dma.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2#include <linux/acpi.h>
 3#include <linux/acpi_iort.h>
 4#include <linux/device.h>
 5#include <linux/dma-direct.h>
 6
 7void acpi_arch_dma_setup(struct device *dev)
 8{
 9	int ret;
10	u64 end, mask;
11	const struct bus_dma_region *map = NULL;
12
13	/*
14	 * If @dev is expected to be DMA-capable then the bus code that created
15	 * it should have initialised its dma_mask pointer by this point. For
16	 * now, we'll continue the legacy behaviour of coercing it to the
17	 * coherent mask if not, but we'll no longer do so quietly.
18	 */
19	if (!dev->dma_mask) {
20		dev_warn(dev, "DMA mask not set\n");
21		dev->dma_mask = &dev->coherent_dma_mask;
22	}
23
24	if (dev->coherent_dma_mask)
25		end = dev->coherent_dma_mask;
26	else
27		end = (1ULL << 32) - 1;
28
29	if (dev->dma_range_map) {
30		dev_dbg(dev, "dma_range_map already set\n");
31		return;
32	}
33
34	ret = acpi_dma_get_range(dev, &map);
35	if (!ret && map) {
36		end = dma_range_map_max(map);
37		dev->dma_range_map = map;
38	}
39
40	if (ret == -ENODEV)
41		ret = iort_dma_get_ranges(dev, &end);
42	if (!ret) {
43		/*
44		 * Limit coherent and dma mask based on size retrieved from
45		 * firmware.
46		 */
47		mask = DMA_BIT_MASK(ilog2(end) + 1);
48		dev->bus_dma_limit = end;
49		dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
50		*dev->dma_mask = min(*dev->dma_mask, mask);
51	}
52}