[PATCH 09/15] net: sun8i_emac: Wrap and simplify cache maintenance operations

[Andre Przywara <andre.przywara@arm.com>]

To meet the current alignment requirements for our cache maintenance
functions, we were explicitly aligning the *arguments* to those calls.
This is not only ugly to read, but also wrong, as we need to make sure
we are not accidentally stepping on other data.

Provide wrapper functions for the common case of cleaning or
invalidating a descriptor, to make the cache maintenance calls more
readable. This fixes a good deal of the problematic calls.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/net/sun8i_emac.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/drivers/net/sun8i_emac.c b/drivers/net/sun8i_emac.c
index b704ec47a3..939dfbade1 100644
--- a/drivers/net/sun8i_emac.c
+++ b/drivers/net/sun8i_emac.c
@@ -376,6 +376,14 @@ static int sun8i_phy_init(struct emac_eth_dev *priv, void *dev)
 	return 0;
 }
 
+#define cache_clean_descriptor(desc)					\
+	flush_dcache_range((uintptr_t)(desc), 				\
+			   (uintptr_t)(desc) + sizeof(struct emac_dma_desc))
+
+#define cache_inv_descriptor(desc)					\
+	invalidate_dcache_range((uintptr_t)(desc),			\
+			       (uintptr_t)(desc) + sizeof(struct emac_dma_desc))
+
 static void rx_descs_init(struct emac_eth_dev *priv)
 {
 	struct emac_dma_desc *desc_table_p = &priv->rx_chain[0];
@@ -432,9 +440,7 @@ static void tx_descs_init(struct emac_eth_dev *priv)
 	desc_p->next =  (uintptr_t)&desc_table_p[0];
 
 	/* Flush the first TX buffer descriptor we will tell the MAC about. */
-	flush_dcache_range((uintptr_t)priv->tx_chain,
-			   (uintptr_t)priv->tx_chain +
-			   sizeof(priv->tx_chain[0]));
+	cache_clean_descriptor(desc_table_p);
 
 	writel((uintptr_t)&desc_table_p[0], priv->mac_reg + EMAC_TX_DMA_DESC);
 	priv->tx_currdescnum = 0;
@@ -570,15 +576,11 @@ static int sun8i_emac_eth_recv(struct udevice *dev, int flags, uchar **packetp)
 	struct emac_dma_desc *desc_p = &priv->rx_chain[desc_num];
 	int length = -EAGAIN;
 	int good_packet = 1;
-	uintptr_t desc_start = (uintptr_t)desc_p;
-	uintptr_t desc_end = desc_start +
-		roundup(sizeof(*desc_p), ARCH_DMA_MINALIGN);
-
 	ulong data_start = (uintptr_t)desc_p->buf_addr;
 	ulong data_end;
 
 	/* Invalidate entire buffer descriptor */
-	invalidate_dcache_range(desc_start, desc_end);
+	cache_inv_descriptor(desc_p);
 
 	status = desc_p->status;
 
@@ -616,10 +618,6 @@ static int sun8i_emac_eth_send(struct udevice *dev, void *packet, int length)
 	struct emac_eth_dev *priv = dev_get_priv(dev);
 	u32 desc_num = priv->tx_currdescnum;
 	struct emac_dma_desc *desc_p = &priv->tx_chain[desc_num];
-	uintptr_t desc_start = (uintptr_t)desc_p;
-	uintptr_t desc_end = desc_start +
-		roundup(sizeof(*desc_p), ARCH_DMA_MINALIGN);
-
 	uintptr_t data_start = (uintptr_t)desc_p->buf_addr;
 	uintptr_t data_end = data_start +
 		roundup(length, ARCH_DMA_MINALIGN);
@@ -635,8 +633,8 @@ static int sun8i_emac_eth_send(struct udevice *dev, void *packet, int length)
 	desc_p->ctl_size |= EMAC_DESC_LAST_DESC | EMAC_DESC_FIRST_DESC;
 	desc_p->status = EMAC_DESC_OWN_DMA;
 
-	/*Descriptors st and status field has changed, so FLUSH it */
-	flush_dcache_range(desc_start, desc_end);
+	/* make sure the MAC reads the actual data from DRAM */
+	cache_clean_descriptor(desc_p);
 
 	/* Move to next Descriptor and wrap around */
 	if (++desc_num >= CONFIG_TX_DESCR_NUM)
@@ -756,15 +754,12 @@ static int sun8i_eth_free_pkt(struct udevice *dev, uchar *packet,
 	struct emac_eth_dev *priv = dev_get_priv(dev);
 	u32 desc_num = priv->rx_currdescnum;
 	struct emac_dma_desc *desc_p = &priv->rx_chain[desc_num];
-	uintptr_t desc_start = (uintptr_t)desc_p;
-	uintptr_t desc_end = desc_start +
-		roundup(sizeof(u32), ARCH_DMA_MINALIGN);
 
-	/* Make the current descriptor valid again */
+	/* give the current descriptor back to the MAC */
 	desc_p->status |= EMAC_DESC_OWN_DMA;
 
 	/* Flush Status field of descriptor */
-	flush_dcache_range(desc_start, desc_end);
+	cache_clean_descriptor(desc_p);
 
 	/* Move to next desc and wrap-around condition. */
 	if (++desc_num >= CONFIG_RX_DESCR_NUM)
-- 
2.17.5