Re: [PATCH v5 3/4] iommu: rockchip: Add internal ops to handle variants

[Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>]

Le 21/05/2021 à 14:58, Robin Murphy a écrit :
> On 2021-05-21 09:36, Benjamin Gaignard wrote:
> > Add internal ops to be able to handle incoming variant v2.
> > The goal is to keep the overall structure of the framework but
> > to allow to add the evolution of this hardware block.
> >
> > The ops are global for a SoC because iommu domains are not
> > attached to a specific devices if they are for a virtuel device like
> > drm. Use a global variable shouldn't be since SoC usually doesn't
> > embedded different versions of the iommu hardware block.
> > If that happen one day a WARN_ON will be displayed at probe time.
>
> IMO it would be a grievous error if such a "virtual device" ever gets 
> near the IOMMU API, so personally I wouldn't use that as a 
> justification for anything :)
>
> FWIW you should be OK to handle things on a per-instance basis, it 
> just means you have to defer some of the domain setup to .attach_dev 
> time, like various other drivers do. That said, there's nothing wrong 
> with the global if we do expect instances to be consistent across any 
> given Rockchip SoC (and my gut feeling is that we probably should).

I have tried that solution first but drm device appear to but such "virtual device" so I had to use the global.

I send a v6 to fix your others remarks.

Thanks for your advice.

