On Thu, Oct 21, 2021 at 04:34:19PM +0530, Viresh Kumar wrote:
> This patch adds IRQ support for the virtio GPIO driver. Note that this
> uses the irq_bus_lock/unlock() callbacks, since those operations over
> virtio may sleep.
>
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
I think this can be merged - while ballot did not close yet
you already have a majority vote Yes. Worst case we'll revert
but I don't expect that.
> ---
> Bartosz,
>
> The spec changes are close to merging now, I will let you know once the ballot
> is closed and the spec changes are merged. You can then pick this patch for
> 5.16.
>
> V6->V7:
> - Use generic_handle_domain_irq.
> - Drop check for IRQ_TYPE_NONE, dead code.
> - Avoid breaking line to fit into 80 columns.
>
> V5->V6:
> - Sent it separately as the other patches are already merged.
> - Queue the buffers only after enabling the irq (as per latest spec).
> - Migrate to raw_spinlock_t.
>
> drivers/gpio/Kconfig | 1 +
> drivers/gpio/gpio-virtio.c | 302 ++++++++++++++++++++++++++++++-
> include/uapi/linux/virtio_gpio.h | 25 +++
> 3 files changed, 324 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index fae5141251e5..bfa723ff8e7c 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1674,6 +1674,7 @@ config GPIO_MOCKUP
> config GPIO_VIRTIO
> tristate "VirtIO GPIO support"
> depends on VIRTIO
> + select GPIOLIB_IRQCHIP
> help
> Say Y here to enable guest support for virtio-based GPIO controllers.
>
> diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c
> index d24f1c9264bc..aeec4bf0b625 100644
> --- a/drivers/gpio/gpio-virtio.c
> +++ b/drivers/gpio/gpio-virtio.c
> @@ -16,6 +16,7 @@
> #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>
> @@ -28,12 +29,30 @@ struct virtio_gpio_line {
> unsigned int rxlen;
> };
>
> +struct vgpio_irq_line {
> + u8 type;
> + bool disabled;
> + bool masked;
> + bool queued;
> + bool update_pending;
> + bool queue_pending;
> +
> + struct virtio_gpio_irq_request ireq ____cacheline_aligned;
> + struct virtio_gpio_irq_response ires ____cacheline_aligned;
> +};
> +
> 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,
> @@ -186,6 +205,238 @@ static void virtio_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
> 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 struct irq_chip vgpio_irq_chip = {
> + .name = "virtio-gpio",
> + .irq_enable = virtio_gpio_irq_enable,
> + .irq_disable = virtio_gpio_irq_disable,
> + .irq_mask = virtio_gpio_irq_mask,
> + .irq_unmask = virtio_gpio_irq_unmask,
> + .irq_set_type = virtio_gpio_irq_set_type,
> +
> + /* These are required to implement irqchip for slow busses */
> + .irq_bus_lock = virtio_gpio_irq_bus_lock,
> + .irq_bus_sync_unlock = virtio_gpio_irq_bus_sync_unlock,
> +};
> +
> +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;
> @@ -210,14 +461,15 @@ static void virtio_gpio_free_vqs(struct virtio_device *vdev)
> static int virtio_gpio_alloc_vqs(struct virtio_gpio *vgpio,
> struct virtio_device *vdev)
> {
> - const char * const names[] = { "requestq" };
> + const char * const names[] = { "requestq", "eventq" };
> vq_callback_t *cbs[] = {
> virtio_gpio_request_vq,
> + virtio_gpio_event_vq,
> };
> - struct virtqueue *vqs[1] = { NULL };
> + struct virtqueue *vqs[2] = { NULL, NULL };
> int ret;
>
> - ret = virtio_find_vqs(vdev, 1, vqs, cbs, names, NULL);
> + ret = virtio_find_vqs(vdev, vgpio->irq_lines ? 2 : 1, vqs, cbs, names, NULL);
> if (ret) {
> dev_err(&vdev->dev, "failed to find vqs: %d\n", ret);
> return ret;
> @@ -225,11 +477,23 @@ static int virtio_gpio_alloc_vqs(struct virtio_gpio *vgpio,
>
> if (!vqs[0]) {
> dev_err(&vdev->dev, "failed to find requestq vq\n");
> - return -ENODEV;
> + 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,
> @@ -325,6 +589,30 @@ static int virtio_gpio_probe(struct virtio_device *vdev)
> 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;
> +
> + /* 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 = &vgpio_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;
> @@ -357,7 +645,13 @@ static const struct virtio_device_id id_table[] = {
> };
> 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,
> diff --git a/include/uapi/linux/virtio_gpio.h b/include/uapi/linux/virtio_gpio.h
> index 0445f905d8cc..d04af9c5f0de 100644
> --- a/include/uapi/linux/virtio_gpio.h
> +++ b/include/uapi/linux/virtio_gpio.h
> @@ -5,12 +5,16 @@
>
> #include <linux/types.h>
>
> +/* Virtio GPIO Feature bits */
> +#define VIRTIO_GPIO_F_IRQ 0
> +
> /* Virtio GPIO request types */
> #define VIRTIO_GPIO_MSG_GET_NAMES 0x0001
> #define VIRTIO_GPIO_MSG_GET_DIRECTION 0x0002
> #define VIRTIO_GPIO_MSG_SET_DIRECTION 0x0003
> #define VIRTIO_GPIO_MSG_GET_VALUE 0x0004
> #define VIRTIO_GPIO_MSG_SET_VALUE 0x0005
> +#define VIRTIO_GPIO_MSG_IRQ_TYPE 0x0006
>
> /* Possible values of the status field */
> #define VIRTIO_GPIO_STATUS_OK 0x0
> @@ -21,6 +25,14 @@
> #define VIRTIO_GPIO_DIRECTION_OUT 0x01
> #define VIRTIO_GPIO_DIRECTION_IN 0x02
>
> +/* Virtio GPIO IRQ types */
> +#define VIRTIO_GPIO_IRQ_TYPE_NONE 0x00
> +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING 0x01
> +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING 0x02
> +#define VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH 0x03
> +#define VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH 0x04
> +#define VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW 0x08
> +
> struct virtio_gpio_config {
> __le16 ngpio;
> __u8 padding[2];
> @@ -44,4 +56,17 @@ struct virtio_gpio_response_get_names {
> __u8 value[];
> };
>
> +/* Virtio GPIO IRQ Request / Response */
> +struct virtio_gpio_irq_request {
> + __le16 gpio;
> +};
> +
> +struct virtio_gpio_irq_response {
> + __u8 status;
> +};
> +
> +/* Possible values of the interrupt status field */
> +#define VIRTIO_GPIO_IRQ_STATUS_INVALID 0x0
> +#define VIRTIO_GPIO_IRQ_STATUS_VALID 0x1
> +
> #endif /* _LINUX_VIRTIO_GPIO_H */
> --
> 2.31.1.272.g89b43f80a514
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