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dmaengine: sprd: Support DMA link-list mode
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The Spreadtrum DMA can support the link-list transaction mode, which means
DMA controller can do transaction one by one automatically once we linked
these transaction by link-list register.

Signed-off-by: Eric Long <eric.long@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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Eric Long authored and Vinod Koul committed Sep 3, 2018
1 parent 5b394b2 commit 4ac6954
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Showing 2 changed files with 143 additions and 7 deletions.
81 changes: 74 additions & 7 deletions drivers/dma/sprd-dma.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,7 @@

/* SPRD_DMA_CHN_CFG register definition */
#define SPRD_DMA_CHN_EN BIT(0)
#define SPRD_DMA_LINKLIST_EN BIT(4)
#define SPRD_DMA_WAIT_BDONE_OFFSET 24
#define SPRD_DMA_DONOT_WAIT_BDONE 1

Expand Down Expand Up @@ -103,7 +104,7 @@
#define SPRD_DMA_REQ_MODE_MASK GENMASK(1, 0)
#define SPRD_DMA_FIX_SEL_OFFSET 21
#define SPRD_DMA_FIX_EN_OFFSET 20
#define SPRD_DMA_LLIST_END_OFFSET 19
#define SPRD_DMA_LLIST_END BIT(19)
#define SPRD_DMA_FRG_LEN_MASK GENMASK(16, 0)

/* SPRD_DMA_CHN_BLK_LEN register definition */
Expand Down Expand Up @@ -164,6 +165,7 @@ struct sprd_dma_desc {
struct sprd_dma_chn {
struct virt_dma_chan vc;
void __iomem *chn_base;
struct sprd_dma_linklist linklist;
struct dma_slave_config slave_cfg;
u32 chn_num;
u32 dev_id;
Expand Down Expand Up @@ -582,15 +584,15 @@ static int sprd_dma_get_step(enum dma_slave_buswidth buswidth)
}

static int sprd_dma_fill_desc(struct dma_chan *chan,
struct sprd_dma_desc *sdesc,
struct sprd_dma_chn_hw *hw,
unsigned int sglen, int sg_index,
dma_addr_t src, dma_addr_t dst, u32 len,
enum dma_transfer_direction dir,
unsigned long flags,
struct dma_slave_config *slave_cfg)
{
struct sprd_dma_dev *sdev = to_sprd_dma_dev(chan);
struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
struct sprd_dma_chn_hw *hw = &sdesc->chn_hw;
u32 req_mode = (flags >> SPRD_DMA_REQ_SHIFT) & SPRD_DMA_REQ_MODE_MASK;
u32 int_mode = flags & SPRD_DMA_INT_MASK;
int src_datawidth, dst_datawidth, src_step, dst_step;
Expand Down Expand Up @@ -670,12 +672,52 @@ static int sprd_dma_fill_desc(struct dma_chan *chan,
temp |= (src_step & SPRD_DMA_TRSF_STEP_MASK) << SPRD_DMA_SRC_TRSF_STEP_OFFSET;
hw->trsf_step = temp;

/* link-list configuration */
if (schan->linklist.phy_addr) {
if (sg_index == sglen - 1)
hw->frg_len |= SPRD_DMA_LLIST_END;

hw->cfg |= SPRD_DMA_LINKLIST_EN;

/* link-list index */
temp = (sg_index + 1) % sglen;
/* Next link-list configuration's physical address offset */
temp = temp * sizeof(*hw) + SPRD_DMA_CHN_SRC_ADDR;
/*
* Set the link-list pointer point to next link-list
* configuration's physical address.
*/
hw->llist_ptr = schan->linklist.phy_addr + temp;
} else {
hw->llist_ptr = 0;
}

hw->frg_step = 0;
hw->src_blk_step = 0;
hw->des_blk_step = 0;
return 0;
}

static int sprd_dma_fill_linklist_desc(struct dma_chan *chan,
unsigned int sglen, int sg_index,
dma_addr_t src, dma_addr_t dst, u32 len,
enum dma_transfer_direction dir,
unsigned long flags,
struct dma_slave_config *slave_cfg)
{
struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
struct sprd_dma_chn_hw *hw;

if (!schan->linklist.virt_addr)
return -EINVAL;

hw = (struct sprd_dma_chn_hw *)(schan->linklist.virt_addr +
sg_index * sizeof(*hw));

return sprd_dma_fill_desc(chan, hw, sglen, sg_index, src, dst, len,
dir, flags, slave_cfg);
}

static struct dma_async_tx_descriptor *
sprd_dma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
size_t len, unsigned long flags)
Expand Down Expand Up @@ -744,10 +786,20 @@ sprd_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
u32 len = 0;
int ret, i;

