/* * Generic pwmlib implementation * * Copyright (C) 2011 Sascha Hauer * Copyright (C) 2011-2012 Avionic Design GmbH * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; see the file COPYING. If not, write to * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include #include #include #include #include #include #include #include #define MAX_PWMS 1024 static DEFINE_MUTEX(pwm_lookup_lock); static LIST_HEAD(pwm_lookup_list); static DEFINE_MUTEX(pwm_lock); static LIST_HEAD(pwm_chips); static DECLARE_BITMAP(allocated_pwms, MAX_PWMS); static RADIX_TREE(pwm_tree, GFP_KERNEL); static struct pwm_device *pwm_to_device(unsigned int pwm) { return radix_tree_lookup(&pwm_tree, pwm); } static int alloc_pwms(int pwm, unsigned int count) { unsigned int from = 0; unsigned int start; if (pwm >= MAX_PWMS) return -EINVAL; if (pwm >= 0) from = pwm; start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from, count, 0); if (pwm >= 0 && start != pwm) return -EEXIST; if (start + count > MAX_PWMS) return -ENOSPC; return start; } static void free_pwms(struct pwm_chip *chip) { unsigned int i; for (i = 0; i < chip->npwm; i++) { struct pwm_device *pwm = &chip->pwms[i]; radix_tree_delete(&pwm_tree, pwm->pwm); } bitmap_clear(allocated_pwms, chip->base, chip->npwm); kfree(chip->pwms); chip->pwms = NULL; } static struct pwm_chip *pwmchip_find_by_name(const char *name) { struct pwm_chip *chip; if (!name) return NULL; mutex_lock(&pwm_lock); list_for_each_entry(chip, &pwm_chips, list) { const char *chip_name = dev_name(chip->dev); if (chip_name && strcmp(chip_name, name) == 0) { mutex_unlock(&pwm_lock); return chip; } } mutex_unlock(&pwm_lock); return NULL; } static int pwm_device_request(struct pwm_device *pwm, const char *label) { int err; if (test_bit(PWMF_REQUESTED, &pwm->flags)) return -EBUSY; if (!try_module_get(pwm->chip->ops->owner)) return -ENODEV; if (pwm->chip->ops->request) { err = pwm->chip->ops->request(pwm->chip, pwm); if (err) { module_put(pwm->chip->ops->owner); return err; } } set_bit(PWMF_REQUESTED, &pwm->flags); pwm->label = label; return 0; } struct pwm_device * of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args) { struct pwm_device *pwm; /* check, whether the driver supports a third cell for flags */ if (pc->of_pwm_n_cells < 3) return ERR_PTR(-EINVAL); /* flags in the third cell are optional */ if (args->args_count < 2) return ERR_PTR(-EINVAL); if (args->args[0] >= pc->npwm) return ERR_PTR(-EINVAL); pwm = pwm_request_from_chip(pc, args->args[0], NULL); if (IS_ERR(pwm)) return pwm; pwm->args.period = args->args[1]; pwm->args.polarity = PWM_POLARITY_NORMAL; if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED) pwm->args.polarity = PWM_POLARITY_INVERSED; return pwm; } EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags); static struct pwm_device * of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) { struct pwm_device *pwm; /* sanity check driver support */ if (pc->of_pwm_n_cells < 2) return ERR_PTR(-EINVAL); /* all cells are required */ if (args->args_count != pc->of_pwm_n_cells) return ERR_PTR(-EINVAL); if (args->args[0] >= pc->npwm) return ERR_PTR(-EINVAL); pwm = pwm_request_from_chip(pc, args->args[0], NULL); if (IS_ERR(pwm)) return pwm; pwm->args.period = args->args[1]; return pwm; } static void of_pwmchip_add(struct pwm_chip *chip) { if (!chip->dev || !chip->dev->of_node) return; if (!chip->of_xlate) { chip->of_xlate = of_pwm_simple_xlate; chip->of_pwm_n_cells = 2; } of_node_get(chip->dev->of_node); } static void of_pwmchip_remove(struct pwm_chip *chip) { if (chip->dev) of_node_put(chip->dev->of_node); } /** * pwm_set_chip_data() - set