Merge tag 'dmaengine-5.4-rc1' of git://git.infradead.org/users/vkoul/slave-dma

[linux-2.6-block.git] / drivers / dma / bcm2835-dma.c

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 970f654611bdd52155712c7e093012b2e16398a6..e4c593f48575c22b6a22c1d14cb05aa03fe675c8 100644 (file)
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -37,10 +37,19 @@
 #define BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED 14
 #define BCM2835_DMA_CHAN_NAME_SIZE 8
 
+/**
+ * struct bcm2835_dmadev - BCM2835 DMA controller
+ * @ddev: DMA device
+ * @base: base address of register map
+ * @dma_parms: DMA parameters (to convey 1 GByte max segment size to clients)
+ * @zero_page: bus address of zero page (to detect transactions copying from
+ *     zero page and avoid accessing memory if so)
+ */
 struct bcm2835_dmadev {
        struct dma_device ddev;
        void __iomem *base;
        struct device_dma_parameters dma_parms;
+       dma_addr_t zero_page;
 };
 
 struct bcm2835_dma_cb {
@@ -687,11 +696,12 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
        size_t period_len, enum dma_transfer_direction direction,
        unsigned long flags)
 {
+       struct bcm2835_dmadev *od = to_bcm2835_dma_dev(chan->device);
        struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
        struct bcm2835_desc *d;
        dma_addr_t src, dst;
        u32 info = BCM2835_DMA_WAIT_RESP;
-       u32 extra = BCM2835_DMA_INT_EN;
+       u32 extra = 0;
        size_t max_len = bcm2835_dma_max_frame_length(c);
        size_t frames;
 
@@ -707,6 +717,11 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
                return NULL;
        }
 
+       if (flags & DMA_PREP_INTERRUPT)
+               extra |= BCM2835_DMA_INT_EN;
+       else
+               period_len = buf_len;
+
        /*
         * warn if buf_len is not a multiple of period_len - this may leed
         * to unexpected latencies for interrupts and thus audiable clicks
@@ -732,6 +747,10 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
                dst = c->cfg.dst_addr;
                src = buf_addr;
                info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
+
+               /* non-lite channels can write zeroes w/o accessing memory */
+               if (buf_addr == od->zero_page && !c->is_lite_channel)
+                       info |= BCM2835_DMA_S_IGNORE;
        }
 
        /* calculate number of frames */
@@ -778,7 +797,10 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
 
        /* stop DMA activity */
        if (c->desc) {
-               vchan_terminate_vdesc(&c->desc->vd);
+               if (c->desc->vd.tx.flags & DMA_PREP_INTERRUPT)
+                       vchan_terminate_vdesc(&c->desc->vd);
+               else
+                       vchan_vdesc_fini(&c->desc->vd);
                c->desc = NULL;
                bcm2835_dma_abort(c);
        }
@@ -831,6 +853,9 @@ static void bcm2835_dma_free(struct bcm2835_dmadev *od)
                list_del(&c->vc.chan.device_node);
                tasklet_kill(&c->vc.task);
        }
+
+       dma_unmap_page_attrs(od->ddev.dev, od->zero_page, PAGE_SIZE,
+                            DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
 }
 
 static const struct of_device_id bcm2835_dma_of_match[] = {
@@ -909,11 +934,20 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
        od->ddev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
                              BIT(DMA_MEM_TO_MEM);
        od->ddev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+       od->ddev.descriptor_reuse = true;
        od->ddev.dev = &pdev->dev;
        INIT_LIST_HEAD(&od->ddev.channels);
 
        platform_set_drvdata(pdev, od);
 
+       od->zero_page = dma_map_page_attrs(od->ddev.dev, ZERO_PAGE(0), 0,
+                                          PAGE_SIZE, DMA_TO_DEVICE,
+                                          DMA_ATTR_SKIP_CPU_SYNC);
+       if (dma_mapping_error(od->ddev.dev, od->zero_page)) {
+               dev_err(&pdev->dev, "Failed to map zero page\n");
+               return -ENOMEM;
+       }
+
        /* Request DMA channel mask from device tree */
        if (of_property_read_u32(pdev->dev.of_node,
                        "brcm,dma-channel-mask",