Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 673 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c
new file mode 100644
index 000000000..ed6e0e90f
--- /dev/null
+++ b/drivers/gpio/gpio-virtio.c
@@ -0,0 +1,673 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * GPIO driver for virtio-based virtual GPIO controllers
+ *
+ * Copyright (C) 2021 metux IT consult
+ * Enrico Weigelt, metux IT consult <info@metux.net>
+ *
+ * Copyright (C) 2021 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ */
+
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/virtio_config.h>
+#include <uapi/linux/virtio_gpio.h>
+#include <uapi/linux/virtio_ids.h>
+
+struct virtio_gpio_line {
+	struct mutex lock; /* Protects line operation */
+	struct completion completion;
+
+	unsigned int rxlen;
+
+	__dma_from_device_group_begin();
+	struct virtio_gpio_request req;
+	struct virtio_gpio_response res;
+	__dma_from_device_group_end();
+};
+
+struct vgpio_irq_line {
+	u8 type;
+	bool disabled;
+	bool masked;
+	bool queued;
+	bool update_pending;
+	bool queue_pending;
+
+	__dma_from_device_group_begin();
+	struct virtio_gpio_irq_request ireq;
+	struct virtio_gpio_irq_response ires;
+	__dma_from_device_group_end();
+};
+
+struct virtio_gpio {
+	struct virtio_device *vdev;
+	struct mutex lock; /* Protects virtqueue operation */
+	struct gpio_chip gc;
+	struct virtio_gpio_line *lines;
+	struct virtqueue *request_vq;
+
+	/* irq support */
+	struct virtqueue *event_vq;
+	struct mutex irq_lock; /* Protects irq operation */
+	raw_spinlock_t eventq_lock; /* Protects queuing of the buffer */
+	struct vgpio_irq_line *irq_lines;
+};
+
+static int _virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
+			    u8 txvalue, u8 *rxvalue, void *response, u32 rxlen)
+{
+	struct virtio_gpio_line *line = &vgpio->lines[gpio];
+	struct virtio_gpio_request *req = &line->req;
+	struct virtio_gpio_response *res = response;
+	struct scatterlist *sgs[2], req_sg, res_sg;
+	struct device *dev = &vgpio->vdev->dev;
+	int ret;
+
+	/*
+	 * Prevent concurrent requests for the same line since we have
+	 * pre-allocated request/response buffers for each GPIO line. Moreover
+	 * Linux always accesses a GPIO line sequentially, so this locking shall
+	 * always go through without any delays.
+	 */
+	mutex_lock(&line->lock);
+
+	req->type = cpu_to_le16(type);
+	req->gpio = cpu_to_le16(gpio);
+	req->value = cpu_to_le32(txvalue);
+
+	sg_init_one(&req_sg, req, sizeof(*req));
+	sg_init_one(&res_sg, res, rxlen);
+	sgs[0] = &req_sg;
+	sgs[1] = &res_sg;
+
+	line->rxlen = 0;
+	reinit_completion(&line->completion);
+
+	/*
+	 * Virtqueue callers need to ensure they don't call its APIs with other
+	 * virtqueue operations at the same time.
