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pwm: Allow chips to support multiple PWMs
Many PWM controllers provide access to more than a single PWM output and may even share some resource among them. Allowing a PWM chip to provide multiple PWM devices enables better sharing of those resources. As a side-effect this change allows easy integration with the device tree where a given PWM can be looked up based on the PWM chip's phandle and a corresponding index. This commit modifies the PWM core to support multiple PWMs per struct pwm_chip. It achieves this in a similar way to how gpiolib works, by allowing PWM ranges to be requested dynamically (pwm_chip.base == -1) or starting at a given offset (pwm_chip.base >= 0). A chip specifies how many PWMs it controls using the npwm member. Each of the functions in the pwm_ops structure gets an additional argument that specified the PWM number (it can be converted to a per-chip index by subtracting the chip's base). The total maximum number of PWM devices is currently fixed to 1024 while the data is actually stored in a radix tree, thus saving resources if not all of them are used. Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> [eric@eukrea.com: fix error handling in pwmchip_add] Signed-off-by: Eric Bénard <eric@eukrea.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
This commit is contained in:
Thierry Reding
parent
0c2498f166
commit
f051c466cf
@ -33,9 +33,12 @@ there only has been the barebone API meaning that each driver has
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to implement the pwm_*() functions itself. This means that it's impossible
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to have multiple PWM drivers in the system. For this reason it's mandatory
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for new drivers to use the generic PWM framework.
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A new PWM device can be added using pwmchip_add() and removed again with
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pwmchip_remove(). pwmchip_add() takes a filled in struct pwm_chip as
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argument which provides the ops and the pwm id to the framework.
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A new PWM controller/chip can be added using pwmchip_add() and removed
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again with pwmchip_remove(). pwmchip_add() takes a filled in struct
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pwm_chip as argument which provides a description of the PWM chip, the
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number of PWM devices provider by the chip and the chip-specific
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implementation of the supported PWM operations to the framework.
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Locking
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-------
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@ -2,6 +2,7 @@
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* Generic pwmlib implementation
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*
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* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
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* Copyright (C) 2011-2012 Avionic Design GmbH
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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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@ -20,66 +21,161 @@
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#include <linux/module.h>
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#include <linux/pwm.h>
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#include <linux/radix-tree.h>
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#include <linux/list.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/device.h>
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struct pwm_device {
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struct pwm_chip *chip;
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const char *label;
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unsigned long flags;
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#define FLAG_REQUESTED 0
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#define FLAG_ENABLED 1
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struct list_head node;
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};
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static LIST_HEAD(pwm_list);
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#define MAX_PWMS 1024
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static DEFINE_MUTEX(pwm_lock);
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static LIST_HEAD(pwm_chips);
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static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
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static RADIX_TREE(pwm_tree, GFP_KERNEL);
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static struct pwm_device *_find_pwm(int pwm_id)
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static struct pwm_device *pwm_to_device(unsigned int pwm)
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{
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struct pwm_device *pwm;
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return radix_tree_lookup(&pwm_tree, pwm);
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}
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list_for_each_entry(pwm, &pwm_list, node) {
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if (pwm->chip->pwm_id == pwm_id)
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return pwm;
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static int alloc_pwms(int pwm, unsigned int count)
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{
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unsigned int from = 0;
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unsigned int start;
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if (pwm >= MAX_PWMS)
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return -EINVAL;
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if (pwm >= 0)
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from = pwm;
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start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
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count, 0);
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if (pwm >= 0 && start != pwm)
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return -EEXIST;
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if (start + count > MAX_PWMS)
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return -ENOSPC;
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return start;
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}
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static void free_pwms(struct pwm_chip *chip)
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{
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unsigned int i;
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for (i = 0; i < chip->npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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radix_tree_delete(&pwm_tree, pwm->pwm);
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}
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return NULL;
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bitmap_clear(allocated_pwms, chip->base, chip->npwm);
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kfree(chip->pwms);
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chip->pwms = NULL;
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}
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static int pwm_device_request(struct pwm_device *pwm, const char *label)
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{
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int err;
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if (test_bit(PWMF_REQUESTED, &pwm->flags))
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return -EBUSY;
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if (!try_module_get(pwm->chip->ops->owner))
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return -ENODEV;
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if (pwm->chip->ops->request) {
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err = pwm->chip->ops->request(pwm->chip, pwm);
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if (err) {
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module_put(pwm->chip->ops->owner);
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return err;
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}
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}
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set_bit(PWMF_REQUESTED, &pwm->flags);
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pwm->label = label;
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return 0;
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}
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/**
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* pwm_set_chip_data() - set private chip data for a PWM
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* @pwm: PWM device
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* @data: pointer to chip-specific data
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*/
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int pwm_set_chip_data(struct pwm_device *pwm, void *data)
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{
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if (!pwm)
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return -EINVAL;
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pwm->chip_data = data;
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return 0;
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}
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/**
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* pwm_get_chip_data() - get private chip data for a PWM
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* @pwm: PWM device
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*/
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void *pwm_get_chip_data(struct pwm_device *pwm)
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{
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return pwm ? pwm->chip_data : NULL;
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}
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/**
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* pwmchip_add() - register a new PWM chip
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* @chip: the PWM chip to add
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*
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* Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
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* will be used.
