| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <657876d1321467a2b23060ac15924aed8c423390.1726819463.git.u.kleine-koenig@baylibre.com>
Date: Fri, 20 Sep 2024 10:58:04 +0200
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: linux-kernel@...r.kernel.org
Cc: Trevor Gamblin <tgamblin@...libre.com>,
David Lechner <dlechner@...libre.com>,
Fabrice Gasnier <fabrice.gasnier@...s.st.com>,
Kent Gibson <warthog618@...il.com>
Subject: [PATCH v5 8/8] pwm: Add support for pwmchip devices for faster and easier userspace access
With this change each pwmchip defining the new-style waveform callbacks
can be accessed from userspace via a character device. Compared to the
sysfs-API this is faster (on a stm32mp157 applying a new configuration
takes approx 25% only) and allows to pass the whole configuration in a
single ioctl allowing atomic application.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...libre.com>
---
drivers/pwm/core.c | 291 +++++++++++++++++++++++++++++++++++++--
include/linux/pwm.h | 3 +
include/uapi/linux/pwm.h | 32 +++++
3 files changed, 311 insertions(+), 15 deletions(-)
create mode 100644 include/uapi/linux/pwm.h
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index ed620e35db61..3c25e0ac682c 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -23,6 +23,8 @@
#include <dt-bindings/pwm/pwm.h>
+#include <uapi/linux/pwm.h>
+
#define CREATE_TRACE_POINTS
#include <trace/events/pwm.h>
@@ -1915,20 +1917,9 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
}
EXPORT_SYMBOL_GPL(pwm_get);
-/**
- * pwm_put() - release a PWM device
- * @pwm: PWM device
- */
-void pwm_put(struct pwm_device *pwm)
+static void __pwm_put(struct pwm_device *pwm)
{
- struct pwm_chip *chip;
-
- if (!pwm)
- return;
-
- chip = pwm->chip;
-
- guard(mutex)(&pwm_lock);
+ struct pwm_chip *chip = pwm->chip;
/*
* Trigger a warning if a consumer called pwm_put() twice.
@@ -1949,6 +1940,20 @@ void pwm_put(struct pwm_device *pwm)
module_put(chip->owner);
}
+
+/**
+ * pwm_put() - release a PWM device
+ * @pwm: PWM device
+ */
+void pwm_put(struct pwm_device *pwm)
+{
+ if (!pwm)
+ return;
+
+ guard(mutex)(&pwm_lock);
+
+ __pwm_put(pwm);
+}
EXPORT_SYMBOL_GPL(pwm_put);
static void devm_pwm_release(void *pwm)
@@ -2018,6 +2023,249 @@ struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
}
EXPORT_SYMBOL_GPL(devm_fwnode_pwm_get);
+struct pwm_cdev_data {
+ struct pwm_chip *chip;
+ struct pwm_device *pwm[];
+};
+
+static int pwm_cdev_open(struct inode *inode, struct file *file)
+{
+ struct pwm_chip *chip = container_of(inode->i_cdev, struct pwm_chip, cdev);
+ struct pwm_cdev_data *cdata;
+
+ guard(mutex)(&pwm_lock);
+
+ if (!chip->operational)
+ return -ENXIO;
+
+ cdata = kzalloc(struct_size(cdata, pwm, chip->npwm), GFP_KERNEL);
+ if (!cdata)
+ return -ENOMEM;
+
+ cdata->chip = chip;
+
+ file->private_data = cdata;
+
+ return nonseekable_open(inode, file);
+}
+
+static int pwm_cdev_release(struct inode *inode, struct file *file)
+{
+ struct pwm_cdev_data *cdata = file->private_data;
+ unsigned int i;
+
+ for (i = 0; i < cdata->chip->npwm; ++i) {
+ if (cdata->pwm[i])
+ pwm_put(cdata->pwm[i]);
+ }
+ kfree(cdata);
+
+ return 0;
+}
+
+static int pwm_cdev_request(struct pwm_cdev_data *cdata, unsigned int hwpwm)
+{
+ struct pwm_chip *chip = cdata->chip;
+
+ if (hwpwm >= chip->npwm)
+ return -EINVAL;
+
+ if (!cdata->pwm[hwpwm]) {
+ struct pwm_device *pwm = &chip->pwms[hwpwm];
+ int ret;
+
