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, 9 insertions, 13 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
index e5dfb6a30182..d87976364ec5 100644
--- a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
@@ -23,6 +23,7 @@
 *******************************************************************************/
 
 #include "common.h"
+#include "descs_com.h"
 
 static int enh_desc_get_tx_status(void *data, struct stmmac_extra_stats *x,
 				  struct dma_desc *p, void __iomem *ioaddr)
@@ -233,10 +234,9 @@ static void enh_desc_init_rx_desc(struct dma_desc *p, unsigned int ring_size,
 	for (i = 0; i < ring_size; i++) {
 		p->des01.erx.own = 1;
 		p->des01.erx.buffer1_size = BUF_SIZE_8KiB - 1;
-		/* To support jumbo frames */
-		p->des01.erx.buffer2_size = BUF_SIZE_8KiB - 1;
-		if (i == ring_size - 1)
-			p->des01.erx.end_ring = 1;
+
+		ehn_desc_rx_set_on_ring_chain(p, (i == ring_size - 1));
+
 		if (disable_rx_ic)
 			p->des01.erx.disable_ic = 1;
 		p++;
@@ -249,8 +249,7 @@ static void enh_desc_init_tx_desc(struct dma_desc *p, unsigned int ring_size)
 
 	for (i = 0; i < ring_size; i++) {
 		p->des01.etx.own = 0;
-		if (i == ring_size - 1)
-			p->des01.etx.end_ring = 1;
+		ehn_desc_tx_set_on_ring_chain(p, (i == ring_size - 1));
 		p++;
 	}
 }
@@ -285,19 +284,16 @@ static void enh_desc_release_tx_desc(struct dma_desc *p)
 	int ter = p->des01.etx.end_ring;
 
 	memset(p, 0, offsetof(struct dma_desc, des2));
-	p->des01.etx.end_ring = ter;
+	enh_desc_end_tx_desc(p, ter);
 }
 
 static void enh_desc_prepare_tx_desc(struct dma_desc *p, int is_fs, int len,
 				     int csum_flag)
 {
 	p->des01.etx.first_segment = is_fs;
-	if (unlikely(len > BUF_SIZE_4KiB)) {
-		p->des01.etx.buffer1_size = BUF_SIZE_4KiB;
-		p->des01.etx.buffer2_size = len - BUF_SIZE_4KiB;
-	} else {
-		p->des01.etx.buffer1_size = len;
-	}
+
+	enh_set_tx_desc_len(p, len);
+
 	if (likely(csum_flag))
 		p->des01.etx.checksum_insertion = cic_full;
 }