Merge tag 'gpio-v5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
 "This is the bulk of GPIO development for the v5.7 kernel cycle.

  Core and userspace API:

   - The userspace API KFIFOs have been imoproved with locks that do not
     block interrupts. This makes us better at getting events to
     userspace without blocking or disturbing new events arriving in the
     same time. This was reviewed by the KFIFO maintainer Stefani. This
     is a generic improvement which paves the road for similar
     improvements in other subsystems.

   - We provide a new ioctl() for monitoring changes in the line
     information, such as when multiple clients are taking lines and
     giving them back, possibly reconfiguring them in the process: we
     can now monitor that and not get stuck with stale static
     information.

   - An example tool 'gpio-watch' is provided to showcase this
     functionality.

   - Timestamps for events are switched to ktime_get_ns() which is
     monotonic. We previously had a 'realtime' stamp which could move
     forward and *backward* in time, which probably would just cause
     silent bugs and weird behaviour. In the long run we see two
     relevant timestamps: ktime_get_ns() or the timestamp sometimes
     provided by the GPIO hardware itself, if that exists.

   - Device Tree overlay support for GPIO hogs. On systems that load
     overlays, these overlays can now contain hogs, and will then be
     respected.

   - Handle pin control interaction with nonexisting pin ranges in the
     GPIO library core instead of in the individual drivers.

  New drivers:

   - New driver for the Mellanox BlueField 2 GPIO controller.

  Driver improvements:

   - Introduce the BGPIOF_NO_SET_ON_INPUT flag to the generic MMIO GPIO
     library and use this flag in the MT7621 driver.

   - Texas Instruments OMAP CPU power management improvements, such as
     blocking of idle on pending GPIO interrupts"

* tag 'gpio-v5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (59 commits)
  Revert "gpio: eic-sprd: Use devm_platform_ioremap_resource()"
  pinctrl: Unconditionally assign .request()/.free()
  gpio: Unconditionally assign .request()/.free()
  gpio: export of_pinctrl_get to modules
  pinctrl: Define of_pinctrl_get() dummy for !PINCTRL
  gpio: Rename variable in core APIs
  gpio: Avoid using pin ranges with !PINCTRL
  gpiolib: Remove unused gpio_chip parameter from gpio_set_bias()
  gpiolib: Pass gpio_desc to gpio_set_config()
  gpiolib: Introduce gpiod_set_config()
  tools: gpio: Fix out-of-tree build regression
  gpio: gpiolib: fix a doc warning
  gpio: tegra186: Add Tegra194 pin ranges for GG.0 and GG.1
  gpio: tegra186: Add support for pin ranges
  gpio: Support GPIO controllers without pin-ranges
  ARM: integrator: impd1: Use GPIO_LOOKUP() helper macro
  gpio: brcmstb: support gpio-line-names property
  tools: gpio: Fix typo in gpio-utils
  tools: gpio-hammer: Apply scripts/Lindent and retain good changes
  gpiolib: gpio_name_to_desc: factor out !name check
  ...

1 files changed, 735 insertions, 564 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 86bde1e30a60..40f2d7f69be2 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -81,14 +81,14 @@ LIST_HEAD(gpio_devices);
 static DEFINE_MUTEX(gpio_machine_hogs_mutex);
 static LIST_HEAD(gpio_machine_hogs);
 
-static void gpiochip_free_hogs(struct gpio_chip *chip);
-static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
+static void gpiochip_free_hogs(struct gpio_chip *gc);
+static int gpiochip_add_irqchip(struct gpio_chip *gc,
 				struct lock_class_key *lock_key,
 				struct lock_class_key *request_key);
-static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
-static int gpiochip_irqchip_init_hw(struct gpio_chip *gpiochip);
-static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
-static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
+static void gpiochip_irqchip_remove(struct gpio_chip *gc);
+static int gpiochip_irqchip_init_hw(struct gpio_chip *gc);
+static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gc);
+static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gc);
 
 static bool gpiolib_initialized;
 
