dma: pl330: Implement device_slave_caps (ca38ff13) · Commits · 戴 / test

Implement the device_slave_caps() callback for the pl330 driver. This allows dmaengine users like the generic ALSA dmaengine PCM driver to query the capabilities of the driver. The PL330 supports all buswidths and both mem-to-dev as well as dev-to-mem transfers. In theory there is no limit on the number of segments that can be transferred (in practice you'll run out of memory eventually) and the number of bytes per segment is limited by the size of the PL330 program buffer. Due to the nature of the PL330 the maximum number of bytes per segment depends on the burstsize, the driver sets it to the value for a 1-byte burstsize, since it is the smallest. Signed-off-by:

Lars-Peter Clausen <lars@metafoo.de> Signed-off-by:

Vinod Koul <vinod.koul@intel.com>

drivers/dma/pl330.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -2855,6 +2855,32 @@ static irqreturn_t pl330_irq_handler(int irq, void *data)
		return IRQ_NONE;
		}

		#define PL330_DMA_BUSWIDTHS \
		BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) \| \
		BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) \| \
		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) \| \
		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) \| \
		BIT(DMA_SLAVE_BUSWIDTH_8_BYTES)

		static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
		struct dma_slave_caps *caps)
		{
		caps->src_addr_widths = PL330_DMA_BUSWIDTHS;
		caps->dstn_addr_widths = PL330_DMA_BUSWIDTHS;
		caps->directions = BIT(DMA_DEV_TO_MEM) \| BIT(DMA_MEM_TO_DEV);
		caps->cmd_pause = false;
		caps->cmd_terminate = true;

		/*
		* This is the limit for transfers with a buswidth of 1, larger
		* buswidths will have larger limits.
		*/
		caps->max_sg_len = 1900800;
		caps->max_sg_nr = 0;

		return 0;
		}

		static int
		pl330_probe(struct amba_device adev, const struct amba_id id)
		{
		@@ -2959,6 +2985,7 @@ pl330_probe(struct amba_device adev, const struct amba_id id)
		pd->device_prep_slave_sg = pl330_prep_slave_sg;
		pd->device_control = pl330_control;
		pd->device_issue_pending = pl330_issue_pending;
		pd->device_slave_caps = pl330_dma_device_slave_caps;

		ret = dma_async_device_register(pd);
		if (ret) {

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