Re: [PATCH v5 3/7] fpga: dfl: introduce interrupt trigger setting API

Xu Yilun
2020-05-13T10:00:53Z

On Mon, May 11, 2020 at 09:16:34PM -0700, Moritz Fischer wrote:
> On Mon, Apr 20, 2020 at 04:11:39PM +0800, Xu Yilun wrote:
> > FPGA user applications may be interested in interrupts generated by
> > DFL features. For example, users can implement their own FPGA
> > logics with interrupts enabled in AFU (Accelerated Function Unit,
> > dynamic region of DFL based FPGA). So user applications need to be
> > notified to handle these interrupts.
> >
> > In order to allow userspace applications to monitor interrupts,
> > driver requires userspace to provide eventfds as interrupt
> > notification channels. Applications then poll/select on the eventfds
> > to get notified.
> >
> > This patch introduces a generic helper functions to do eventfds binding
> > with given interrupts.
> >
> > Sub feature drivers are expected to use XXX_GET_IRQ_NUM to query irq
> > info, and XXX_SET_IRQ to set eventfds for interrupts. This patch also
> > introduces helper functions for these 2 ioctls.
> >
> > Signed-off-by: Luwei Kang <luwei.kang@intel.com>
> > Signed-off-by: Wu Hao <hao.wu@intel.com>
> > Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> > Acked-by: Wu Hao <hao.wu@intel.com>
> > ----
> > v2: use unsigned int instead of int for irq array indexes in
> > dfl_fpga_set_irq_triggers()
> > Improves comments for NULL fds param in dfl_fpga_set_irq_triggers()
> > v3: Improve comments of dfl_fpga_set_irq_triggers()
> > refines code for dfl_fpga_set_irq_triggers, delete local variable j
> > v4: Introduce 2 helper functions to help handle the XXX_GET_IRQ_NUM &
> > XXX_SET_IRQ ioctls for sub feature drivers.
> > v5: Some minor fix for Hao's comments
> > ---
> > drivers/fpga/dfl.c | 156 ++++++++++++++++++++++++++++++++++++++++++
> > drivers/fpga/dfl.h | 17 +++++
> > include/uapi/linux/fpga-dfl.h | 13 ++++
> > 3 files changed, 186 insertions(+)
> >
> > diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> > index b49fbed..208d8f0 100644
> > --- a/drivers/fpga/dfl.c
> > +++ b/drivers/fpga/dfl.c
> > @@ -10,7 +10,9 @@
> > * Wu Hao <hao.wu@intel.com>
> > * Xiao Guangrong <guangrong.xiao@linux.intel.com>
> > */
> > +#include <linux/fpga-dfl.h>
> > #include <linux/module.h>
> > +#include <linux/uaccess.h>
> >
> > #include "dfl.h"
> >
> > @@ -534,6 +536,7 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
> > unsigned int i;
> >
> > /* save resource information for each feature */
> > + feature->dev = fdev;
> > feature->id = finfo->fid;
> > feature->resource_index = index;
> > feature->ioaddr = finfo->ioaddr;
> > @@ -1395,6 +1398,159 @@ int dfl_fpga_cdev_config_ports_vf(struct dfl_fpga_cdev *cdev, int num_vfs)
> > }
> > EXPORT_SYMBOL_GPL(dfl_fpga_cdev_config_ports_vf);
> >
> > +static irqreturn_t dfl_irq_handler(int irq, void *arg)
> > +{
> > + struct eventfd_ctx *trigger = arg;
> > +
> > + eventfd_signal(trigger, 1);
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int do_set_irq_trigger(struct dfl_feature *feature, unsigned int idx,
> > + int fd)
> > +{
> > + struct platform_device *pdev = feature->dev;
> > + struct eventfd_ctx *trigger;
> > + int irq, ret;
> > +
> > + if (idx >= feature->nr_irqs)
> > + return -EINVAL;
> > +
> > + irq = feature->irq_ctx[idx].irq;
> > +
> > + if (feature->irq_ctx[idx].trigger) {
> > + free_irq(irq, feature->irq_ctx[idx].trigger);
> > + kfree(feature->irq_ctx[idx].name);
> > + eventfd_ctx_put(feature->irq_ctx[idx].trigger);
> > + feature->irq_ctx[idx].trigger = NULL;
> > + }
> > +
> > + if (fd < 0)
> > + return 0;
> > +
> > + feature->irq_ctx[idx].name =
> > + kasprintf(GFP_KERNEL, "fpga-irq[%u](%s-%llx)", idx,
> > + dev_name(&pdev->dev),
> > + (unsigned long long)feature->id);
> > + if (!feature->irq_ctx[idx].name)
> > + return -ENOMEM;
> > +
> > + trigger = eventfd_ctx_fdget(fd);
> > + if (IS_ERR(trigger)) {
> > + ret = PTR_ERR(trigger);
> > + goto free_name;
> > + }
> > +
> > + ret = request_irq(irq, dfl_irq_handler, 0,
> > + feature->irq_ctx[idx].name, trigger);
> > + if (!ret) {
> > + feature->irq_ctx[idx].trigger = trigger;
> > + return ret;
> > + }
> > +
> > + eventfd_ctx_put(trigger);
> > +free_name:
> > + kfree(feature->irq_ctx[idx].name);
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * dfl_fpga_set_irq_triggers - set eventfd triggers for dfl feature interrupts
> > + *
> > + * @feature: dfl sub feature.
> > + * @start: start of irq index in this dfl sub feature.
> > + * @count: number of irqs.
> > + * @fds: eventfds to bind with irqs. unbind related irq if fds[n] is negative.
> > + * unbind "count" specified number of irqs if fds ptr is NULL.
> > + *
> > + * Bind given eventfds with irqs in this dfl sub feature. Unbind related irq if
> > + * fds[n] is negative. Unbind "count" specified number of irqs if fds ptr is
> > + * NULL.
> > + *
> > + * Return: 0 on success, negative error code otherwise.
> > + */
> > +int dfl_fpga_set_irq_triggers(struct dfl_feature *feature, unsigned int start,
> > + unsigned int count, int32_t *fds)
> > +{
> > + unsigned int i;
> > + int ret = 0;
> > +
> > + if (start + count < start || start + count > feature->nr_irqs)
> > + return -EINVAL;
> Up to you, but have you considered to break up the condition above into
> two if () ?

