diff options
Diffstat (limited to 'drivers/pwm/core.c')
| -rw-r--r-- | drivers/pwm/core.c | 713 |
1 files changed, 713 insertions, 0 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c new file mode 100644 index 000000000000..ecb76909e946 --- /dev/null +++ b/drivers/pwm/core.c @@ -0,0 +1,713 @@ +/* + * Generic pwmlib implementation + * + * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de> + * 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 <linux/module.h> +#include <linux/pwm.h> +#include <linux/radix-tree.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/device.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> + +#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; +} + +static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc, + const struct of_phandle_args *args) +{ + struct pwm_device *pwm; + + if (pc->of_pwm_n_cells < 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_set_period(pwm, args->args[1]); + + return pwm; +} + +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); +} + +void of_pwmchip_remove(struct pwm_chip *chip) +{ + if (chip->dev && chip->dev->of_node) + 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 + */ +int pwm_set_chip_data(struct pwm_device *pwm, void *data) +{ + if (!pwm) + return -EINVAL; + + pwm->chip_data = data; + + return 0; +} + +/** + * pwm_get_chip_data() - get private chip data for a PWM + * @pwm: PWM device + */ +void *pwm_get_chip_data(struct pwm_device *pwm) +{ + return pwm ? pwm->chip_data : NULL; +} + +/** + * 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. + */ +int pwmchip_add(struct pwm_chip *chip) +{ + struct pwm_device *pwm; + unsigned int i; + int ret; + + if (!chip || !chip->dev || !chip->ops || !chip->ops->config || + !chip->ops->enable || !chip->ops->disable) + return -EINVAL; + + mutex_lock(&pwm_lock); + + ret = alloc_pwms(chip->base, chip->npwm); + if (ret < 0) + goto out; + + chip->pwms = kzalloc(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; + + 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); + +out: + mutex_unlock(&pwm_lock); + return ret; +} +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. + */ +int pwmchip_remove(struct pwm_chip *chip) +{ + unsigned int i; + int ret = 0; + + 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); + +out: + mutex_unlock(&pwm_lock); + return ret; +} +EXPORT_SYMBOL_GPL(pwmchip_remove); + +/** + * pwm_request() - request a PWM device + * @pwm_id: global PWM device index + * @label: PWM device label + * + * This function is deprecated, use pwm_get() instead. + */ +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 the PWM 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_config() - change a PWM device configuration + * @pwm: PWM device + * @duty_ns: "on" time (in nanoseconds) + * @period_ns: duration (in nanoseconds) of one cycle + */ +int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) +{ + if (!pwm || period_ns == 0 || duty_ns > period_ns) + return -EINVAL; + + return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns); +} +EXPORT_SYMBOL_GPL(pwm_config); + +/** + * pwm_enable() - start a PWM output toggling + * @pwm: PWM device + */ +int pwm_enable(struct pwm_device *pwm) +{ + if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) + return pwm->chip->ops->enable(pwm->chip, pwm); + + return pwm ? 0 : -EINVAL; +} +EXPORT_SYMBOL_GPL(pwm_enable); + +/** + * pwm_disable() - stop a PWM output toggling + * @pwm: PWM device + */ +void pwm_disable(struct pwm_device *pwm) +{ + if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags)) + pwm->chip->ops->disable(pwm->chip, pwm); +} +EXPORT_SYMBOL_GPL(pwm_disable); + +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_request() - 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. + */ +static struct pwm_device *of_pwm_request(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_debug("%s(): can't parse \"pwms\" property\n", __func__); + return ERR_PTR(err); + } + + pc = of_node_to_pwmchip(args.np); + if (IS_ERR(pc)) { + pr_debug("%s(): PWM chip not found\n", __func__); + pwm = ERR_CAST(pc); + goto put; + } + + if (args.args_count != pc->of_pwm_n_cells) { + pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name, + args.np->full_name); + pwm = ERR_PTR(-EINVAL); + 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; +} + +/** + * pwm_add_table() - register PWM device consumers + * @table: array of consumers to register + * @num: number of consumers in table + */ +void __init 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_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. + */ +struct pwm_device *pwm_get(struct device *dev, const char *con_id) +{ + struct pwm_device *pwm = ERR_PTR(-EPROBE_DEFER); + const char *dev_id = dev ? dev_name(dev): NULL; + struct pwm_chip *chip = NULL; + unsigned int index = 0; + unsigned int best = 0; + struct pwm_lookup *p; + unsigned int match; + + /* look up via DT first */ + if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) + return of_pwm_request(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) { + chip = pwmchip_find_by_name(p->provider); + index = p->index; + + if (match != 3) + best = match; + else + break; + } + } + + if (chip) + pwm = pwm_request_from_chip(chip, index, con_id ?: dev_id); + + mutex_unlock(&pwm_lookup_lock); + + 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_warning("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); + +#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]; + + seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label); + + if (test_bit(PWMF_REQUESTED, &pwm->flags)) + seq_printf(s, " requested"); + + if (test_bit(PWMF_ENABLED, &pwm->flags)) + seq_printf(s, " enabled"); + + seq_printf(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 */ |