Add a simple sysfs interface to the PWM framework.
/sys/class/pwm/
`-- pwmchipN/ for each PWM chip
|-- export (w/o) ask the kernel to export a PWM to userspace
|-- npwm (r/o) number of PWM in pwmchipN
|-- pwmN/ for each exported PWM
| |-- duty_ns (r/w) duty cycle (in nanoseconds)
| |-- enable (r/w) enable/disable PWM
| |-- period_ns (r/w) period (in nanoseconds)
| `-- polarity (r/w) polarity of PWM
`-- unexport (w/o) return a PWM to the kernel
Signed-off-by: H Hartley Sweeten <hswee...@visionengravers.com>
Cc: Thierry Reding <thierry.red...@avionic-design.de>
Cc: Lars Poeschel <poesc...@lemonage.de>
---
This is based on previous work by Lars Poeshel.
drivers/pwm/Kconfig | 6 +
drivers/pwm/Makefile | 1 +
drivers/pwm/core.c | 25 +++-
drivers/pwm/pwm-sysfs.c | 357 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pwm.h | 28 ++++
5 files changed, 415 insertions(+), 2 deletions(-)
create mode 100644 drivers/pwm/pwm-sysfs.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 115b644..61a53b5 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -28,6 +28,12 @@ menuconfig PWM
if PWM
+config PWM_SYSFS
+ bool "/sys/class/pwm/... (sysfs interface)"
+ depends on SYSFS
+ help
+ Say Y here to provide a sysfs interface to control PWMs.
+
config PWM_AB8500
tristate "AB8500 PWM support"
depends on AB8500_CORE && ARCH_U8500
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 94ba21e..fb92e1d 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_PWM) += core.o
+obj-$(CONFIG_PWM_SYSFS) += pwm-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 32221cb..f67465c 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 = 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/pwm-sysfs.c b/drivers/pwm/pwm-sysfs.c
new file mode 100644
index 0000000..6a2bf76
--- /dev/null
+++ b/drivers/pwm/pwm-sysfs.c
@@ -0,0 +1,357 @@
+/*
+ * A simple sysfs interface for the generic PWM framework
+ *
+ * Copyright (C) 2013 H Hartley Sweeten <hswee...@visionengravers.com>
+ *
+ * Based on previous work by Lars Poeschel <poesc...@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 dev;
+ struct pwm_device *pwm;
+};
+
+static struct pwm_export *dev_to_pwm_export(struct device *dev)
+{
+ return container_of(dev, struct pwm_export, dev);
+}
+
+static struct pwm_device *dev_to_pwm_device(struct device *dev)
+{
+ struct pwm_export *pwm_export = dev_to_pwm_export(dev);
+
+ return pwm_export->pwm;
+}
+
+static ssize_t pwm_period_ns_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_device *pwm = dev_to_pwm_device(dev);
+
+ return sprintf(buf, "%u\n", pwm->period);
+}
+
+static ssize_t pwm_period_ns_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_device *pwm = dev_to_pwm_device(dev);
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val <= pwm->duty)
+ return -EINVAL;
+
+ pwm->period = val;
+
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ ret = pwm_config(pwm, pwm->duty, pwm->period);
+
+ return ret ? : size;
+}
+
+static ssize_t pwm_duty_ns_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_device *pwm = dev_to_pwm_device(dev);
+
+ return sprintf(buf, "%u\n", pwm->duty);
+}
+
+static ssize_t pwm_duty_ns_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_device *pwm = dev_to_pwm_device(dev);
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val >= pwm->period)
+ return -EINVAL;
+
+ pwm->duty = val;
+
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ ret = pwm_config(pwm, pwm->duty, pwm->period);
+
+ return ret ? : size;
+}
+
+static ssize_t pwm_enable_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_device *pwm = dev_to_pwm_device(dev);
+ int enabled = test_bit(PWMF_ENABLED, &pwm->flags);
+
+ return sprintf(buf, "%sabled\n", enabled ? "en" : "dis");
+}
+
+static ssize_t pwm_enable_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_device *pwm = dev_to_pwm_device(dev);
+ int val;
+ int ret;
+
+ ret = kstrtoint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val) {
+ ret = pwm_config(pwm, pwm->duty, pwm->period);
+ if (ret)
+ return ret;
+ ret = pwm_enable(pwm);
+ } else {
+ pwm_disable(pwm);
+ }
+
+ return ret ? : size;
+}
+
+static ssize_t pwm_polarity_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_device *pwm = dev_to_pwm_device(dev);
+ int polarity = (pwm->polarity == PWM_POLARITY_NORMAL);
+
+ return sprintf(buf, "%s\n", polarity ? "normal" : "inversed");
+}
+
+static ssize_t pwm_polarity_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_device *pwm = dev_to_pwm_device(dev);
