stmmac: add CHAINED descriptor mode support (V4)

This patch enhances the STMMAC driver to support CHAINED mode of
descriptor.

STMMAC supports DMA descriptor to operate both in dual buffer(RING)
and linked-list(CHAINED) mode. In RING mode (default) each descriptor
points to two data buffer pointers whereas in CHAINED mode they point
to only one data buffer pointer.

In CHAINED mode each descriptor will have pointer to next descriptor in
the list, hence creating the explicit chaining in the descriptor itself,
whereas such explicit chaining is not possible in RING mode.

First version of this work has been done by Rayagond.
Then the patch has been reworked avoiding ifdef inside the C code.
A new header file has been added to define all the functions needed for
managing enhanced and normal descriptors.
In fact, these have to be specialized according to the ring/chain usage.
Two new C files have been also added to implement the helper routines
needed to manage: jumbo frames, chain and ring setup (i.e. desc3).

Signed-off-by: Rayagond Kokatanur <rayagond@vayavyalabs.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 13 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
index e13226b80d47..f7e8ba7f501a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
@@ -23,6 +23,7 @@
 *******************************************************************************/
 
 #include "common.h"
+#include "descs_com.h"
 
 static int ndesc_get_tx_status(void *data, struct stmmac_extra_stats *x,
 			       struct dma_desc *p, void __iomem *ioaddr)
@@ -126,9 +127,9 @@ static void ndesc_init_rx_desc(struct dma_desc *p, unsigned int ring_size,
 	for (i = 0; i < ring_size; i++) {
 		p->des01.rx.own = 1;
 		p->des01.rx.buffer1_size = BUF_SIZE_2KiB - 1;
-		p->des01.rx.buffer2_size = BUF_SIZE_2KiB - 1;
-		if (i == ring_size - 1)
-			p->des01.rx.end_ring = 1;
+
+		ndesc_rx_set_on_ring_chain(p, (i == ring_size - 1));
+
 		if (disable_rx_ic)
 			p->des01.rx.disable_ic = 1;
 		p++;
@@ -140,8 +141,7 @@ static void ndesc_init_tx_desc(struct dma_desc *p, unsigned int ring_size)
 	int i;
 	for (i = 0; i < ring_size; i++) {
 		p->des01.tx.own = 0;
-		if (i == ring_size - 1)
-			p->des01.tx.end_ring = 1;
+		ndesc_tx_set_on_ring_chain(p, (i == (ring_size - 1)));
 		p++;
 	}
 }
@@ -176,20 +176,14 @@ static void ndesc_release_tx_desc(struct dma_desc *p)
 	int ter = p->des01.tx.end_ring;
 
 	memset(p, 0, offsetof(struct dma_desc, des2));
-	/* set termination field */
-	p->des01.tx.end_ring = ter;
+	ndesc_end_tx_desc(p, ter);
 }
 
 static void ndesc_prepare_tx_desc(struct dma_desc *p, int is_fs, int len,
 				  int csum_flag)
 {
 	p->des01.tx.first_segment = is_fs;
-
-	if (unlikely(len > BUF_SIZE_2KiB)) {
-		p->des01.etx.buffer1_size = BUF_SIZE_2KiB - 1;
-		p->des01.etx.buffer2_size = len - p->des01.etx.buffer1_size;
-	} else
-		p->des01.tx.buffer1_size = len;
+	norm_set_tx_desc_len(p, len);
 }
 
 static void ndesc_clear_tx_ic(struct dma_desc *p)