Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755476Ab0BBHPO (ORCPT ); Tue, 2 Feb 2010 02:15:14 -0500 Received: from mail-iw0-f186.google.com ([209.85.223.186]:51405 "EHLO mail-iw0-f186.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755338Ab0BBHOL (ORCPT ); Tue, 2 Feb 2010 02:14:11 -0500 From: Bill Gatliff To: linux-embedded@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Bill Gatliff Subject: [PWM PATCH 1/5] API to consolidate PWM devices behind a common user and kernel interface Date: Tue, 2 Feb 2010 01:14:52 -0600 Message-Id: X-Mailer: git-send-email 1.6.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 31755 Lines: 1139 Signed-off-by: Bill Gatliff --- Documentation/pwm.txt | 260 +++++++++++++++++++ drivers/pwm/pwm.c | 633 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/pwm.h | 31 --- include/linux/pwm/pwm.h | 170 +++++++++++++ 4 files changed, 1063 insertions(+), 31 deletions(-) create mode 100644 Documentation/pwm.txt create mode 100644 drivers/pwm/pwm.c delete mode 100644 include/linux/pwm.h create mode 100644 include/linux/pwm/pwm.h diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt new file mode 100644 index 0000000..2c41ca5 --- /dev/null +++ b/Documentation/pwm.txt @@ -0,0 +1,260 @@ + Generic PWM Device API + + February 1, 2010 + Bill Gatliff + + + + +The code in drivers/pwm and include/linux/pwm/ implements an API for +applications involving pulse-width-modulation signals. This document +describes how the API implementation facilitates both PWM-generating +devices, and users of those devices. + + + +Motivation + +The primary goals for implementing the "generic PWM API" are to +consolidate the various PWM implementations within a consistent and +redundancy-reducing framework, and to facilitate the use of +hotpluggable PWM devices. + +Previous PWM-related implementations within the Linux kernel achieved +their consistency via cut-and-paste, but did not need to (and didn't) +facilitate more than one PWM-generating device within the system--- +hotplug or otherwise. The Generic PWM Device API might be most +appropriately viewed as an update to those implementations, rather +than a complete rewrite. + + + +Challenges + +One of the difficulties in implementing a generic PWM framework is the +fact that pulse-width-modulation applications involve real-world +signals, which often must be carefully managed to prevent destruction +of hardware that is linked to those signals. A DC motor that +experiences a brief interruption in the PWM signal controlling it +might destructively overheat; it could suddenly change speed, losing +synchronization with a sensor; it could even suddenly change direction +or torque, breaking the mechanical device connected to it. + +(A generic PWM device framework is not directly responsible for +preventing the above scenarios: that responsibility lies with the +hardware designer, and the application and driver authors. But it +must to the greatest extent possible make it easy to avoid such +problems). + +A generic PWM device framework must accommodate the substantial +differences between available PWM-generating hardware devices, without +becoming sub-optimal for any of them. + +Finally, a generic PWM device framework must be relatively +lightweight, computationally speaking. Some PWM users demand +high-speed outputs, plus the ability to regulate those outputs +quickly. A device framework must be able to "keep up" with such +hardware, while still leaving time to do real work. + +The Generic PWM Device API is an attempt to meet all of the above +requirements. At its initial publication, the API was already in use +managing small DC motors, sensors and solenoids through a +custom-designed, optically-isolated H-bridge driver. + + + +Functional Overview + +The Generic PWM Device API framework is implemented in +include/linux/pwm/pwm.h and drivers/pwm/pwm.c. The functions therein +use information from pwm_device, pwm_channel and pwm_channel_config +structures to invoke services in PWM peripheral device drivers. +Consult drivers/pwm/atmel-pwm.c for an example driver. + +There are two classes of adopters of the PWM framework: + + "Users" -- those wishing to employ the API merely to produce PWM + signals; once they have identified the appropriate physical output + on the platform in question, they don't care about the details of + the underlying hardware + + "Driver authors" -- those wishing to bind devices that can generate + PWM signals to the Generic PWM Device API, so that the services of + those devices become available to users. Assuming the hardware can + support the needs of a user, driver authors don't care about the + details of the user's application + +Generally speaking, users will first invoke pwm_request() to obtain a +handle to a PWM device. They will then pass that handle to functions +like pwm_duty_ns() and pwm_period_ns() to set the duty cycle and +period of the PWM signal, respectively. They will also invoke +pwm_start() and pwm_stop() to turn the signal on and off. + +The Generic PWM API framework also provides a sysfs interface to PWM +devices, which is adequate for basic application needs and testing. + +Driver authors fill out a pwm_device structure, which describes the +capabilities of the PWM hardware being constructed--- including the +number of distinct output "channels" the peripheral offers. They then +invoke pwm_register() (usually from within their device's probe() +handler) to make the PWM API aware of their device. The framework +will call back to the methods described in the pwm_device structure as +users begin to configure and utilize the hardware. + +Note that PWM signals can be produced by a variety of peripherals, +beyond the true "PWM hardware" offered by many system-on-chip devices. +Other possibilities include timer/counters with compare-match +capabilities, carefully-programmed synchronous serial ports +(e.g. SPI), and GPIO pins driven by kernel interval timers. With a +proper pwm_device structure, these devices and pseudo-devices can all +be accommodated by the Generic PWM Device API framework. + + + +Using the API to Generate PWM Signals -- Basic Functions for Users + + +pwm_request() -- Returns a pwm_channel pointer, which is subsequently +passed to the other user-related PWM functions. Once requested, a PWM +channel is marked as in-use and subsequent requests prior to +pwm_free() will fail. + +The names used to refer to PWM devices are defined by driver authors. +Typically they are platform device bus identifiers, and this +convention is encouraged for consistency. + + +pwm_free() -- Marks a PWM channel as no longer in use. The PWM device +is stopped before it is released by the API. + + +pwm_period_ns() -- Specifies the PWM signal's period, in nanoseconds. + + +pwm_duty_ns() -- Specifies the PWM signal's active duration, in nanoseconds. + + +pwm_duty_percent() -- Specifies the PWM signal's active duration, as a +percentage of the current period of the signal. NOTE: this value is +not recalculated if the period of the signal is subsequently changed. + + +pwm_start(), pwm_stop() -- Turns the PWM signal on and off. Except +where stated otherwise by a driver author, signals are stopped at the +end of the current period, at which time the output is set to its +inactive state. + + +pwm_polarity() -- Defines whether the PWM signal output's active +region is "1" or "0". A 10% duty-cycle, polarity=1 signal will +conventionally be at 5V (or 3.3V, or 1000V, or whatever the platform +hardware does) for 10% of the period. The same configuration of a +polarity=0 signal will be at 5V (or 3.3V, or ...) for 90% of the +period. + + + +Using the API to Generate PWM Signals -- Advanced Functions + + +pwm_config() -- Passes a pwm_channel_config structure to the +associated device driver. This function is invoked by pwm_start(), +pwm_duty_ns(), etc. and is one of two main entry points to the PWM +driver for the hardware being used. The configuration change is +guaranteed atomic if multiple configuration changes are specified. +This function might sleep, depending on what the device driver has to +do to satisfy the request. All PWM device drivers must support this +entry point. + + +pwm_config_nosleep() -- Passes a pwm_channel_config structure to the +associated device driver. If the driver must sleep in order to +implement the requested configuration