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*/
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int pwmchip_add(struct pwm_chip *chip)
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{
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struct pwm_device *pwm;
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int ret = 0;
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unsigned int i;
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int ret;
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pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
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if (!pwm)
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return -ENOMEM;
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pwm->chip = chip;
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if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
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!chip->ops->enable || !chip->ops->disable)
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return -EINVAL;
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mutex_lock(&pwm_lock);
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if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) {
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ret = -EBUSY;
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ret = alloc_pwms(chip->base, chip->npwm);
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if (ret < 0)
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goto out;
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chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
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if (!chip->pwms) {
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ret = -ENOMEM;
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goto out;
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}
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list_add_tail(&pwm->node, &pwm_list);
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chip->base = ret;
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for (i = 0; i < chip->npwm; i++) {
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pwm = &chip->pwms[i];
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pwm->chip = chip;
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pwm->pwm = chip->base + i;
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pwm->hwpwm = i;
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radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
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}
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bitmap_set(allocated_pwms, chip->base, chip->npwm);
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INIT_LIST_HEAD(&chip->list);
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list_add(&chip->list, &pwm_chips);
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ret = 0;
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out:
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mutex_unlock(&pwm_lock);
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if (ret)
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kfree(pwm);
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return ret;
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}
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EXPORT_SYMBOL_GPL(pwmchip_add);
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@ -93,28 +189,25 @@ EXPORT_SYMBOL_GPL(pwmchip_add);
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*/
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int pwmchip_remove(struct pwm_chip *chip)
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{
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struct pwm_device *pwm;
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unsigned int i;
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int ret = 0;
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mutex_lock(&pwm_lock);
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pwm = _find_pwm(chip->pwm_id);
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if (!pwm) {
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ret = -ENOENT;
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goto out;
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for (i = 0; i < chip->npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
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ret = -EBUSY;
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goto out;
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}
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}
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if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
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ret = -EBUSY;
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goto out;
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}
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list_del_init(&chip->list);
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free_pwms(chip);
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list_del(&pwm->node);
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kfree(pwm);
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out:
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mutex_unlock(&pwm_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(pwmchip_remove);
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@ -124,51 +217,65 @@ EXPORT_SYMBOL_GPL(pwmchip_remove);
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* @pwm_id: global PWM device index
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* @label: PWM device label
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*/
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struct pwm_device *pwm_request(int pwm_id, const char *label)
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struct pwm_device *pwm_request(int pwm, const char *label)
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{
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struct pwm_device *pwm;
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int ret;
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struct pwm_device *dev;
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int err;
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if (pwm < 0 || pwm >= MAX_PWMS)
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return ERR_PTR(-EINVAL);
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mutex_lock(&pwm_lock);
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pwm = _find_pwm(pwm_id);
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if (!pwm) {
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pwm = ERR_PTR(-ENOENT);
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dev = pwm_to_device(pwm);
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if (!dev) {
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dev = ERR_PTR(-EPROBE_DEFER);
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goto out;
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}
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if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
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pwm = ERR_PTR(-EBUSY);
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goto out;
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}
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err = pwm_device_request(dev, label);
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if (err < 0)
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dev = ERR_PTR(err);
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if (!try_module_get(pwm->chip->ops->owner)) {
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pwm = ERR_PTR(-ENODEV);
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goto out;
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}
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if (pwm->chip->ops->request) {
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ret = pwm->chip->ops->request(pwm->chip);
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if (ret) {
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pwm = ERR_PTR(ret);
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goto out_put;
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}
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}
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pwm->label = label;
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set_bit(FLAG_REQUESTED, &pwm->flags);
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goto out;
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out_put:
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module_put(pwm->chip->ops->owner);
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out:
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mutex_unlock(&pwm_lock);
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return pwm;
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return dev;
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}
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EXPORT_SYMBOL_GPL(pwm_request);
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/**
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* pwm_request_from_chip() - request a PWM device relative to a PWM chip
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* @chip: PWM chip
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* @index: per-chip index of the PWM to request
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* @label: a literal description string of this PWM
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*
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* Returns the PWM at the given index of the given PWM chip. A negative error
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* code is returned if the index is not valid for the specified PWM chip or
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* if the PWM device cannot be requested.