Benjamin

> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> > version 5:
> >   - Use of_device_get_match_data()
> >   - Add internal ops inside the driver
> >
> >   drivers/iommu/rockchip-iommu.c | 69 ++++++++++++++++++++++++----------
> >   1 file changed, 50 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/iommu/rockchip-iommu.c 
> > b/drivers/iommu/rockchip-iommu.c
> > index 7a2932772fdf..e7b9bcf174b1 100644
> > --- a/drivers/iommu/rockchip-iommu.c
> > +++ b/drivers/iommu/rockchip-iommu.c
> > @@ -19,6 +19,7 @@
> >   #include <linux/iopoll.h>
> >   #include <linux/list.h>
> >   #include <linux/mm.h>
> > +#include <linux/module.h>
>
> This seems to be an unrelated and unnecessary change.
>
> >   #include <linux/init.h>
> >   #include <linux/of.h>
> >   #include <linux/of_iommu.h>
> > @@ -96,6 +97,14 @@ static const char * const rk_iommu_clocks[] = {
> >       "aclk", "iface",
> >   };
> >   +struct rk_iommu_ops {
> > +    phys_addr_t (*pt_address)(u32 dte);
> > +    u32 (*mk_dtentries)(dma_addr_t pt_dma);
> > +    u32 (*mk_ptentries)(phys_addr_t page, int prot);
> > +    phys_addr_t (*dte_addr_phys)(phys_addr_t addr);
> > +    u32 pt_address_mask;
> > +};
> > +
> >   struct rk_iommu {
> >       struct device *dev;
> >       void __iomem **bases;
> > @@ -116,6 +125,7 @@ struct rk_iommudata {
> >   };
> >     static struct device *dma_dev;
> > +static const struct rk_iommu_ops *rk_ops;
> >     static inline void rk_table_flush(struct rk_iommu_domain *dom, 
> > dma_addr_t dma,
> >                     unsigned int count)
> > @@ -215,11 +225,6 @@ static inline u32 rk_mk_dte(dma_addr_t pt_dma)
> >   #define RK_PTE_PAGE_READABLE      BIT(1)
> >   #define RK_PTE_PAGE_VALID         BIT(0)
> >   -static inline phys_addr_t rk_pte_page_address(u32 pte)
> > -{
> > -    return (phys_addr_t)pte & RK_PTE_PAGE_ADDRESS_MASK;
> > -}
> > -
> >   static inline bool rk_pte_is_page_valid(u32 pte)
> >   {
> >       return pte & RK_PTE_PAGE_VALID;
> > @@ -451,7 +456,7 @@ static int rk_iommu_force_reset(struct rk_iommu 
> > *iommu)
> >           rk_iommu_write(iommu->bases[i], RK_MMU_DTE_ADDR, 
> > DTE_ADDR_DUMMY);
> >             dte_addr = rk_iommu_read(iommu->bases[i], RK_MMU_DTE_ADDR);
> > -        if (dte_addr != (DTE_ADDR_DUMMY & RK_DTE_PT_ADDRESS_MASK)) {
> > +        if (dte_addr != (DTE_ADDR_DUMMY & rk_ops->pt_address_mask)) {
>
> Nit: might it make more sense to do something like:
>
>         dte_addr = rk_ops->pt_address(... DTE_ADDR_DUMMY);
>         rk_iommu_write(... dte_addr)
>         if (rk_iommu_read(...) != dte_addr)
>
> so that you don't need to bother defining ->pt_address_mask for just 
> this one sanity-check?
>
> >               dev_err(iommu->dev, "Error during raw reset. 
> > MMU_DTE_ADDR is not functioning\n");
> >               return -EFAULT;
> >           }
> > @@ -470,6 +475,11 @@ static int rk_iommu_force_reset(struct rk_iommu 
> > *iommu)
> >       return 0;
> >   }
> >   +static inline phys_addr_t rk_dte_addr_phys(phys_addr_t addr)
>
> The argument type here should be u32, since it's a DTE, not a physical 
> address...
>
> > +{
> > +    return addr;
> > +}
> > +
> >   static void log_iova(struct rk_iommu *iommu, int index, dma_addr_t 
> > iova)
> >   {
> >       void __iomem *base = iommu->bases[index];
> > @@ -489,7 +499,7 @@ static void log_iova(struct rk_iommu *iommu, int 
> > index, dma_addr_t iova)
> >       page_offset = rk_iova_page_offset(iova);
> >         mmu_dte_addr = rk_iommu_read(base, RK_MMU_DTE_ADDR);
> > -    mmu_dte_addr_phys = (phys_addr_t)mmu_dte_addr;
> > +    mmu_dte_addr_phys = 
> > rk_ops->dte_addr_phys((phys_addr_t)mmu_dte_addr);
>
> ...and the cast here should not be here, since it *is* the conversion 
> that the called function is supposed to be performing.
>
> >       dte_addr_phys = mmu_dte_addr_phys + (4 * dte_index);
> >       dte_addr = phys_to_virt(dte_addr_phys);
> > @@ -498,14 +508,14 @@ static void log_iova(struct rk_iommu *iommu, 
> > int index, dma_addr_t iova)
> >       if (!rk_dte_is_pt_valid(dte))
> >           goto print_it;
> >   -    pte_addr_phys = rk_dte_pt_address(dte) + (pte_index * 4);
> > +    pte_addr_phys = rk_ops->pt_address(dte) + (pte_index * 4);
> >       pte_addr = phys_to_virt(pte_addr_phys);
> >       pte = *pte_addr;
> >         if (!rk_pte_is_page_valid(pte))
> >           goto print_it;
> >   -    page_addr_phys = rk_pte_page_address(pte) + page_offset;
> > +    page_addr_phys = rk_ops->pt_address(pte) + page_offset;
> >       page_flags = pte & RK_PTE_PAGE_FLAGS_MASK;
> >     print_it:
> > @@ -601,13 +611,13 @@ static phys_addr_t rk_iommu_iova_to_phys(struct 
> > iommu_domain *domain,
> >       if (!rk_dte_is_pt_valid(dte))
> >           goto out;
> >   -    pt_phys = rk_dte_pt_address(dte);
> > +    pt_phys = rk_ops->pt_address(dte);
> >       page_table = (u32 *)phys_to_virt(pt_phys);
> >       pte = page_table[rk_iova_pte_index(iova)];
> >       if (!rk_pte_is_page_valid(pte))
> >           goto out;
> >   -    phys = rk_pte_page_address(pte) + rk_iova_page_offset(iova);
> > +    phys = rk_ops->pt_address(pte) + rk_iova_page_offset(iova);
> >   out:
