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, 126 insertions, 0 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/descs_com.h b/drivers/net/ethernet/stmicro/stmmac/descs_com.h
new file mode 100644
index 000000000000..dd8d6e19dff6
--- /dev/null
+++ b/drivers/net/ethernet/stmicro/stmmac/descs_com.h
@@ -0,0 +1,126 @@
+/*******************************************************************************
+  Header File to describe Normal/enhanced descriptor functions used for RING
+  and CHAINED modes.
+
+  Copyright(C) 2011  STMicroelectronics Ltd
+
+  It defines all the functions used to handle the normal/enhanced
+  descriptors in case of the DMA is configured to work in chained or
+  in ring mode.
+
+  This program is free software; you can redistribute it and/or modify it
+  under the terms and conditions of the GNU General Public License,
+  version 2, as published by the Free Software Foundation.
+
+  This program is distributed in the hope it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+  more details.
+
+  You should have received a copy of the GNU General Public License along with
+  this program; if not, write to the Free Software Foundation, Inc.,
+  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+
+  The full GNU General Public License is included in this distribution in
+  the file called "COPYING".
+
+  Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
+*******************************************************************************/
+
+#if defined(CONFIG_STMMAC_RING)
+static inline void ehn_desc_rx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	p->des01.erx.buffer2_size = BUF_SIZE_8KiB - 1;
+	if (end)
+		p->des01.erx.end_ring = 1;
+}
+
+static inline void ehn_desc_tx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	if (end)
+		p->des01.etx.end_ring = 1;
+}
+
+static inline void enh_desc_end_tx_desc(struct dma_desc *p, int ter)
+{
+	p->des01.etx.end_ring = ter;
+}
+
+static inline void enh_set_tx_desc_len(struct dma_desc *p, int len)
+{
+	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;
+}
+
+static inline void ndesc_rx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	p->des01.rx.buffer2_size = BUF_SIZE_2KiB - 1;
+	if (end)
+		p->des01.rx.end_ring = 1;
+}
+
+static inline void ndesc_tx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	if (end)
+		p->des01.tx.end_ring = 1;
+}
+
+static inline void ndesc_end_tx_desc(struct dma_desc *p, int ter)
+{
+	p->des01.tx.end_ring = ter;
+}
+
+static inline void norm_set_tx_desc_len(struct dma_desc *p, int len)
+{
+	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;
+}
+
+#else
+
+static inline void ehn_desc_rx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	p->des01.erx.second_address_chained = 1;
+}
+
+static inline void ehn_desc_tx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	p->des01.etx.second_address_chained = 1;
+}
+
+static inline void enh_desc_end_tx_desc(struct dma_desc *p, int ter)
+{
+	p->des01.etx.second_address_chained = 1;
+}
+
+static inline void enh_set_tx_desc_len(struct dma_desc *p, int len)
+{
+	p->des01.etx.buffer1_size = len;
+}
+
+static inline void ndesc_rx_set_on_ring_chain(struct dma_desc *p, int end)
+{
+	p->des01.rx.second_address_chained = 1;
+}
+
+static inline void ndesc_tx_set_on_ring_chain(struct dma_desc *p, int ring_size)
+{
+	p->des01.tx.second_address_chained = 1;
+}
+
+static inline void ndesc_end_tx_desc(struct dma_desc *p, int ter)
+{
+	p->des01.tx.second_address_chained = 1;
+}
+
+static inline void norm_set_tx_desc_len(struct dma_desc *p, int len)
+{
+	p->des01.tx.buffer1_size = len;
+}
+#endif