diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-pwm | 79 | ||||
| -rw-r--r-- | Documentation/pwm.txt | 37 | ||||
| -rw-r--r-- | drivers/pwm/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/pwm/Makefile | 1 | ||||
| -rw-r--r-- | drivers/pwm/core.c | 25 | ||||
| -rw-r--r-- | drivers/pwm/sysfs.c | 352 | ||||
| -rw-r--r-- | include/linux/pwm.h | 29 |
7 files changed, 524 insertions, 3 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-pwm b/Documentation/ABI/testing/sysfs-class-pwm new file mode 100644 index 00000000000..c479d77b67c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-pwm @@ -0,0 +1,79 @@ +What: /sys/class/pwm/ +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + The pwm/ class sub-directory belongs to the Generic PWM + Framework and provides a sysfs interface for using PWM + channels. + +What: /sys/class/pwm/pwmchipN/ +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + A /sys/class/pwm/pwmchipN directory is created for each + probed PWM controller/chip where N is the base of the + PWM chip. + +What: /sys/class/pwm/pwmchipN/npwm +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + The number of PWM channels supported by the PWM chip. + +What: /sys/class/pwm/pwmchipN/export +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Exports a PWM channel from the PWM chip for sysfs control. + Value is between 0 and /sys/class/pwm/pwmchipN/npwm - 1. + +What: /sys/class/pwm/pwmchipN/unexport +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Unexports a PWM channel. + +What: /sys/class/pwm/pwmchipN/pwmX +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + A /sys/class/pwm/pwmchipN/pwmX directory is created for + each exported PWM channel where X is the exported PWM + channel number. + +What: /sys/class/pwm/pwmchipN/pwmX/period +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Sets the PWM signal period in nanoseconds. + +What: /sys/class/pwm/pwmchipN/pwmX/duty_cycle +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Sets the PWM signal duty cycle in nanoseconds. + +What: /sys/class/pwm/pwmchipN/pwmX/polarity +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Sets the output polarity of the PWM signal to "normal" or + "inversed". + +What: /sys/class/pwm/pwmchipN/pwmX/enable +Date: May 2013 +KernelVersion: 3.11 +Contact: H Hartley Sweeten <hsweeten@visionengravers.com> +Description: + Enable/disable the PWM signal. + 0 is disabled + 1 is enabled diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 7d2b4c9b544..1039b68fe9c 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -45,6 +45,43 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); To start/stop toggling the PWM output use pwm_enable()/pwm_disable(). +Using PWMs with the sysfs interface +----------------------------------- + +If CONFIG_SYSFS is enabled in your kernel configuration a simple sysfs +interface is provided to use the PWMs from userspace. It is exposed at +/sys/class/pwm/. Each probed PWM controller/chip will be exported as +pwmchipN, where N is the base of the PWM chip. Inside the directory you +will find: + +npwm - The number of PWM channels this chip supports (read-only). + +export - Exports a PWM channel for use with sysfs (write-only). + +unexport - Unexports a PWM channel from sysfs (write-only). + +The PWM channels are numbered using a per-chip index from 0 to npwm-1. + +When a PWM channel is exported a pwmX directory will be created in the +pwmchipN directory it is associated with, where X is the number of the +channel that was exported. The following properties will then be available: + +period - The total period of the PWM signal (read/write). + Value is in nanoseconds and is the sum of the active and inactive + time of the PWM. + +duty_cycle - The active time of the PWM signal (read/write). + Value is in nanoseconds and must be less than the period. + +polarity - Changes the polarity of the PWM signal (read/write). + Writes to this property only work if the PWM chip supports changing + the polarity. The polarity can only be changed if the PWM is not + enabled. Value is the string "normal" or "inversed". + +enable - Enable/disable the PWM signal (read/write). + 0 - disabled + 1 - enabled + Implementing a PWM driver ------------------------- diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index d3fe3205d29..406a4d94ddb 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -28,6 +28,10 @@ menuconfig PWM if PWM +config PWM_SYSFS + bool + default y if SYSFS + config PWM_AB8500 tristate "AB8500 PWM support" depends on AB8500_CORE && ARCH_U8500 diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index b3afc0a1800..85969222404 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -1,4 +1,5 @@ obj-$(CONFIG_PWM) += core.o +obj-$(CONFIG_PWM_SYSFS) += sysfs.o obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 0cf0f65eb03..dfbfbc52176 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -274,6 +274,8 @@ int pwmchip_add(struct pwm_chip *chip) if (IS_ENABLED(CONFIG_OF)) of_pwmchip_add(chip); + pwmchip_sysfs_export(chip); + out: