net: pch_gbe: Add cache maintenance

On MIPS systems DMA isn't coherent with the CPU caches unless an IOCU is
present. When there is no IOCU we need to writeback or invalidate the
data caches at appropriate points. Perform this cache maintenance in
the pch_gbe driver which is used on the MIPS Boston development board.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/pch_gbe.c

@@ -120,6 +120,8 @@ static void pch_gbe_rx_descs_init(struct udevice *dev)
 		rx_desc[i].buffer_addr = dm_pci_virt_to_mem(priv->dev,
 			priv->rx_buff[i]);
 
+	flush_dcache_range((ulong)rx_desc, (ulong)&rx_desc[PCH_GBE_DESC_NUM]);
+
 	writel(dm_pci_virt_to_mem(priv->dev, rx_desc),
 	       &mac_regs->rx_dsc_base);
 	writel(sizeof(struct pch_gbe_rx_desc) * (PCH_GBE_DESC_NUM - 1),
@@ -137,6 +139,8 @@ static void pch_gbe_tx_descs_init(struct udevice *dev)
 
 	memset(tx_desc, 0, sizeof(struct pch_gbe_tx_desc) * PCH_GBE_DESC_NUM);
 
+	flush_dcache_range((ulong)tx_desc, (ulong)&tx_desc[PCH_GBE_DESC_NUM]);
+
 	writel(dm_pci_virt_to_mem(priv->dev, tx_desc),
 	       &mac_regs->tx_dsc_base);
 	writel(sizeof(struct pch_gbe_tx_desc) * (PCH_GBE_DESC_NUM - 1),
@@ -245,6 +249,8 @@ static int pch_gbe_send(struct udevice *dev, void *packet, int length)
 	u32 int_st;
 	ulong start;
 
+	flush_dcache_range((ulong)packet, (ulong)packet + length);
+
 	tx_head = &priv->tx_desc[0];
 	tx_desc = &priv->tx_desc[priv->tx_idx];
 
@@ -258,6 +264,8 @@ static int pch_gbe_send(struct udevice *dev, void *packet, int length)
 	tx_desc->dma_status = 0;
 	tx_desc->gbec_status = 0;
 
+	flush_dcache_range((ulong)tx_desc, (ulong)&tx_desc[1]);
+
 	/* Test the wrap-around condition */
 	if (++priv->tx_idx >= PCH_GBE_DESC_NUM)
 		priv->tx_idx = 0;
@@ -295,8 +303,12 @@ static int pch_gbe_recv(struct udevice *dev, int flags, uchar **packetp)
 	if (virt_to_phys(rx_desc) == hw_desc)
 		return -EAGAIN;
 
+	/* Invalidate the descriptor */
+	invalidate_dcache_range((ulong)rx_desc, (ulong)&rx_desc[1]);
+
 	length = rx_desc->rx_words_eob - 3 - ETH_FCS_LEN;
 	buffer = dm_pci_mem_to_virt(priv->dev, rx_desc->buffer_addr, length, 0);
+	invalidate_dcache_range((ulong)buffer, (ulong)buffer + length);
 	*packetp = (uchar *)buffer;
 
 	return length;