+	 */
+	mutex_lock(&vgpio->lock);
+	ret = virtqueue_add_sgs(vgpio->request_vq, sgs, 1, 1, line, GFP_KERNEL);
+	if (ret) {
+		dev_err(dev, "failed to add request to vq\n");
+		mutex_unlock(&vgpio->lock);
+		goto out;
+	}
+
+	virtqueue_kick(vgpio->request_vq);
+	mutex_unlock(&vgpio->lock);
+
+	wait_for_completion(&line->completion);
+
+	if (unlikely(res->status != VIRTIO_GPIO_STATUS_OK)) {
+		dev_err(dev, "GPIO request failed: %d\n", gpio);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (unlikely(line->rxlen != rxlen)) {
+		dev_err(dev, "GPIO operation returned incorrect len (%u : %u)\n",
+			rxlen, line->rxlen);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (rxvalue)
+		*rxvalue = res->value;
+
+out:
+	mutex_unlock(&line->lock);
+	return ret;
+}
+
+static int virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
+			   u8 txvalue, u8 *rxvalue)
+{
+	struct virtio_gpio_line *line = &vgpio->lines[gpio];
+	struct virtio_gpio_response *res = &line->res;
+
+	return _virtio_gpio_req(vgpio, type, gpio, txvalue, rxvalue, res,
+				sizeof(*res));
+}
+
+static void virtio_gpio_free(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+
+	virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
+			VIRTIO_GPIO_DIRECTION_NONE, NULL);
+}
+
+static int virtio_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	u8 direction;
+	int ret;
+
+	ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_DIRECTION, gpio, 0,
+			      &direction);
+	if (ret)
+		return ret;
+
+	switch (direction) {
+	case VIRTIO_GPIO_DIRECTION_IN:
+		return GPIO_LINE_DIRECTION_IN;
+	case VIRTIO_GPIO_DIRECTION_OUT:
+		return GPIO_LINE_DIRECTION_OUT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int virtio_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+
+	return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
+			       VIRTIO_GPIO_DIRECTION_IN, NULL);
+}
+
+static int virtio_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
+					int value)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	int ret;
+
+	ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value, NULL);
+	if (ret)
+		return ret;
+
+	return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
+			       VIRTIO_GPIO_DIRECTION_OUT, NULL);
+}
+
+static int virtio_gpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	u8 value;
+	int ret;
+
+	ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_VALUE, gpio, 0, &value);
+	return ret ? ret : value;
+}
+
+static int virtio_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
+{
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+
+	return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value,
+			       NULL);
+}
+
+/* Interrupt handling */
+static void virtio_gpio_irq_prepare(struct virtio_gpio *vgpio, u16 gpio)
+{
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[gpio];
+	struct virtio_gpio_irq_request *ireq = &irq_line->ireq;
+	struct virtio_gpio_irq_response *ires = &irq_line->ires;
+	struct scatterlist *sgs[2], req_sg, res_sg;
+	int ret;
+
+	if (WARN_ON(irq_line->queued || irq_line->masked || irq_line->disabled))
+		return;
+
+	ireq->gpio = cpu_to_le16(gpio);
+	sg_init_one(&req_sg, ireq, sizeof(*ireq));
+	sg_init_one(&res_sg, ires, sizeof(*ires));
+	sgs[0] = &req_sg;
+	sgs[1] = &res_sg;
+
+	ret = virtqueue_add_sgs(vgpio->event_vq, sgs, 1, 1, irq_line, GFP_ATOMIC);
+	if (ret) {
+		dev_err(&vgpio->vdev->dev, "failed to add request to eventq\n");
+		return;
+	}
+
+	irq_line->queued = true;
+	virtqueue_kick(vgpio->event_vq);
+}
+
+static void virtio_gpio_irq_enable(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+
+	raw_spin_lock(&vgpio->eventq_lock);
+	irq_line->disabled = false;
+	irq_line->masked = false;
+	irq_line->queue_pending = true;
