ALSA: memalloc: Allow NULL device for SNDRV_DMA_TYPE_CONTINUOUS type

dependent on the bus. For normal devices, pass the device pointer

(typically identical as ``card->dev``) to the third argument with

``SNDRV_DMA_TYPE_DEV`` type. For the continuous buffer unrelated to the

bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type and the

``snd_dma_continuous_data(GFP_KERNEL)`` device pointer, where

``GFP_KERNEL`` is the kernel allocation flag to use. For the

scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the device

pointer (see the `Non-Contiguous Buffers`_

section).

bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type.

You can pass NULL to the device pointer in that case, which is the

default mode implying to allocate with ``GFP_KRENEL`` flag.

If you need a different GFP flag, you can pass it by encoding the flag

into the device pointer via a special macro

:c:func:`snd_dma_continuous_data()`.

For the scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the

device pointer (see the `Non-Contiguous Buffers`_ section).

Once the buffer is pre-allocated, you can use the allocator in the

``hw_params`` callback:

 *

 */

static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev)

{

	if (!dev)

		return GFP_KERNEL;

	else

		return (__force gfp_t)(unsigned long)dev;

}

/**

 * snd_dma_alloc_pages - allocate the buffer area according to the given type

		return -ENXIO;

	if (WARN_ON(!dmab))

		return -ENXIO;

	if (WARN_ON(!device))

		return -EINVAL;

	dmab->dev.type = type;

	dmab->dev.dev = device;

	switch (type) {

	case SNDRV_DMA_TYPE_CONTINUOUS:

		dmab->area = alloc_pages_exact(size,

					       (__force gfp_t)(unsigned long)device);

					       snd_mem_get_gfp_flags(device));

		dmab->addr = 0;

		break;

#ifdef CONFIG_HAS_DMA