Messages in this thread | | | Date | Mon, 24 Oct 2022 07:56:11 -0700 (PDT) | From | matthew.gerlach@linux ... | Subject | Re: [PATCH v4 3/4] fpga: dfl: add basic support DFHv1 |
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On Fri, 21 Oct 2022, Andy Shevchenko wrote:
> On Thu, Oct 20, 2022 at 02:26:09PM -0700, matthew.gerlach@linux.intel.com wrote: >> From: Matthew Gerlach <matthew.gerlach@linux.intel.com> >> >> Add generic support for MSI-X interrupts for DFL devices. >> >> The location of a feature's registers is explicitly >> described in DFHv1 and can be relative to the base of the DFHv1 >> or an absolute address. Parse the location and pass the information >> to DFL driver. > > ... > >> +static void *find_param(void *base, resource_size_t max, int param) > > Why base can't be u64 * to begin with?
It can be u64, and I will consider it for the next iteration. > >> +{ >> + int off = 0; >> + u64 v, next; >> + >> + while (off < max) { > > Maybe you need a comment somewhere to tell that the caller guarantees that max > won't provoke OOB accesses. > >> + v = *(u64 *)(base + off); > > Okay, if offset is not multiple of at least 4, how do you guarantee no > exception on the architectures with disallowed misaligned accesses? > > Making base to be u64 * solves this, but you need to take care to provide > offset in terms of u64 words.
The masking of next below ensures that the offset it at least 4 byte aligned, but it might make sense to define the next field in terms of 8 byte words.
> >> + if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v)) >> + return base + off + DFHv1_PARAM_DATA; >> + >> + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v); >> + off += next & ~DFHv1_PARAM_HDR_NEXT_MASK; >> + if (next & DFHv1_PARAM_HDR_NEXT_EOL) >> + break; >> + >> + } >> + >> + return NULL; >> +} > > ... > >> + /* >> + * DFHv0 only provides mmio resource information for each feature > > MMIO
I'll change mmio to MMIO here and a place in the documentation that I noticed.
> >> + * in the DFL header. There is no generic interrupt information. >> + * Instead, features with interrupt functionality provide >> + * the information in feature specific registers. >> + */ > > ... > >> + if (!finfo->param_size) >> break; > > This is redundant as it's implied by find_param().
I will remove the redundant code.
> >> + p = find_param(params, finfo->param_size, DFHv1_PARAM_ID_MSI_X); >> + if (!p) >> break; > > ... > >> +static int dfh_get_psize(void __iomem *dfh_base, resource_size_t max) >> +{ >> + int size = 0; >> + u64 v, next; >> + >> + if (!FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS, >> + readq(dfh_base + DFHv1_CSR_SIZE_GRP))) >> + return 0; >> + >> + while (size + DFHv1_PARAM_HDR < max) { >> + v = readq(dfh_base + DFHv1_PARAM_HDR + size); >> + >> + next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v); >> + if (!(next & ~DFHv1_PARAM_HDR_NEXT_MASK)) >> + return -EINVAL; >> + >> + size += next & ~DFHv1_PARAM_HDR_NEXT_MASK; >> + >> + if (next & DFHv1_PARAM_HDR_NEXT_EOL) >> + return size; > > These 3 looks like they deserve different fields and hence separate FIELD_GET() > will return exactly what we need without additional masking, right?
I agree separate FIELD_GET() calls will be cleaner.
> >> + } >> + >> + return -ENOENT; >> +} > > ... > >> + if (dfh_psize > 0) { > > Isn't this implied by memcpy_fromio()? I mean if it's 0, nothing bad will > happen if you call the above directly. > >> + memcpy_fromio(finfo->params, >> + binfo->ioaddr + ofst + DFHv1_PARAM_HDR, dfh_psize); >> + finfo->param_size = dfh_psize; >> + } > > ... > >> finfo->mmio_res.flags = IORESOURCE_MEM; >> + if (dfh_ver == 1) { >> + v = readq(binfo->ioaddr + ofst + DFHv1_CSR_ADDR); >> + if (v & DFHv1_CSR_ADDR_REL) >> + finfo->mmio_res.start = v & ~DFHv1_CSR_ADDR_REL; >> + else >> + finfo->mmio_res.start = binfo->start + ofst + >> + FIELD_GET(DFHv1_CSR_ADDR_MASK, v); >> + >> + v = readq(binfo->ioaddr + ofst + DFHv1_CSR_SIZE_GRP); >> + finfo->mmio_res.end = finfo->mmio_res.start + >> + FIELD_GET(DFHv1_CSR_SIZE_GRP_SIZE, v) - 1; >> + } else { >> + finfo->mmio_res.start = binfo->start + ofst; >> + finfo->mmio_res.end = finfo->mmio_res.start + size - 1; >> + } > > You may define > > resource_size_t start, end; > > locally and simplify above quite a bit.
That is a good suggestion that should clean up the code quite a bit.
> > ... > >> +void *dfh_find_param(struct dfl_device *dfl_dev, int param); > > + Blank line. > >> #endif /* __LINUX_DFL_H */ > > -- > With Best Regards, > Andy Shevchenko > > >
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