@@ -132,17 +132,17 @@ EXPORT_SYMBOL_GPL(gpio_to_desc);
 /**
  * gpiochip_get_desc - get the GPIO descriptor corresponding to the given
  *                     hardware number for this chip
- * @chip: GPIO chip
+ * @gc: GPIO chip
  * @hwnum: hardware number of the GPIO for this chip
  *
  * Returns:
- * A pointer to the GPIO descriptor or %ERR_PTR(-EINVAL) if no GPIO exists
+ * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists
  * in the given chip for the specified hardware number.
  */
-struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
+struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc,
 				    unsigned int hwnum)
 {
-	struct gpio_device *gdev = chip->gpiodev;
+	struct gpio_device *gdev = gc->gpiodev;
 
 	if (hwnum >= gdev->ngpio)
 		return ERR_PTR(-EINVAL);
@@ -214,11 +214,11 @@ static int gpiochip_find_base(int ngpio)
  */
 int gpiod_get_direction(struct gpio_desc *desc)
 {
-	struct gpio_chip *chip;
+	struct gpio_chip *gc;
 	unsigned offset;
 	int ret;
 
-	chip = gpiod_to_chip(desc);
+	gc = gpiod_to_chip(desc);
 	offset = gpio_chip_hwgpio(desc);
 
 	/*
@@ -229,10 +229,10 @@ int gpiod_get_direction(struct gpio_desc *desc)
 	    test_bit(FLAG_IS_OUT, &desc->flags))
 		return 0;
 
-	if (!chip->get_direction)
+	if (!gc->get_direction)
 		return -ENOTSUPP;
 
-	ret = chip->get_direction(chip, offset);
+	ret = gc->get_direction(gc, offset);
 	if (ret < 0)
 		return ret;
 
@@ -302,6 +302,9 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
 	struct gpio_device *gdev;
 	unsigned long flags;
 
+	if (!name)
+		return NULL;
+
 	spin_lock_irqsave(&gpio_lock, flags);
 
 	list_for_each_entry(gdev, &gpio_devices, list) {
@@ -310,7 +313,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
 		for (i = 0; i != gdev->ngpio; ++i) {
 			struct gpio_desc *desc = &gdev->descs[i];
 
-			if (!desc->name || !name)
+			if (!desc->name)
 				continue;
 
 			if (!strcmp(desc->name, name)) {
@@ -357,16 +360,16 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
 	return 0;
 }
 
-static unsigned long *gpiochip_allocate_mask(struct gpio_chip *chip)
+static unsigned long *gpiochip_allocate_mask(struct gpio_chip *gc)
 {
 	unsigned long *p;
 
-	p = bitmap_alloc(chip->ngpio, GFP_KERNEL);
+	p = bitmap_alloc(gc->ngpio, GFP_KERNEL);
 	if (!p)
 		return NULL;
 
 	/* Assume by default all GPIOs are valid */
-	bitmap_fill(p, chip->ngpio);
+	bitmap_fill(p, gc->ngpio);
 
 	return p;
 }
@@ -393,10 +396,10 @@ static int gpiochip_init_valid_mask(struct gpio_chip *gc)
 	return 0;
 }
 
-static void gpiochip_free_valid_mask(struct gpio_chip *gpiochip)
+static void gpiochip_free_valid_mask(struct gpio_chip *gc)
 {
-	bitmap_free(gpiochip->valid_mask);
-	gpiochip->valid_mask = NULL;
+	bitmap_free(gc->valid_mask);
+	gc->valid_mask = NULL;
 }
 
 static int gpiochip_add_pin_ranges(struct gpio_chip *gc)
@@ -407,13 +410,13 @@ static int gpiochip_add_pin_ranges(struct gpio_chip *gc)
 	return 0;
 }
 
-bool gpiochip_line_is_valid(const struct gpio_chip *gpiochip,
+bool gpiochip_line_is_valid(const struct gpio_chip *gc,
 				unsigned int offset)
 {
 	/* No mask means all valid */
-	if (likely(!gpiochip->valid_mask))
+	if (likely(!gc->valid_mask))
 		return true;
-	return test_bit(offset, gpiochip->valid_mask);
+	return test_bit(offset, gc->valid_mask);
 }
 EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
 