+ ret = pwm_device_request(pwm, "pwm-cdev");
+ if (ret < 0)
+ return ret;
+
+ cdata->pwm[hwpwm] = pwm;
+ }
+
+ return 0;
+}
+
+static int pwm_cdev_free(struct pwm_cdev_data *cdata, unsigned int hwpwm)
+{
+ struct pwm_chip *chip = cdata->chip;
+
+ if (hwpwm >= chip->npwm)
+ return -EINVAL;
+
+ if (cdata->pwm[hwpwm]) {
+ struct pwm_device *pwm = cdata->pwm[hwpwm];
+
+ __pwm_put(pwm);
+
+ cdata->pwm[hwpwm] = NULL;
+ }
+
+ return 0;
+}
+
+static struct pwm_device *pwm_cdev_get_requested_pwm(struct pwm_cdev_data *cdata,
+ u32 hwpwm)
+{
+ struct pwm_chip *chip = cdata->chip;
+
+ if (hwpwm >= chip->npwm)
+ return ERR_PTR(-EINVAL);
+
+ if (cdata->pwm[hwpwm])
+ return cdata->pwm[hwpwm];
+
+ return ERR_PTR(-EINVAL);
+}
+
+static long pwm_cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ int ret = 0;
+ struct pwm_cdev_data *cdata = file->private_data;
+ struct pwm_chip *chip = cdata->chip;
+
+ guard(mutex)(&pwm_lock);
+
+ if (!chip->operational)
+ return -ENODEV;
+
+ switch (cmd) {
+ case PWM_IOCTL_REQUEST:
+ {
+ unsigned int hwpwm = arg;
+
+ return pwm_cdev_request(cdata, hwpwm);
+ }
+ break;
+
+ case PWM_IOCTL_FREE:
+ {
+ unsigned int hwpwm = arg;
+
+ return pwm_cdev_free(cdata, hwpwm);
+ }
+ break;
+
+ case PWM_IOCTL_ROUNDWF:
+ {
+ struct pwmchip_waveform cwf;
+ struct pwm_waveform wf;
+ struct pwm_device *pwm;
+
+ ret = copy_from_user(&cwf,
+ (struct pwmchip_waveform __user *)arg,
+ sizeof(cwf));
+ if (ret)
+ return -EFAULT;
+
+ if (cwf.__pad != 0)
+ return -EINVAL;
+
+ pwm = pwm_cdev_get_requested_pwm(cdata, cwf.hwpwm);
+ if (IS_ERR(pwm))
+ return PTR_ERR(pwm);
+
+ wf = (struct pwm_waveform) {
+ .period_length_ns = cwf.period_length_ns,
+ .duty_length_ns = cwf.duty_length_ns,
+ .duty_offset_ns = cwf.duty_offset_ns,
+ };
+
+ ret = pwm_round_waveform_might_sleep(pwm, &wf);
+ if (ret)
+ return ret;
+
+ cwf = (struct pwmchip_waveform) {
+ .hwpwm = cwf.hwpwm,
+ .period_length_ns = wf.period_length_ns,
+ .duty_length_ns = wf.duty_length_ns,
+ .duty_offset_ns = wf.duty_offset_ns,
+ };
+
+ return copy_to_user((struct pwmchip_waveform __user *)arg,
+ &cwf, sizeof(cwf));
+ }
+ break;
+
+ case PWM_IOCTL_GETWF:
+ {
+ struct pwmchip_waveform cwf;
+ struct pwm_waveform wf;
+ struct pwm_device *pwm;
+
+ ret = copy_from_user(&cwf,
+ (struct pwmchip_waveform __user *)arg,
+ sizeof(cwf));
+ if (ret)
+ return -EFAULT;
+
+ if (cwf.__pad != 0)
+ return -EINVAL;
+
+ pwm = pwm_cdev_get_requested_pwm(cdata, cwf.hwpwm);
+ if (IS_ERR(pwm))
+ return PTR_ERR(pwm);
+
+ ret = pwm_get_waveform_might_sleep(pwm, &wf);
+ if (ret)
+ return ret;
+
+ cwf.period_length_ns = wf.period_length_ns;
+ cwf.duty_length_ns = wf.duty_length_ns;
+ cwf.duty_offset_ns = wf.duty_offset_ns;
+
+ return copy_to_user((struct pwmchip_waveform __user *)arg,
+ &cwf, sizeof(cwf));
+ }
+ break;
+
+ case PWM_IOCTL_SETROUNDEDWF:
+ case PWM_IOCTL_SETEXACTWF:
+ {
+ struct pwmchip_waveform cwf;
+ struct pwm_waveform wf;
+ struct pwm_device *pwm;
+
+ ret = copy_from_user(&cwf,
+ (struct pwmchip_waveform __user *)arg,
+ sizeof(cwf));
+ if (ret)
+ return -EFAULT;
+
+ if (cwf.__pad != 0)
+ return -EINVAL;
+
+ wf = (struct pwm_waveform){
+ .period_length_ns = cwf.period_length_ns,
+ .duty_length_ns = cwf.duty_length_ns,
+ .duty_offset_ns = cwf.duty_offset_ns,
+ };
+
+ if (!pwm_wf_valid(&wf))
+ return -EINVAL;
+
+ pwm = pwm_cdev_get_requested_pwm(cdata, cwf.hwpwm);
+ if (IS_ERR(pwm))
+ return PTR_ERR(pwm);
+
