@@ -546,6 +546,9 @@ static long linehandle_set_config(struct linehandle_state *lh,
if (ret)
return ret;
}
+
+ atomic_notifier_call_chain(&desc->gdev->notifier,
+ GPIOLINE_CHANGED_CONFIG, desc);
}
return 0;
}
@@ -1201,14 +1204,25 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
spin_unlock_irqrestore(&gpio_lock, flags);
}
+struct gpio_chardev_data {
+ struct gpio_device *gdev;
+ wait_queue_head_t wait;
+ DECLARE_KFIFO(events, struct gpioline_info_changed, 32);
+ struct notifier_block lineinfo_changed_nb;
+ unsigned long *watched_lines;
+};
+
/*
* gpio_ioctl() - ioctl handler for the GPIO chardev
*/
static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
- struct gpio_device *gdev = filp->private_data;
+ struct gpio_chardev_data *priv = filp->private_data;
+ struct gpio_device *gdev = priv->gdev;
struct gpio_chip *chip = gdev->chip;
void __user *ip = (void __user *)arg;
+ struct gpio_desc *desc;
+ __u32 offset;
/* We fail any subsequent ioctl():s when the chip is gone */
if (!chip)
@@ -1230,9 +1244,9 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
return -EFAULT;
return 0;
- } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
+ } else if (cmd == GPIO_GET_LINEINFO_IOCTL ||
+ cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
struct gpioline_info lineinfo;
- struct gpio_desc *desc;
if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;
@@ -1245,11 +1259,25 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
return -EFAULT;
+
+ if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL)
+ set_bit(desc_to_gpio(desc), priv->watched_lines);
+
return 0;
} else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
return linehandle_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
return lineevent_create(gdev, ip);
+ } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
+ if (copy_from_user(&offset, ip, sizeof(offset)))
+ return -EFAULT;
+
+ desc = gpiochip_get_desc(chip, offset);
+ if (IS_ERR(desc))
+ return PTR_ERR(desc);
+
+ clear_bit(desc_to_gpio(desc), &desc->flags);
+ return 0;
}
return -EINVAL;
}
@@ -1262,6 +1290,101 @@ static long gpio_ioctl_compat(struct file *filp, unsigned int cmd,
}
#endif
+static struct gpio_chardev_data *
+to_gpio_chardev_data(struct notifier_block *nb)
+{
+ return container_of(nb, struct gpio_chardev_data, lineinfo_changed_nb);
+}
+
+static int lineinfo_changed_notify(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct gpio_chardev_data *priv = to_gpio_chardev_data(nb);
+ struct gpioline_info_changed chg;
+ struct gpio_desc *desc = data;
+ int ret;
+
+ if (!test_bit(desc_to_gpio(desc), priv->watched_lines))
+ return NOTIFY_DONE;
+
+ memset(&chg, 0, sizeof(chg));
+ chg.info.line_offset = gpio_chip_hwgpio(desc);
+ chg.event_type = action;
+ chg.timestamp = ktime_get_ns();
+ gpio_desc_to_lineinfo(desc, &chg.info);
+
+ ret = kfifo_in_spinlocked(&priv->events, &chg, 1, &priv->wait.lock);
+ if (ret)
+ wake_up_poll(&priv->wait, EPOLLIN);
+ else
+ pr_debug_ratelimited("lineinfo event FIFO is full - event dropped\n");
+
+ return NOTIFY_OK;
+}
+
+static __poll_t lineinfo_watch_poll(struct file *filep,
+ struct poll_table_struct *pollt)
+{
+ struct gpio_chardev_data *priv = filep->private_data;
+ __poll_t events = 0;
+
+ poll_wait(filep, &priv->wait, pollt);
+
+ if (!kfifo_is_empty_spinlocked_noirqsave(&priv->events,
+ &priv->wait.lock))
+ events = EPOLLIN | EPOLLRDNORM;
+
+ return events;
+}
+
+static ssize_t lineinfo_watch_read(struct file *filep, char __user *buf,
+ size_t count, loff_t *off)
+{
+ struct gpio_chardev_data *priv = filep->private_data;
+ struct gpioline_info_changed event;
+ ssize_t bytes_read = 0;
+ int ret;
+
+ if (count < sizeof(event))
+ return -EINVAL;
+
+ do {
+ spin_lock(&priv->wait.lock);
+ if (kfifo_is_empty(&priv->events)) {
+ if (bytes_read) {
+ spin_unlock(&priv->wait.lock);
+ return bytes_read;
+ }
+
+ if (filep->f_flags & O_NONBLOCK) {
+ spin_unlock(&priv->wait.lock);
+ return -EAGAIN;
+ }
+
+ ret = wait_event_interruptible_locked(priv->wait,
+ !kfifo_is_empty(&priv->events));
+ if (ret) {
+ spin_unlock(&priv->wait.lock);
+ return ret;
+ }
+ }
+
+ ret = kfifo_out(&priv->events, &event, 1);
+ spin_unlock(&priv->wait.lock);
+ if (ret != 1) {
+ ret = -EIO;
+ break;
+ /* We should never get here. See lineevent_read(). */
+ }
+
+ if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
+ return -EFAULT;
+ bytes_read += sizeof(event);
+ } while (count >= bytes_read + sizeof(event));
+
+ return bytes_read;
+}
+
/**
* gpio_chrdev_open() - open the chardev for ioctl operations
