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    Subject[PATCH V6] gpio: virtio: Add IRQ support
    Date
    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@linaro.org>
    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    ---
    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.

    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 | 310 ++++++++++++++++++++++++++++++-
    include/uapi/linux/virtio_gpio.h | 25 +++
    3 files changed, 332 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..73fbe2eda4b9 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 +205,244 @@ 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_NONE:
    + type = VIRTIO_GPIO_IRQ_TYPE_NONE;
    + break;
    + 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 irq, 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;
    +
    + irq = irq_find_mapping(vgpio->gc.irq.domain, gpio);
    + WARN_ON(!irq);
    +
    + ret = generic_handle_irq(irq);
    + 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 +467,15 @@ 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 +483,23 @@ 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 +595,32 @@ 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 +653,13 @@ 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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      Last update: 2021-10-20 12:08    [W:3.572 / U:0.484 seconds]
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