[PATCH v4 01/10] dmaengine: Actions: get rid of bit fields from dma descriptor

Amit Singh Tomar
2020-06-09T10:17:42Z

At the moment, Driver uses bit fields to describe registers of the DMA
descriptor structure that makes it less portable and maintainable, and
Andre suugested(and even sketched important bits for it) to make use of
array to describe this DMA descriptors instead. It gives the flexibility
while extending support for other platform such as Actions S700.

This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
uses array to describe DMA descriptor.

Suggested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
---
Changes since v3:
* Added description for enum fields.
* Restored the old comment.
* Added detailed comment about, the way FLEN
and FCNT values are filled.
Changes since v2:
* No change.
Changes since v1:
* Defined macro for frame count value.
* Introduced llc_hw_flen() from patch 2/9.
* Removed the unnecessary line break.
Changes since rfc:
* No change.
---
drivers/dma/owl-dma.c | 98 +++++++++++++++++++++++++++++----------------------
1 file changed, 56 insertions(+), 42 deletions(-)

diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index 66ef70b00ec0..948d1bead860 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -120,30 +120,33 @@
#define BIT_FIELD(val, width, shift, newshift) \
((((val) >> (shift)) & ((BIT(width)) - 1)) << (newshift))

+/* Frame count value is fixed as 1 */
+#define FCNT_VAL 0x1
+
/**
- * struct owl_dma_lli_hw - Hardware link list for dma transfer
- * @next_lli: physical address of the next link list
- * @saddr: source physical address
- * @daddr: destination physical address
- * @flen: frame length
- * @fcnt: frame count
- * @src_stride: source stride
- * @dst_stride: destination stride
- * @ctrla: dma_mode and linklist ctrl config
- * @ctrlb: interrupt config
- * @const_num: data for constant fill
+ * owl_dmadesc_offsets - Describe DMA descriptor, hardware link
+ * list for dma transfer
+ * @OWL_DMADESC_NEXT_LLI: physical address of the next link list
+ * @OWL_DMADESC_SADDR: source physical address
+ * @OWL_DMADESC_DADDR: destination physical address
+ * @OWL_DMADESC_FLEN: frame length
+ * @OWL_DMADESC_SRC_STRIDE: source stride
+ * @OWL_DMADESC_DST_STRIDE: destination stride
+ * @OWL_DMADESC_CTRLA: dma_mode and linklist ctrl config
+ * @OWL_DMADESC_CTRLB: interrupt config
+ * @OWL_DMADESC_CONST_NUM: data for constant fill
*/
-struct owl_dma_lli_hw {
- u32 next_lli;
- u32 saddr;
- u32 daddr;
- u32 flen:20;
- u32 fcnt:12;
- u32 src_stride;
- u32 dst_stride;
- u32 ctrla;
- u32 ctrlb;
- u32 const_num;
+enum owl_dmadesc_offsets {
+ OWL_DMADESC_NEXT_LLI = 0,
+ OWL_DMADESC_SADDR,
+ OWL_DMADESC_DADDR,
+ OWL_DMADESC_FLEN,
+ OWL_DMADESC_SRC_STRIDE,
+ OWL_DMADESC_DST_STRIDE,
+ OWL_DMADESC_CTRLA,
+ OWL_DMADESC_CTRLB,
+ OWL_DMADESC_CONST_NUM,
+ OWL_DMADESC_SIZE
};

/**
@@ -153,7 +156,7 @@ struct owl_dma_lli_hw {
* @node: node for txd's lli_list
*/
struct owl_dma_lli {
- struct owl_dma_lli_hw hw;
+ u32 hw[OWL_DMADESC_SIZE];
dma_addr_t phys;
struct list_head node;
};
@@ -318,6 +321,11 @@ static inline u32 llc_hw_ctrlb(u32 int_ctl)
return ctl;
}

+static u32 llc_hw_flen(struct owl_dma_lli *lli)
+{
+ return lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
+}
+
static void owl_dma_free_lli(struct owl_dma *od,
struct owl_dma_lli *lli)
{
@@ -349,8 +357,9 @@ static struct owl_dma_lli *owl_dma_add_lli(struct owl_dma_txd *txd,
list_add_tail(&next->node, &txd->lli_list);

if (prev) {
- prev->hw.next_lli = next->phys;
- prev->hw.ctrla |= llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
+ prev->hw[OWL_DMADESC_NEXT_LLI] = next->phys;
+ prev->hw[OWL_DMADESC_CTRLA] |=
+ llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
}

return next;
@@ -363,8 +372,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
struct dma_slave_config *sconfig,
bool is_cyclic)
{
- struct owl_dma_lli_hw *hw = &lli->hw;
- u32 mode;
+ u32 mode, ctrlb;

mode = OWL_DMA_MODE_PW(0);

@@ -405,22 +413,28 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
return -EINVAL;
}

- hw->next_lli = 0; /* One link list by default */
- hw->saddr = src;
- hw->daddr = dst;
-
- hw->fcnt = 1; /* Frame count fixed as 1 */
- hw->flen = len; /* Max frame length is 1MB */
- hw->src_stride = 0;
- hw->dst_stride = 0;
- hw->ctrla = llc_hw_ctrla(mode,
- OWL_DMA_LLC_SAV_LOAD_NEXT |
- OWL_DMA_LLC_DAV_LOAD_NEXT);
+ lli->hw[OWL_DMADESC_CTRLA] = llc_hw_ctrla(mode,
+ OWL_DMA_LLC_SAV_LOAD_NEXT |
+ OWL_DMA_LLC_DAV_LOAD_NEXT);

if (is_cyclic)
- hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
+ ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
else
- hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+ ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+
+ lli->hw[OWL_DMADESC_NEXT_LLI] = 0; /* One link list by default */
+ lli->hw[OWL_DMADESC_SADDR] = src;
+ lli->hw[OWL_DMADESC_DADDR] = dst;
+ lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
+ lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
+ /*
+ * Word starts from offset 0xC is shared between frame length
+ * (max frame length is 1MB) and frame count, where first 20
+ * bits are for frame length and rest of 12 bits are for frame
+ * count.
+ */
+ lli->hw[OWL_DMADESC_FLEN] = len | FCNT_VAL << 20;
+ lli->hw[OWL_DMADESC_CTRLB] = ctrlb;

return 0;
}
@@ -752,7 +766,7 @@ static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
/* Start from the next active node */
if (lli->phys == next_lli_phy) {
list_for_each_entry(lli, &txd->lli_list, node)
- bytes += lli->hw.flen;
+ bytes += llc_hw_flen(lli);
break;
}
}
@@ -783,7 +797,7 @@ static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
if (vd) {
txd = to_owl_txd(&vd->tx);
list_for_each_entry(lli, &txd->lli_list, node)
- bytes += lli->hw.flen;
+ bytes += llc_hw_flen(lli);
} else {
bytes = owl_dma_getbytes_chan(vchan);
}
--
2.7.4