drivers/pwm/sysfs.c

// 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;
}

#ifdef CONFIG_PWM_ROCKCHIP_ONESHOT
static ssize_t oneshot_count_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.oneshot_count);
}

static ssize_t oneshot_count_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;
    unsigned int val;
    int ret;

    ret = kstrtouint(buf, 0, &val);
    if (ret) {
        return ret;
    }

    mutex_lock(&export->lock);
    pwm_get_state(pwm, &state);
    state.oneshot_count = val;
    ret = pwm_apply_state(pwm, &state);
    mutex_unlock(&export->lock);

    return ret ?: size;
}
#endif

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);
#ifdef CONFIG_PWM_ROCKCHIP_ONESHOT
static DEVICE_ATTR_RW(oneshot_count);
#endif
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,
#ifdef CONFIG_PWM_ROCKCHIP_ONESHOT
                                        &dev_attr_oneshot_count.attr,
#endif
                                        &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);