+	raw_spin_unlock(&vgpio->eventq_lock);
+
+	irq_line->update_pending = true;
+}
+
+static void virtio_gpio_irq_disable(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+
+	raw_spin_lock(&vgpio->eventq_lock);
+	irq_line->disabled = true;
+	irq_line->masked = true;
+	irq_line->queue_pending = false;
+	raw_spin_unlock(&vgpio->eventq_lock);
+
+	irq_line->update_pending = true;
+}
+
+static void virtio_gpio_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+
+	raw_spin_lock(&vgpio->eventq_lock);
+	irq_line->masked = true;
+	raw_spin_unlock(&vgpio->eventq_lock);
+}
+
+static void virtio_gpio_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+
+	raw_spin_lock(&vgpio->eventq_lock);
+	irq_line->masked = false;
+
+	/* Queue the buffer unconditionally on unmask */
+	virtio_gpio_irq_prepare(vgpio, d->hwirq);
+	raw_spin_unlock(&vgpio->eventq_lock);
+}
+
+static int virtio_gpio_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		type = VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		type = VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		type = VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH;
+		break;
+	default:
+		dev_err(&vgpio->vdev->dev, "unsupported irq type: %u\n", type);
+		return -EINVAL;
+	}
+
+	irq_line->type = type;
+	irq_line->update_pending = true;
+
+	return 0;
+}
+
+static void virtio_gpio_irq_bus_lock(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+
+	mutex_lock(&vgpio->irq_lock);
+}
+
+static void virtio_gpio_irq_bus_sync_unlock(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct virtio_gpio *vgpio = gpiochip_get_data(gc);
+	struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
+	u8 type = irq_line->disabled ? VIRTIO_GPIO_IRQ_TYPE_NONE : irq_line->type;
+	unsigned long flags;
+
+	if (irq_line->update_pending) {
+		irq_line->update_pending = false;
+		virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_IRQ_TYPE, d->hwirq, type,
+				NULL);
+
+		/* Queue the buffer only after interrupt is enabled */
+		raw_spin_lock_irqsave(&vgpio->eventq_lock, flags);
+		if (irq_line->queue_pending) {
+			irq_line->queue_pending = false;
+			virtio_gpio_irq_prepare(vgpio, d->hwirq);
+		}
+		raw_spin_unlock_irqrestore(&vgpio->eventq_lock, flags);
+	}
+
+	mutex_unlock(&vgpio->irq_lock);
+}
+
+static bool ignore_irq(struct virtio_gpio *vgpio, int gpio,
+		       struct vgpio_irq_line *irq_line)
+{
+	bool ignore = false;
+
+	raw_spin_lock(&vgpio->eventq_lock);
+	irq_line->queued = false;
+
+	/* Interrupt is disabled currently */
+	if (irq_line->masked || irq_line->disabled) {
+		ignore = true;
+		goto unlock;
+	}
+
+	/*
+	 * Buffer is returned as the interrupt was disabled earlier, but is
+	 * enabled again now. Requeue the buffers.
+	 */
+	if (irq_line->ires.status == VIRTIO_GPIO_IRQ_STATUS_INVALID) {
+		virtio_gpio_irq_prepare(vgpio, gpio);
+		ignore = true;
+		goto unlock;
+	}
+
+	if (WARN_ON(irq_line->ires.status != VIRTIO_GPIO_IRQ_STATUS_VALID))
+		ignore = true;
+
+unlock:
+	raw_spin_unlock(&vgpio->eventq_lock);
+
+	return ignore;
+}
+
+static void virtio_gpio_event_vq(struct virtqueue *vq)
+{
+	struct virtio_gpio *vgpio = vq->vdev->priv;
+	struct device *dev = &vgpio->vdev->dev;
+	struct vgpio_irq_line *irq_line;
+	int gpio, ret;
+	unsigned int len;
+
+	while (true) {
+		irq_line = virtqueue_get_buf(vgpio->event_vq, &len);
+		if (!irq_line)
+			break;
+
+		if (len != sizeof(irq_line->ires)) {
+			dev_err(dev, "irq with incorrect length (%u : %u)\n",
+				len, (unsigned int)sizeof(irq_line->ires));
+			continue;
+		}
+
+		/*
+		 * Find GPIO line number from the offset of irq_line within the
+		 * irq_lines block. We can also get GPIO number from
+		 * irq-request, but better not to rely on a buffer returned by
+		 * remote.