@@ -547,6 +550,9 @@ 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;
 }
@@ -788,8 +794,6 @@ out_free_lh:
  * @irq: the interrupt that trigger in response to events on this GPIO
  * @wait: wait queue that handles blocking reads of events
  * @events: KFIFO for the GPIO events
- * @read_lock: mutex lock to protect reads from colliding with adding
- * new events to the FIFO
  * @timestamp: cache for the timestamp storing it between hardirq
  * and IRQ thread, used to bring the timestamp close to the actual
  * event
@@ -802,7 +806,6 @@ struct lineevent_state {
 	int irq;
 	wait_queue_head_t wait;
 	DECLARE_KFIFO(events, struct gpioevent_data, 16);
-	struct mutex read_lock;
 	u64 timestamp;
 };
 
@@ -818,7 +821,7 @@ static __poll_t lineevent_poll(struct file *filep,
 
 	poll_wait(filep, &le->wait, wait);
 
-	if (!kfifo_is_empty(&le->events))
+	if (!kfifo_is_empty_spinlocked_noirqsave(&le->events, &le->wait.lock))
 		events = EPOLLIN | EPOLLRDNORM;
 
 	return events;
@@ -831,43 +834,52 @@ static ssize_t lineevent_read(struct file *filep,
 			      loff_t *f_ps)
 {
 	struct lineevent_state *le = filep->private_data;
-	unsigned int copied;
+	struct gpioevent_data ge;
+	ssize_t bytes_read = 0;
 	int ret;
 
-	if (count < sizeof(struct gpioevent_data))
+	if (count < sizeof(ge))
 		return -EINVAL;
 
 	do {
+		spin_lock(&le->wait.lock);
 		if (kfifo_is_empty(&le->events)) {
-			if (filep->f_flags & O_NONBLOCK)
+			if (bytes_read) {
+				spin_unlock(&le->wait.lock);
+				return bytes_read;
+			}
+
+			if (filep->f_flags & O_NONBLOCK) {
+				spin_unlock(&le->wait.lock);
 				return -EAGAIN;
+			}
 
-			ret = wait_event_interruptible(le->wait,
+			ret = wait_event_interruptible_locked(le->wait,
 					!kfifo_is_empty(&le->events));
-			if (ret)
+			if (ret) {
+				spin_unlock(&le->wait.lock);
 				return ret;
+			}
 		}
 
-		if (mutex_lock_interruptible(&le->read_lock))
-			return -ERESTARTSYS;
-		ret = kfifo_to_user(&le->events, buf, count, &copied);
-		mutex_unlock(&le->read_lock);
-
-		if (ret)
-			return ret;
-
-		/*
-		 * If we couldn't read anything from the fifo (a different
-		 * thread might have been faster) we either return -EAGAIN if
-		 * the file descriptor is non-blocking, otherwise we go back to
-		 * sleep and wait for more data to arrive.
-		 */
-		if (copied == 0 && (filep->f_flags & O_NONBLOCK))
-			return -EAGAIN;
+		ret = kfifo_out(&le->events, &ge, 1);
+		spin_unlock(&le->wait.lock);
+		if (ret != 1) {
+			/*
+			 * This should never happen - we were holding the lock
+			 * from the moment we learned the fifo is no longer
+			 * empty until now.
+			 */
+			ret = -EIO;
+			break;
+		}
 
-	} while (copied == 0);
+		if (copy_to_user(buf + bytes_read, &ge, sizeof(ge)))
+			return -EFAULT;
+		bytes_read += sizeof(ge);
+	} while (count >= bytes_read + sizeof(ge));
 
-	return copied;
+	return bytes_read;
 }
 
 static int lineevent_release(struct inode *inode, struct file *filep)
@@ -946,7 +958,7 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p)
 	 * we didn't get the timestamp from lineevent_irq_handler().
 	 */
 	if (!le->timestamp)
-		ge.timestamp = ktime_get_real_ns();
+		ge.timestamp = ktime_get_ns();
 	else
 		ge.timestamp = le->timestamp;
 
@@ -969,9 +981,12 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p)
 		return IRQ_NONE;
 	}
 