mutex_unlock(&pwm_lock); return ret; @@ -310,6 +312,8 @@ int pwmchip_remove(struct pwm_chip *chip) free_pwms(chip); + pwmchip_sysfs_unexport(chip); + out: mutex_unlock(&pwm_lock); return ret; @@ -402,10 +406,19 @@ EXPORT_SYMBOL_GPL(pwm_free); */ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) { + int err; + if (!pwm || duty_ns < 0 || period_ns <= 0 || duty_ns > period_ns) return -EINVAL; - return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns); + err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns); + if (err) + return err; + + pwm->duty_cycle = duty_ns; + pwm->period = period_ns; + + return 0; } EXPORT_SYMBOL_GPL(pwm_config); @@ -418,6 +431,8 @@ EXPORT_SYMBOL_GPL(pwm_config); */ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) { + int err; + if (!pwm || !pwm->chip->ops) return -EINVAL; @@ -427,7 +442,13 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) if (test_bit(PWMF_ENABLED, &pwm->flags)) return -EBUSY; - return pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); + err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); + if (err) + return err; + + pwm->polarity = polarity; + + return 0; } EXPORT_SYMBOL_GPL(pwm_set_polarity); diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c new file mode 100644 index 00000000000..8ca5de316d3 --- /dev/null +++ b/drivers/pwm/sysfs.c @@ -0,0 +1,352 @@ +/* + * A simple sysfs interface for the generic PWM framework + * + * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com> + * + * Based on previous work by Lars Poeschel <poeschel@lemonage.de> + * + * 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. + */ + +#include <linux/device.h> +#include <linux/mutex.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/kdev_t.h> +#include <linux/pwm.h> + +struct pwm_export { + struct device child; + struct pwm_device *pwm; +}; + +static struct pwm_export *child_to_pwm_export(struct device *child) +{ + return container_of(child, struct pwm_export, child); +} + +static struct pwm_device *child_to_pwm_device(struct device *child) +{ + struct pwm_export *export = child_to_pwm_export(child); + + return export->pwm; +} + +static ssize_t pwm_period_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_device *pwm = child_to_pwm_device(child); + + return sprintf(buf, "%u\n", pwm->period); +} + +static ssize_t pwm_period_store(struct device *child, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + unsigned int val; + int ret; + + ret = kstrtouint(buf, 0, &val); + if (ret) + return ret; + + ret = pwm_config(pwm, pwm->duty_cycle, val); + + return ret ? : size; +} + +static ssize_t pwm_duty_cycle_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_device *pwm = child_to_pwm_device(child); + + return sprintf(buf, "%u\n", pwm->duty_cycle); +} + +static ssize_t pwm_duty_cycle_store(struct device *child, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + unsigned int val; + int ret; + + ret = kstrtouint(buf, 0, &val); + if (ret) + return ret; + + ret = pwm_config(pwm, val, pwm->period); + + return ret ? : size; +} + +static ssize_t pwm_enable_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_device *pwm = child_to_pwm_device(child); + int enabled = test_bit(PWMF_ENABLED, &pwm->flags); + + return sprintf(buf, "%d\n", enabled); +} + +static ssize_t pwm_enable_store(struct device *child, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + int val, ret; + + ret = kstrtoint(buf, 0, &val); + if (ret) + return ret; + + switch (val) { + case 0: + pwm_disable(pwm); + break; + case 1: + ret = pwm_enable(pwm); + break; + default: + ret = -EINVAL; + break; + } + + return ret ? : size; +} + +static ssize_t pwm_polarity_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_device *pwm = child_to_pwm_device(child); + + return sprintf(buf, "%s\n", pwm->polarity ? "inversed" : "normal"); +} + +static ssize_t pwm_polarity_store(struct device *child, + struct device_attribute *attr, + const char *buf, size_t size) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + enum pwm_polarity polarity; + int ret; + + if (sysfs_streq(buf, "normal")) + polarity = PWM_POLARITY_NORMAL; + else if (sysfs_streq(buf, "inversed")) + polarity = PWM_POLARITY_INVERSED; + else + return -EINVAL; + + ret = pwm_set_polarity(pwm, polarity); + + return ret ? : size; +} + +static DEVICE_ATTR(period, 0644, pwm_period_show, pwm_period_store); +static DEVICE_ATTR(duty_cycle, 0644, pwm_duty_cycle_show, pwm_duty_cycle_store); +static DEVICE_ATTR(enable, 0644, pwm_enable_show, pwm_enable_store); +static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store); + +static struct attribute *pwm_attrs[] = { + &dev_attr_period.attr, + &dev_attr_duty_cycle.attr, + &dev_attr_enable.attr, + &dev_attr_polarity.attr, + NULL +}; + +static const struct attribute_group pwm_attr_group = { + .attrs = pwm_attrs, +}; + +static const struct attribute_group *pwm_attr_groups[] = { + &pwm_attr_group, + NULL, +}; + +static void pwm_export_release(struct device *child) +{ + struct pwm_export *export = child_to_pwm_export(child); + + kfree(export); +} + +static int pwm_export_child(struct device *parent, struct pwm_device *pwm) +{ + struct pwm_export *export; + int ret; + + if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) + return -EBUSY; + + export = kzalloc(sizeof(*export), GFP_KERNEL); + if (!export) { + clear_bit(PWMF_EXPORTED, &pwm->flags); + return -ENOMEM; + } + + export->pwm = pwm; + + export->child.release = pwm_export_release; + export->child.parent = parent; + export->child.devt = MKDEV(0, 0); + export->child.groups = pwm_attr_groups; + dev_set_name(&export->child, "pwm%u", pwm->hwpwm); + + ret = device_register(&export->child); + if (ret) { + clear_bit(PWMF_EXPORTED, &pwm->flags); + kfree(export); + return ret; + } + + return 0; +} + +static int pwm_unexport_match(struct device *child, void *data) +{ + return child_to_pwm_device(child) == data; +} + +static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) +{ + struct device *child; + + if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) + return -ENODEV; + + child = device_find_child(parent, pwm, pwm_unexport_match); + if (!child) + return -ENODEV; + + /* for device_find_child() */ + put_device(child); + device_unregister(child); + pwm_put(pwm); + + return 0; +} + +static ssize_t pwm_export_store(struct device *parent, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct pwm_chip *chip = dev_get_drvdata(parent); + struct pwm_device *pwm; + unsigned int hwpwm; + int ret; + + ret = kstrtouint(buf, 0, &hwpwm); + if (ret < 0) + return ret; + + if (hwpwm >= chip->npwm) + return -ENODEV; + + pwm = pwm_request_from_chip(chip, hwpwm, "sysfs"); + if (IS_ERR(pwm)) + return PTR_ERR(pwm); + + ret = pwm_export_child(parent, pwm); + if (ret < 0) + pwm_put(pwm); + + return ret ? : len; +} + +static ssize_t pwm_unexport_store(struct device *parent, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct pwm_chip *chip = dev_get_drvdata(parent); + unsigned int hwpwm; + int ret; + + ret = kstrtouint(buf, 0, &hwpwm); + if (ret < 0) + return ret; + + if (hwpwm >= chip->npwm) + return -ENODEV; + + ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]); + + return ret ? : len; +} + +static ssize_t pwm_npwm_show(struct device *parent, + struct device_attribute *attr, + char *buf) +{ + const struct pwm_chip *chip = dev_get_drvdata(parent); + + return sprintf(buf, "%u\n", chip->npwm); +} + +static struct device_attribute pwm_chip_attrs[] = { + __ATTR(export, 0200, NULL, pwm_export_store), + __ATTR(unexport, 0200, NULL, pwm_unexport_store), + __ATTR(npwm, 0444, pwm_npwm_show, NULL), + __ATTR_NULL, +}; + +static struct class pwm_class = { + .name = "pwm", + .owner = THIS_MODULE, + .dev_attrs = pwm_chip_attrs, +}; + +static int pwmchip_sysfs_match(struct device *parent, const void *data) +{ + return dev_get_drvdata(parent) == data; +} + +void pwmchip_sysfs_export(struct pwm_chip *chip) +{ + struct device *parent; + + /* + * If device_create() fails the pwm_chip is still usable by + * the kernel its just not exported. + */ + parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip, + "pwmchip%d", chip->base); + if (IS_ERR(parent)) { + dev_warn(chip->dev, + "device_create failed for pwm_chip sysfs export\n"); + } +} + +void pwmchip_sysfs_unexport(struct pwm_chip *chip) +{ + struct device *parent; + + parent = class_find_device(&pwm_class, NULL, chip, + pwmchip_sysfs_match); + if (parent) { + /* for class_find_device() */ + put_device(parent); + device_unregister(parent); + } +} + +static int __init pwm_sysfs_init(void) +{ + return class_register(&pwm_class); +} +subsys_initcall(pwm_sysfs_init); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index a4df2042b79..f0feafd184a 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -76,6 +76,7 @@ enum pwm_polarity { enum { PWMF_REQUESTED = 1 << 0, PWMF_ENABLED = 1 << 1, + PWMF_EXPORTED = 1 << 2, }; struct pwm_device { @@ -86,7 +87,9 @@ struct pwm_device { struct pwm_chip *chip; void *chip_data; - unsigned int period; /* in nanoseconds */ + unsigned int period; /* in nanoseconds */ + unsigned int duty_cycle; /* in nanoseconds */ + enum pwm_polarity polarity; }; static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period) @@ -100,6 +103,17 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm) return pwm ? pwm->period : 0; } +static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty) +{ + if (pwm) + pwm->duty_cycle = duty; +} + +static inline unsigned int pwm_get_duty_cycle(struct pwm_device *pwm) +{ + return pwm ? pwm->duty_cycle : 0; +} + /* * pwm_set_polarity - configure the polarity of a PWM signal */ @@ -278,4 +292,17 @@ static inline void pwm_add_table(struct pwm_lookup *table, size_t num) } #endif +#ifdef CONFIG_PWM_SYSFS +void pwmchip_sysfs_export(struct pwm_chip *chip); +void pwmchip_sysfs_unexport(struct pwm_chip *chip); +#else +static inline void pwmchip_sysfs_export(struct pwm_chip *chip) +{ +} + +static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip) +{ +} +#endif /* CONFIG_PWM_SYSFS */ + #endif /* __LINUX_PWM_H */ |