+		 */
+		gpio = irq_line - vgpio->irq_lines;
+		WARN_ON(gpio >= vgpio->gc.ngpio);
+
+		if (unlikely(ignore_irq(vgpio, gpio, irq_line)))
+			continue;
+
+		ret = generic_handle_domain_irq(vgpio->gc.irq.domain, gpio);
+		if (ret)
+			dev_err(dev, "failed to handle interrupt: %d\n", ret);
+	}
+}
+
+static void virtio_gpio_request_vq(struct virtqueue *vq)
+{
+	struct virtio_gpio_line *line;
+	unsigned int len;
+
+	do {
+		line = virtqueue_get_buf(vq, &len);
+		if (!line)
+			return;
+
+		line->rxlen = len;
+		complete(&line->completion);
+	} while (1);
+}
+
+static void virtio_gpio_free_vqs(struct virtio_device *vdev)
+{
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+}
+
+static int virtio_gpio_alloc_vqs(struct virtio_gpio *vgpio,
+				 struct virtio_device *vdev)
+{
+	struct virtqueue_info vqs_info[] = {
+		{ "requestq", virtio_gpio_request_vq },
+		{ "eventq", virtio_gpio_event_vq },
+	};
+	struct virtqueue *vqs[2] = { NULL, NULL };
+	int ret;
+
+	ret = virtio_find_vqs(vdev, vgpio->irq_lines ? 2 : 1, vqs,
+			      vqs_info, NULL);
+	if (ret) {
+		dev_err(&vdev->dev, "failed to find vqs: %d\n", ret);
+		return ret;
+	}
+
+	if (!vqs[0]) {
+		dev_err(&vdev->dev, "failed to find requestq vq\n");
+		goto out;
+	}
+	vgpio->request_vq = vqs[0];
+
+	if (vgpio->irq_lines && !vqs[1]) {
+		dev_err(&vdev->dev, "failed to find eventq vq\n");
+		goto out;
+	}
+	vgpio->event_vq = vqs[1];
+
+	return 0;
+
+out:
+	if (vqs[0] || vqs[1])
+		virtio_gpio_free_vqs(vdev);
+
+	return -ENODEV;
+}
+
+static const char **virtio_gpio_get_names(struct virtio_gpio *vgpio,
+					  u32 gpio_names_size, u16 ngpio)
+{
+	struct virtio_gpio_response_get_names *res;
+	struct device *dev = &vgpio->vdev->dev;
+	u8 *gpio_names, *str;
+	const char **names;
+	int i, ret, len;
+
+	if (!gpio_names_size)
+		return NULL;
+
+	len = sizeof(*res) + gpio_names_size;
+	res = devm_kzalloc(dev, len, GFP_KERNEL);
+	if (!res)
+		return NULL;
+	gpio_names = res->value;
+
+	ret = _virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_NAMES, 0, 0, NULL,
+			       res, len);
+	if (ret) {
+		dev_err(dev, "Failed to get GPIO names: %d\n", ret);
+		return NULL;
+	}
+
+	names = devm_kcalloc(dev, ngpio, sizeof(*names), GFP_KERNEL);
+	if (!names)
+		return NULL;
+
+	/* NULL terminate the string instead of checking it */
+	gpio_names[gpio_names_size - 1] = '\0';
+
+	for (i = 0, str = gpio_names; i < ngpio; i++) {
+		names[i] = str;
+		str += strlen(str) + 1; /* zero-length strings are allowed */
+
+		if (str > gpio_names + gpio_names_size) {
+			dev_err(dev, "gpio_names block is too short (%d)\n", i);
+			return NULL;
+		}
+	}
+
+	return names;
+}
+
+static int virtio_gpio_probe(struct virtio_device *vdev)
+{
+	struct device *dev = &vdev->dev;
+	struct virtio_gpio *vgpio;
+	struct irq_chip *gpio_irq_chip;
+	u32 gpio_names_size;
+	u16 ngpio;
+	int ret, i;
+
+	vgpio = devm_kzalloc(dev, sizeof(*vgpio), GFP_KERNEL);
+	if (!vgpio)
+		return -ENOMEM;
+
+	/* Read configuration */
+	gpio_names_size =
+		virtio_cread32(vdev, offsetof(struct virtio_gpio_config,
+					      gpio_names_size));
+	ngpio =  virtio_cread16(vdev, offsetof(struct virtio_gpio_config,
+					       ngpio));
+	if (!ngpio) {
+		dev_err(dev, "Number of GPIOs can't be zero\n");
+		return -EINVAL;
+	}
+
+	vgpio->lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->lines), GFP_KERNEL);
+	if (!vgpio->lines)
+		return -ENOMEM;
+