private chip data for a PWM * @pwm: PWM device * @data: pointer to chip-specific data * * Returns: 0 on success or a negative error code on failure. */ int pwm_set_chip_data(struct pwm_device *pwm, void *data) { if (!pwm) return -EINVAL; pwm->chip_data = data; return 0; } EXPORT_SYMBOL_GPL(pwm_set_chip_data); /** * pwm_get_chip_data() - get private chip data for a PWM * @pwm: PWM device * * Returns: A pointer to the chip-private data for the PWM device. */ void *pwm_get_chip_data(struct pwm_device *pwm) { return pwm ? pwm->chip_data : NULL; } EXPORT_SYMBOL_GPL(pwm_get_chip_data); static bool pwm_ops_check(const struct pwm_ops *ops) { /* driver supports legacy, non-atomic operation */ if (ops->config && ops->enable && ops->disable) return true; /* driver supports atomic operation */ if (ops->apply) return true; return false; } /** * pwmchip_add_with_polarity() - register a new PWM chip * @chip: the PWM chip to add * @polarity: initial polarity of PWM channels * * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base * will be used. The initial polarity for all channels is specified by the * @polarity parameter. * * Returns: 0 on success or a negative error code on failure. */ int pwmchip_add_with_polarity(struct pwm_chip *chip, enum pwm_polarity polarity) { struct pwm_device *pwm; unsigned int i; int ret; if (!chip || !chip->dev || !chip->ops || !chip->npwm) return -EINVAL; if (!pwm_ops_check(chip->ops)) return -EINVAL; mutex_lock(&pwm_lock); ret = alloc_pwms(chip->base, chip->npwm); if (ret < 0) goto out; chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL); if (!chip->pwms) { ret = -ENOMEM; goto out; } chip->base = ret; for (i = 0; i < chip->npwm; i++) { pwm = &chip->pwms[i]; pwm->chip = chip; pwm->pwm = chip->base + i; pwm->hwpwm = i; pwm->state.polarity = polarity; if (chip->ops->get_state) chip->ops->get_state(chip, pwm, &pwm->state); radix_tree_insert(&pwm_tree, pwm->pwm, pwm); } bitmap_set(allocated_pwms, chip->base, chip->npwm); INIT_LIST_HEAD(&chip->list); list_add(&chip->list, &pwm_chips); ret = 0; if (IS_ENABLED(CONFIG_OF)) of_pwmchip_add(chip); pwmchip_sysfs_export(chip); out: mutex_unlock(&pwm_lock); return ret; } EXPORT_SYMBOL_GPL(pwmchip_add_with_polarity); /** * pwmchip_add() - register a new PWM chip * @chip: the PWM chip to add * * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base * will be used. The initial polarity for all channels is normal. * * Returns: 0 on success or a negative error code on failure. */ int pwmchip_add(struct pwm_chip *chip) { return pwmchip_add_with_polarity(chip, PWM_POLARITY_NORMAL); } EXPORT_SYMBOL_GPL(pwmchip_add); /** * pwmchip_remove() - remove a PWM chip * @chip: the PWM chip to remove * * Removes a PWM chip. This function may return busy if the PWM chip provides * a PWM device that is still requested. * * Returns: 0 on success or a negative error code on failure. */ int pwmchip_remove(struct pwm_chip *chip) { unsigned int i; int ret = 0; pwmchip_sysfs_unexport_children(chip); mutex_lock(&pwm_lock); for (i = 0; i < chip->npwm; i++) { struct pwm_device *pwm = &chip->pwms[i]; if (test_bit(PWMF_REQUESTED, &pwm->flags)) { ret = -EBUSY; goto out; } } list_del_init(&chip->list); if (IS_ENABLED(CONFIG_OF)) of_pwmchip_remove(chip); free_pwms(chip); pwmchip_sysfs_unexport(chip); out: mutex_unlock(&pwm_lock); return ret; } EXPORT_SYMBOL_GPL(pwmchip_remove); /** * pwm_request() - request a PWM device * @pwm: global PWM device index * @label: PWM device label * * This function is deprecated, use pwm_get() instead. * * Returns: A pointer to a PWM device or an ERR_PTR()-encoded error code on * failure. */ struct