diff options
author | Christian Borntraeger <borntraeger@de.ibm.com> | 2016-02-03 06:46:32 +0100 |
---|---|---|
committer | Michael S. Tsirkin <mst@redhat.com> | 2016-03-02 16:01:55 +0100 |
commit | a8463d4b0e47d1f37af684d97884ffcf35de043b (patch) | |
tree | 22edc03944c201629c6fd2c77805b014c05f9fbc | |
parent | vhost: fix error path in vhost_init_used() (diff) | |
download | linux-a8463d4b0e47d1f37af684d97884ffcf35de043b.tar.xz linux-a8463d4b0e47d1f37af684d97884ffcf35de043b.zip |
dma: Provide simple noop dma ops
We are going to require dma_ops for several common drivers, even for
systems that do have an identity mapping. Lets provide some minimal
no-op dma_ops that can be used for that purpose.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r-- | include/linux/dma-mapping.h | 2 | ||||
-rw-r--r-- | lib/Makefile | 1 | ||||
-rw-r--r-- | lib/dma-noop.c | 75 |
3 files changed, 78 insertions, 0 deletions
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 75857cda38e9..c0b27ff2c784 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -70,6 +70,8 @@ struct dma_map_ops { int is_phys; }; +extern struct dma_map_ops dma_noop_ops; + #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1)) #define DMA_MASK_NONE 0x0ULL diff --git a/lib/Makefile b/lib/Makefile index a7c26a41a738..a572b86a1b1d 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -18,6 +18,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_SMP) += cpumask.o +lib-$(CONFIG_HAS_DMA) += dma-noop.o lib-y += kobject.o klist.o obj-y += lockref.o diff --git a/lib/dma-noop.c b/lib/dma-noop.c new file mode 100644 index 000000000000..72145646857e --- /dev/null +++ b/lib/dma-noop.c @@ -0,0 +1,75 @@ +/* + * lib/dma-noop.c + * + * Simple DMA noop-ops that map 1:1 with memory + */ +#include <linux/export.h> +#include <linux/mm.h> +#include <linux/dma-mapping.h> +#include <linux/scatterlist.h> + +static void *dma_noop_alloc(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + struct dma_attrs *attrs) +{ + void *ret; + + ret = (void *)__get_free_pages(gfp, get_order(size)); + if (ret) + *dma_handle = virt_to_phys(ret); + return ret; +} + +static void dma_noop_free(struct device *dev, size_t size, + void *cpu_addr, dma_addr_t dma_addr, + struct dma_attrs *attrs) +{ + free_pages((unsigned long)cpu_addr, get_order(size)); +} + +static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page, + unsigned long offset, size_t size, + enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + return page_to_phys(page) + offset; +} + +static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents, + enum dma_data_direction dir, struct dma_attrs *attrs) +{ + int i; + struct scatterlist *sg; + + for_each_sg(sgl, sg, nents, i) { + void *va; + + BUG_ON(!sg_page(sg)); + va = sg_virt(sg); + sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va); + sg_dma_len(sg) = sg->length; + } + + return nents; +} + +static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr) +{ + return 0; +} + +static int dma_noop_supported(struct device *dev, u64 mask) +{ + return 1; +} + +struct dma_map_ops dma_noop_ops = { + .alloc = dma_noop_alloc, + .free = dma_noop_free, + .map_page = dma_noop_map_page, + .map_sg = dma_noop_map_sg, + .mapping_error = dma_noop_mapping_error, + .dma_supported = dma_noop_supported, +}; + +EXPORT_SYMBOL(dma_noop_ops); |