+	for (i = 0; i < ngpio; i++) {
+		mutex_init(&vgpio->lines[i].lock);
+		init_completion(&vgpio->lines[i].completion);
+	}
+
+	mutex_init(&vgpio->lock);
+	vdev->priv = vgpio;
+
+	vgpio->vdev			= vdev;
+	vgpio->gc.free			= virtio_gpio_free;
+	vgpio->gc.get_direction		= virtio_gpio_get_direction;
+	vgpio->gc.direction_input	= virtio_gpio_direction_input;
+	vgpio->gc.direction_output	= virtio_gpio_direction_output;
+	vgpio->gc.get			= virtio_gpio_get;
+	vgpio->gc.set			= virtio_gpio_set;
+	vgpio->gc.ngpio			= ngpio;
+	vgpio->gc.base			= -1; /* Allocate base dynamically */
+	vgpio->gc.label			= dev_name(dev);
+	vgpio->gc.parent		= dev;
+	vgpio->gc.owner			= THIS_MODULE;
+	vgpio->gc.can_sleep		= true;
+
+	/* Interrupt support */
+	if (virtio_has_feature(vdev, VIRTIO_GPIO_F_IRQ)) {
+		vgpio->irq_lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->irq_lines), GFP_KERNEL);
+		if (!vgpio->irq_lines)
+			return -ENOMEM;
+
+		gpio_irq_chip = devm_kzalloc(dev, sizeof(*gpio_irq_chip), GFP_KERNEL);
+		if (!gpio_irq_chip)
+			return -ENOMEM;
+
+		gpio_irq_chip->name = dev_name(dev);
+		gpio_irq_chip->irq_enable = virtio_gpio_irq_enable;
+		gpio_irq_chip->irq_disable = virtio_gpio_irq_disable;
+		gpio_irq_chip->irq_mask = virtio_gpio_irq_mask;
+		gpio_irq_chip->irq_unmask = virtio_gpio_irq_unmask;
+		gpio_irq_chip->irq_set_type = virtio_gpio_irq_set_type;
+		gpio_irq_chip->irq_bus_lock = virtio_gpio_irq_bus_lock;
+		gpio_irq_chip->irq_bus_sync_unlock = virtio_gpio_irq_bus_sync_unlock;
+
+		/* The event comes from the outside so no parent handler */
+		vgpio->gc.irq.parent_handler	= NULL;
+		vgpio->gc.irq.num_parents	= 0;
+		vgpio->gc.irq.parents		= NULL;
+		vgpio->gc.irq.default_type	= IRQ_TYPE_NONE;
+		vgpio->gc.irq.handler		= handle_level_irq;
+		vgpio->gc.irq.chip		= gpio_irq_chip;
+
+		for (i = 0; i < ngpio; i++) {
+			vgpio->irq_lines[i].type = VIRTIO_GPIO_IRQ_TYPE_NONE;
+			vgpio->irq_lines[i].disabled = true;
+			vgpio->irq_lines[i].masked = true;
+		}
+
+		mutex_init(&vgpio->irq_lock);
+		raw_spin_lock_init(&vgpio->eventq_lock);
+	}
+
+	ret = virtio_gpio_alloc_vqs(vgpio, vdev);
+	if (ret)
+		return ret;
+
+	/* Mark the device ready to perform operations from within probe() */
+	virtio_device_ready(vdev);
+
+	vgpio->gc.names = virtio_gpio_get_names(vgpio, gpio_names_size, ngpio);
+
+	ret = gpiochip_add_data(&vgpio->gc, vgpio);
+	if (ret) {
+		virtio_gpio_free_vqs(vdev);
+		dev_err(dev, "Failed to add virtio-gpio controller\n");
+	}
+
+	return ret;
+}
+
+static void virtio_gpio_remove(struct virtio_device *vdev)
+{
+	struct virtio_gpio *vgpio = vdev->priv;
+
+	gpiochip_remove(&vgpio->gc);
+	virtio_gpio_free_vqs(vdev);
+}
+
+static const struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_GPIO, VIRTIO_DEV_ANY_ID },
+	{},
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+static const unsigned int features[] = {
+	VIRTIO_GPIO_F_IRQ,
+};
+
+static struct virtio_driver virtio_gpio_driver = {
+	.feature_table		= features,
+	.feature_table_size	= ARRAY_SIZE(features),
+	.id_table		= id_table,
+	.probe			= virtio_gpio_probe,
+	.remove			= virtio_gpio_remove,
+	.driver			= {
+		.name		= KBUILD_MODNAME,
+	},
+};
+module_virtio_driver(virtio_gpio_driver);
+
+MODULE_AUTHOR("Enrico Weigelt, metux IT consult <info@metux.net>");
+MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
+MODULE_DESCRIPTION("VirtIO GPIO driver");
+MODULE_LICENSE("GPL");