-	ret = kfifo_put(&le->events, ge);
+	ret = kfifo_in_spinlocked_noirqsave(&le->events, &ge,
+					    1, &le->wait.lock);
 	if (ret)
 		wake_up_poll(&le->wait, EPOLLIN);
+	else
+		pr_debug_ratelimited("event FIFO is full - event dropped\n");
 
 	return IRQ_HANDLED;
 }
@@ -984,7 +999,7 @@ static irqreturn_t lineevent_irq_handler(int irq, void *p)
 	 * Just store the timestamp in hardirq context so we get it as
 	 * close in time as possible to the actual event.
 	 */
-	le->timestamp = ktime_get_real_ns();
+	le->timestamp = ktime_get_ns();
 
 	return IRQ_WAKE_THREAD;
 }
@@ -1084,7 +1099,6 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 
 	INIT_KFIFO(le->events);
 	init_waitqueue_head(&le->wait);
-	mutex_init(&le->read_lock);
 
 	/* Request a thread to read the events */
 	ret = request_threaded_irq(le->irq,
@@ -1140,17 +1154,82 @@ out_free_le:
 	return ret;
 }
 
+static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
+				  struct gpioline_info *info)
+{
+	struct gpio_chip *gc = desc->gdev->chip;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (desc->name) {
+		strncpy(info->name, desc->name, sizeof(info->name));
+		info->name[sizeof(info->name) - 1] = '\0';
+	} else {
+		info->name[0] = '\0';
+	}
+
+	if (desc->label) {
+		strncpy(info->consumer, desc->label, sizeof(info->consumer));
+		info->consumer[sizeof(info->consumer) - 1] = '\0';
+	} else {
+		info->consumer[0] = '\0';
+	}
+
+	/*
+	 * Userspace only need to know that the kernel is using this GPIO so
+	 * it can't use it.
+	 */
+	info->flags = 0;
+	if (test_bit(FLAG_REQUESTED, &desc->flags) ||
+	    test_bit(FLAG_IS_HOGGED, &desc->flags) ||
+	    test_bit(FLAG_USED_AS_IRQ, &desc->flags) ||
+	    test_bit(FLAG_EXPORT, &desc->flags) ||
+	    test_bit(FLAG_SYSFS, &desc->flags) ||
+	    !pinctrl_gpio_can_use_line(gc->base + info->line_offset))
+		info->flags |= GPIOLINE_FLAG_KERNEL;
+	if (test_bit(FLAG_IS_OUT, &desc->flags))
+		info->flags |= GPIOLINE_FLAG_IS_OUT;
+	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
+		info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
+	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
+		info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
+				GPIOLINE_FLAG_IS_OUT);
+	if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
+		info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
+				GPIOLINE_FLAG_IS_OUT);
+	if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
+		info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
+	if (test_bit(FLAG_PULL_DOWN, &desc->flags))
+		info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
+	if (test_bit(FLAG_PULL_UP, &desc->flags))
+		info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
+
+	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_chip *chip = gdev->chip;
+	struct gpio_chardev_data *priv = filp->private_data;
+	struct gpio_device *gdev = priv->gdev;
+	struct gpio_chip *gc = 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)
+	if (!gc)
 		return -ENODEV;
 
 	/* Fill in the struct and pass to userspace */
@@ -1169,68 +1248,40 @@ 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;
 
-		desc = gpiochip_get_desc(chip, lineinfo.line_offset);
+		desc = gpiochip_get_desc(gc, lineinfo.line_offset);
 		if (IS_ERR(desc))
 			return PTR_ERR(desc);
 
-		if (desc->name) {
-			strncpy(lineinfo.name, desc->name,
-				sizeof(lineinfo.name));
-			lineinfo.name[sizeof(lineinfo.name)-1] = '\0';
-		} else {
-			lineinfo.name[0] = '\0';
-		}
-		if (desc->label) {
-			strncpy(lineinfo.consumer, desc->label,
-				sizeof(lineinfo.consumer));
-			lineinfo.consumer[sizeof(lineinfo.consumer)-1] = '\0';
-		} else {
-			lineinfo.consumer[0] = '\0';
-		}
-
-		/*
-		 * Userspace only need to know that the kernel is using
-		 * this GPIO so it can't use it.
-		 */
-		lineinfo.flags = 0;
-		if (test_bit(FLAG_REQUESTED, &desc->flags) ||
-		    test_bit(FLAG_IS_HOGGED, &desc->flags) ||
-		    test_bit(FLAG_USED_AS_IRQ, &desc->flags) ||
-		    test_bit(FLAG_EXPORT, &desc->flags) ||
-		    test_bit(FLAG_SYSFS, &desc->flags) ||
-		    !pinctrl_gpio_can_use_line(chip->base + lineinfo.line_offset))
-			lineinfo.flags |= GPIOLINE_FLAG_KERNEL;
-		if (test_bit(FLAG_IS_OUT, &desc->flags))
-			lineinfo.flags |= GPIOLINE_FLAG_IS_OUT;
-		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
-			lineinfo.flags |= GPIOLINE_FLAG_ACTIVE_LOW;
-		if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
-			lineinfo.flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
-					   GPIOLINE_FLAG_IS_OUT);
-		if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
-			lineinfo.flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
-					   GPIOLINE_FLAG_IS_OUT);
-		if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
-			lineinfo.flags |= GPIOLINE_FLAG_BIAS_DISABLE;
-		if (test_bit(FLAG_PULL_DOWN, &desc->flags))
-			lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
-		if (test_bit(FLAG_PULL_UP, &desc->flags))
-			lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
+		gpio_desc_to_lineinfo(desc, &lineinfo);
 
