[PATCH for-next 3/4] dmaengine: ti: k3-udma: Move the TR counter calculation to helper function

Peter Ujfalusi
2020-01-27T13:20:45Z

Move the TR counter parameter configuration code out from the prep_memcpy
callback to a helper function to allow a generic re-usable code for other
TR based transfers.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
drivers/dma/ti/k3-udma.c | 74 +++++++++++++++++++++++++++-------------
1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index cb9259e104b4..9b00013d6f63 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -2029,6 +2029,51 @@ static struct udma_desc *udma_alloc_tr_desc(struct udma_chan *uc,
return d;
}

+/**
+ * udma_get_tr_counters - calculate TR counters for a given length
+ * @len: Length of the trasnfer
+ * @align_to: Preferred alignment
+ * @tr0_cnt0: First TR icnt0
+ * @tr0_cnt1: First TR icnt1
+ * @tr1_cnt0: Second (if used) TR icnt0
+ *
+ * For len < SZ_64K only one TR is enough, tr1_cnt0 is not updated
+ * For len >= SZ_64K two TRs are used in a simple way:
+ * First TR: SZ_64K-alignment blocks (tr0_cnt0, tr0_cnt1)
+ * Second TR: the remaining length (tr1_cnt0)
+ *
+ * Returns the number of TRs the length needs (1 or 2)
+ * -EINVAL if the length can not be supported
+ */
+static int udma_get_tr_counters(size_t len, unsigned long align_to,
+ u16 *tr0_cnt0, u16 *tr0_cnt1, u16 *tr1_cnt0)
+{
+ if (len < SZ_64K) {
+ *tr0_cnt0 = len;
+ *tr0_cnt1 = 1;
+
+ return 1;
+ }
+
+ if (align_to > 3)
+ align_to = 3;
+
+realign:
+ *tr0_cnt0 = SZ_64K - BIT(align_to);
+ if (len / *tr0_cnt0 >= SZ_64K) {
+ if (align_to) {
+ align_to--;
+ goto realign;
+ }
+ return -EINVAL;
+ }
+
+ *tr0_cnt1 = len / *tr0_cnt0;
+ *tr1_cnt0 = len % *tr0_cnt0;
+
+ return 2;
+}
+
static struct udma_desc *
udma_prep_slave_sg_tr(struct udma_chan *uc, struct scatterlist *sgl,
unsigned int sglen, enum dma_transfer_direction dir,
@@ -2581,29 +2626,12 @@ udma_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
return NULL;
}

- if (len < SZ_64K) {
- num_tr = 1;
- tr0_cnt0 = len;
- tr0_cnt1 = 1;
- } else {
- unsigned long align_to = __ffs(src | dest);
-
- if (align_to > 3)
- align_to = 3;
- /*
- * Keep simple: tr0: SZ_64K-alignment blocks,
- * tr1: the remaining
- */
- num_tr = 2;
- tr0_cnt0 = (SZ_64K - BIT(align_to));
- if (len / tr0_cnt0 >= SZ_64K) {
- dev_err(uc->ud->dev, "size %zu is not supported\n",
- len);
- return NULL;
- }
-
- tr0_cnt1 = len / tr0_cnt0;
- tr1_cnt0 = len % tr0_cnt0;
+ num_tr = udma_get_tr_counters(len, __ffs(src | dest), &tr0_cnt0,
+ &tr0_cnt1, &tr1_cnt0);
+ if (num_tr < 0) {
+ dev_err(uc->ud->dev, "size %zu is not supported\n",
+ len);
+ return NULL;
}

d = udma_alloc_tr_desc(uc, tr_size, num_tr, DMA_MEM_TO_MEM);
--
Peter