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. Also the notifications for the eventq are processed using a work item to allow sleep-able operations.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- drivers/gpio/Kconfig | 1 + drivers/gpio/gpio-virtio.c | 281 ++++++++++++++++++++++++++++++- include/uapi/linux/virtio_gpio.h | 25 +++ 3 files changed, 303 insertions(+), 4 deletions(-)
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index e5993d6864fb..222f4ae98a35 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -1672,6 +1672,7 @@ 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 3ed4240fe670..0be132d75396 100644 --- a/drivers/gpio/gpio-virtio.c +++ b/drivers/gpio/gpio-virtio.c @@ -17,6 +17,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/virtio_config.h> +#include <linux/workqueue.h> #include <uapi/linux/virtio_gpio.h> #include <uapi/linux/virtio_ids.h>
@@ -28,6 +29,16 @@ struct virtio_gpio_line { unsigned int rxlen; };
+struct vgpio_irq_line { + u8 type; + bool masked; + bool update_pending; + bool queued; + + struct virtio_gpio_irq_request ireq; + struct virtio_gpio_irq_response ires; +}; + struct virtio_gpio { struct virtio_device *vdev; struct mutex lock; /* Protects virtqueue operation */ @@ -35,6 +46,12 @@ struct virtio_gpio { struct virtio_gpio_config config; struct virtio_gpio_line *lines; struct virtqueue *request_vq; + + /* fields for irq support */ + struct virtqueue *event_vq; + struct mutex irq_lock; /* Protects irq operation */ + struct work_struct work; + struct vgpio_irq_line *irq_lines; };
static int _virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio, @@ -187,6 +204,220 @@ 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; + + 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_KERNEL); + if (ret) { + dev_err(&vgpio->vdev->dev, "failed to add request to eventq\n"); + return; + } + + WARN_ON(irq_line->queued); + + irq_line->queued = true; + virtqueue_kick(vgpio->event_vq); +} + +static void virtio_gpio_irq_eoi(struct irq_data *d) +{ + /* + * Queue buffers, by calling virtio_gpio_irq_prepare(), from + * virtio_gpio_event_vq() itself, after taking into consideration the + * masking status of the interrupt. + */ +} + +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]; + + irq_line->masked = true; + irq_line->update_pending = true; +} + +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]; + + irq_line->masked = false; + irq_line->update_pending = true; +} + +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 update_irq_type(struct virtio_gpio *vgpio, u16 gpio, u8 type) +{ + virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_IRQ_TYPE, gpio, type, NULL); +} + +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); + int gpio = d->hwirq; + struct vgpio_irq_line *irq_line = &vgpio->irq_lines[gpio]; + + if (unlikely(!irq_line->update_pending)) + goto out; + + if (irq_line->masked) { + update_irq_type(vgpio, gpio, VIRTIO_GPIO_IRQ_TYPE_NONE); + } else { + update_irq_type(vgpio, gpio, irq_line->type); + virtio_gpio_irq_prepare(vgpio, gpio); + } + + irq_line->update_pending = false; + +out: + mutex_unlock(&vgpio->irq_lock); +} + +static struct irq_chip vgpio_irq_chip = { + .name = "virtio-gpio", + .irq_eoi = virtio_gpio_irq_eoi, + .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 void vgpio_work_handler(struct work_struct *work) +{ + struct virtio_gpio *vgpio = container_of(work, struct virtio_gpio, + work); + struct device *dev = &vgpio->vdev->dev; + struct vgpio_irq_line *irq_line; + int irq, gpio, ret; + unsigned int len; + + mutex_lock(&vgpio->irq_lock); + + 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 : %lu)\n", + len, sizeof(irq_line->ires)); + continue; + } + + WARN_ON(!irq_line->queued); + irq_line->queued = false; + + /* Buffer is returned after interrupt is masked */ + if (irq_line->ires.status == VIRTIO_GPIO_IRQ_STATUS_INVALID) + continue; + + if (WARN_ON(irq_line->ires.status != VIRTIO_GPIO_IRQ_STATUS_VALID)) + 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 rely on a value returned by + * remote. + */ + gpio = irq_line - vgpio->irq_lines; + WARN_ON(gpio >= vgpio->config.ngpio); + + irq = irq_find_mapping(vgpio->gc.irq.domain, gpio); + WARN_ON(!irq); + + local_irq_disable(); + ret = generic_handle_irq(irq); + local_irq_enable(); + + if (ret) + dev_err(dev, "failed to handle interrupt: %d\n", ret); + + /* The interrupt may have been disabled by now */ + if (irq_line->update_pending && irq_line->masked) + update_irq_type(vgpio, gpio, VIRTIO_GPIO_IRQ_TYPE_NONE); + else + virtio_gpio_irq_prepare(vgpio, gpio); + + irq_line->update_pending = false; + }; + + mutex_unlock(&vgpio->irq_lock); +} + +static void virtio_gpio_event_vq(struct virtqueue *vq) +{ + struct virtio_gpio *vgpio = vq->vdev->priv; + + /* + * We can't initiate virtio-gpio operations from hard irq context, as + * they need sleep-able context. + */ + schedule_work(&vgpio->work); +} + static void virtio_gpio_request_vq(struct virtqueue *vq) { struct virtio_gpio_line *line; @@ -211,14 +442,15 @@ 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; @@ -226,11 +458,23 @@ 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) @@ -326,6 +570,29 @@ 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, config->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_fasteoi_irq; + vgpio->gc.irq.chip = &vgpio_irq_chip; + + for (i = 0; i < config->ngpio; i++) + vgpio->irq_lines[i].type = VIRTIO_GPIO_IRQ_TYPE_NONE; + + mutex_init(&vgpio->irq_lock); + INIT_WORK(&vgpio->work, vgpio_work_handler); + } + ret = virtio_gpio_alloc_vqs(vgpio, vdev); if (ret) return ret; @@ -358,7 +625,13 @@ 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 844574acf095..297ffdae1a5d 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 { __u16 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 { + __u16 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 */