Re: [PATCH v2 2/5] iommu: Implement of_iommu_get_resv_regions()

[Dmitry Osipenko <digetx@gmail.com>]

16.07.2021 17:41, Rob Herring пишет:
> On Fri, Jul 2, 2021 at 8:05 AM Dmitry Osipenko <digetx@gmail.com> wrote:
>>
>> 23.04.2021 19:32, Thierry Reding пишет:
>>> +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
>>> +{
>>> +     struct of_phandle_iterator it;
>>> +     int err;
>>> +
>>> +     of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
>>> +             struct iommu_resv_region *region;
>>> +             struct of_phandle_args args;
>>> +             struct resource res;
>>> +
>>> +             args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
>>> +
>>> +             err = of_address_to_resource(it.node, 0, &res);
>>> +             if (err < 0) {
>>> +                     dev_err(dev, "failed to parse memory region %pOF: %d\n",
>>> +                             it.node, err);
>>> +                     continue;
>>> +             }
>>> +
>>> +             if (args.args_count > 0) {
>>> +                     /*
>>> +                      * Active memory regions are expected to be accessed by hardware during
>>> +                      * boot and must therefore have an identity mapping created prior to the
>>> +                      * driver taking control of the hardware. This ensures that non-quiescent
>>> +                      * hardware doesn't cause IOMMU faults during boot.
>>> +                      */
>>> +                     if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
>>> +                             region = iommu_alloc_resv_region(res.start, resource_size(&res),
>>> +                                                              IOMMU_READ | IOMMU_WRITE,
>>> +                                                              IOMMU_RESV_DIRECT_RELAXABLE);
>>> +                             if (!region)
>>> +                                     continue;
>>> +
>>> +                             list_add_tail(&region->list, list);
>>> +                     }
>>> +             }
>>> +     }
>>> +}
>>> +EXPORT_SYMBOL(of_iommu_get_resv_regions);
>>
>> Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
>> logic behind the OF symbols in general since it looks like half of them
>> are GPL.
> 
> Generally, new ones are _GPL. Old ones probably predate _GPL.
> 
> This one is up to the IOMMU maintainers.

Thank you.