Re: [PATCH v1 4/5] fpga: dfl: add generic support for MSIX interrupts

Xu Yilun
2022-09-11T09:16:32Z

On 2022-09-06 at 12:04:25 -0700, matthew.gerlach@linux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>
> Define and use a DFHv1 parameter to add generic support for MSIX
> interrupts for DFL devices.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> ---
> drivers/fpga/dfl.c | 59 +++++++++++++++++++++++++++++++++------------
> include/linux/dfl.h | 13 ++++++++++
> 2 files changed, 57 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index b9aae85ba930..17f704dc8483 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -941,25 +941,11 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
> void __iomem *base = binfo->ioaddr + ofst;
> unsigned int i, ibase, inr = 0;
> enum dfl_id_type type;
> - int virq;
> + int virq, off;
> u64 v;
>
> type = feature_dev_id_type(binfo->feature_dev);
>
> - /*
> - * Ideally DFL framework should only read info from DFL header, but
> - * current version DFL only provides mmio resources information for
> - * each feature in DFL Header, no field for interrupt resources.
> - * Interrupt resource information is provided by specific mmio
> - * registers of each private feature which supports interrupt. So in
> - * order to parse and assign irq resources, DFL framework has to look
> - * into specific capability registers of these private features.
> - *
> - * Once future DFL version supports generic interrupt resource
> - * information in common DFL headers, the generic interrupt parsing
> - * code will be added. But in order to be compatible to old version
> - * DFL, the driver may still fall back to these quirks.
> - */

I don't think we should just remove the entire comments here, we still
need these quirks for DFHv0.

> if (type == PORT_ID) {
> switch (fid) {
> case PORT_FEATURE_ID_UINT:
> @@ -981,6 +967,28 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
> }
> }
>
> + if (fid != FEATURE_ID_AFU && fid != PORT_FEATURE_ID_ERROR &&
> + fid != PORT_FEATURE_ID_UINT && fid != FME_FEATURE_ID_GLOBAL_ERR) {

Is it possible we don't list all quirks again?

> + v = readq(base);
> + v = FIELD_GET(DFH_VERSION, v);
> +
> + if (v == 1) {
> + v = readq(base + DFHv1_CSR_SIZE_GRP);
> + if (FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS, v)) {
> + off = dfl_find_param(base + DFHv1_PARAM_HDR, ofst,
> + DFHv1_PARAM_ID_MSIX);
> + if (off >= 0) {
> + ibase = readl(base + DFHv1_PARAM_HDR +
> + off + DFHv1_PARAM_MSIX_STARTV);
> + inr = readl(base + DFHv1_PARAM_HDR +
> + off + DFHv1_PARAM_MSIX_NUMV);
> + dev_dbg(binfo->dev, "%s start %d num %d fid 0x%x\n",
> + __func__, ibase, inr, fid);
> + }
> + }
> + }
> + }

Please help describe how the new irq params works with existing irq
capable features. Some possible cases?

If version = v1, has irq param, no feature quirk.
If version = v1, no irq param, has feature quirk.
If version = v1, has irq param, has feature quirk.

Thanks,
Yilun

> +
> if (!inr) {
> *irq_base = 0;
> *nr_irqs = 0;
> @@ -1879,6 +1887,27 @@ long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
> }
> EXPORT_SYMBOL_GPL(dfl_feature_ioctl_set_irq);
>
> +int dfl_find_param(void __iomem *base, resource_size_t max, int param)
> +{
> + int off = 0;
> + u64 v, next;
> +
> + while (off < max) {
> + v = readq(base + off);
> + if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
> + return off;
> +
> + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
> + if (!next)
> + break;
> +
> + off += next;
> + }
> +
> + return -ENOENT;
> +}
> +EXPORT_SYMBOL_GPL(dfl_find_param);
> +
> static void __exit dfl_fpga_exit(void)
> {
> dfl_chardev_uinit();
> diff --git a/include/linux/dfl.h b/include/linux/dfl.h
> index 61bcf20c1bc8..5652879ab48e 100644
> --- a/include/linux/dfl.h
> +++ b/include/linux/dfl.h
> @@ -69,6 +69,10 @@
> #define DFHv1_PARAM_HDR_VERSION GENMASK_ULL(31, 16) /* Version Param */
> #define DFHv1_PARAM_HDR_NEXT_OFFSET GENMASK_ULL(63, 32) /* Offset of next Param */
>
> +#define DFHv1_PARAM_ID_MSIX 0x1
> +#define DFHv1_PARAM_MSIX_STARTV 0x8
> +#define DFHv1_PARAM_MSIX_NUMV 0xc
> +
> /**
> * enum dfl_id_type - define the DFL FIU types
> */
> @@ -142,4 +146,13 @@ void dfl_driver_unregister(struct dfl_driver *dfl_drv);
> module_driver(__dfl_driver, dfl_driver_register, \
> dfl_driver_unregister)
>
> +/*
> + * dfl_find_param() - find the offset of the given parameter
> + * @base: base pointer to start of dfl parameters in DFH
> + * @max: maximum offset to search
> + * @param: id of dfl parameter
> + *
> + * Return: positive offset on success, negative error code otherwise.
> + */
> +int dfl_find_param(void __iomem *base, resource_size_t max, int param);
> #endif /* __LINUX_DFL_H */
> --
> 2.25.1
>