Hi All,
On Tue, 2021-01-12 at 16:03 -0800, Florian Fainelli wrote:
> On 1/5/21 7:41 PM, Claire Chang wrote:
> > Add the initialization function to create restricted DMA pools from
> > matching reserved-memory nodes in the device tree.
> >
> > Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
> > ---
> > include/linux/device.h | 4 ++
> > include/linux/swiotlb.h | 7 +-
> > kernel/dma/Kconfig | 1 +
> > kernel/dma/swiotlb.c | 144 ++++++++++++++++++++++++++++++++++------
> > 4 files changed, 131 insertions(+), 25 deletions(-)
> >
> > diff --git a/include/linux/device.h b/include/linux/device.h
> > index 89bb8b84173e..ca6f71ec8871 100644
> > --- a/include/linux/device.h
> > +++ b/include/linux/device.h
> > @@ -413,6 +413,7 @@ struct dev_links_info {
> > * @dma_pools: Dma pools (if dma'ble device).
> > * @dma_mem: Internal for coherent mem override.
> > * @cma_area: Contiguous memory area for dma allocations
> > + * @dma_io_tlb_mem: Internal for swiotlb io_tlb_mem override.
> > * @archdata: For arch-specific additions.
> > * @of_node: Associated device tree node.
> > * @fwnode: Associated device node supplied by platform firmware.
> > @@ -515,6 +516,9 @@ struct device {
> > #ifdef CONFIG_DMA_CMA
> > struct cma *cma_area; /* contiguous memory area for dma
> > allocations */
> > +#endif
> > +#ifdef CONFIG_SWIOTLB
> > + struct io_tlb_mem *dma_io_tlb_mem;
> > #endif
> > /* arch specific additions */
> > struct dev_archdata archdata;
> > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> > index dd8eb57cbb8f..a1bbd7788885 100644
> > --- a/include/linux/swiotlb.h
> > +++ b/include/linux/swiotlb.h
> > @@ -76,12 +76,13 @@ extern enum swiotlb_force swiotlb_force;
> > *
> > * @start: The start address of the swiotlb memory pool. Used to do a quick
> > * range check to see if the memory was in fact allocated by this
> > - * API.
> > + * API. For restricted DMA pool, this is device tree adjustable.
>
> Maybe write it as this is "firmware adjustable" such that when/if ACPI
> needs something like this, the description does not need updating.
>
> [snip]
>
> > +static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
> > + struct device *dev)
> > +{
> > + struct io_tlb_mem *mem = rmem->priv;
> > + int ret;
> > +
> > + if (dev->dma_io_tlb_mem)
> > + return -EBUSY;
> > +
> > + if (!mem) {
> > + mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> > + if (!mem)
> > + return -ENOMEM;
> > +
> > + if (!memremap(rmem->base, rmem->size, MEMREMAP_WB)) {
>
> MEMREMAP_WB sounds appropriate as a default.
As per the binding 'no-map' has to be disabled here. So AFAIU, this memory will
be part of the linear mapping. Is this really needed then?
> Documentation/devicetree/bindings/reserved-memory/ramoops.txt does
> define an "unbuffered" property which in premise could be applied to the
> generic reserved memory binding as well and that we may have to be
> honoring here, if we were to make it more generic. Oh well, this does
> not need to be addressed right now I guess.
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