/* TODO: now we only support one sg for each DMA configuration. */
if (!is_slave_direction(dir) || sglen > 1)
if (!is_slave_direction(dir))
return NULL;

if (context) {
struct sprd_dma_linklist *ll_cfg =
(struct sprd_dma_linklist *)context;

schan->linklist.phy_addr = ll_cfg->phy_addr;
schan->linklist.virt_addr = ll_cfg->virt_addr;
} else {
schan->linklist.phy_addr = 0;
schan->linklist.virt_addr = 0;
}

sdesc = kzalloc(sizeof(*sdesc), GFP_NOWAIT);
if (!sdesc)
return NULL;
Expand All @@ -762,10 +814,25 @@ sprd_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
src = slave_cfg->src_addr;
dst = sg_dma_address(sg);
}

/*
* The link-list mode needs at least 2 link-list
* configurations. If there is only one sg, it doesn't
* need to fill the link-list configuration.
*/
if (sglen < 2)
break;

ret = sprd_dma_fill_linklist_desc(chan, sglen, i, src, dst, len,
dir, flags, slave_cfg);
if (ret) {
kfree(sdesc);
return NULL;
}
}

ret = sprd_dma_fill_desc(chan, sdesc, src, dst, len, dir, flags,
slave_cfg);
ret = sprd_dma_fill_desc(chan, &sdesc->chn_hw, 0, 0, src, dst, len,
dir, flags, slave_cfg);
if (ret) {
kfree(sdesc);
return NULL;
Expand Down
69 changes: 69 additions & 0 deletions include/linux/dma/sprd-dma.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,4 +58,73 @@ enum sprd_dma_int_type {
SPRD_DMA_CFGERR_INT,
};

/*
* struct sprd_dma_linklist - DMA link-list address structure
* @virt_addr: link-list virtual address to configure link-list node
* @phy_addr: link-list physical address to link DMA transfer
*
* The Spreadtrum DMA controller supports the link-list mode, that means slaves
* can supply several groups configurations (each configuration represents one
* DMA transfer) saved in memory, and DMA controller will link these groups
* configurations by writing the physical address of each configuration into the
* link-list register.
*
* Just as shown below, the link-list pointer register will be pointed to the
* physical address of 'configuration 1', and the 'configuration 1' link-list
* pointer will be pointed to 'configuration 2', and so on.
* Once trigger the DMA transfer, the DMA controller will load 'configuration
* 1' to its registers automatically, after 'configuration 1' transaction is
* done, DMA controller will load 'configuration 2' automatically, until all
* DMA transactions are done.
*
* Note: The last link-list pointer should point to the physical address
* of 'configuration 1', which can avoid DMA controller loads incorrect
* configuration when the last configuration transaction is done.
*
* DMA controller linklist memory
* ====================== -----------------------
*| | | configuration 1 |<---
*| DMA controller | ------->| | |
*| | | | | |
*| | | | | |
*| | | | | |
*| linklist pointer reg |---- ----| linklist pointer | |
* ====================== | ----------------------- |
* | |
* | ----------------------- |
* | | configuration 2 | |
* --->| | |
* | | |
* | | |
* | | |
* ----| linklist pointer | |
* | ----------------------- |
* | |
* | ----------------------- |
* | | configuration 3 | |
* --->| | |
* | | |
* | . | |
* . |
* . |
* . |
* | . |
* | ----------------------- |
* | | configuration n | |
* --->| | |
* | | |
* | | |
* | | |
* | linklist pointer |----
* -----------------------
*
* To support the link-list mode, DMA slaves should allocate one segment memory
* from always-on IRAM or dma coherent memory to store these groups of DMA
* configuration, and pass the virtual and physical address to DMA controller.
*/
struct sprd_dma_linklist {
unsigned long virt_addr;
phys_addr_t phy_addr;
};

#endif

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