linux-kernel - Re: [PATCH 01/11] RISC-V: drivers/iommu: Add RISC-V IOMMU

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Message-ID: <20230802-maimed-spotted-5fa1fe4be386@spud>
Date:   Wed, 2 Aug 2023 21:25:15 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Tomasz Jeznach <tjeznach@...osinc.com>
Cc:     Zong Li <zong.li@...ive.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Albert Ou <aou@...s.berkeley.edu>, linux@...osinc.com,
        linux-kernel@...r.kernel.org, Sebastien Boeuf <seb@...osinc.com>,
        iommu@...ts.linux.dev, Palmer Dabbelt <palmer@...belt.com>,
        Nick Kossifidis <mick@....forth.gr>,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 01/11] RISC-V: drivers/iommu: Add RISC-V IOMMU - Ziommu
 support.

On Wed, Aug 02, 2023 at 01:15:22PM -0700, Tomasz Jeznach wrote:
> On Thu, Jul 27, 2023 at 7:42 PM Zong Li <zong.li@...ive.com> wrote:
> >
> > On Thu, Jul 20, 2023 at 3:34 AM Tomasz Jeznach <tjeznach@...osinc.com> wrote:
> > >
> > > +static int riscv_iommu_platform_probe(struct platform_device *pdev)
> > > +{
> > > +       struct device *dev = &pdev->dev;
> > > +       struct riscv_iommu_device *iommu = NULL;
> > > +       struct resource *res = NULL;
> > > +       int ret = 0;
> > > +
> > > +       iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
> > > +       if (!iommu)
> > > +               return -ENOMEM;
> > > +
> > > +       iommu->dev = dev;
> > > +       dev_set_drvdata(dev, iommu);
> > > +
> > > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > +       if (!res) {
> > > +               dev_err(dev, "could not find resource for register region\n");
> > > +               return -EINVAL;
> > > +       }
> > > +
> > > +       iommu->reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> > > +       if (IS_ERR(iommu->reg)) {
> > > +               ret = dev_err_probe(dev, PTR_ERR(iommu->reg),
> > > +                                   "could not map register region\n");
> > > +               goto fail;
> > > +       };
> > > +
> > > +       iommu->reg_phys = res->start;
> > > +
> > > +       ret = -ENODEV;
> > > +
> > > +       /* Sanity check: Did we get the whole register space ? */
> > > +       if ((res->end - res->start + 1) < RISCV_IOMMU_REG_SIZE) {
> > > +               dev_err(dev, "device region smaller than register file (0x%llx)\n",
> > > +                       res->end - res->start);
> > > +               goto fail;
> > > +       }
> >
> > Could we assume that DT should be responsible for specifying the right size?
> >
> 
> This only to validate DT provided info and driver expected register
> file size. Expectation is that DT will provide right size.

FWIW this check seems needless to me, it's not the kernels job to
validate the devicetree.


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