pwm_device *pwm_request(int pwm, const char *label) { struct pwm_device *dev; int err; if (pwm < 0 || pwm >= MAX_PWMS) return ERR_PTR(-EINVAL); mutex_lock(&pwm_lock); dev = pwm_to_device(pwm); if (!dev) { dev = ERR_PTR(-EPROBE_DEFER); goto out; } err = pwm_device_request(dev, label); if (err < 0) dev = ERR_PTR(err); out: mutex_unlock(&pwm_lock); return dev; } EXPORT_SYMBOL_GPL(pwm_request); /** * pwm_request_from_chip() - request a PWM device relative to a PWM chip * @chip: PWM chip * @index: per-chip index of the PWM to request * @label: a literal description string of this PWM * * Returns: A pointer to the PWM device at the given index of the given PWM * chip. A negative error code is returned if the index is not valid for the * specified PWM chip or if the PWM device cannot be requested. */ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip, unsigned int index, const char *label) { struct pwm_device *pwm; int err; if (!chip || index >= chip->npwm) return ERR_PTR(-EINVAL); mutex_lock(&pwm_lock); pwm = &chip->pwms[index]; err = pwm_device_request(pwm, label); if (err < 0) pwm = ERR_PTR(err); mutex_unlock(&pwm_lock); return pwm; } EXPORT_SYMBOL_GPL(pwm_request_from_chip); /** * pwm_free() - free a PWM device * @pwm: PWM device * * This function is deprecated, use pwm_put() instead. */ void pwm_free(struct pwm_device *pwm) { pwm_put(pwm); } EXPORT_SYMBOL_GPL(pwm_free); /** * pwm_apply_state() - atomically apply a new state to a PWM device * @pwm: PWM device * @state: new state to apply. This can be adjusted by the PWM driver * if the requested config is not achievable, for example, * ->duty_cycle and ->period might be approximated. */ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) { int err; if (!pwm || !state || !state->period || state->duty_cycle > state->period) return -EINVAL; if (!memcmp(state, &pwm->state, sizeof(*state))) return 0; if (pwm->chip->ops->apply) { err = pwm->chip->ops->apply(pwm->chip, pwm, state); if (err) return err; pwm->state = *state; } else { /* * FIXME: restore the initial state in case of error. */ if (state->polarity != pwm->state.polarity) { if (!pwm->chip->ops->set_polarity) return -ENOTSUPP; /* * Changing the polarity of a running PWM is * only allowed when the PWM driver implements * ->apply(). */ if (pwm->state.enabled) { pwm->chip->ops->disable(pwm->chip, pwm); pwm->state.enabled = false; } err = pwm->chip->ops->set_polarity(pwm->chip, pwm, state->polarity); if (err) return err; pwm->state.polarity = state->polarity; } if (state->period != pwm->state.period || state->duty_cycle != pwm->state.duty_cycle) { err = pwm->chip->ops->config(pwm->chip, pwm, state->duty_cycle, state->period); if (err) return err; pwm->state.duty_cycle = state->duty_cycle; pwm->state.period = state->period; } if (state->enabled != pwm->state.enabled) { if (state->enabled) { err = pwm->chip->ops->enable(pwm->chip, pwm); if (err) return err; } else { pwm->chip->ops->disable(pwm->chip, pwm); } pwm->state.enabled = state->enabled; } } return 0; } EXPORT_SYMBOL_GPL(pwm_apply_state); /** * pwm_capture() - capture and report a PWM signal * @pwm: PWM device * @result: structure to fill with capture result * @timeout: time to wait, in milliseconds, before giving up on capture * * Returns: 0 on success or a negative error code on failure. */ int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, unsigned long timeout) { int err; if (!pwm || !pwm->chip->ops) return -EINVAL; if (!pwm->chip->ops->capture) return -ENOSYS; mutex_lock(&pwm_lock); err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout); mutex_unlock(&pwm_lock); return