int of_dma_configure_id()

in device.c [111:213]

• 67 lines of code
• 19 McCabe index (conditional complexity)

int of_dma_configure_id(struct device *dev, struct device_node *np,
			bool force_dma, const u32 *id)
{
	const struct iommu_ops *iommu;
	const struct bus_dma_region *map = NULL;
	u64 dma_start = 0;
	u64 mask, end, size = 0;
	bool coherent;
	int ret;

	ret = of_dma_get_range(np, &map);
	if (ret < 0) {
		/*
		 * For legacy reasons, we have to assume some devices need
		 * DMA configuration regardless of whether "dma-ranges" is
		 * correctly specified or not.
		 */
		if (!force_dma)
			return ret == -ENODEV ? 0 : ret;
	} else {
		const struct bus_dma_region *r = map;
		u64 dma_end = 0;

		/* Determine the overall bounds of all DMA regions */
		for (dma_start = ~0; r->size; r++) {
			/* Take lower and upper limits */
			if (r->dma_start < dma_start)
				dma_start = r->dma_start;
			if (r->dma_start + r->size > dma_end)
				dma_end = r->dma_start + r->size;
		}
		size = dma_end - dma_start;

		/*
		 * Add a work around to treat the size as mask + 1 in case
		 * it is defined in DT as a mask.
		 */
		if (size & 1) {
			dev_warn(dev, "Invalid size 0x%llx for dma-range(s)\n",
				 size);
			size = size + 1;
		}

		if (!size) {
			dev_err(dev, "Adjusted size 0x%llx invalid\n", size);
			kfree(map);
			return -EINVAL;
		}
	}

	/*
	 * If @dev is expected to be DMA-capable then the bus code that created
	 * it should have initialised its dma_mask pointer by this point. For
	 * now, we'll continue the legacy behaviour of coercing it to the
	 * coherent mask if not, but we'll no longer do so quietly.
	 */
	if (!dev->dma_mask) {
		dev_warn(dev, "DMA mask not set\n");
		dev->dma_mask = &dev->coherent_dma_mask;
	}

	if (!size && dev->coherent_dma_mask)
		size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
	else if (!size)
		size = 1ULL << 32;

	/*
	 * Limit coherent and dma mask based on size and default mask
	 * set by the driver.
	 */
	end = dma_start + size - 1;
	mask = DMA_BIT_MASK(ilog2(end) + 1);
	dev->coherent_dma_mask &= mask;
	*dev->dma_mask &= mask;
	/* ...but only set bus limit and range map if we found valid dma-ranges earlier */
	if (!ret) {
		dev->bus_dma_limit = end;
		dev->dma_range_map = map;
	}

	coherent = of_dma_is_coherent(np);
	dev_dbg(dev, "device is%sdma coherent\n",
		coherent ? " " : " not ");

	iommu = of_iommu_configure(dev, np, id);
	if (PTR_ERR(iommu) == -EPROBE_DEFER) {
		/* Don't touch range map if it wasn't set from a valid dma-ranges */
		if (!ret)
			dev->dma_range_map = NULL;
		kfree(map);
		return -EPROBE_DEFER;
	}

	dev_dbg(dev, "device is%sbehind an iommu\n",
		iommu ? " " : " not ");

	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);

	if (!iommu)
		of_dma_set_restricted_buffer(dev, np);

	return 0;
}