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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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