change, -EWOULDBLOCK is +returned. Users may call this function from interrupt handlers, for +example. This is the other main entry point into the PWM hardware +driver, but not all device drivers support this entry point. + + +pwm_synchronize(), pwm_unsynchronize() -- "Synchronizes" two or more +PWM channels, if the underlying hardware permits. (If it doesn't, the +framework facilitates emulating this capability but it is not yet +implemented). Synchronized channels will start and stop +simultaneously when any single channel in the group is started or +stopped. Use pwm_unsynchronize(..., NULL) to completely detach a +channel from any other synchronized channels. By default, all PWM +channels are unsynchronized. + + +pwm_set_handler() -- Defines an end-of-period callback. The indicated +function will be invoked in a worker thread at the end of each PWM +period, and can subsequently invoke pwm_config(), etc. Must be used +with extreme care for high-speed PWM outputs. Set the handler +function to NULL to un-set the handler. + + + +Implementing a PWM Device API Driver -- Functions for Driver Authors + + +Fill out the appropriate fields in a pwm_device structure, and submit +to pwm_register(): + + +bus_id -- the plain-text name of the device. Users will bind to a +channel on the device using this name plus the channel number. For +example, the Atmel PWMC's bus_id is "atmel_pwmc", the same as used by +the platform device driver (recommended). The first device registered +thereby receives bus_id "atmel_pwmc.0", which is what you put in +pwm_device.bus_id. Channels are then named "atmel_pwmc.0:[0-3]". +(Hint: just use pdev->dev.bus_id in your probe() method). + + +nchan -- the number of distinct output channels provided by the device. + + +request -- (optional) Invoked each time a user requests a channel. +Use to turn on clocks, clean up register states, etc. The framework +takes care of device locking/unlocking; you will see only successful +requests. + + +free -- (optional) Callback for each time a user relinquishes a +channel. The framework will have already stopped, unsynchronized and +un-handled the channel. Use to turn off clocks, etc. as necessary. + + +synchronize, unsynchronize -- (optional) Callbacks to +synchronize/unsynchronize channels. Some devices provide this +capability in hardware; for others, it can be emulated (see +atmel_pwmc.c's sync_mask for an example). + + +set_callback -- (optional) Invoked when a user requests a handler. If +the hardware supports an end-of-period interrupt, invoke the function +indicated during your interrupt handler. The callback function itself +is always internal to the API, and does not map directly to the user's +callback function. + + +config -- Invoked to change the device configuration, always from a +sleep-capable context. All the changes indicated must be performed +atomically, ideally synchronized to an end-of-period event (so that +you avoid short or long output pulses). You may sleep, etc. as +necessary within this function. + + +config_nosleep -- (optional) Invoked to change device configuration +from within a context that is not allowed to sleep. If you cannot +perform the requested configuration changes without sleeping, return +-EWOULDBLOCK. + + + +Acknowledgements + + +The author expresses his gratitude to the countless developers who +have reviewed and submitted feedback on the various versions of the +Generic PWM Device API code, and those who have submitted drivers and +applications that use the framework. You know who you are. ;) + diff --git a/drivers/pwm/pwm.c b/drivers/pwm/pwm.c new file mode 100644 index 0000000..f369384 --- /dev/null +++ b/drivers/pwm/pwm.c @@ -0,0 +1,633 @@ +/* + * drivers/pwm/pwm.c + * + * Copyright (C) 2010 Bill Gatliff + * + * This program is free software; you may redistribute and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 + * USA + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static int __pwm_create_sysfs(struct pwm_device *pwm); + +static LIST_HEAD(pwm_device_list); +static DEFINE_MUTEX(device_list_mutex); +static struct class pwm_class; +static struct workqueue_struct *pwm_handler_workqueue; + +int