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Message-ID: <20250317022220.423966-2-craig@mcqueen.au>
Date: Mon, 17 Mar 2025 13:22:20 +1100
From: Craig McQueen <craig@...ueen.au>
To: linux-leds@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Craig McQueen <craig@...ueen.au>
Subject: [PATCH v3 2/2] leds: Add some setup ioctls to uleds driver
* Add an ioctl for setup as an alternative to doing a write.
This is similar to the ioctl that was added to uinput for setup.
* Add an ioctl to set a default trigger for the LED.
Signed-off-by: Craig McQueen <craig@...ueen.au>
---
Documentation/leds/uleds.rst | 6 ++
drivers/leds/uleds.c | 125 ++++++++++++++++++++++++++++-------
include/uapi/linux/uleds.h | 30 ++++++++-
3 files changed, 137 insertions(+), 24 deletions(-)
diff --git a/Documentation/leds/uleds.rst b/Documentation/leds/uleds.rst
index 4077745dae00..0512e577d63a 100644
--- a/Documentation/leds/uleds.rst
+++ b/Documentation/leds/uleds.rst
@@ -24,6 +24,12 @@ A new LED class device will be created with the name given. The name can be
any valid sysfs device node name, but consider using the LED class naming
convention of "devicename:color:function".
+Alternatively, setup can be done with an ioctl call, passing a pointer to
+the structure.
+
+There is also an ioctl call to configure a default trigger for the LED, by
+passing a pointer to a structure containing the name of a trigger.
+
The current brightness is found by reading an int value from the character
device. Reading will block until the brightness changes. The device node can
also be polled to notify when the brightness value changes.
diff --git a/drivers/leds/uleds.c b/drivers/leds/uleds.c
index 374a841f18c3..598e376a4b1b 100644
--- a/drivers/leds/uleds.c
+++ b/drivers/leds/uleds.c
@@ -6,6 +6,7 @@
*
* Based on uinput.c: Aristeu Sergio Rozanski Filho <aris@...hedrallabs.org>
*/
+#include <linux/ctype.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/leds.h>
@@ -25,13 +26,14 @@ enum uleds_state {
};
struct uleds_device {
- struct uleds_user_dev user_dev;
- struct led_classdev led_cdev;
- struct mutex mutex;
- enum uleds_state state;
- wait_queue_head_t waitq;
- int brightness;
- bool new_data;
+ struct uleds_user_dev user_dev;
+ struct uleds_user_trigger default_trigger;
+ struct led_classdev led_cdev;
+ struct mutex mutex;
+ enum uleds_state state;
+ wait_queue_head_t waitq;
+ int brightness;
+ bool new_data;
};
static struct miscdevice uleds_misc;
@@ -70,15 +72,17 @@ static int uleds_open(struct inode *inode, struct file *file)
return 0;
}
-static ssize_t uleds_write(struct file *file, const char __user *buffer,
- size_t count, loff_t *ppos)
+static bool is_led_name_valid(const char *name)
{
- struct uleds_device *udev = file->private_data;
- const char *name;
- int ret;
+ return ((name[0] != '\0') &&
+ (strcmp(name, ".") != 0) &&
+ (strcmp(name, "..") != 0) &&
+ (strchr(name, '/') == NULL));
+}
- if (count == 0)
- return 0;
+static int dev_setup(struct uleds_device *udev, const char __user *buffer)
+{
+ int ret;
ret = mutex_lock_interruptible(&udev->mutex);
if (ret)
@@ -89,20 +93,13 @@ static ssize_t uleds_write(struct file *file, const char __user *buffer,
goto out;
}
- if (count != sizeof(struct uleds_user_dev)) {
- ret = -EINVAL;
- goto out;
- }
-
if (copy_from_user(&udev->user_dev, buffer,
sizeof(struct uleds_user_dev))) {
ret = -EFAULT;
goto out;
}
- name = udev->user_dev.name;
- if (!name[0] || !strcmp(name, ".") || !strcmp(name, "..") ||
- strchr(name, '/')) {
+ if (!is_led_name_valid(udev->user_dev.name)) {
ret = -EINVAL;
goto out;
}
@@ -120,7 +117,6 @@ static ssize_t uleds_write(struct file *file, const char __user *buffer,
udev->new_data = true;
udev->state = ULEDS_STATE_REGISTERED;
- ret = count;
out:
mutex_unlock(&udev->mutex);
@@ -128,6 +124,23 @@ static ssize_t uleds_write(struct file *file, const char __user *buffer,
return ret;
}
+static ssize_t uleds_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ struct uleds_device *udev = file->private_data;
+ int ret;
+
+ if (count == 0)
+ return 0;
+ if (count != sizeof(struct uleds_user_dev))
+ return -EINVAL;
+
+ ret = dev_setup(udev, buffer);
+ if (ret < 0)
+ return ret;
+ return count;
+}
+
static ssize_t uleds_read(struct file *file, char __user *buffer, size_t count,
loff_t *ppos)
{
@@ -179,6 +192,71 @@ static __poll_t uleds_poll(struct file *file, poll_table *wait)
return 0;
}
+/*
+ * Trigger name validation: Allow only alphanumeric, hyphen or underscore.