err; } EXPORT_SYMBOL_GPL(pwm_capture); /** * pwm_adjust_config() - adjust the current PWM config to the PWM arguments * @pwm: PWM device * * This function will adjust the PWM config to the PWM arguments provided * by the DT or PWM lookup table. This is particularly useful to adapt * the bootloader config to the Linux one. */ int pwm_adjust_config(struct pwm_device *pwm) { struct pwm_state state; struct pwm_args pargs; pwm_get_args(pwm, &pargs); pwm_get_state(pwm, &state); /* * If the current period is zero it means that either the PWM driver * does not support initial state retrieval or the PWM has not yet * been configured. * * In either case, we setup the new period and polarity, and assign a * duty cycle of 0. */ if (!state.period) { state.duty_cycle = 0; state.period = pargs.period; state.polarity = pargs.polarity; return pwm_apply_state(pwm, &state); } /* * Adjust the PWM duty cycle/period based on the period value provided * in PWM args. */ if (pargs.period != state.period) { u64 dutycycle = (u64)state.duty_cycle * pargs.period; do_div(dutycycle, state.period); state.duty_cycle = dutycycle; state.period = pargs.period; } /* * If the polarity changed, we should also change the duty cycle. */ if (pargs.polarity != state.polarity) { state.polarity = pargs.polarity; state.duty_cycle = state.period - state.duty_cycle; } return pwm_apply_state(pwm, &state); } EXPORT_SYMBOL_GPL(pwm_adjust_config); static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) { struct pwm_chip *chip; mutex_lock(&pwm_lock); list_for_each_entry(chip, &pwm_chips, list) if (chip->dev && chip->dev->of_node == np) { mutex_unlock(&pwm_lock); return chip; } mutex_unlock(&pwm_lock); return ERR_PTR(-EPROBE_DEFER); } /** * of_pwm_get() - request a PWM via the PWM framework * @np: device node to get the PWM from * @con_id: consumer name * * Returns the PWM device parsed from the phandle and index specified in the * "pwms" property of a device tree node or a negative error-code on failure. * Values parsed from the device tree are stored in the returned PWM device * object. * * If con_id is NULL, the first PWM device listed in the "pwms" property will * be requested. Otherwise the "pwm-names" property is used to do a reverse * lookup of the PWM index. This also means that the "pwm-names" property * becomes mandatory for devices that look up the PWM device via the con_id * parameter. * * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded * error code on failure. */ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) { struct pwm_device *pwm = NULL; struct of_phandle_args args; struct pwm_chip *pc; int index = 0; int err; if (con_id) { index = of_property_match_string(np, "pwm-names", con_id); if (index < 0) return ERR_PTR(index); } err = of_parse_phandle_with_args(np, "pwms", "#pwm-cells", index, &args); if (err) { pr_err("%s(): can't parse \"pwms\" property\n", __func__); return ERR_PTR(err); } pc = of_node_to_pwmchip(args.np); if (IS_ERR(pc)) { pr_err("%s(): PWM chip not found\n", __func__); pwm = ERR_CAST(pc); goto put; } pwm = pc->of_xlate(pc, &args); if (IS_ERR(pwm)) goto put; /* * If a consumer name was not given, try to look it up from the * "pwm-names" property if it exists. Otherwise use the name of * the user device node. */ if (!con_id) { err = of_property_read_string_index(np, "pwm-names", index, &con_id); if (err < 0) con_id = np->name; } pwm->label = con_id; put: of_node_put(args.np); return pwm; } EXPORT_SYMBOL_GPL(of_pwm_get); /** * pwm_add_table() - register PWM device consumers * @table: array of consumers to register * @num: number of consumers in table */ void pwm_add_table(struct pwm_lookup *table, size_t num) { mutex_lock(&pwm_lookup_lock); while (num--) { list_add_tail(&table->list, &pwm_lookup_list); table++; } mutex_unlock(&pwm_lookup_lock); } /** * pwm_remove_table() - unregister PWM device consumers * @table: array of consumers to unregister * @num: number of consumers in table */ void pwm_remove_table(struct pwm_lookup *table, size_t num) { mutex_lock(&pwm_lookup_lock); while (num--) { list_del(&table->list); table++; } mutex_unlock(&pwm_lookup_lock); } /** * pwm_get() - look up and request a PWM device * @dev: device for PWM consumer * @con_id: consumer name * * Lookup is first attempted using DT. If the device was not instantiated from * a device tree, a PWM chip and a relative index is looked up via a table * supplied by board setup code (see pwm_add_table()). * * Once a PWM chip has been found the specified PWM device will be requested * and is ready to be used. * * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded * error code on failure. */ struct pwm_device *pwm_get(struct device *dev, const char *con_id) { const char *dev_id = dev ? dev_name(dev) : NULL; struct pwm_device *pwm; struct pwm_chip *chip; unsigned int best = 0; struct pwm_lookup *p, *chosen = NULL; unsigned int match; /* look up via DT first */ if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) return of_pwm_get(dev->of_node, con_id); /* * We look up the provider in the static table typically provided by * board setup code. We first try to lookup the consumer device by * name. If the consumer device was passed in as NULL or if no match * was found, we try to find the consumer by directly looking it up * by name. * * If a match is found, the provider PWM chip is looked up by name * and a PWM device is requested using the PWM device per-chip index. * * The lookup algorithm was shamelessly taken from the clock * framework: * * We do slightly fuzzy matching here: * An entry with a NULL ID is assumed to be a wildcard. * If an entry has a device ID, it must match * If an entry has a connection ID, it must match * Then we take the most specific entry - with the following order * of precedence: dev+con > dev only > con only. */ mutex_lock(&pwm_lookup_lock); list_for_each_entry(p, &pwm_lookup_list, list) { match = 0; if (p->dev_id) { if (!dev_id || strcmp(p->dev_id, dev_id)) continue; match += 2; } if (p->con_id) { if (!con_id || strcmp(p->con_id, con_id)) continue; match += 1; } if (match > best) { chosen = p; if (match != 3) best = match; else break; } } mutex_unlock(&pwm_lookup_lock); if (!chosen) return ERR_PTR(-ENODEV); chip = pwmchip_find_by_name(chosen->provider); if (!chip) return ERR_PTR(-EPROBE_DEFER); pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id); if (IS_ERR(pwm)) return pwm; pwm->args.period = chosen->period; pwm->args.polarity = chosen->polarity; return pwm; } EXPORT_SYMBOL_GPL(pwm_get); /** * pwm_put() - release a PWM device * @pwm: PWM device */ void pwm_put(struct pwm_device *pwm) { if (!pwm) return; mutex_lock(&pwm_lock); if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) { pr_warn("PWM device already freed\n"); goto out; } if (pwm->chip->ops->free) pwm->chip->ops->free(pwm->chip, pwm); pwm->label = NULL; module_put(pwm->chip->ops->owner); out: mutex_unlock(&pwm_lock); } EXPORT_SYMBOL_GPL(pwm_put); static void devm_pwm_release(struct device *dev, void *res) { pwm_put(*(struct pwm_device **)res); } /** * devm_pwm_get() - resource managed pwm_get() * @dev: device for PWM consumer * @con_id: consumer name * * This function performs like pwm_get() but the acquired PWM device will * automatically be released on driver