 		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
 			return -EFAULT;
+
+		if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL)
+			set_bit(gpio_chip_hwgpio(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(gc, offset);
+		if (IS_ERR(desc))
+			return PTR_ERR(desc);
+
+		clear_bit(gpio_chip_hwgpio(desc), priv->watched_lines);
+		return 0;
 	}
 	return -EINVAL;
 }
@@ -1243,6 +1294,101 @@ 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(gpio_chip_hwgpio(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
@@ -1253,14 +1399,48 @@ 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;
 }
 
 /**
@@ -1271,17 +1451,23 @@ 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,
@@ -1333,12 +1519,12 @@ err_remove_device:
 	return ret;
 }
 
-static void gpiochip_machine_hog(struct gpio_chip *chip, struct gpiod_hog *hog)
+static void gpiochip_machine_hog(struct gpio_chip *gc, struct gpiod_hog *hog)
 {
 	struct gpio_desc *desc;
 	int rv;
 
-	desc = gpiochip_get_desc(chip, hog->chip_hwnum);
+	desc = gpiochip_get_desc(gc, hog->chip_hwnum);
 	if (IS_ERR(desc)) {
 		pr_err("%s: unable to get GPIO desc: %ld\n",
 		       __func__, PTR_ERR(desc));
@@ -1351,18 +1537,18 @@ static void gpiochip_machine_hog(struct gpio_chip *chip, struct gpiod_hog *hog)
 	rv = gpiod_hog(desc, hog->line_name, hog->lflags, hog->dflags);
 	if (rv)
 		pr_err("%s: unable to hog GPIO line (%s:%u): %d\n",
-		       __func__, chip->label, hog->chip_hwnum, rv);
+		       __func__, gc->label, hog->chip_hwnum, rv);
 }
 
-static void machine_gpiochip_add(struct gpio_chip *chip)
+static void machine_gpiochip_add(struct gpio_chip *gc)
 {
 	struct gpiod_hog *hog;
 
 	mutex_lock(&gpio_machine_hogs_mutex);
 
 	list_for_each_entry(hog, &gpio_machine_hogs, list) {
-		if (!strcmp(chip->label, hog->chip_label))
-			gpiochip_machine_hog(chip, hog);
+		if (!strcmp(gc->label, hog->chip_label))
+			gpiochip_machine_hog(gc, hog);
 	}
 
 	mutex_unlock(&gpio_machine_hogs_mutex);
@@ -1381,14 +1567,14 @@ static void gpiochip_setup_devs(void)
 	}
 }
 
-int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
+int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 			       struct lock_class_key *lock_key,
 			       struct lock_class_key *request_key)
 {
 	unsigned long	flags;
 	int		ret = 0;
 	unsigned	i;
-	int		base = chip->base;
+	int		base = gc->base;
 	struct gpio_device *gdev;
 
 	/*
@@ -1399,19 +1585,19 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	if (!gdev)
 		return -ENOMEM;
 	gdev->dev.bus = &gpio_bus_type;
-	gdev->chip = chip;
-	chip->gpiodev = gdev;
-	if (chip->parent) {
-		gdev->dev.parent = chip->parent;
-		gdev->dev.of_node = chip->parent->of_node;
+	gdev->chip = gc;
+	gc->gpiodev = gdev;
+	if (gc->parent) {
+		gdev->dev.parent = gc->parent;
+		gdev->dev.of_node = gc->parent->of_node;
 	}
 
