); static struct attribute *pwm_attrs[] = { &dev_attr_period.attr, &dev_attr_duty_cycle.attr, &dev_attr_enable.attr, &dev_attr_polarity.attr, &dev_attr_capture.attr, NULL }; ATTRIBUTE_GROUPS(pwm); static void pwm_export_release(struct device *child) { struct pwm_export *export = child_to_pwm_export(child); kfree(export); } static int pwm_export_child(struct device *parent, struct pwm_device *pwm) { struct pwm_export *export; char *pwm_prop[2]; int ret; if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) return -EBUSY; export = kzalloc(sizeof(*export), GFP_KERNEL); if (!export) { clear_bit(PWMF_EXPORTED, &pwm->flags); return -ENOMEM; } export->pwm = pwm; mutex_init(&export->lock); export->child.release = pwm_export_release; export->child.parent = parent; export->child.devt = MKDEV(0, 0); export->child.groups = pwm_groups; dev_set_name(&export->child, "pwm%u", pwm->hwpwm); ret = device_register(&export->child); if (ret) { clear_bit(PWMF_EXPORTED, &pwm->flags); put_device(&export->child); export = NULL; return ret; } pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm); pwm_prop[1] = NULL; kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop); kfree(pwm_prop[0]); return 0; } static int pwm_unexport_match(struct device *child, void *data) { return child_to_pwm_device(child) == data; } static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) { struct device *child; char *pwm_prop[2]; if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) return -ENODEV; child = device_find_child(parent, pwm, pwm_unexport_match); if (!child) return -ENODEV; pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm); pwm_prop[1] = NULL; kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop); kfree(pwm_prop[0]); /* for device_find_child() */ put_device(child); device_unregister(child); pwm_put(pwm); return 0; } static ssize_t export_store(struct device *parent, struct device_attribute *attr, const char *buf, size_t len) { 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; } static DEVICE_ATTR_WO(export); static ssize_t unexport_store(struct device *parent, struct device_attribute *attr, const char *buf, size_t len) { 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; } static DEVICE_ATTR_WO(unexport); static ssize_t npwm_show(struct device *parent, struct device_attribute *attr, char *buf) { const struct pwm_chip *chip = dev_get_drvdata(parent); return sprintf(buf, "%u\n", chip->npwm); } static DEVICE_ATTR_RO(npwm); static struct attribute *pwm_chip_attrs[] = { &dev_attr_export.attr, &dev_attr_unexport.attr, &dev_attr_npwm.attr, NULL, }; ATTRIBUTE_GROUPS(pwm_chip); /* 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); static struct class pwm_class = { .name = "pwm", .owner = THIS_MODULE, .dev_groups = pwm_chip_groups, .pm = &pwm_class_pm_ops, }; 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 * the kernel it's just not exported. */ 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) { 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); } put_device(parent); device_unregister(parent); } static int __init pwm_sysfs_init(void) { return class_register(&pwm_class); } subsys_initcall(pwm_sysfs_init);