Commit c2b94954 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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: default avatarTakashi Iwai <tiwai@suse.de>
parent e8ad415b

include/sound/core.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

sound/core/isadma.c

+38 −0
Original line number Diff line number Diff line
@@ -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);