> >       spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
> >   @@ -679,14 +689,14 @@ static u32 *rk_dte_get_page_table(struct 
> > rk_iommu_domain *rk_domain,
> >           return ERR_PTR(-ENOMEM);
> >       }
> >   -    dte = rk_mk_dte(pt_dma);
> > +    dte = rk_ops->mk_dtentries(pt_dma);
> >       *dte_addr = dte;
> >         rk_table_flush(rk_domain, pt_dma, NUM_PT_ENTRIES);
> >       rk_table_flush(rk_domain,
> >                  rk_domain->dt_dma + dte_index * sizeof(u32), 1);
> >   done:
> > -    pt_phys = rk_dte_pt_address(dte);
> > +    pt_phys = rk_ops->pt_address(dte);
> >       return (u32 *)phys_to_virt(pt_phys);
> >   }
> >   @@ -728,7 +738,7 @@ static int rk_iommu_map_iova(struct 
> > rk_iommu_domain *rk_domain, u32 *pte_addr,
> >           if (rk_pte_is_page_valid(pte))
> >               goto unwind;
> >   -        pte_addr[pte_count] = rk_mk_pte(paddr, prot);
> > +        pte_addr[pte_count] = rk_ops->mk_ptentries(paddr, prot);
> >             paddr += SPAGE_SIZE;
> >       }
> > @@ -750,7 +760,7 @@ static int rk_iommu_map_iova(struct 
> > rk_iommu_domain *rk_domain, u32 *pte_addr,
> >                   pte_count * SPAGE_SIZE);
> >         iova += pte_count * SPAGE_SIZE;
> > -    page_phys = rk_pte_page_address(pte_addr[pte_count]);
> > +    page_phys = rk_ops->pt_address(pte_addr[pte_count]);
> >       pr_err("iova: %pad already mapped to %pa cannot remap to phys: 
> > %pa prot: %#x\n",
> >              &iova, &page_phys, &paddr, prot);
> >   @@ -785,7 +795,8 @@ static int rk_iommu_map(struct iommu_domain 
> > *domain, unsigned long _iova,
> >       dte_index = rk_domain->dt[rk_iova_dte_index(iova)];
> >       pte_index = rk_iova_pte_index(iova);
> >       pte_addr = &page_table[pte_index];
> > -    pte_dma = rk_dte_pt_address(dte_index) + pte_index * sizeof(u32);
> > +
> > +    pte_dma = rk_ops->pt_address(dte_index) + pte_index * sizeof(u32);
> >       ret = rk_iommu_map_iova(rk_domain, pte_addr, pte_dma, iova,
> >                   paddr, size, prot);
> >   @@ -821,7 +832,7 @@ static size_t rk_iommu_unmap(struct 
> > iommu_domain *domain, unsigned long _iova,
> >           return 0;
> >       }
> >   -    pt_phys = rk_dte_pt_address(dte);
> > +    pt_phys = rk_ops->pt_address(dte);
> >       pte_addr = (u32 *)phys_to_virt(pt_phys) + rk_iova_pte_index(iova);
> >       pte_dma = pt_phys + rk_iova_pte_index(iova) * sizeof(u32);
> >       unmap_size = rk_iommu_unmap_iova(rk_domain, pte_addr, pte_dma, 
> > size);
> > @@ -1037,7 +1048,7 @@ static void rk_iommu_domain_free(struct 
> > iommu_domain *domain)
> >       for (i = 0; i < NUM_DT_ENTRIES; i++) {
> >           u32 dte = rk_domain->dt[i];
> >           if (rk_dte_is_pt_valid(dte)) {
> > -            phys_addr_t pt_phys = rk_dte_pt_address(dte);
> > +            phys_addr_t pt_phys = rk_ops->pt_address(dte);
> >               u32 *page_table = phys_to_virt(pt_phys);
> >               dma_unmap_single(dma_dev, pt_phys,
> >                        SPAGE_SIZE, DMA_TO_DEVICE);
> > @@ -1138,6 +1149,15 @@ static int rk_iommu_probe(struct 
> > platform_device *pdev)
> >       iommu->dev = dev;
> >       iommu->num_mmu = 0;
> >   +    if (!rk_ops)
> > +        rk_ops = of_device_get_match_data(dev);
> > +
> > +    /*
> > +     * That should not happen unless different versions of the
> > +     * hardware block are embedded the same SoC
> > +     */
> > +    WARN_ON(rk_ops != of_device_get_match_data(dev));
>
> Nit: calling of_device_get_match_data() twice seems rather untidy - 
> how about something like:
>
>     ops = of_device_get_match_data(dev);
>     if (!rk_ops)
>         rk_ops = ops;
>     else if (WARN_ON(rk_ops != ops))
>         return -EINVAL;
>
> Either way I think it would be good to treat unexpected inconsistentcy 
> as an actual error, rather than second-guessing the DT and carrying on 
> under the assumption the device is something other than it claimed to be.
>
> > +
> >       iommu->bases = devm_kcalloc(dev, num_res, sizeof(*iommu->bases),
> >                       GFP_KERNEL);
> >       if (!iommu->bases)
> > @@ -1277,10 +1297,21 @@ static const struct dev_pm_ops 
> > rk_iommu_pm_ops = {
> >                   pm_runtime_force_resume)
> >   };
> >   +static struct rk_iommu_ops iommu_data_ops_v1 = {
> > +    .pt_address = &rk_dte_pt_address,
> > +    .mk_dtentries = &rk_mk_dte,
> > +    .mk_ptentries = &rk_mk_pte,
> > +    .dte_addr_phys = &rk_dte_addr_phys,
> > +    .pt_address_mask = RK_DTE_PT_ADDRESS_MASK,
> > +};
> > +
> >   static const struct of_device_id rk_iommu_dt_ids[] = {
> > -    { .compatible = "rockchip,iommu" },
> > +    {    .compatible = "rockchip,iommu",
> > +        .data = &iommu_data_ops_v1,
> > +    },
> >       { /* sentinel */ }
> >   };
> > +MODULE_DEVICE_TABLE(of, rk_iommu_dt_ids);
>
> As before, unrelated and unnecessary since this driver is still bool 
> in the Kconfig. If you do want to support modular builds you'll also 
> need to ensure rk_iommu_ops.owner is set, but do it all as a separate 
> patch please.
>
> Thanks,
> Robin.
>
> >     static struct platform_driver rk_iommu_driver = {
> >       .probe = rk_iommu_probe,