Re: [PATCH v2 1/2] of/pci: add of_pci_dma_configure() update dma configuration

Rob Herring
2014-12-26T19:33:48Z

On Wed, Dec 24, 2014 at 4:11 PM, Murali Karicheri <m-karicheri2@ti.com> wrote:
> Add of_pci_dma_configure() to allow updating the dma configuration
> of the pci device using the configuration from DT of the parent of
> the root bridge device.
>
> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
> ---
> drivers/of/of_pci.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/of_pci.h | 12 ++++++++
> 2 files changed, 85 insertions(+)
>
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 88471d3..6d43f59 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -229,6 +229,79 @@ parse_failed:
> return err;
> }
> EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
> +
> +/**
> + * of_get_pci_root_bridge_parent - Helper function to get the OF node of
> + * the root bridge's parent

I believe this has to be a one line description for DocBook.

> + * @dev: ptr to pci_dev struct of the pci device
> + *
> + * This function will traverse the bus up to the root bus starting with
> + * the child and return the of node ptr to bridge device's parent device.
> + */
> +struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev)
> +{
> + struct pci_bus *bus = dev->bus;
> + struct device *bridge;
> +
> + while (!pci_is_root_bus(bus))
> + bus = bus->parent;
> + bridge = bus->bridge;
> +
> + return bridge->parent->of_node;
> +}
> +EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
> +
> +/**
> + * of_pci_dma_configure - Setup DMA configuration
> + * @dev: ptr to pci_dev struct of the pci device
> + *
> + * Try to get PCI devices's DMA configuration from DT and update it
> + * accordingly. This is similar to of_dma_configure() in of/platform.c
> + */
> +void of_pci_dma_configure(struct pci_dev *pci_dev)
> +{
> + struct device *dev = &pci_dev->dev;
> + u64 dma_addr, paddr, size;
> + struct device_node *parent_np;
> + unsigned long offset;
> + bool coherent;
> + int ret;
> +
> + parent_np = of_get_pci_root_bridge_parent(pci_dev);
> +
> + if (parent_np) {

Save a level of indentation and do:

if (!parent_np)
return;

> + /*
> + * Set default dma-mask to 32 bit. Drivers are expected to setup
> + * the correct supported dma_mask.
> + */
> + dev->coherent_dma_mask = DMA_BIT_MASK(32);
> +
> + /*
> + * Set it to coherent_dma_mask by default if the architecture
> + * code has not set it.
> + */
> + if (!dev->dma_mask)
> + dev->dma_mask = &dev->coherent_dma_mask;
> +
> + ret = of_dma_get_range(parent_np, &dma_addr, &paddr, &size);
> + if (ret < 0) {
> + dma_addr = offset = 0;
> + size = dev->coherent_dma_mask + 1;
> + } else {
> + offset = PFN_DOWN(paddr - dma_addr);
> + dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
> + }
> + dev->dma_pfn_offset = offset;
> +
> + coherent = of_dma_is_coherent(parent_np);
> + dev_dbg(dev, "device is%sdma coherent\n",
> + coherent ? " " : " not ");
> +
> + arch_setup_dma_ops(dev, dma_addr, size, NULL, coherent);

This is the same code as of_dma_configure. The only difference I see
is which node ptr is passed to of_dma_get_range. You need to make that
a function param of of_dma_configure.

of_dma_configure also has iommu handling now. You will probably need
something similar for PCI in that you setup an iommu based on the root
bus DT properties.

Rob