detach. * * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded * error code on failure. */ struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id) { struct pwm_device **ptr, *pwm; ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); pwm = pwm_get(dev, con_id); if (!IS_ERR(pwm)) { *ptr = pwm; devres_add(dev, ptr); } else { devres_free(ptr); } return pwm; } EXPORT_SYMBOL_GPL(devm_pwm_get); /** * devm_of_pwm_get() - resource managed of_pwm_get() * @dev: device for PWM consumer * @np: device node to get the PWM from * @con_id: consumer name * * This function performs like of_pwm_get() but the acquired PWM device will * automatically be released on driver detach. * * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded * error code on failure. */ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np, const char *con_id) { struct pwm_device **ptr, *pwm; ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); pwm = of_pwm_get(np, con_id); if (!IS_ERR(pwm)) { *ptr = pwm; devres_add(dev, ptr); } else { devres_free(ptr); } return pwm; } EXPORT_SYMBOL_GPL(devm_of_pwm_get); static int devm_pwm_match(struct device *dev, void *res, void *data) { struct pwm_device **p = res; if (WARN_ON(!p || !*p)) return 0; return *p == data; } /** * devm_pwm_put() - resource managed pwm_put() * @dev: device for PWM consumer * @pwm: PWM device * * Release a PWM previously allocated using devm_pwm_get(). Calling this * function is usually not needed because devm-allocated resources are * automatically released on driver detach. */ void devm_pwm_put(struct device *dev, struct pwm_device *pwm) { WARN_ON(devres_release(dev, devm_pwm_release, devm_pwm_match, pwm)); } EXPORT_SYMBOL_GPL(devm_pwm_put); #ifdef CONFIG_DEBUG_FS static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) { unsigned int i; for (i = 0; i < chip->npwm; i++) { struct pwm_device *pwm = &chip->pwms[i]; struct pwm_state state; pwm_get_state(pwm, &state); seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label); if (test_bit(PWMF_REQUESTED, &pwm->flags)) seq_puts(s, " requested"); if (state.enabled) seq_puts(s, " enabled"); seq_printf(s, " period: %u ns", state.period); seq_printf(s, " duty: %u ns", state.duty_cycle); seq_printf(s, " polarity: %s", state.polarity ? "inverse" : "normal"); seq_puts(s, "\n"); } } static void *pwm_seq_start(struct seq_file *s, loff_t *pos) { mutex_lock(&pwm_lock); s->private = ""; return seq_list_start(&pwm_chips, *pos); } static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos) { s->private = "\n"; return seq_list_next(v, &pwm_chips, pos); } static void pwm_seq_stop(struct seq_file *s, void *v) { mutex_unlock(&pwm_lock); } static int pwm_seq_show(struct seq_file *s, void *v) { struct pwm_chip *chip = list_entry(v, struct pwm_chip, list); seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private, chip->dev->bus ? chip->dev->bus->name : "no-bus", dev_name(chip->dev), chip->npwm, (chip->npwm != 1) ? "s" : ""); if (chip->ops->dbg_show) chip->ops->dbg_show(chip, s); else pwm_dbg_show(chip, s); return 0; } static const struct seq_operations pwm_seq_ops = { .start = pwm_seq_start, .next = pwm_seq_next, .stop = pwm_seq_stop, .show = pwm_seq_show, }; static int pwm_seq_open(struct inode *inode, struct file *file) { return seq_open(file, &pwm_seq_ops); } static const struct file_operations pwm_debugfs_ops = { .owner = THIS_MODULE, .open = pwm_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; static int __init pwm_debugfs_init(void) { debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL, &pwm_debugfs_ops); return 0; } subsys_initcall(pwm_debugfs_init); #endif /* CONFIG_DEBUG_FS */