+ return pwm_set_waveform_might_sleep(pwm, &wf,
+ cmd == PWM_IOCTL_SETEXACTWF);
+ }
+ break;
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+static const struct file_operations pwm_cdev_fileops = {
+ .open = pwm_cdev_open,
+ .release = pwm_cdev_release,
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .unlocked_ioctl = pwm_cdev_ioctl,
+};
+
+static dev_t pwm_devt;
+
/**
* __pwmchip_add() - register a new PWM chip
* @chip: the PWM chip to add
@@ -2070,7 +2318,13 @@ int __pwmchip_add(struct pwm_chip *chip, struct module *owner)
scoped_guard(pwmchip, chip)
chip->operational = true;
- ret = device_add(&chip->dev);
+ if (chip->id < 256 && chip->ops->write_waveform)
+ chip->dev.devt = MKDEV(MAJOR(pwm_devt), chip->id);
+
+ cdev_init(&chip->cdev, &pwm_cdev_fileops);
+ chip->cdev.owner = owner;
+
+ ret = cdev_device_add(&chip->cdev, &chip->dev);
if (ret)
goto err_device_add;
@@ -2121,7 +2375,7 @@ void pwmchip_remove(struct pwm_chip *chip)
idr_remove(&pwm_chips, chip->id);
}
- device_del(&chip->dev);
+ cdev_device_del(&chip->cdev, &chip->dev);
}
EXPORT_SYMBOL_GPL(pwmchip_remove);
@@ -2262,9 +2516,16 @@ static int __init pwm_init(void)
{
int ret;
+ ret = alloc_chrdev_region(&pwm_devt, 0, 256, "pwm");
+ if (ret) {
+ pr_warn("Failed to initialize chrdev region for PWM usage\n");
+ return ret;
+ }
+
ret = class_register(&pwm_class);
if (ret) {
pr_err("Failed to initialize PWM class (%pe)\n", ERR_PTR(ret));
+ unregister_chrdev_region(pwm_devt, 256);
return ret;
}
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index c3d9ddeafa65..f43dbfaef1a1 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -2,6 +2,7 @@
#ifndef __LINUX_PWM_H
#define __LINUX_PWM_H
+#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/module.h>
@@ -304,6 +305,7 @@ struct pwm_ops {
/**
* struct pwm_chip - abstract a PWM controller
* @dev: device providing the PWMs
+ * @cdev: &struct cdev for this device
* @ops: callbacks for this PWM controller
* @owner: module providing this chip
* @id: unique number of this PWM chip
@@ -318,6 +320,7 @@ struct pwm_ops {
*/
struct pwm_chip {
struct device dev;
+ struct cdev cdev;
const struct pwm_ops *ops;
struct module *owner;
unsigned int id;
diff --git a/include/uapi/linux/pwm.h b/include/uapi/linux/pwm.h
new file mode 100644
index 000000000000..0a9cdaa0fe37
--- /dev/null
+++ b/include/uapi/linux/pwm.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+
+#ifndef _UAPI_PWM_H_
+#define _UAPI_PWM_H_
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+/**
+ * struct pwmchip_waveform - Describe a PWM waveform for a pwm_chip's PWM channel
+ * @hwpwm: per-chip relative index of the PWM device
+ * @__pad: padding, must be zero
+ * @period_length_ns: duration of the repeating period
+ * @duty_length_ns: duration of the active part in each period
+ * @duty_offset_ns: offset of the rising edge from a period's start
+ */
+struct pwmchip_waveform {
+ __u32 hwpwm;
+ __u32 __pad;
+ __u64 period_length_ns;
+ __u64 duty_length_ns;
+ __u64 duty_offset_ns;
+};
+
+#define PWM_IOCTL_REQUEST _IO(0x75, 1)
+#define PWM_IOCTL_FREE _IO(0x75, 2)
+#define PWM_IOCTL_ROUNDWF _IOWR(0x75, 3, struct pwmchip_waveform)
+#define PWM_IOCTL_GETWF _IOWR(0x75, 4, struct pwmchip_waveform)
+#define PWM_IOCTL_SETROUNDEDWF _IOW(0x75, 5, struct pwmchip_waveform)
+#define PWM_IOCTL_SETEXACTWF _IOW(0x75, 6, struct pwmchip_waveform)
+
+#endif /* _UAPI_PWM_H_ */
--
2.45.2
Powered by blists - more mailing lists