 #ifdef CONFIG_OF_GPIO
 	/* If the gpiochip has an assigned OF node this takes precedence */
-	if (chip->of_node)
-		gdev->dev.of_node = chip->of_node;
+	if (gc->of_node)
+		gdev->dev.of_node = gc->of_node;
 	else
-		chip->of_node = gdev->dev.of_node;
+		gc->of_node = gdev->dev.of_node;
 #endif
 
 	gdev->id = ida_simple_get(&gpio_ida, 0, 0, GFP_KERNEL);
@@ -1422,37 +1608,37 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	dev_set_name(&gdev->dev, GPIOCHIP_NAME "%d", gdev->id);
 	device_initialize(&gdev->dev);
 	dev_set_drvdata(&gdev->dev, gdev);
-	if (chip->parent && chip->parent->driver)
-		gdev->owner = chip->parent->driver->owner;
-	else if (chip->owner)
+	if (gc->parent && gc->parent->driver)
+		gdev->owner = gc->parent->driver->owner;
+	else if (gc->owner)
 		/* TODO: remove chip->owner */
-		gdev->owner = chip->owner;
+		gdev->owner = gc->owner;
 	else
 		gdev->owner = THIS_MODULE;
 
-	gdev->descs = kcalloc(chip->ngpio, sizeof(gdev->descs[0]), GFP_KERNEL);
+	gdev->descs = kcalloc(gc->ngpio, sizeof(gdev->descs[0]), GFP_KERNEL);
 	if (!gdev->descs) {
 		ret = -ENOMEM;
 		goto err_free_ida;
 	}
 
-	if (chip->ngpio == 0) {
-		chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
+	if (gc->ngpio == 0) {
+		chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
 		ret = -EINVAL;
 		goto err_free_descs;
 	}
 
-	if (chip->ngpio > FASTPATH_NGPIO)
-		chip_warn(chip, "line cnt %u is greater than fast path cnt %u\n",
-			  chip->ngpio, FASTPATH_NGPIO);
+	if (gc->ngpio > FASTPATH_NGPIO)
+		chip_warn(gc, "line cnt %u is greater than fast path cnt %u\n",
+			  gc->ngpio, FASTPATH_NGPIO);
 
-	gdev->label = kstrdup_const(chip->label ?: "unknown", GFP_KERNEL);
+	gdev->label = kstrdup_const(gc->label ?: "unknown", GFP_KERNEL);
 	if (!gdev->label) {
 		ret = -ENOMEM;
 		goto err_free_descs;
 	}
 
-	gdev->ngpio = chip->ngpio;
+	gdev->ngpio = gc->ngpio;
 	gdev->data = data;
 
 	spin_lock_irqsave(&gpio_lock, flags);
@@ -1465,7 +1651,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	 * of the sysfs interface anyways.
 	 */
 	if (base < 0) {
-		base = gpiochip_find_base(chip->ngpio);
+		base = gpiochip_find_base(gc->ngpio);
 		if (base < 0) {
 			ret = base;
 			spin_unlock_irqrestore(&gpio_lock, flags);
@@ -1477,7 +1663,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 		 * see if anyone makes use of this, else drop this and assign
 		 * a poison instead.
 		 */
-		chip->base = base;
+		gc->base = base;
 	}
 	gdev->base = base;
 
@@ -1487,60 +1673,62 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 		goto err_free_label;
 	}
 
-	for (i = 0; i < chip->ngpio; i++)
+	for (i = 0; i < gc->ngpio; i++)
 		gdev->descs[i].gdev = gdev;
 
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
+	ATOMIC_INIT_NOTIFIER_HEAD(&gdev->notifier);
+
 #ifdef CONFIG_PINCTRL
 	INIT_LIST_HEAD(&gdev->pin_ranges);
 #endif
 
-	ret = gpiochip_set_desc_names(chip);
+	ret = gpiochip_set_desc_names(gc);
 	if (ret)
 		goto err_remove_from_list;
 