I think maybe we could keep this. The 2 conditions are all for start &
count check, that's why I prefer to put them in one code block.

Thanks,
Yilun.

> > +
> > + for (i = 0; i < count; i++) {
> > + int fd = fds ? fds[i] : -1;
> > +
> > + ret = do_set_irq_trigger(feature, start + i, fd);
> > + if (ret) {
> > + while (i--)
> > + do_set_irq_trigger(feature, start + i, -1);
> > + break;
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_fpga_set_irq_triggers);
> > +
> > +/**
> > + * dfl_feature_ioctl_get_num_irqs - dfl feature _GET_IRQ_NUM ioctl interface.
> > + * @pdev: the feature device which has the sub feature
> > + * @feature: the dfl sub feature
> > + * @arg: ioctl argument
> > + *
> > + * Return: 0 on success, negative error code otherwise.
> > + */
> > +long dfl_feature_ioctl_get_num_irqs(struct platform_device *pdev,
> > + struct dfl_feature *feature,
> > + unsigned long arg)
> > +{
> > + return put_user(feature->nr_irqs, (__u32 __user *)arg);
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_feature_ioctl_get_num_irqs);
> > +
> > +/**
> > + * dfl_feature_ioctl_set_irq - dfl feature _SET_IRQ ioctl interface.
> > + * @pdev: the feature device which has the sub feature
> > + * @feature: the dfl sub feature
> > + * @arg: ioctl argument
> > + *
> > + * Return: 0 on success, negative error code otherwise.
> > + */
> > +long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
> > + struct dfl_feature *feature,
> > + unsigned long arg)
> > +{
> > + struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
> > + struct dfl_fpga_irq_set hdr;
> > + s32 *fds;
> > + long ret;
> > +
> > + if (!feature->nr_irqs)
> > + return -ENOENT;
> > +
> > + if (copy_from_user(&hdr, (void __user *)arg, sizeof(hdr)))
> > + return -EFAULT;
> > +
> > + if (!hdr.count || (hdr.start + hdr.count > feature->nr_irqs) ||
> > + (hdr.start + hdr.count < hdr.start))
> > + return -EINVAL;
> > +
> > + fds = memdup_user((void __user *)(arg + sizeof(hdr)),
> > + hdr.count * sizeof(s32));
> > + if (IS_ERR(fds))
> > + return PTR_ERR(fds);
> > +
> > + mutex_lock(&pdata->lock);
> > + ret = dfl_fpga_set_irq_triggers(feature, hdr.start, hdr.count, fds);
> > + mutex_unlock(&pdata->lock);
> > +
> > + kfree(fds);
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dfl_feature_ioctl_set_irq);
> > +
> > static void __exit dfl_fpga_exit(void)
> > {
> > dfl_chardev_uinit();
> > diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> > index 4bc165f..f7a8c59 100644
> > --- a/drivers/fpga/dfl.h
> > +++ b/drivers/fpga/dfl.h
> > @@ -17,7 +17,9 @@
> > #include <linux/bitfield.h>
> > #include <linux/cdev.h>
> > #include <linux/delay.h>
> > +#include <linux/eventfd.h>
