From f051c466cf690ac661d713d3ceb56b4efcecc853 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Wed, 14 Dec 2011 11:12:23 +0100 Subject: pwm: Allow chips to support multiple PWMs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Shawn Guo [eric@eukrea.com: fix error handling in pwmchip_add] Signed-off-by: Eric Bénard Signed-off-by: Thierry Reding --- Documentation/pwm.txt | 9 +- drivers/pwm/core.c | 267 +++++++++++++++++++++++++++++++++++--------------- include/linux/pwm.h | 71 +++++++++++--- 3 files changed, 254 insertions(+), 93 deletions(-) diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 03e39d145911..48f598acdd16 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -33,9 +33,12 @@ there only has been the barebone API meaning that each driver has to implement the pwm_*() functions itself. This means that it's impossible to have multiple PWM drivers in the system. For this reason it's mandatory for new drivers to use the generic PWM framework. -A new PWM device can be added using pwmchip_add() and removed again with -pwmchip_remove(). pwmchip_add() takes a filled in struct pwm_chip as -argument which provides the ops and the pwm id to the framework. + +A new PWM controller/chip can be added using pwmchip_add() and removed +again with pwmchip_remove(). pwmchip_add() takes a filled in struct +pwm_chip as argument which provides a description of the PWM chip, the +number of PWM devices provider by the chip and the chip-specific +implementation of the supported PWM operations to the framework. Locking ------- diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 0b8a38eca23c..a447be128328 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -2,6 +2,7 @@ * 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 @@ -20,66 +21,161 @@ #include #include +#include #include #include #include #include #include -struct pwm_device { - struct pwm_chip *chip; - const char *label; - unsigned long flags; -#define FLAG_REQUESTED 0 -#define FLAG_ENABLED 1 - struct list_head node; -}; - -static LIST_HEAD(pwm_list); +#define MAX_PWMS 1024 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 *_find_pwm(int pwm_id) +static struct pwm_device *pwm_to_device(unsigned int pwm) { - struct pwm_device *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; - list_for_each_entry(pwm, &pwm_list, node) { - if (pwm->chip->pwm_id == pwm_id) - return 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); } - return NULL; + bitmap_clear(allocated_pwms, chip->base, chip->npwm); + + kfree(chip->pwms); + chip->pwms = 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; +} + +/** + * 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; - int ret = 0; - - pwm = kzalloc(sizeof(*pwm), GFP_KERNEL); - if (!pwm) - return -ENOMEM; + unsigned int i; + int ret; - pwm->chip = chip; + if (!chip || !chip->dev || !chip->ops || !chip->ops->config || + !chip->ops->enable || !chip->ops->disable) + return -EINVAL; mutex_lock(&pwm_lock); - if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) { - ret = -EBUSY; + 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; } - list_add_tail(&pwm->node, &pwm_list); -out: - mutex_unlock(&pwm_lock); + 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; - if (ret) - kfree(pwm); + 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; + +out: + mutex_unlock(&pwm_lock); return ret; } EXPORT_SYMBOL_GPL(pwmchip_add); @@ -93,28 +189,25 @@ EXPORT_SYMBOL_GPL(pwmchip_add); */ int pwmchip_remove(struct pwm_chip *chip) { - struct pwm_device *pwm; + unsigned int i; int ret = 0; mutex_lock(&pwm_lock); - pwm = _find_pwm(chip->pwm_id); - if (!pwm) { - ret = -ENOENT; - goto out; - } + for (i = 0; i < chip->npwm; i++) { + struct pwm_device *pwm = &chip->pwms[i]; - if (test_bit(FLAG_REQUESTED, &pwm->flags)) { - ret = -EBUSY; - goto out; + if (test_bit(PWMF_REQUESTED, &pwm->flags)) { + ret = -EBUSY; + goto out; + } } - list_del(&pwm->node); + list_del_init(&chip->list); + free_pwms(chip); - kfree(pwm); out: mutex_unlock(&pwm_lock); - return ret; } EXPORT_SYMBOL_GPL(pwmchip_remove); @@ -124,50 +217,64 @@ EXPORT_SYMBOL_GPL(pwmchip_remove); * @pwm_id: global PWM device index * @label: PWM device label */ -struct pwm_device *pwm_request(int pwm_id, const char *label) +struct pwm_device *pwm_request(int pwm, const char *label) { - struct pwm_device *pwm; - int