+ */
+static bool is_trigger_name_valid(const char *name)
+{
+ size_t i;
+
+ if (name[0] == '\0')
+ return false;
+
+ for (i = 0; i < TRIG_NAME_MAX; i++) {
+ if (name[i] == '\0')
+ break;
+ if (!isalnum(name[i]) && name[i] != '-' && name[i] != '_')
+ return false;
+ }
+ /* Length check and avoid any special names. */
+ return ((i < TRIG_NAME_MAX) &&
+ (strcmp(name, "default") != 0));
+}
+
+static long uleds_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct uleds_device *udev = file->private_data;
+ struct uleds_user_trigger default_trigger;
+ int retval = 0;
+
+ switch (cmd) {
+ case ULEDS_IOC_DEV_SETUP:
+ retval = dev_setup(udev, (const char __user *)arg);
+ break;
+
+ case ULEDS_IOC_SET_DEFAULT_TRIGGER:
+ retval = copy_from_user(&default_trigger,
+ (struct uleds_user_trigger __user *)arg,
+ sizeof(default_trigger));
+ if (retval)
+ return retval;
+ retval = mutex_lock_interruptible(&udev->mutex);
+ if (retval)
+ return retval;
+ if (default_trigger.name[0] == '\0') {
+ udev->led_cdev.default_trigger = NULL;
+ } else {
+ if (!is_trigger_name_valid(default_trigger.name)) {
+ mutex_unlock(&udev->mutex);
+ return -EINVAL;
+ }
+ memcpy(&udev->default_trigger, &default_trigger,
+ sizeof(udev->default_trigger));
+ udev->led_cdev.default_trigger = udev->default_trigger.name;
+ }
+ if (udev->state == ULEDS_STATE_REGISTERED)
+ led_trigger_set_default(&udev->led_cdev);
+ mutex_unlock(&udev->mutex);
+ break;
+
+ default:
+ retval = -ENOIOCTLCMD;
+ break;
+ }
+
+ return retval;
+}
+
static int uleds_release(struct inode *inode, struct file *file)
{
struct uleds_device *udev = file->private_data;
@@ -200,6 +278,7 @@ static const struct file_operations uleds_fops = {
.read = uleds_read,
.write = uleds_write,
.poll = uleds_poll,
+ .unlocked_ioctl = uleds_ioctl,
};
static struct miscdevice uleds_misc = {
diff --git a/include/uapi/linux/uleds.h b/include/uapi/linux/uleds.h
index 4d32a39965f8..0e9861a8c31f 100644
--- a/include/uapi/linux/uleds.h
+++ b/include/uapi/linux/uleds.h
@@ -15,11 +15,39 @@
#ifndef _UAPI__ULEDS_H_
#define _UAPI__ULEDS_H_
-#define LED_MAX_NAME_SIZE 64
+#define LED_MAX_NAME_SIZE 64
+#define ULEDS_TRIGGER_MAX_NAME_SIZE 64
struct uleds_user_dev {
char name[LED_MAX_NAME_SIZE];
int max_brightness;
};
+struct uleds_user_trigger {
+ char name[ULEDS_TRIGGER_MAX_NAME_SIZE];
+};
+
+
+/* ioctl commands */
+
+#define ULEDS_IOC_MAGIC 'l'
+
+/*
+ * Initial setup.
+ * E.g.:
+ * int retval;
+ * struct uleds_user_dev dev_setup = { "mainboard:green:battery", 255 };
+ * retval = ioctl(fd, ULEDS_IOC_DEV_SETUP, &dev_setup);
+ */
+#define ULEDS_IOC_DEV_SETUP _IOW(ULEDS_IOC_MAGIC, 0x01, struct uleds_user_dev)
+
+/*
+ * Set the default trigger.
+ * E.g.:
+ * int retval;
+ * struct uleds_user_trigger default_trigger = { "battery" };
+ * retval = ioctl(fd, ULEDS_IOC_SET_DEFAULT_TRIGGER, &default_trigger);
+ */
+#define ULEDS_IOC_SET_DEFAULT_TRIGGER _IOW(ULEDS_IOC_MAGIC, 0x02, struct uleds_user_trigger)
+
#endif /* _UAPI__ULEDS_H_ */
--
2.48.1
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