> > #include <linux/fs.h>
> > +#include <linux/interrupt.h>
> > #include <linux/iopoll.h>
> > #include <linux/io-64-nonatomic-lo-hi.h>
> > #include <linux/platform_device.h>
> > @@ -213,14 +215,19 @@ struct dfl_feature_driver {
> > * struct dfl_feature_irq_ctx - dfl private feature interrupt context
> > *
> > * @irq: Linux IRQ number of this interrupt.
> > + * @trigger: eventfd context to signal when interrupt happens.
> > + * @name: irq name needed when requesting irq.
> > */
> > struct dfl_feature_irq_ctx {
> > int irq;
> > + struct eventfd_ctx *trigger;
> > + char *name;
> > };
> >
> > /**
> > * struct dfl_feature - sub feature of the feature devices
> > *
> > + * @dev: ptr to pdev of the feature device which has the sub feature.
> > * @id: sub feature id.
> > * @resource_index: each sub feature has one mmio resource for its registers.
> > * this index is used to find its mmio resource from the
> > @@ -231,6 +238,7 @@ struct dfl_feature_irq_ctx {
> > * @ops: ops of this sub feature.
> > */
> > struct dfl_feature {
> > + struct platform_device *dev;
> > u64 id;
> > int resource_index;
> > void __iomem *ioaddr;
> > @@ -506,4 +514,13 @@ int dfl_fpga_cdev_release_port(struct dfl_fpga_cdev *cdev, int port_id);
> > int dfl_fpga_cdev_assign_port(struct dfl_fpga_cdev *cdev, int port_id);
> > void dfl_fpga_cdev_config_ports_pf(struct dfl_fpga_cdev *cdev);
> > int dfl_fpga_cdev_config_ports_vf(struct dfl_fpga_cdev *cdev, int num_vf);
> > +int dfl_fpga_set_irq_triggers(struct dfl_feature *feature, unsigned int start,
> > + unsigned int count, int32_t *fds);
> > +long dfl_feature_ioctl_get_num_irqs(struct platform_device *pdev,
> > + struct dfl_feature *feature,
> > + unsigned long arg);
> > +long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
> > + struct dfl_feature *feature,
> > + unsigned long arg);
> > +
> > #endif /* __FPGA_DFL_H */
> > diff --git a/include/uapi/linux/fpga-dfl.h b/include/uapi/linux/fpga-dfl.h
> > index ec70a0746..7331350 100644
> > --- a/include/uapi/linux/fpga-dfl.h
> > +++ b/include/uapi/linux/fpga-dfl.h
> > @@ -151,6 +151,19 @@ struct dfl_fpga_port_dma_unmap {
> >
> > #define DFL_FPGA_PORT_DMA_UNMAP _IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 4)
> >
> > +/**
> > + * struct dfl_fpga_irq_set - the argument for DFL_FPGA_XXX_SET_IRQ ioctl.
> > + *
> > + * @start: Index of the first irq.
> > + * @count: The number of eventfd handler.
> > + * @evtfds: Eventfd handlers.
> > + */
> > +struct dfl_fpga_irq_set {
> > + __u32 start;
> > + __u32 count;
> > + __s32 evtfds[];
> > +};
> > +
> > /* IOCTLs for FME file descriptor */
> >
> > /**
> > --
> > 2.7.4
> >
> Thanks,
> Moritz