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, 13 insertions, 0 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index ffba014..9100c10 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -287,10 +287,22 @@ struct mii_regs {
 	unsigned int data;	/* MII Data */
 };
 
+struct stmmac_ring_mode_ops {
+	unsigned int (*is_jumbo_frm) (int len, int ehn_desc);
+	unsigned int (*jumbo_frm) (void *priv, struct sk_buff *skb, int csum);
+	void (*refill_desc3) (int bfsize, struct dma_desc *p);
+	void (*init_desc3) (int des3_as_data_buf, struct dma_desc *p);
+	void (*init_dma_chain) (struct dma_desc *des, dma_addr_t phy_addr,
+				unsigned int size);
+	void (*clean_desc3) (struct dma_desc *p);
+	int (*set_16kib_bfsize) (int mtu);
+};
+
 struct mac_device_info {
 	const struct stmmac_ops		*mac;
 	const struct stmmac_desc_ops	*desc;
 	const struct stmmac_dma_ops	*dma;
+	const struct stmmac_ring_mode_ops	*ring;
 	struct mii_regs mii;	/* MII register Addresses */
 	struct mac_link link;
 	unsigned int synopsys_uid;
@@ -304,3 +316,4 @@ extern void stmmac_set_mac_addr(void __iomem *ioaddr, u8 addr[6],
 extern void stmmac_get_mac_addr(void __iomem *ioaddr, unsigned char *addr,
 				unsigned int high, unsigned int low);
 extern void dwmac_dma_flush_tx_fifo(void __iomem *ioaddr);
+extern const struct stmmac_ring_mode_ops ring_mode_ops;