-	ret = gpiochip_alloc_valid_mask(chip);
+	ret = gpiochip_alloc_valid_mask(gc);
 	if (ret)
 		goto err_remove_from_list;
 
-	ret = of_gpiochip_add(chip);
+	ret = of_gpiochip_add(gc);
 	if (ret)
 		goto err_free_gpiochip_mask;
 
-	ret = gpiochip_init_valid_mask(chip);
+	ret = gpiochip_init_valid_mask(gc);
 	if (ret)
 		goto err_remove_of_chip;
 
-	for (i = 0; i < chip->ngpio; i++) {
+	for (i = 0; i < gc->ngpio; i++) {
 		struct gpio_desc *desc = &gdev->descs[i];
 
-		if (chip->get_direction && gpiochip_line_is_valid(chip, i)) {
+		if (gc->get_direction && gpiochip_line_is_valid(gc, i)) {
 			assign_bit(FLAG_IS_OUT,
-				   &desc->flags, !chip->get_direction(chip, i));
+				   &desc->flags, !gc->get_direction(gc, i));
 		} else {
 			assign_bit(FLAG_IS_OUT,
-				   &desc->flags, !chip->direction_input);
+				   &desc->flags, !gc->direction_input);
 		}
 	}
 
-	ret = gpiochip_add_pin_ranges(chip);
+	ret = gpiochip_add_pin_ranges(gc);
 	if (ret)
 		goto err_remove_of_chip;
 
-	acpi_gpiochip_add(chip);
+	acpi_gpiochip_add(gc);
 
-	machine_gpiochip_add(chip);
+	machine_gpiochip_add(gc);
 
-	ret = gpiochip_irqchip_init_valid_mask(chip);
+	ret = gpiochip_irqchip_init_valid_mask(gc);
 	if (ret)
 		goto err_remove_acpi_chip;
 
-	ret = gpiochip_irqchip_init_hw(chip);
+	ret = gpiochip_irqchip_init_hw(gc);
 	if (ret)
 		goto err_remove_acpi_chip;
 
-	ret = gpiochip_add_irqchip(chip, lock_key, request_key);
+	ret = gpiochip_add_irqchip(gc, lock_key, request_key);
 	if (ret)
 		goto err_remove_irqchip_mask;
 
@@ -1560,17 +1748,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	return 0;
 
 err_remove_irqchip:
-	gpiochip_irqchip_remove(chip);
+	gpiochip_irqchip_remove(gc);
 err_remove_irqchip_mask:
-	gpiochip_irqchip_free_valid_mask(chip);
+	gpiochip_irqchip_free_valid_mask(gc);
 err_remove_acpi_chip:
-	acpi_gpiochip_remove(chip);
+	acpi_gpiochip_remove(gc);
 err_remove_of_chip:
-	gpiochip_free_hogs(chip);
-	of_gpiochip_remove(chip);
+	gpiochip_free_hogs(gc);
+	of_gpiochip_remove(gc);
 err_free_gpiochip_mask:
-	gpiochip_remove_pin_ranges(chip);
-	gpiochip_free_valid_mask(chip);
+	gpiochip_remove_pin_ranges(gc);
+	gpiochip_free_valid_mask(gc);
 err_remove_from_list:
 	spin_lock_irqsave(&gpio_lock, flags);
 	list_del(&gdev->list);
@@ -1585,7 +1773,7 @@ err_free_gdev:
 	/* failures here can mean systems won't boot... */
 	pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__,
 	       gdev->base, gdev->base + gdev->ngpio - 1,
-	       chip->label ? : "generic", ret);
+	       gc->label ? : "generic", ret);
 	kfree(gdev);
 	return ret;
 }
@@ -1593,41 +1781,39 @@ EXPORT_SYMBOL_GPL(gpiochip_add_data_with_key);
 
 /**
  * gpiochip_get_data() - get per-subdriver data for the chip
- * @chip: GPIO chip
+ * @gc: GPIO chip
  *
  * Returns:
  * The per-subdriver data for the chip.
  */
-void *gpiochip_get_data(struct gpio_chip *chip)
+void *gpiochip_get_data(struct gpio_chip *gc)
 {
-	return chip->gpiodev->data;
+	return gc->gpiodev->data;
 }
 EXPORT_SYMBOL_GPL(gpiochip_get_data);
 