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*/
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struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
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unsigned int index,
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const char *label)
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{
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struct pwm_device *pwm;
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int err;
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if (!chip || index >= chip->npwm)
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return ERR_PTR(-EINVAL);
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mutex_lock(&pwm_lock);
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pwm = &chip->pwms[index];
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err = pwm_device_request(pwm, label);
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if (err < 0)
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pwm = ERR_PTR(err);
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mutex_unlock(&pwm_lock);
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return pwm;
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}
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EXPORT_SYMBOL_GPL(pwm_request_from_chip);
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/**
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* pwm_free() - free a PWM device
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* @pwm: PWM device
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@ -177,11 +284,14 @@ void pwm_free(struct pwm_device *pwm)
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{
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mutex_lock(&pwm_lock);
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if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags)) {
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if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
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pr_warning("PWM device already freed\n");
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goto out;
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}
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if (pwm->chip->ops->free)
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pwm->chip->ops->free(pwm->chip, pwm);
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pwm->label = NULL;
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module_put(pwm->chip->ops->owner);
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@ -198,7 +308,10 @@ EXPORT_SYMBOL_GPL(pwm_free);
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*/
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
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if (!pwm || period_ns == 0 || duty_ns > period_ns)
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return -EINVAL;
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return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
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}
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EXPORT_SYMBOL_GPL(pwm_config);
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@ -208,10 +321,10 @@ EXPORT_SYMBOL_GPL(pwm_config);
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*/
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int pwm_enable(struct pwm_device *pwm)
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{
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if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
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return pwm->chip->ops->enable(pwm->chip);
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if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
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return pwm->chip->ops->enable(pwm->chip, pwm);
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return 0;
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return pwm ? 0 : -EINVAL;
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}
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EXPORT_SYMBOL_GPL(pwm_enable);
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@ -221,7 +334,7 @@ EXPORT_SYMBOL_GPL(pwm_enable);
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*/
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void pwm_disable(struct pwm_device *pwm)
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{
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if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
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pwm->chip->ops->disable(pwm->chip);
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if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
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pwm->chip->ops->disable(pwm->chip, pwm);
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}
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EXPORT_SYMBOL_GPL(pwm_disable);
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@ -31,6 +31,33 @@ void pwm_disable(struct pwm_device *pwm);
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#ifdef CONFIG_PWM
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struct pwm_chip;
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enum {
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PWMF_REQUESTED = 1 << 0,
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PWMF_ENABLED = 1 << 1,
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};
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struct pwm_device {
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const char *label;
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unsigned long flags;
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unsigned int hwpwm;
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unsigned int pwm;
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struct pwm_chip *chip;
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void *chip_data;
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unsigned int period; /* in nanoseconds */
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};
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static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
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{
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if (pwm)
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pwm->period = period;
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}
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static inline unsigned int pwm_get_period(struct pwm_device *pwm)
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{
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return pwm ? pwm->period : 0;
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}
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/**
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* struct pwm_ops - PWM controller operations
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* @request: optional hook for requesting a PWM
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@ -41,29 +68,47 @@ struct pwm_chip;
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* @owner: helps prevent removal of modules exporting active PWMs
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*/
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struct pwm_ops {
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int (*request)(struct pwm_chip *chip);
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void (*free)(struct pwm_chip *chip);
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int (*config)(struct pwm_chip *chip, int duty_ns,
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int period_ns);
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int (*enable)(struct pwm_chip *chip);
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void (*disable)(struct pwm_chip *chip);
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int (*request)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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void (*free)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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int (*config)(struct pwm_chip *chip,
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struct pwm_device *pwm,
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int duty_ns, int period_ns);
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int (*enable)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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void (*disable)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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struct module *owner;
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};
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/**
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* struct pwm_chip - abstract a PWM
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* @pwm_id: global PWM device index
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* @label: PWM device label
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* @ops: controller operations
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* struct pwm_chip - abstract a PWM controller
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* @dev: device providing the PWMs
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* @list: list node for internal use
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* @ops: callbacks for this PWM controller
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* @base: number of first PWM controlled by this chip
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* @npwm: number of PWMs controlled by this chip
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* @pwms: array of PWM devices allocated by the framework
|
||||
*/
|
||||
struct pwm_chip {
|
||||
int pwm_id;
|
||||
const char *label;
|
||||
struct pwm_ops *ops;
|
||||
struct device *dev;
|
||||
struct list_head list;
|
||||
const struct pwm_ops *ops;
|
||||
int base;
|
||||
unsigned int npwm;
|
||||
|
||||
struct pwm_device *pwms;
|
||||
};
|
||||
|
||||
int pwm_set_chip_data(struct pwm_device *pwm, void *data);
|
||||
void *pwm_get_chip_data(struct pwm_device *pwm);
|
||||
|
||||
int pwmchip_add(struct pwm_chip *chip);
|
||||
int pwmchip_remove(struct pwm_chip *chip);
|
||||
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
|
||||
unsigned int index,
|
||||
const char *label);
|
||||
#endif
|
||||
|
||||
#endif /* __LINUX_PWM_H */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user