From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Add slave_sg support to bcm2835-dma using shared allocation
code for bcm2835_desc and DMA-control blocks already used by
dma_cyclic.
Note that bcm2835_dma_callback had to get modified to support
both modes of operation (cyclic and non-cyclic).
Tested using:
* Hifiberry I2S card (using cyclic DMA)
* fb_st7735r SPI-framebuffer (using slave_sg DMA via spi-bcm2835)
playing BigBuckBunny for audio and video.
Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
---
drivers/dma/bcm2835-dma.c | 113 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 108 insertions(+), 5 deletions(-)
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 41a4f0b..0db8ddb 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -236,6 +236,23 @@ static inline size_t bcm2835_dma_frames_for_length(size_t len,
return DIV_ROUND_UP(len, period_len);
}
+static inline size_t bcm2835_dma_count_frames_for_sg(
+ struct bcm2835_chan *c,
+ struct scatterlist *sgl,
+ unsigned int sg_len)
+{
+ size_t frames = 0;
+ struct scatterlist *sgent;
+ unsigned int i;
+ size_t plength = bcm2835_dma_max_frame_length(c);
+
+ for_each_sg(sgl, sgent, sg_len, i)
+ frames += bcm2835_dma_frames_for_length(
+ sg_dma_len(sgent), plength);
+
+ return frames;
+}
+
/**
* bcm2835_dma_create_cb_chain - create a control block and fills data in
*
@@ -347,6 +364,32 @@ error_cb:
return NULL;
}
+static void bcm2835_dma_fill_cb_chain_with_sg(
+ struct dma_chan *chan,
+ enum dma_transfer_direction direction,
+ struct bcm2835_cb_entry *cb,
+ struct scatterlist *sgl,
+ unsigned int sg_len)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ size_t max_len = bcm2835_dma_max_frame_length(c);
+ unsigned int i, len;
+ dma_addr_t addr;
+ struct scatterlist *sgent;
+
+ for_each_sg(sgl, sgent, sg_len, i) {
+ for (addr = sg_dma_address(sgent), len = sg_dma_len(sgent);
+ len > 0;
+ addr += cb->cb->length, len -= cb->cb->length, cb++) {
+ if (direction == DMA_DEV_TO_MEM)
+ cb->cb->dst = addr;
+ else
+ cb->cb->src = addr;
+ cb->cb->length = min(len, max_len);
+ }
+ }
+}
+
static int bcm2835_dma_abort(void __iomem *chan_base)
{
unsigned long cs;
@@ -423,12 +466,18 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
d = c->desc;
if (d) {
- /* TODO Only works for cyclic DMA */
- vchan_cyclic_callback(&d->vd);
- }
+ if (d->cyclic) {
+ /* call the cyclic callback */
+ vchan_cyclic_callback(&d->vd);
- /* Keep the DMA engine running */
- writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
+ /* Keep the DMA engine running */
+ writel(BCM2835_DMA_ACTIVE,
+ c->chan_base + BCM2835_DMA_CS);
+ } else {
+ vchan_cookie_complete(&c->desc->vd);
+ bcm2835_dma_start_desc(c);
+ }
+ }
spin_unlock_irqrestore(&c->vc.lock, flags);
@@ -544,6 +593,58 @@ static void bcm2835_dma_issue_pending(struct dma_chan *chan)
spin_unlock_irqrestore(&c->vc.lock, flags);
}
+static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
+ struct dma_chan *chan,
+ struct scatterlist *sgl, unsigned int sg_len,
+ enum dma_transfer_direction direction,
+ unsigned long flags, void *context)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ struct bcm2835_desc *d;
+ dma_addr_t src = 0, dst = 0;
+ u32 info = BCM2835_DMA_WAIT_RESP;
+ u32 extra = BCM2835_DMA_INT_EN;
+ size_t frames;
+
+ if (!is_slave_direction(direction)) {
+ dev_err(chan->device->dev,
+ "%s: bad direction?\n", __func__);
+ return NULL;
+ }
+
+ if (c->dreq != 0)
+ info |= BCM2835_DMA_PER_MAP(c->dreq);
+
+ if (direction == DMA_DEV_TO_MEM) {
+ if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+ return NULL;
+ src = c->cfg.src_addr;
+ info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
+ } else {
+ if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+ return NULL;
+ dst = c->cfg.dst_addr;
+ info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
+ }
+
+ /* count frames in sg list */
+ frames = bcm2835_dma_count_frames_for_sg(c, sgl, sg_len);
+
+ /* allocate the CB chain */
+ d = bcm2835_dma_create_cb_chain(chan, direction, false,
+ info, extra,
+ frames, src, dst, 0, 0,
+ GFP_KERNEL);
+ if (!d)
+ return NULL;
+
+ /* fill in frames with scatterlist pointers */
+ bcm2835_dma_fill_cb_chain_with_sg(chan, direction, d->cb_list,
+ sgl, sg_len);
+
+ return vchan_tx_prep(&c->vc, &d->vd, flags);
+}
+
static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
size_t period_len, enum dma_transfer_direction direction,
@@ -772,11 +873,13 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
dma_cap_set(DMA_PRIVATE, od->ddev.cap_mask);
dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
+ dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
od->ddev.device_alloc_chan_resources = bcm2835_dma_alloc_chan_resources;
od->ddev.device_free_chan_resources = bcm2835_dma_free_chan_resources;
od->ddev.device_tx_status = bcm2835_dma_tx_status;
od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
+ od->ddev.device_prep_slave_sg = bcm2835_dma_prep_slave_sg;
od->ddev.device_config = bcm2835_dma_slave_config;
od->ddev.device_terminate_all = bcm2835_dma_terminate_all;
od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
--
1.7.10.4
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