ret; + struct pwm_device *dev; + int err; + + if (pwm < 0 || pwm >= MAX_PWMS) + return ERR_PTR(-EINVAL); mutex_lock(&pwm_lock); - pwm = _find_pwm(pwm_id); - if (!pwm) { - pwm = ERR_PTR(-ENOENT); + dev = pwm_to_device(pwm); + if (!dev) { + dev = ERR_PTR(-EPROBE_DEFER); goto out; } - if (test_bit(FLAG_REQUESTED, &pwm->flags)) { - pwm = ERR_PTR(-EBUSY); - goto out; - } + err = pwm_device_request(dev, label); + if (err < 0) + dev = ERR_PTR(err); - if (!try_module_get(pwm->chip->ops->owner)) { - pwm = ERR_PTR(-ENODEV); - goto out; - } +out: + mutex_unlock(&pwm_lock); - if (pwm->chip->ops->request) { - ret = pwm->chip->ops->request(pwm->chip); - if (ret) { - pwm = ERR_PTR(ret); - goto out_put; - } - } + return dev; +} +EXPORT_SYMBOL_GPL(pwm_request); - pwm->label = label; - set_bit(FLAG_REQUESTED, &pwm->flags); +/** + * 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; - goto out; + if (!chip || index >= chip->npwm) + return ERR_PTR(-EINVAL); -out_put: - module_put(pwm->chip->ops->owner); -out: - mutex_unlock(&pwm_lock); + 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); +EXPORT_SYMBOL_GPL(pwm_request_from_chip); /** * pwm_free() - free a PWM device @@ -177,11 +284,14 @@ void pwm_free(struct pwm_device *pwm) { mutex_lock(&pwm_lock); - if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags)) { + 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); @@ -198,7 +308,10 @@ EXPORT_SYMBOL_GPL(pwm_free); */ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) { - return pwm->chip->ops->config(pwm->chip, duty_ns, 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); @@ -208,10 +321,10 @@ EXPORT_SYMBOL_GPL(pwm_config); */ int pwm_enable(struct pwm_device *pwm) { - if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags)) - return pwm->chip->ops->enable(pwm->chip); + if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) + return pwm->chip->ops->enable(pwm->chip, pwm); - return 0; + return pwm ? 0 : -EINVAL; } EXPORT_SYMBOL_GPL(pwm_enable); @@ -221,7 +334,7 @@ EXPORT_SYMBOL_GPL(pwm_enable); */ void pwm_disable(struct pwm_device *pwm) { - if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags)) - pwm->chip->ops->disable(pwm->chip); + if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags)) + pwm->chip->ops->disable(pwm->chip, pwm); } EXPORT_SYMBOL_GPL(pwm_disable); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 1f308a13105f..57103911f4c7 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -31,6 +31,33 @@ void pwm_disable(struct pwm_device *pwm); #ifdef CONFIG_PWM struct pwm_chip; +enum { + PWMF_REQUESTED = 1 << 0, + PWMF_ENABLED = 1 << 1, +}; + +struct pwm_device { + const char *label; + unsigned long flags; + unsigned int hwpwm; + unsigned int pwm; + struct pwm_chip *chip; + void *chip_data; + + unsigned int period; /* in nanoseconds */ +}; + +static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period) +{ + if (pwm) + pwm->period = period; +} + +static inline unsigned int pwm_get_period(struct pwm_device *pwm) +{ + return pwm ? pwm->period : 0; +} + /** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM @@ -41,29 +68,47 @@ struct pwm_chip; * @owner: helps prevent removal of modules exporting active PWMs */ struct pwm_ops { - int (*request)(struct pwm_chip *chip); - void (*free)(struct pwm_chip *chip); - int (*config)(struct pwm_chip *chip, int duty_ns, - int period_ns); - int (*enable)(struct pwm_chip *chip); - void (*disable)(struct pwm_chip *chip); + int (*request)(struct pwm_chip *chip, + struct pwm_device *pwm); + void (*free)(struct pwm_chip *chip, + struct pwm_device *pwm); + int (*config)(struct pwm_chip *chip, + struct pwm_device *pwm, + int duty_ns, int period_ns); + int (*enable)(struct pwm_chip *chip, + struct pwm_device *pwm); + void (*disable)(struct pwm_chip *chip, + struct pwm_device *pwm); struct module *owner; }; /** - * struct pwm_chip - abstract a PWM - * @pwm_id: global PWM device index - * @label: PWM device label - * @ops: controller operations + * struct pwm_chip - abstract a PWM controller + * @dev: device providing the PWMs + * @list: list node for internal use + * @ops: callbacks for this PWM controller + * @base: number of first PWM controlled by this chip + * @npwm: number of PWMs controlled by this chip + * @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 */ -- cgit v1.2.3