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ALSA: core: Add device-managed request_dma() 

This patch adds a devres-supported helper for requesting an ISA DMA
channel that will be automatically freed at the device unbinding.
It'll be used by quite a few ISA sound drivers.

Link: https://lore.kernel.org/r/20210715075941.23332-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2021-07-15 09:58:25 +02:00
parent e8ad415b7a
commit c2b94954ad
2 changed files with 39 additions and 0 deletions
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1
include/sound/core.h
View File

@ -329,6 +329,7 @@ int snd_device_get_state(struct snd_card *card, void *device_data);
void snd_dma_program(unsigned long dma, unsigned long addr, unsigned int size, unsigned short mode);
void snd_dma_disable(unsigned long dma);
unsigned int snd_dma_pointer(unsigned long dma, unsigned int size);
int snd_devm_request_dma(struct device *dev, int dma, const char *name);
#endif
/* misc.c */

38
sound/core/isadma.c
View File

@ -97,3 +97,41 @@ unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
return size - result;
}
EXPORT_SYMBOL(snd_dma_pointer);
struct snd_dma_data {
int dma;
};
static void __snd_release_dma(struct device *dev, void *data)
{
struct snd_dma_data *p = data;
snd_dma_disable(p->dma);
free_dma(p->dma);
}
/**
* snd_devm_request_dma - the managed version of request_dma()
* @dev: the device pointer
* @dma: the dma number
* @name: the name string of the requester
*
* Returns zero on success, or a negative error code.
* The requested DMA will be automatically released at unbinding via devres.
*/
int snd_devm_request_dma(struct device *dev, int dma, const char *name)
{
struct snd_dma_data *p;
if (request_dma(dma, name))
return -EBUSY;
p = devres_alloc(__snd_release_dma, sizeof(*p), GFP_KERNEL);
if (!p) {
free_dma(dma);
return -ENOMEM;
}
p->dma = dma;
devres_add(dev, p);
return 0;
}
EXPORT_SYMBOL_GPL(snd_devm_request_dma);