This allows device drivers to specify a DMA-heap where they want their buffers to be allocated from. This information is then exposed as sysfs link between the device and the DMA-heap.
Useful for userspace when in need to decide from which provider to allocate a buffer.
Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-heap.c | 41 ++++++++++++++++++++++++++++++-------- include/linux/dma-heap.h | 35 ++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index c9e41e8a9e27..0f7cf713c22f 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -31,6 +31,7 @@ * @heap_devt heap device node * @list list head connecting to list of heaps * @heap_cdev heap char device + * @dev: heap device in sysfs * * Represents a heap of memory from which buffers can be made. */ @@ -41,6 +42,7 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; + struct device *dev; };
static LIST_HEAD(heap_list); @@ -49,6 +51,33 @@ static dev_t dma_heap_devt; static struct class *dma_heap_class; static DEFINE_XARRAY_ALLOC(dma_heap_minors);
+int dma_heap_create_device_link(struct device *dev, const char *heap) +{ + struct dma_heap *h; + + /* check the name is valid */ + mutex_lock(&heap_list_lock); + list_for_each_entry(h, &heap_list, list) { + if (!strcmp(h->name, heap)) + break; + } + mutex_unlock(&heap_list_lock); + + if (list_entry_is_head(h, &heap_list, list)) { + pr_err("dma_heap: Link to invalid heap requested %s\n", heap); + return -EINVAL; + } + + return sysfs_create_link(&dev->kobj, &h->dev->kobj, DEVNAME); +} +EXPORT_SYMBOL(dma_heap_create_device_link); + +void dma_heap_remove_device_link(struct device *dev) +{ + sysfs_remove_link(&dev->kobj, DEVNAME); +} +EXPORT_SYMBOL(dma_heap_remove_device_link); + static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, unsigned int fd_flags, unsigned int heap_flags) @@ -219,7 +248,6 @@ const char *dma_heap_get_name(struct dma_heap *heap) struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; - struct device *dev_ret; unsigned int minor; int ret;
@@ -261,14 +289,11 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) goto err1; }
- dev_ret = device_create(dma_heap_class, - NULL, - heap->heap_devt, - NULL, - heap->name); - if (IS_ERR(dev_ret)) { + heap->dev = device_create(dma_heap_class, NULL, heap->heap_devt, NULL, + heap->name); + if (IS_ERR(heap->dev)) { pr_err("dma_heap: Unable to create device\n"); - err_ret = ERR_CAST(dev_ret); + err_ret = ERR_CAST(heap->dev); goto err2; }
diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 0c05561cad6e..097076766496 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -65,4 +65,39 @@ const char *dma_heap_get_name(struct dma_heap *heap); */ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info);
+#ifdef CONFIG_DMABUF_HEAPS + +/** + * dma_heap_create_device_link() - add link between device and heap + * @dev: the device which should be linked to a heap + * @heap: name of the heap to link to + * + * Add a sysfs link between a device and a DMA-heap. This link can then be used + * by userspace to figure out from which DMA-heap a device wants it's buffers + * to be allocated. + */ +int dma_heap_create_device_link(struct device *dev, const char *heap); + +/** + * dma_heap_remove_device_link() - remove link between device and heap + * @dev: the device which should be unlinked + * + * Removes the sysfs link between the device and it's DMA-heap again when a + * driver is unloaded. + */ +void dma_heap_remove_device_link(struct device *dev); + +#else + +int dma_heap_create_device_link(struct device *dev, const char *heap) +{ + return 0; +} + +void dma_heap_remove_device_link(struct device *dev) +{ +} + +#endif + #endif /* _DMA_HEAPS_H */