pwm_register(struct pwm_device *pwm) +{ + struct pwm_channel *p; + int wchan; + int ret; + + spin_lock_init(&pwm->list_lock); + + p = kcalloc(pwm->nchan, sizeof(*p), GFP_KERNEL); + if (!p) + return -ENOMEM; + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + spin_lock_init(&p[wchan].lock); + init_completion(&p[wchan].complete); + p[wchan].chan = wchan; + p[wchan].pwm = pwm; + } + + pwm->channels = p; + + mutex_lock(&device_list_mutex); + + list_add_tail(&pwm->list, &pwm_device_list); + ret = __pwm_create_sysfs(pwm); + if (ret) { + mutex_unlock(&device_list_mutex); + goto err_create_sysfs; + } + + mutex_unlock(&device_list_mutex); + + dev_info(pwm->dev, "%d channel%s\n", pwm->nchan, + pwm->nchan > 1 ? "s" : ""); + return 0; + +err_create_sysfs: + kfree(p); + + return ret; +} +EXPORT_SYMBOL(pwm_register); + +static int __match_device(struct device *dev, void *data) +{ + return dev_get_drvdata(dev) == data; +} + +int pwm_unregister(struct pwm_device *pwm) +{ + int wchan; + struct device *dev; + + mutex_lock(&device_list_mutex); + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + if (pwm->channels[wchan].flags & FLAG_REQUESTED) { + mutex_unlock(&device_list_mutex); + return -EBUSY; + } + } + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + dev = class_find_device(&pwm_class, NULL, + &pwm->channels[wchan], + __match_device); + if (dev) { + put_device(dev); + device_unregister(dev); + } + } + + kfree(pwm->channels); + list_del(&pwm->list); + mutex_unlock(&device_list_mutex); + + return 0; +} +EXPORT_SYMBOL(pwm_unregister); + +static struct pwm_device * +__pwm_find_device(const char *bus_id) +{ + struct pwm_device *p; + + list_for_each_entry(p, &pwm_device_list, list) { + if (!strcmp(bus_id, p->bus_id)) + return p; + } + return NULL; +} + +static int +__pwm_request_channel(struct pwm_channel *p, + const char *requester) +{ + int ret; + + if (test_and_set_bit(FLAG_REQUESTED, &p->flags)) + return -EBUSY; + + if (p->pwm->request) { + ret = p->pwm->request(p); + if (ret) { + clear_bit(FLAG_REQUESTED, &p->flags); + return ret; + } + } + + p->requester = requester; + return 0; +} + +struct pwm_channel * +pwm_request(const char *bus_id, + int chan, + const char *requester) +{ + struct pwm_device *p; + int ret; + + mutex_lock(&device_list_mutex); + + p = __pwm_find_device(bus_id); + if (!p || chan >= p->nchan) + goto err_no_device; + + if (!try_module_get(p->owner)) + goto err_module_get_failed; + + ret = __pwm_request_channel(&p->channels[chan], requester); + if (ret) + goto err_request_failed; + + mutex_unlock(&device_list_mutex); + return &p->channels[chan]; + +err_request_failed: + module_put(p->owner); +err_module_get_failed: +err_no_device: + mutex_unlock(&device_list_mutex); + return NULL; +} +EXPORT_SYMBOL(pwm_request); + +void pwm_free(struct pwm_channel *p) +{ + mutex_lock(&device_list_mutex); + + if (!test_and_clear_bit(FLAG_REQUESTED, &p->flags)) + goto done; + + pwm_stop(p); + pwm_unsynchronize(p, NULL); + pwm_set_handler(p, NULL, NULL); + + if (p->pwm->free) + p->pwm->free(p); + module_put(p->pwm->owner); +done: + mutex_unlock(&device_list_mutex); +} +EXPORT_SYMBOL(pwm_free); + +unsigned long pwm_ns_to_ticks(struct pwm_channel *p, + unsigned long nsecs) +{ + unsigned long long ticks; + + ticks = nsecs; + ticks *= p->tick_hz; + do_div(ticks, 1000000000); + return ticks; +} +EXPORT_SYMBOL(pwm_ns_to_ticks); + +unsigned long pwm_ticks_to_ns(struct pwm_channel *p, + unsigned long ticks) +{ + unsigned long long ns; + + if (!p->tick_hz) + return 0; + + ns = ticks; + ns *= 1000000000UL; + do_div(ns, p->tick_hz); + return ns; +} +EXPORT_SYMBOL(pwm_ticks_to_ns); + +static void +pwm_config_ns_to_ticks(struct pwm_channel *p, + struct pwm_channel_config *c) +{ + if (c->config_mask & PWM_CONFIG_PERIOD_NS) { + c->period_ticks = pwm_ns_to_ticks(p, c->period_ns); + c->config_mask &= ~PWM_CONFIG_PERIOD_NS; + c->config_mask |= PWM_CONFIG_PERIOD_TICKS; + } + + if (c->config_mask & PWM_CONFIG_DUTY_NS) { + c->duty_ticks = pwm_ns_to_ticks(p, c->duty_ns); + c->config_mask &= ~PWM_CONFIG_DUTY_NS; + c->config_mask |= PWM_CONFIG_DUTY_TICKS; + } +} + +static void +pwm_config_percent_to_ticks(struct pwm_channel *p, + struct pwm_channel_config *c) +{ + if (c->config_mask & PWM_CONFIG_DUTY_PERCENT) { + if (c->config_mask & PWM_CONFIG_PERIOD_TICKS) + c->duty_ticks = c->period_ticks; + else + c->duty_ticks = p->period_ticks; + + c->duty_ticks *= c->duty_percent; + c->duty_ticks /= 100; + c->config_mask &= ~PWM_CONFIG_DUTY_PERCENT; + c->config_mask |= PWM_CONFIG_DUTY_TICKS; + } +} + +int pwm_config_nosleep(struct pwm_channel *p, + struct pwm_channel_config *c) +{ + if (!p->pwm->config_nosleep) + return -EINVAL; + + pwm_config_ns_to_ticks(p, c); + pwm_config_percent_to_ticks(p, c); + + return p->pwm->config_nosleep(p, c); +} +EXPORT_SYMBOL(pwm_config_nosleep); + +int pwm_config(struct pwm_channel *p, + struct pwm_channel_config *c) +{ + int ret = 0; + + if (unlikely(!p->pwm->config)) + return -EINVAL; + + pwm_config_ns_to_ticks(p, c); + pwm_config_percent_to_ticks(p, c); + + switch (c->config_mask & (PWM_CONFIG_PERIOD_TICKS + | PWM_CONFIG_DUTY_TICKS)) { + case PWM_CONFIG_PERIOD_TICKS: + if (p->duty_ticks > c->period_ticks) { + ret = -EINVAL; + goto err; + } + break; + case PWM_CONFIG_DUTY_TICKS: + if (p->period_ticks < c->duty_ticks) { + ret = -EINVAL; + goto err; + } + break; + case PWM_CONFIG_DUTY_TICKS | PWM_CONFIG_PERIOD_TICKS: + if (c->duty_ticks > c->period_ticks) { + ret = -EINVAL; + goto err; + } + break; + default: + break; + } + +err: + dev_dbg(p->pwm->dev, "%s: config_mask %d period_ticks %lu duty_ticks %lu" + " polarity %d duty_ns %lu period_ns %lu duty_percent %d\n", + __func__, c->config_mask, c->period_ticks, c->duty_ticks, + c->polarity, c->duty_ns, c->period_ns, c->duty_percent); + + if (ret) + return ret; + return p->pwm->config(p, c); +} +EXPORT_SYMBOL(pwm_config); + +int pwm_set_period_ns(struct pwm_channel *p, + unsigned long period_ns) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_PERIOD_TICKS, + .period_ticks = pwm_ns_to_ticks(p, period_ns), + }; + + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_set_period_ns); + +unsigned long pwm_get_period_ns(struct pwm_channel *p) +{ + return pwm_ticks_to_ns(p, p->period_ticks); +} +EXPORT_SYMBOL(pwm_get_period_ns); + +int pwm_set_duty_ns(struct pwm_channel *p, + unsigned long duty_ns) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_DUTY_TICKS, + .duty_ticks = pwm_ns_to_ticks(p, duty_ns), + }; + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_set_duty_ns); + +unsigned long pwm_get_duty_ns(struct pwm_channel *p) +{ + return pwm_ticks_to_ns(p, p->duty_ticks); +} +EXPORT_SYMBOL(pwm_get_duty_ns); + +int pwm_set_duty_percent(struct pwm_channel *p, + int percent) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_DUTY_PERCENT, + .duty_percent = percent, + }; + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_set_duty_percent); + +int pwm_set_polarity(struct pwm_channel *p, + int active_high) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_POLARITY, + .polarity = active_high, + }; + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_set_polarity); + +int pwm_start(struct pwm_channel *p) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_START, + }; + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_start); + +int pwm_stop(struct pwm_channel *p) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_STOP, + }; + return pwm_config(p, &c); +} +EXPORT_SYMBOL(pwm_stop); + +int pwm_synchronize(struct pwm_channel *p, + struct pwm_channel *to_p) +{ + if (p->pwm != to_p->pwm) { + /* TODO: support cross-device synchronization */ + return -EINVAL; + } + + if (!p->pwm->synchronize) + return -EINVAL; + + return p->pwm->synchronize(p, to_p); +} +EXPORT_SYMBOL(pwm_synchronize); + +int pwm_unsynchronize(struct pwm_channel *p, + struct pwm_channel *from_p) +{ + if (from_p && (p->pwm != from_p->pwm)) { + /* TODO: support cross-device synchronization */ + return -EINVAL; + } + + if (!p->pwm->unsynchronize) + return -EINVAL; + + return p->pwm->unsynchronize(p, from_p); +} +EXPORT_SYMBOL(pwm_unsynchronize); + +static void pwm_handler(struct work_struct *w) +{ + struct pwm_channel *p = container_of(w, struct pwm_channel, + handler_work); + if (p->handler && p->handler(p, p->handler_data)) + pwm_stop(p); +} + +static void __pwm_callback(struct pwm_channel *p) +{ + queue_work(pwm_handler_workqueue, &p->handler_work); + dev_dbg(p->pwm->dev, "handler %p scheduled with data %p\n", + p->handler, p->handler_data); +} + +int pwm_set_handler(struct pwm_channel *p, + pwm_handler_t handler, + void *data) +{ + if (p->pwm->set_callback) { + p->handler_data = data; + p->handler = handler; + INIT_WORK(&p->handler_work, pwm_handler); + return p->pwm->set_callback(p, handler ? __pwm_callback : NULL); + } + return -EINVAL; +} +EXPORT_SYMBOL(pwm_set_handler); + +static ssize_t pwm_run_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + if (sysfs_streq(buf, "1")) + pwm_start(p); + else if (sysfs_streq(buf, "0")) + pwm_stop(p); + return len; +} +static DEVICE_ATTR(run, 0200, NULL, pwm_run_store); + +static ssize_t pwm_duty_ns_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%lu\n", pwm_get_duty_ns(p)); +} + +static ssize_t pwm_duty_ns_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + unsigned long duty_ns; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%lu", &duty_ns)) + pwm_set_duty_ns(p, duty_ns); + return len; +} +static DEVICE_ATTR(duty_ns, 0644, pwm_duty_ns_show, pwm_duty_ns_store); + +static ssize_t pwm_period_ns_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%lu\n", pwm_get_period_ns(p)); +} + +static ssize_t pwm_period_ns_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + unsigned long period_ns; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%lu", &period_ns)) + pwm_set_period_ns(p, period_ns); + return len; +} +static DEVICE_ATTR(period_ns, 0644, pwm_period_ns_show, pwm_period_ns_store); + +static ssize_t pwm_polarity_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%d\n", p->active_low ? 0 : 1); +} + +static ssize_t pwm_polarity_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + int polarity; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%d", &polarity)) + pwm_set_polarity(p, polarity); + return len; +} +static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store); + +static ssize_t pwm_request_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + mutex_lock(&device_list_mutex); + __pwm_request_channel(p, "sysfs"); + mutex_unlock(&device_list_mutex); + + return sprintf(buf, "%s\n", p->requester); +} + +static ssize_t pwm_request_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + pwm_free(p); + return len; +} +static DEVICE_ATTR(request, 0644, pwm_request_show, pwm_request_store); + +static const struct attribute *pwm_attrs[] = +{ + &dev_attr_run.attr, + &dev_attr_polarity.attr, + &dev_attr_duty_ns.attr, + &dev_attr_period_ns.attr, + &dev_attr_request.attr, + NULL, +}; + +static const struct attribute_group pwm_device_attr_group = { + .attrs = (struct attribute **)pwm_attrs, +}; + +static int __pwm_create_sysfs(struct pwm_device *pwm) +{ + int ret = 0; + struct device *dev; + int wchan; + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + dev = device_create(&pwm_class, pwm->dev, MKDEV(0, 0), + pwm->channels + wchan, + "%s:%d", pwm->bus_id, wchan); + if (!dev) + goto err_dev_create; + ret = sysfs_create_group(&dev->kobj, &pwm_device_attr_group); + if (ret) + goto err_dev_create; + } + + return ret; + +err_dev_create: + for (wchan = 0; wchan < pwm->nchan; wchan++) { + dev = class_find_device(&pwm_class, NULL, + &pwm->channels[wchan], + __match_device); + if (dev) { + put_device(dev); + device_unregister(dev); + } + } + + return ret; +} + +static struct class_attribute pwm_class_attrs[] = { + __ATTR_NULL, +}; + +static struct class pwm_class = { + .name = "pwm", + .owner = THIS_MODULE, + + .class_attrs = pwm_class_attrs, +}; + +static int __init pwm_init(void) +{ + int ret; + + /* TODO: how to deal with devices that register very early? */ + + ret = class_register(&pwm_class); + if (ret < 0) + return ret; + + pwm_handler_workqueue = create_workqueue("pwmd"); + + return 0; +} +postcore_initcall(pwm_init); diff --git a/include/linux/pwm.h b/include/linux/pwm.h deleted file mode 100644 index 7c77575..0000000 --- a/include/linux/pwm.h +++ /dev/null @@ -1,31 +0,0 @@ -#ifndef __LINUX_PWM_H -#define __LINUX_PWM_H - -struct pwm_device; - -/* - * pwm_request - request a PWM device - */ -struct pwm_device *pwm_request(int pwm_id, const char *label); - -/* - * pwm_free - free a PWM device - */ -void pwm_free(struct pwm_device *pwm); - -/* - * pwm_config - change a PWM device configuration - */ -int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); - -/* - * pwm_enable - start a PWM output toggling - */ -int pwm_enable(struct pwm_device *pwm); - -/* - * pwm_disable - stop a PWM output toggling - */ -void pwm_disable(struct pwm_device *pwm); - -#endif /* __LINUX_PWM_H */ diff --git a/include/linux/pwm/pwm.h b/include/linux/pwm/pwm.h new file mode 100644 index 0000000..848cd76 --- /dev/null +++ b/include/linux/pwm/pwm.h @@ -0,0 +1,170 @@ +#ifndef __LINUX_PWM_H +#define __LINUX_PWM_H + +/* + * include/linux/pwm.h + * + * Copyright (C) 2008 Bill Gatliff + * + * 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 of the License, 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; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include +#include +#include +#include + +enum { + PWM_CONFIG_DUTY_TICKS = BIT(0), + PWM_CONFIG_PERIOD_TICKS = BIT(1), + PWM_CONFIG_POLARITY = BIT(2), + PWM_CONFIG_START = BIT(3), + PWM_CONFIG_STOP = BIT(4), + + PWM_CONFIG_HANDLER = BIT(5), + + PWM_CONFIG_DUTY_NS = BIT(6), + PWM_CONFIG_DUTY_PERCENT = BIT(7), + PWM_CONFIG_PERIOD_NS = BIT(8), +}; + +struct pwm_channel; +struct work_struct; + +typedef int (*pwm_handler_t)(struct pwm_channel *p, void *data); +typedef void (*pwm_callback_t)(struct pwm_channel *p); + +struct pwm_channel_config { + int config_mask; + unsigned long duty_ticks; + unsigned long period_ticks; + int polarity; + + pwm_handler_t handler; + + unsigned long duty_ns; + unsigned long period_ns; + int duty_percent; +}; + +struct pwm_device { + struct list_head list; + spinlock_t list_lock; + struct device *dev; + struct module *owner; + struct pwm_channel *channels; + + const char *bus_id; + int nchan; + + int (*request) (struct pwm_channel *p); + void (*free) (struct pwm_channel *p); + int (*config) (struct pwm_channel *p, + struct pwm_channel_config *c); + int (*config_nosleep)(struct pwm_channel *p, + struct pwm_channel_config *c); + int (*synchronize) (struct pwm_channel *p, + struct pwm_channel *to_p); + int (*unsynchronize)(struct pwm_channel *p, + struct pwm_channel *from_p); + int (*set_callback) (struct pwm_channel *p, + pwm_callback_t callback); +}; + +int pwm_register(struct pwm_device *pwm); +int pwm_unregister(struct pwm_device *pwm); + +enum { + FLAG_REQUESTED = 0, + FLAG_STOP = 1, +}; + +struct pwm_channel { + struct list_head list; + struct pwm_device *pwm; + const char *requester; + int chan; + unsigned long flags; + unsigned long tick_hz; + + spinlock_t lock; + struct completion complete; + + pwm_callback_t callback; + + struct work_struct handler_work; + pwm_handler_t handler; + void *handler_data; + + int active_low; + unsigned long period_ticks; + unsigned long duty_ticks; +}; + +struct gpio_pwm_platform_data { + int gpio; +}; + +struct pwm_channel * +pwm_request(const char *bus_id, int chan, + const char *requester); + +void pwm_free(struct pwm_channel *pwm); + +int pwm_config_nosleep(struct pwm_channel *pwm, + struct pwm_channel_config *c); + +int pwm_config(struct pwm_channel *pwm, + struct pwm_channel_config *c); + +unsigned long pwm_ns_to_ticks(struct pwm_channel *pwm, + unsigned long nsecs); + +unsigned long pwm_ticks_to_ns(struct pwm_channel *pwm, + unsigned long ticks); + +int pwm_set_period_ns(struct pwm_channel *pwm, + unsigned long period_ns); + +unsigned long int pwm_get_period_ns(struct pwm_channel *pwm); + +int pwm_set_duty_ns(struct pwm_channel *pwm, + unsigned long duty_ns); + +int pwm_set_duty_percent(struct pwm_channel *pwm, + int percent); + +unsigned long pwm_get_duty_ns(struct pwm_channel *pwm); + +int pwm_set_polarity(struct pwm_channel *pwm, + int active_high); + +int pwm_start(struct pwm_channel *pwm); + +int pwm_stop(struct pwm_channel *pwm); + +int pwm_set_handler(struct pwm_channel *pwm, + pwm_handler_t handler, + void *data); + +int pwm_synchronize(struct pwm_channel *p, + struct pwm_channel *to_p); + + +int pwm_unsynchronize(struct pwm_channel *p, + struct pwm_channel *from_p); + + +#endif /* __LINUX_PWM_H */ -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/