* @inode: inode for this chardev
@@ -1272,14 +1395,48 @@ static int gpio_chrdev_open(struct inode *inode, struct file *filp)
{
struct gpio_device *gdev = container_of(inode->i_cdev,
struct gpio_device, chrdev);
+ struct gpio_chardev_data *priv;
+ int ret = -ENOMEM;
/* Fail on open if the backing gpiochip is gone */
if (!gdev->chip)
return -ENODEV;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->watched_lines = bitmap_zalloc(gdev->chip->ngpio, GFP_KERNEL);
+ if (!priv->watched_lines)
+ goto out_free_priv;
+
+ init_waitqueue_head(&priv->wait);
+ INIT_KFIFO(priv->events);
+ priv->gdev = gdev;
+
+ priv->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify;
+ ret = atomic_notifier_chain_register(&gdev->notifier,
+ &priv->lineinfo_changed_nb);
+ if (ret)
+ goto out_free_bitmap;
+
get_device(&gdev->dev);
- filp->private_data = gdev;
+ filp->private_data = priv;
- return nonseekable_open(inode, filp);
+ ret = nonseekable_open(inode, filp);
+ if (ret)
+ goto out_unregister_notifier;
+
+ return ret;
+
+out_unregister_notifier:
+ atomic_notifier_chain_unregister(&gdev->notifier,
+ &priv->lineinfo_changed_nb);
+out_free_bitmap:
+ bitmap_free(priv->watched_lines);
+out_free_priv:
+ kfree(priv);
+ return ret;
}
/**
@@ -1290,17 +1447,23 @@ static int gpio_chrdev_open(struct inode *inode, struct file *filp)
*/
static int gpio_chrdev_release(struct inode *inode, struct file *filp)
{
- struct gpio_device *gdev = container_of(inode->i_cdev,
- struct gpio_device, chrdev);
+ struct gpio_chardev_data *priv = filp->private_data;
+ struct gpio_device *gdev = priv->gdev;
+ bitmap_free(priv->watched_lines);
+ atomic_notifier_chain_unregister(&gdev->notifier,
+ &priv->lineinfo_changed_nb);
put_device(&gdev->dev);
+ kfree(priv);
+
return 0;
}
-
static const struct file_operations gpio_fileops = {
.release = gpio_chrdev_release,
.open = gpio_chrdev_open,
+ .poll = lineinfo_watch_poll,
+ .read = lineinfo_watch_read,
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = gpio_ioctl,
@@ -1511,6 +1674,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
for (i = 0; i < chip->ngpio; i++)
gdev->descs[i].gdev = gdev;
+ ATOMIC_INIT_NOTIFIER_HEAD(&gdev->notifier);
+
#ifdef CONFIG_PINCTRL
INIT_LIST_HEAD(&gdev->pin_ranges);
#endif
@@ -2866,6 +3031,8 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
}
done:
spin_unlock_irqrestore(&gpio_lock, flags);
+ atomic_notifier_call_chain(&desc->gdev->notifier,
+ GPIOLINE_CHANGED_REQUESTED, desc);
return ret;
}
@@ -2963,6 +3130,9 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
}
spin_unlock_irqrestore(&gpio_lock, flags);
+ atomic_notifier_call_chain(&desc->gdev->notifier,
+ GPIOLINE_CHANGED_RELEASED, desc);
+
return ret;
}
@@ -56,6 +56,7 @@ struct gpio_device {
const char *label;
void *data;
struct list_head list;
+ struct atomic_notifier_head notifier;
#ifdef CONFIG_PINCTRL
/*
@@ -59,6 +59,34 @@ struct gpioline_info {
/* Maximum number of requested handles */
#define GPIOHANDLES_MAX 64
+/* Possible line status change events */
+enum {
+ GPIOLINE_CHANGED_REQUESTED = 1,
+ GPIOLINE_CHANGED_RELEASED,
+ GPIOLINE_CHANGED_CONFIG,
+};
+
+/**
+ * struct gpioline_info_changed - Information about a change in status
+ * of a GPIO line
+ * @info: updated line information
+ * @timestamp: estimate of time of status change occurrence, in nanoseconds
+ * and GPIOLINE_CHANGED_CONFIG
+ * @event_type: one of GPIOLINE_CHANGED_REQUESTED, GPIOLINE_CHANGED_RELEASED
+ *
+ * Note: struct gpioline_info embedded here has 32-bit alignment on its own,
+ * but it works fine with 64-bit alignment too. With its 72 byte size, we can
+ * guarantee there are no implicit holes between it and subsequent members.
+ * The 20-byte padding at the end makes sure we don't add any implicit padding
+ * at the end of the structure on 64-bit architectures.
+ */
+struct gpioline_info_changed {
+ struct gpioline_info info;
+ __u64 timestamp;
+ __u32 event_type;
+ __u32 padding[5]; /* for future use */
+};
+
/* Linerequest flags */
#define GPIOHANDLE_REQUEST_INPUT (1UL << 0)
#define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1)
@@ -176,6 +204,8 @@ struct gpioevent_data {
#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info)
#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
+#define GPIO_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x0b, struct gpioline_info)
+#define GPIO_GET_LINEINFO_UNWATCH_IOCTL _IOWR(0xB4, 0x0c, __u32)
#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
#define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request)