 /**
  * gpiochip_remove() - unregister a gpio_chip
- * @chip: the chip to unregister
+ * @gc: the chip to unregister
  *
  * A gpio_chip with any GPIOs still requested may not be removed.
  */
-void gpiochip_remove(struct gpio_chip *chip)
+void gpiochip_remove(struct gpio_chip *gc)
 {
-	struct gpio_device *gdev = chip->gpiodev;
-	struct gpio_desc *desc;
+	struct gpio_device *gdev = gc->gpiodev;
 	unsigned long	flags;
-	unsigned	i;
-	bool		requested = false;
+	unsigned int	i;
 
 	/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
 	gpiochip_sysfs_unregister(gdev);
-	gpiochip_free_hogs(chip);
+	gpiochip_free_hogs(gc);
 	/* Numb the device, cancelling all outstanding operations */
 	gdev->chip = NULL;
-	gpiochip_irqchip_remove(chip);
-	acpi_gpiochip_remove(chip);
-	of_gpiochip_remove(chip);
-	gpiochip_remove_pin_ranges(chip);
-	gpiochip_free_valid_mask(chip);
+	gpiochip_irqchip_remove(gc);
+	acpi_gpiochip_remove(gc);
+	of_gpiochip_remove(gc);
+	gpiochip_remove_pin_ranges(gc);
+	gpiochip_free_valid_mask(gc);
 	/*
 	 * We accept no more calls into the driver from this point, so
 	 * NULL the driver data pointer
@@ -1636,13 +1822,12 @@ void gpiochip_remove(struct gpio_chip *chip)
 
 	spin_lock_irqsave(&gpio_lock, flags);
 	for (i = 0; i < gdev->ngpio; i++) {
-		desc = &gdev->descs[i];
-		if (test_bit(FLAG_REQUESTED, &desc->flags))
-			requested = true;
+		if (gpiochip_is_requested(gc, i))
+			break;
 	}
 	spin_unlock_irqrestore(&gpio_lock, flags);
 
-	if (requested)
+	if (i != gdev->ngpio)
 		dev_crit(&gdev->dev,
 			 "REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
 
@@ -1657,52 +1842,6 @@ void gpiochip_remove(struct gpio_chip *chip)
 }
 EXPORT_SYMBOL_GPL(gpiochip_remove);
 
-static void devm_gpio_chip_release(struct device *dev, void *res)
-{
-	struct gpio_chip *chip = *(struct gpio_chip **)res;
-
-	gpiochip_remove(chip);
-}
-
-/**
- * devm_gpiochip_add_data() - Resource managed gpiochip_add_data()
- * @dev: pointer to the device that gpio_chip belongs to.
- * @chip: the chip to register, with chip->base initialized
- * @data: driver-private data associated with this chip
- *
- * Context: potentially before irqs will work
- *
- * The gpio chip automatically be released when the device is unbound.
- *
- * Returns:
- * A negative errno if the chip can't be registered, such as because the
- * chip->base is invalid or already associated with a different chip.
- * Otherwise it returns zero as a success code.
- */
-int devm_gpiochip_add_data(struct device *dev, struct gpio_chip *chip,
-			   void *data)
-{
-	struct gpio_chip **ptr;
-	int ret;
-
-	ptr = devres_alloc(devm_gpio_chip_release, sizeof(*ptr),
-			     GFP_KERNEL);
-	if (!ptr)
-		return -ENOMEM;
-
-	ret = gpiochip_add_data(chip, data);
-	if (ret < 0) {
-		devres_free(ptr);
-		return ret;
-	}
-
-	*ptr = chip;
-	devres_add(dev, ptr);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(devm_gpiochip_add_data);
-
 /**
  * gpiochip_find() - iterator for locating a specific gpio_chip
  * @data: data to pass to match function
@@ -1715,31 +1854,31 @@ EXPORT_SYMBOL_GPL(devm_gpiochip_add_data);
  * more gpio_chips.
  */
 struct gpio_chip *gpiochip_find(void *data,
-				int (*match)(struct gpio_chip *chip,
+				int (*match)(struct gpio_chip *gc,
 					     void *data))
 {
 	struct gpio_device *gdev;
-	struct gpio_chip *chip = NULL;
+	struct gpio_ch