| Message ID | 20221117182720.2290761-3-thierry.reding@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mmc: sdhci: Add Tegra234 support | expand |
On Thu, 17 Nov 2022 at 19:27, Thierry Reding <thierry.reding@gmail.com> wrote: > > From: Thierry Reding <treding@nvidia.com> > > Access to the internals of struct iommu_fwspec by non-IOMMU drivers is > discouraged. Many drivers for Tegra SoCs, however, need access to their > IOMMU stream IDs so that they can be programmed into various hardware > registers. > > Formalize this access into a common helper to make it easier to audit > and maintain. > > Signed-off-by: Thierry Reding <treding@nvidia.com> > --- > include/linux/iommu.h | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index dc5e6f5c14fc..f0d72acad7db 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -1186,4 +1186,25 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) > } > #endif /* CONFIG_IOMMU_SVA */ > > +/* > + * Newer generations of Tegra SoCs require devices' stream IDs to be directly programmed into > + * some registers. These are always paired with a Tegra SMMU or ARM SMMU, for which the contents > + * of the struct iommu_fwspec are known. Use this helper to formalize access to these internals. > + */ > +#define TEGRA_STREAM_ID_BYPASS 0x7f > + > +static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream_id) > +{ > +#ifdef CONFIG_IOMMU_API > + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > + > + if (fwspec && fwspec->num_ids == 1) { > + *stream_id = fwspec->ids[0] & 0xffff; > + return true; > + } > +#endif It's totally up to iommu maintainers to decide, but I personally would prefer to replace the below part with a stub function, defined when CONFIG_IOMMU_API is unset. > + > + return false; > +} > + > #endif /* __LINUX_IOMMU_H */ > -- > 2.38.1 > Other than that, both patch1 and patch2 look good to me. I can pick up the series, after an ack from Robin or Joerg. Kind regards Uffe
On Fri, Nov 18, 2022 at 09:08:17AM +0100, Ulf Hansson wrote: > On Thu, 17 Nov 2022 at 19:27, Thierry Reding <thierry.reding@gmail.com> wrote: > > > > From: Thierry Reding <treding@nvidia.com> > > > > Access to the internals of struct iommu_fwspec by non-IOMMU drivers is > > discouraged. Many drivers for Tegra SoCs, however, need access to their > > IOMMU stream IDs so that they can be programmed into various hardware > > registers. > > > > Formalize this access into a common helper to make it easier to audit > > and maintain. > > > > Signed-off-by: Thierry Reding <treding@nvidia.com> > > --- > > include/linux/iommu.h | 21 +++++++++++++++++++++ > > 1 file changed, 21 insertions(+) > > > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > > index dc5e6f5c14fc..f0d72acad7db 100644 > > --- a/include/linux/iommu.h > > +++ b/include/linux/iommu.h > > @@ -1186,4 +1186,25 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) > > } > > #endif /* CONFIG_IOMMU_SVA */ > > > > +/* > > + * Newer generations of Tegra SoCs require devices' stream IDs to be directly programmed into > > + * some registers. These are always paired with a Tegra SMMU or ARM SMMU, for which the contents > > + * of the struct iommu_fwspec are known. Use this helper to formalize access to these internals. > > + */ > > +#define TEGRA_STREAM_ID_BYPASS 0x7f > > + > > +static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream_id) > > +{ > > +#ifdef CONFIG_IOMMU_API > > + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > > + > > + if (fwspec && fwspec->num_ids == 1) { > > + *stream_id = fwspec->ids[0] & 0xffff; > > + return true; > > + } > > +#endif > > It's totally up to iommu maintainers to decide, but I personally would > prefer to replace the below part with a stub function, defined when > CONFIG_IOMMU_API is unset. Yeah, that's what I had done originally, but then it felt a bit at odds with Robin's request to move this into a central location. Ultimately the result is the same and this has the benefit of standing out a bit more as unusual. I don't feel strongly, though, so if Joerg and/or Robin want to see this split up into an implementation and a stub, I can do that. Thierry
diff --git a/include/linux/iommu.h b/include/linux/iommu.h index dc5e6f5c14fc..f0d72acad7db 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -1186,4 +1186,25 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) } #endif /* CONFIG_IOMMU_SVA */ +/* + * Newer generations of Tegra SoCs require devices' stream IDs to be directly programmed into + * some registers. These are always paired with a Tegra SMMU or ARM SMMU, for which the contents + * of the struct iommu_fwspec are known. Use this helper to formalize access to these internals. + */ +#define TEGRA_STREAM_ID_BYPASS 0x7f + +static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream_id) +{ +#ifdef CONFIG_IOMMU_API + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); + + if (fwspec && fwspec->num_ids == 1) { + *stream_id = fwspec->ids[0] & 0xffff; + return true; + } +#endif + + return false; +} + #endif /* __LINUX_IOMMU_H */