+ enum pwm_polarity polarity;
+ int val;
+ int ret;
+
+ ret = kstrtoint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ switch (val) {
+ case 0:
+ polarity = PWM_POLARITY_NORMAL;
+ break;
+ case 1:
+ polarity = PWM_POLARITY_INVERSED;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ ret = pwm_set_polarity(pwm, polarity);
+
+ return ret ? : size;
+}
+
+static DEVICE_ATTR(period_ns, 0644, pwm_period_ns_show, pwm_period_ns_store);
+static DEVICE_ATTR(duty_ns, 0644, pwm_duty_ns_show, pwm_duty_ns_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_ns.attr,
+ &dev_attr_duty_ns.attr,
+ &dev_attr_enable.attr,
+ NULL
+};
+
+static struct attribute_group pwm_attr_group = {
+ .attrs = pwm_attrs,
+};
+
+static void pwm_export_release(struct device *dev)
+{
+ struct pwm_export *pwm_export = dev_to_pwm_export(dev);
+
+ kfree(pwm_export);
+}
+
+static int pwm_export(struct device *dev, struct pwm_device *pwm)
+{
+ struct pwm_export *pwm_export;
+ struct kobject *kobj;
+ int ret;
+
+ if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
+ return -EBUSY;
+
+ pwm_export = kzalloc(sizeof(*pwm_export), GFP_KERNEL);
+ if (!pwm_export)
+ return -ENOMEM;
+
+ pwm_export->pwm = pwm;
+
+ pwm_export->dev.release = pwm_export_release;
+ pwm_export->dev.parent = dev;
+ pwm_export->dev.devt = MKDEV(0, 0);
+ dev_set_name(&pwm_export->dev, "pwm%u", pwm->hwpwm);
+ ret = device_register(&pwm_export->dev);
+ if (ret)
+ return ret;
+
+ kobj = &pwm_export->dev.kobj;
+
+ ret = sysfs_create_group(kobj, &pwm_attr_group);
+ if (ret)
+ return ret;
+
+ if (pwm->chip->ops->set_polarity) {
+ ret = sysfs_create_file(kobj, &dev_attr_polarity.attr);
+ if (ret) {
+ sysfs_remove_group(kobj, &pwm_attr_group);
+ }
+ }
+
+ return ret;
+}
+
+static int pwm_unexport_match(struct device *dev, void *data)
+{
+ return dev_to_pwm_device(dev) == data;
+}
+
+static int pwm_unexport(struct device *dev, struct pwm_device *pwm)
+{
+ if (test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) {
+ struct device *export_dev;
+ struct pwm_export *pwm_export;
+ struct kobject *kobj;
+
+ export_dev = device_find_child(dev, pwm, pwm_unexport_match);
+ pwm_export = dev_to_pwm_export(export_dev);
+ kobj = &pwm_export->dev.kobj;
+
+ if (pwm->chip->ops->set_polarity)
+ sysfs_remove_file(kobj, &dev_attr_polarity.attr);
+
+ sysfs_remove_group(kobj, &pwm_attr_group);
+
+ put_device(&pwm_export->dev);
+ device_unregister(&pwm_export->dev);
+ pwm_put(pwm);
+ }
+ return 0;
+}
+
+static ssize_t pwm_export_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct pwm_chip *chip = dev_get_drvdata(dev);
+ 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(dev, pwm);
+ if (ret < 0)
+ pwm_put(pwm);
+
+ return ret ? : len;
+}
+
+static ssize_t pwm_unexport_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct pwm_chip *chip = dev_get_drvdata(dev);
+ unsigned int hwpwm;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &hwpwm);
+ if (ret < 0)
+ return ret;
+
+ if (hwpwm >= chip->npwm)
+ return -ENODEV;
+
+ ret = pwm_unexport(dev, &chip->pwms[hwpwm]);
+
+ return ret ? : len;
+}
+
+static ssize_t pwm_npwm_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_chip *chip = dev_get_drvdata(dev);
+
+ 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,
+};
+
+void pwmchip_sysfs_export(struct pwm_chip *chip)
+{
+ chip->dev = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
+ "pwmchip%d", chip->base);
+}
+
+void pwmchip_sysfs_unexport(struct pwm_chip *chip)
+{
+ if (chip->dev) {
+ put_device(chip->dev);
+ device_unregister(chip->dev);
+ }
+}
+
+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 a4df204..e734ce6 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 +87,10 @@ struct pwm_device {
struct pwm_chip *chip;
void *chip_data;
+ struct device *dev; /* for sysfs export */
unsigned int period; /* in nanoseconds */
+ unsigned int duty; /* in nanoseconds */
+ enum pwm_polarity polarity;
};
static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
@@ -100,6 +104,17 @@ 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 = duty;
+}
+
+static inline unsigned int pwm_get_duty_cycle(struct pwm_device *pwm)
+{
+ return pwm ? pwm->duty : 0;
+}
+
/*
* pwm_set_polarity - configure the polarity of a PWM signal
*/
@@ -278,4 +293,17 @@ 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 */
--
1.8.1.4
--
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